105 files changed, 3371 insertions, 1747 deletions

diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index 77c92512a..eae4fbcb5 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -95,9 +95,6 @@ jobs:
       - name: Copy vscode extension
         run: mkdir -p ./dist/code && cp ./editors/code/*.vsix ./dist/
 
-      - name: Copy emacs mode
-        run: cp ./editors/emacs/rust-analyzer.el ./dist/rust-analyzer.el
-
       - name: Upload artifacts
         uses: actions/upload-artifact@v1
         with:
@@ -109,6 +106,17 @@ jobs:
     runs-on: ubuntu-latest
     needs: ['build-server', 'build-clients']
     steps:
+      - name: Install Nodejs
+        uses: actions/setup-node@v1
+        with:
+          node-version: 12.x
+
+      - run: echo "::set-env name=TAG::$(date --iso)"
+      - run: 'echo "TAG: $TAG"'
+
+      - name: Checkout repository
+        uses: actions/checkout@v1
+
       - uses: actions/download-artifact@v1
         with:
           name: editor-plugins
@@ -127,9 +135,6 @@ jobs:
           path: dist
       - run: ls -all ./dist
 
-      - run: echo "::set-env name=TAG::$(date --iso)"
-      - run: 'echo "TAG: $TAG"'
-
       - name: Create Release
         id: create_release
         # uses: actions/create-release@v1
@@ -179,11 +184,10 @@ jobs:
           asset_name: rust-analyzer-0.1.0.vsix
           asset_content_type: application/octet-stream
 
-      - uses: actions/[email protected]
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          upload_url: ${{ steps.create_release.outputs.upload_url }}
-          asset_path: ./dist/rust-analyzer.el
-          asset_name: rust-analyzer.el
-          asset_content_type: text/plain
+      - run: npm ci
+        working-directory: ./editors/code
+
+      - name: Publish Extension
+        working-directory: ./editors/code
+        # token from https://dev.azure.com/rust-analyzer/
+        run: npx vsce publish 0.1.$(date +%Y%m%d) --pat ${{ secrets.MARKETPLACE_TOKEN }}
diff --git a/.vscode/launch.json b/.vscode/launch.json
index 55a2f10f2..b1bd98d4a 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -2,39 +2,61 @@
   // Use IntelliSense to learn about possible attributes.
   // Hover to view descriptions of existing attributes.
   // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+
+  // NOTE: --disable-extensions
+  // Disable all installed extensions to increase performance of the debug instance
+  // and prevent potential conflicts with other installed extensions.
+
   "version": "0.2.0",
   "configurations": [
     {
+      // Used for testing the extension with the installed LSP server.
       "name": "Run Extension",
       "type": "extensionHost",
       "request": "launch",
       "runtimeExecutable": "${execPath}",
       "args": [
+        "--disable-extensions",
         "--extensionDevelopmentPath=${workspaceFolder}/editors/code"
       ],
       "outFiles": [
         "${workspaceFolder}/editors/code/out/**/*.js"
       ],
-      "preLaunchTask": "Build Extension"
+      "preLaunchTask": "Build Extension",
+      "skipFiles": [
+        "<node_internals>/**/*.js"
+      ]
     },
     {
+      // Used for testing the extension with a local build of the LSP server (in `target/debug`).
       "name": "Run Extension (Dev Server)",
       "type": "extensionHost",
       "request": "launch",
       "runtimeExecutable": "${execPath}",
       "args": [
+        "--disable-extensions",
         "--extensionDevelopmentPath=${workspaceFolder}/editors/code"
       ],
       "outFiles": [
         "${workspaceFolder}/editors/code/out/**/*.js"
       ],
       "preLaunchTask": "Build Extension",
+      "skipFiles": [
+        "<node_internals>/**/*.js"
+      ],
       "env": {
         "__RA_LSP_SERVER_DEBUG": "${workspaceFolder}/target/debug/ra_lsp_server"
       }
     },
     {
-      "name": "Debug Lsp Server",
+      // Used to attach LLDB to a running LSP server.
+      // NOTE: Might require root permissions. For this run:
+      //
+      // `echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope`
+      //
+      // Don't forget to set `debug = 2` in `Cargo.toml` before building the server
+
+      "name": "Attach To Server",
       "type": "lldb",
       "request": "attach",
       "program": "${workspaceFolder}/target/debug/ra_lsp_server",
diff --git a/Cargo.lock b/Cargo.lock
index e29ff898d..f44e514dd 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -110,9 +110,9 @@ dependencies = [
 
 [[package]]
 name = "byteorder"
-version = "1.3.2"
+version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7c3dd8985a7111efc5c80b44e23ecdd8c007de8ade3b96595387e812b957cf5"
+checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 
 [[package]]
 name = "c2-chacha"
@@ -1015,6 +1015,7 @@ name = "ra_cli"
 version = "0.1.0"
 dependencies = [
  "env_logger",
+ "itertools",
  "pico-args",
  "ra_batch",
  "ra_db",
@@ -1024,6 +1025,7 @@ dependencies = [
  "ra_ide",
  "ra_prof",
  "ra_syntax",
+ "rand 0.7.3",
 ]
 
 [[package]]
@@ -1070,6 +1072,7 @@ dependencies = [
  "drop_bomb",
  "either",
  "insta",
+ "itertools",
  "log",
  "once_cell",
  "ra_arena",
@@ -1173,7 +1176,6 @@ dependencies = [
  "ra_prof",
  "ra_syntax",
  "ra_text_edit",
- "rand 0.7.3",
  "rayon",
  "rustc-hash",
  "superslice",
@@ -1246,6 +1248,7 @@ dependencies = [
 name = "ra_project_model"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "cargo_metadata",
  "log",
  "ra_arena",
@@ -1563,12 +1566,9 @@ checksum = "4c691c0e608126e00913e33f0ccf3727d5fc84573623b8d65b2df340b5201783"
 
 [[package]]
 name = "rustc-hash"
-version = "1.0.1"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7540fc8b0c49f096ee9c961cda096467dce8084bec6bdca2fc83895fd9b28cb8"
-dependencies = [
- "byteorder",
-]
+checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
 [[package]]
 name = "rustc_lexer"
@@ -1675,9 +1675,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.46"
+version = "1.0.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "21b01d7f0288608a01dca632cf1df859df6fd6ffa885300fc275ce2ba6221953"
+checksum = "15913895b61e0be854afd32fd4163fcd2a3df34142cf2cb961b310ce694cbf90"
 dependencies = [
  "itoa",
  "ryu",
diff --git a/Cargo.toml b/Cargo.toml
index e5620b1b7..c034e2424 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -31,3 +31,8 @@ opt-level = 0
 
 [patch.'crates-io']
 # rowan = { path = "../rowan" }
+
+[patch.'https://github.com/rust-lang/chalk.git']
+# chalk-solve = { path = "../chalk/chalk-solve" }
+# chalk-rust-ir = { path = "../chalk/chalk-rust-ir" }
+# chalk-ir = { path = "../chalk/chalk-ir" }
diff --git a/crates/ra_assists/src/handlers/auto_import.rs b/crates/ra_assists/src/handlers/auto_import.rs
index 1fb701da5..c4aea2a06 100644
--- a/crates/ra_assists/src/handlers/auto_import.rs
+++ b/crates/ra_assists/src/handlers/auto_import.rs
@@ -1,10 +1,18 @@
-use ra_ide_db::imports_locator::ImportsLocator;
-use ra_syntax::ast::{self, AstNode};
-
 use crate::{
     assist_ctx::{Assist, AssistCtx},
     insert_use_statement, AssistId,
 };
+use hir::{
+    db::HirDatabase, AsAssocItem, AssocItemContainer, ModPath, Module, ModuleDef, PathResolution,
+    SourceAnalyzer, Trait, Type,
+};
+use ra_ide_db::{imports_locator::ImportsLocator, RootDatabase};
+use ra_prof::profile;
+use ra_syntax::{
+    ast::{self, AstNode},
+    SyntaxNode,
+};
+use rustc_hash::FxHashSet;
 use std::collections::BTreeSet;
 
 // Assist: auto_import
@@ -27,52 +35,24 @@ use std::collections::BTreeSet;
 // # pub mod std { pub mod collections { pub struct HashMap { } } }
 // ```
 pub(crate) fn auto_import(ctx: AssistCtx) -> Option<Assist> {
-    let path_under_caret: ast::Path = ctx.find_node_at_offset()?;
-    if path_under_caret.syntax().ancestors().find_map(ast::UseItem::cast).is_some() {
-        return None;
-    }
-
-    let module = path_under_caret.syntax().ancestors().find_map(ast::Module::cast);
-    let position = match module.and_then(|it| it.item_list()) {
-        Some(item_list) => item_list.syntax().clone(),
-        None => {
-            let current_file =
-                path_under_caret.syntax().ancestors().find_map(ast::SourceFile::cast)?;
-            current_file.syntax().clone()
-        }
-    };
-    let source_analyzer = ctx.source_analyzer(&position, None);
-    let module_with_name_to_import = source_analyzer.module()?;
-
-    let name_ref_to_import =
-        path_under_caret.syntax().descendants().find_map(ast::NameRef::cast)?;
-    if source_analyzer
-        .resolve_path(ctx.db, &name_ref_to_import.syntax().ancestors().find_map(ast::Path::cast)?)
-        .is_some()
-    {
-        return None;
-    }
-
-    let name_to_import = name_ref_to_import.syntax().to_string();
-    let proposed_imports = ImportsLocator::new(ctx.db)
-        .find_imports(&name_to_import)
-        .into_iter()
-        .filter_map(|module_def| module_with_name_to_import.find_use_path(ctx.db, module_def))
-        .filter(|use_path| !use_path.segments.is_empty())
-        .take(20)
-        .collect::<BTreeSet<_>>();
-
+    let auto_import_assets = AutoImportAssets::new(&ctx)?;
+    let proposed_imports = auto_import_assets.search_for_imports(ctx.db);
     if proposed_imports.is_empty() {
         return None;
     }
 
-    let mut group = ctx.add_assist_group(format!("Import {}", name_to_import));
+    let assist_group_name = if proposed_imports.len() == 1 {
+        format!("Import `{}`", proposed_imports.iter().next().unwrap())
+    } else {
+        auto_import_assets.get_import_group_message()
+    };
+    let mut group = ctx.add_assist_group(assist_group_name);
     for import in proposed_imports {
         group.add_assist(AssistId("auto_import"), format!("Import `{}`", &import), |edit| {
-            edit.target(path_under_caret.syntax().text_range());
+            edit.target(auto_import_assets.syntax_under_caret.text_range());
             insert_use_statement(
-                &position,
-                path_under_caret.syntax(),
+                &auto_import_assets.syntax_under_caret,
+                &auto_import_assets.syntax_under_caret,
                 &import,
                 edit.text_edit_builder(),
             );
@@ -81,11 +61,232 @@ pub(crate) fn auto_import(ctx: AssistCtx) -> Option<Assist> {
     group.finish()
 }
 
+struct AutoImportAssets {
+    import_candidate: ImportCandidate,
+    module_with_name_to_import: Module,
+    syntax_under_caret: SyntaxNode,
+}
+
+impl AutoImportAssets {
+    fn new(ctx: &AssistCtx) -> Option<Self> {
+        if let Some(path_under_caret) = ctx.find_node_at_offset::<ast::Path>() {
+            Self::for_regular_path(path_under_caret, &ctx)
+        } else {
+            Self::for_method_call(ctx.find_node_at_offset()?, &ctx)
+        }
+    }
+
+    fn for_method_call(method_call: ast::MethodCallExpr, ctx: &AssistCtx) -> Option<Self> {
+        let syntax_under_caret = method_call.syntax().to_owned();
+        let source_analyzer = ctx.source_analyzer(&syntax_under_caret, None);
+        let module_with_name_to_import = source_analyzer.module()?;
+        Some(Self {
+            import_candidate: ImportCandidate::for_method_call(
+                &method_call,
+                &source_analyzer,
+                ctx.db,
+            )?,
+            module_with_name_to_import,
+            syntax_under_caret,
+        })
+    }
+
+    fn for_regular_path(path_under_caret: ast::Path, ctx: &AssistCtx) -> Option<Self> {
+        let syntax_under_caret = path_under_caret.syntax().to_owned();
+        if syntax_under_caret.ancestors().find_map(ast::UseItem::cast).is_some() {
+            return None;
+        }
+
+        let source_analyzer = ctx.source_analyzer(&syntax_under_caret, None);
+        let module_with_name_to_import = source_analyzer.module()?;
+        Some(Self {
+            import_candidate: ImportCandidate::for_regular_path(
+                &path_under_caret,
+                &source_analyzer,
+                ctx.db,
+            )?,
+            module_with_name_to_import,
+            syntax_under_caret,
+        })
+    }
+
+    fn get_search_query(&self) -> &str {
+        match &self.import_candidate {
+            ImportCandidate::UnqualifiedName(name) => name,
+            ImportCandidate::QualifierStart(qualifier_start) => qualifier_start,
+            ImportCandidate::TraitAssocItem(_, trait_assoc_item_name) => trait_assoc_item_name,
+            ImportCandidate::TraitMethod(_, trait_method_name) => trait_method_name,
+        }
+    }
+
+    fn get_import_group_message(&self) -> String {
+        match &self.import_candidate {
+            ImportCandidate::UnqualifiedName(name) => format!("Import {}", name),
+            ImportCandidate::QualifierStart(qualifier_start) => {
+                format!("Import {}", qualifier_start)
+            }
+            ImportCandidate::TraitAssocItem(_, trait_assoc_item_name) => {
+                format!("Import a trait for item {}", trait_assoc_item_name)
+            }
+            ImportCandidate::TraitMethod(_, trait_method_name) => {
+                format!("Import a trait for method {}", trait_method_name)
+            }
+        }
+    }
+
+    fn search_for_imports(&self, db: &RootDatabase) -> BTreeSet<ModPath> {
+        let _p = profile("auto_import::search_for_imports");
+        let current_crate = self.module_with_name_to_import.krate();
+        ImportsLocator::new(db)
+            .find_imports(&self.get_search_query())
+            .into_iter()
+            .filter_map(|module_def| match &self.import_candidate {
+                ImportCandidate::TraitAssocItem(assoc_item_type, _) => {
+                    let located_assoc_item = match module_def {
+                        ModuleDef::Function(located_function) => located_function
+                            .as_assoc_item(db)
+                            .map(|assoc| assoc.container(db))
+                            .and_then(Self::assoc_to_trait),
+                        ModuleDef::Const(located_const) => located_const
+                            .as_assoc_item(db)
+                            .map(|assoc| assoc.container(db))
+                            .and_then(Self::assoc_to_trait),
+                        _ => None,
+                    }?;
+
+                    let mut trait_candidates = FxHashSet::default();
+                    trait_candidates.insert(located_assoc_item.into());
+
+                    assoc_item_type
+                        .iterate_path_candidates(
+                            db,
+                            current_crate,
+                            &trait_candidates,
+                            None,
+                            |_, assoc| Self::assoc_to_trait(assoc.container(db)),
+                        )
+                        .map(ModuleDef::from)
+                }
+                ImportCandidate::TraitMethod(function_callee, _) => {
+                    let located_assoc_item =
+                        if let ModuleDef::Function(located_function) = module_def {
+                            located_function
+                                .as_assoc_item(db)
+                                .map(|assoc| assoc.container(db))
+                                .and_then(Self::assoc_to_trait)
+                        } else {
+                            None
+                        }?;
+
+                    let mut trait_candidates = FxHashSet::default();
+                    trait_candidates.insert(located_assoc_item.into());
+
+                    function_callee
+                        .iterate_method_candidates(
+                            db,
+                            current_crate,
+                            &trait_candidates,
+                            None,
+                            |_, function| {
+                                Self::assoc_to_trait(function.as_assoc_item(db)?.container(db))
+                            },
+                        )
+                        .map(ModuleDef::from)
+                }
+                _ => Some(module_def),
+            })
+            .filter_map(|module_def| self.module_with_name_to_import.find_use_path(db, module_def))
+            .filter(|use_path| !use_path.segments.is_empty())
+            .take(20)
+            .collect::<BTreeSet<_>>()
+    }
+
+    fn assoc_to_trait(assoc: AssocItemContainer) -> Option<Trait> {
+        if let AssocItemContainer::Trait(extracted_trait) = assoc {
+            Some(extracted_trait)
+        } else {
+            None
+        }
+    }
+}
+
+#[derive(Debug)]
+enum ImportCandidate {
+    /// Simple name like 'HashMap'
+    UnqualifiedName(String),
+    /// First part of the qualified name.
+    /// For 'std::collections::HashMap', that will be 'std'.
+    QualifierStart(String),
+    /// A trait associated function (with no self parameter) or associated constant.
+    /// For 'test_mod::TestEnum::test_function', `Type` is the `test_mod::TestEnum` expression type
+    /// and `String` is the `test_function`
+    TraitAssocItem(Type, String),
+    /// A trait method with self parameter.
+    /// For 'test_enum.test_method()', `Type` is the `test_enum` expression type
+    /// and `String` is the `test_method`
+    TraitMethod(Type, String),
+}
+
+impl ImportCandidate {
+    fn for_method_call(
+        method_call: &ast::MethodCallExpr,
+        source_analyzer: &SourceAnalyzer,
+        db: &impl HirDatabase,
+    ) -> Option<Self> {
+        if source_analyzer.resolve_method_call(method_call).is_some() {
+            return None;
+        }
+        Some(Self::TraitMethod(
+            source_analyzer.type_of(db, &method_call.expr()?)?,
+            method_call.name_ref()?.syntax().to_string(),
+        ))
+    }
+
+    fn for_regular_path(
+        path_under_caret: &ast::Path,
+        source_analyzer: &SourceAnalyzer,
+        db: &impl HirDatabase,
+    ) -> Option<Self> {
+        if source_analyzer.resolve_path(db, path_under_caret).is_some() {
+            return None;
+        }
+
+        let segment = path_under_caret.segment()?;
+        if let Some(qualifier) = path_under_caret.qualifier() {
+            let qualifier_start = qualifier.syntax().descendants().find_map(ast::NameRef::cast)?;
+            let qualifier_start_path =
+                qualifier_start.syntax().ancestors().find_map(ast::Path::cast)?;
+            if let Some(qualifier_start_resolution) =
+                source_analyzer.resolve_path(db, &qualifier_start_path)
+            {
+                let qualifier_resolution = if qualifier_start_path == qualifier {
+                    qualifier_start_resolution
+                } else {
+                    source_analyzer.resolve_path(db, &qualifier)?
+                };
+                if let PathResolution::Def(ModuleDef::Adt(assoc_item_path)) = qualifier_resolution {
+                    Some(ImportCandidate::TraitAssocItem(
+                        assoc_item_path.ty(db),
+                        segment.syntax().to_string(),
+                    ))
+                } else {
+                    None
+                }
+            } else {
+                Some(ImportCandidate::QualifierStart(qualifier_start.syntax().to_string()))
+            }
+        } else {
+            Some(ImportCandidate::UnqualifiedName(
+                segment.syntax().descendants().find_map(ast::NameRef::cast)?.syntax().to_string(),
+            ))
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
-
     use super::*;
+    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
 
     #[test]
     fn applicable_when_found_an_import() {
@@ -290,4 +491,303 @@ mod tests {
             ",
         );
     }
+
+    #[test]
+    fn not_applicable_for_imported_function() {
+        check_assist_not_applicable(
+            auto_import,
+            r"
+            pub mod test_mod {
+                pub fn test_function() {}
+            }
+
+            use test_mod::test_function;
+            fn main() {
+                test_function<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_struct_function() {
+        check_assist(
+            auto_import,
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    pub fn test_function() {}
+                }
+            }
+
+            fn main() {
+                TestStruct::test_function<|>
+            }
+            ",
+            r"
+            use test_mod::TestStruct;
+
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    pub fn test_function() {}
+                }
+            }
+
+            fn main() {
+                TestStruct::test_function<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_struct_const() {
+        check_assist(
+            auto_import,
+            r"
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                TestStruct::TEST_CONST<|>
+            }
+            ",
+            r"
+            use test_mod::TestStruct;
+
+            mod test_mod {
+                pub struct TestStruct {}
+                impl TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                TestStruct::TEST_CONST<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn associated_trait_function() {
+        check_assist(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::test_function<|>
+            }
+            ",
+            r"
+            use test_mod::TestTrait;
+
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_function() {}
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::test_function<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_function() {
+        check_assist_not_applicable(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_function();
+                }
+                pub trait TestTrait2 {
+                    fn test_function();
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    fn test_function() {}
+                }
+                impl TestTrait for TestEnum {
+                    fn test_function() {}
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                test_mod::TestEnum::test_function<|>;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn associated_trait_const() {
+        check_assist(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::TEST_CONST<|>
+            }
+            ",
+            r"
+            use test_mod::TestTrait;
+
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            fn main() {
+                test_mod::TestStruct::TEST_CONST<|>
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_const() {
+        check_assist_not_applicable(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    const TEST_CONST: u8;
+                }
+                pub trait TestTrait2 {
+                    const TEST_CONST: f64;
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    const TEST_CONST: f64 = 42.0;
+                }
+                impl TestTrait for TestEnum {
+                    const TEST_CONST: u8 = 42;
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                test_mod::TestEnum::TEST_CONST<|>;
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn trait_method() {
+        check_assist(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            ",
+            r"
+            use test_mod::TestTrait;
+
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub struct TestStruct {}
+                impl TestTrait for TestStruct {
+                    fn test_method(&self) {}
+                }
+            }
+
+            fn main() {
+                let test_struct = test_mod::TestStruct {};
+                test_struct.test_meth<|>od()
+            }
+            ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_imported_trait_for_method() {
+        check_assist_not_applicable(
+            auto_import,
+            r"
+            mod test_mod {
+                pub trait TestTrait {
+                    fn test_method(&self);
+                }
+                pub trait TestTrait2 {
+                    fn test_method(&self);
+                }
+                pub enum TestEnum {
+                    One,
+                    Two,
+                }
+                impl TestTrait2 for TestEnum {
+                    fn test_method(&self) {}
+                }
+                impl TestTrait for TestEnum {
+                    fn test_method(&self) {}
+                }
+            }
+
+            use test_mod::TestTrait2;
+            fn main() {
+                let one = test_mod::TestEnum::One;
+                one.test<|>_method();
+            }
+            ",
+        )
+    }
 }
diff --git a/crates/ra_assists/src/handlers/fill_match_arms.rs b/crates/ra_assists/src/handlers/fill_match_arms.rs
index 0908fc246..ae2437ed3 100644
--- a/crates/ra_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ra_assists/src/handlers/fill_match_arms.rs
@@ -75,10 +75,10 @@ pub(crate) fn fill_match_arms(ctx: AssistCtx) -> Option<Assist> {
 }
 
 fn is_trivial(arm: &ast::MatchArm) -> bool {
-    arm.pats().any(|pat| match pat {
-        ast::Pat::PlaceholderPat(..) => true,
+    match arm.pat() {
+        Some(ast::Pat::PlaceholderPat(..)) => true,
         _ => false,
-    })
+    }
 }
 
 fn resolve_enum_def(
diff --git a/crates/ra_assists/src/handlers/merge_match_arms.rs b/crates/ra_assists/src/handlers/merge_match_arms.rs
index 670614dd8..b2a194cb5 100644
--- a/crates/ra_assists/src/handlers/merge_match_arms.rs
+++ b/crates/ra_assists/src/handlers/merge_match_arms.rs
@@ -75,7 +75,7 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
         } else {
             arms_to_merge
                 .iter()
-                .flat_map(ast::MatchArm::pats)
+                .filter_map(ast::MatchArm::pat)
                 .map(|x| x.syntax().to_string())
                 .collect::<Vec<String>>()
                 .join(" | ")
@@ -96,10 +96,10 @@ pub(crate) fn merge_match_arms(ctx: AssistCtx) -> Option<Assist> {
 }
 
 fn contains_placeholder(a: &ast::MatchArm) -> bool {
-    a.pats().any(|x| match x {
-        ra_syntax::ast::Pat::PlaceholderPat(..) => true,
+    match a.pat() {
+        Some(ra_syntax::ast::Pat::PlaceholderPat(..)) => true,
         _ => false,
-    })
+    }
 }
 
 fn next_arm(arm: &ast::MatchArm) -> Option<ast::MatchArm> {
diff --git a/crates/ra_assists/src/handlers/move_guard.rs b/crates/ra_assists/src/handlers/move_guard.rs
index 2b91ce7c4..a61a2ba3e 100644
--- a/crates/ra_assists/src/handlers/move_guard.rs
+++ b/crates/ra_assists/src/handlers/move_guard.rs
@@ -90,7 +90,7 @@ pub(crate) fn move_guard_to_arm_body(ctx: AssistCtx) -> Option<Assist> {
 // ```
 pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
     let match_arm: MatchArm = ctx.find_node_at_offset::<MatchArm>()?;
-    let last_match_pat = match_arm.pats().last()?;
+    let match_pat = match_arm.pat()?;
 
     let arm_body = match_arm.expr()?;
     let if_expr: IfExpr = IfExpr::cast(arm_body.syntax().clone())?;
@@ -122,8 +122,8 @@ pub(crate) fn move_arm_cond_to_match_guard(ctx: AssistCtx) -> Option<Assist> {
                 _ => edit.replace(if_expr.syntax().text_range(), then_block.syntax().text()),
             }
 
-            edit.insert(last_match_pat.syntax().text_range().end(), buf);
-            edit.set_cursor(last_match_pat.syntax().text_range().end() + TextUnit::from(1));
+            edit.insert(match_pat.syntax().text_range().end(), buf);
+            edit.set_cursor(match_pat.syntax().text_range().end() + TextUnit::from(1));
         },
     )
 }
diff --git a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
index b70c88ec2..eac452413 100644
--- a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -431,7 +431,12 @@ fn best_action_for_target(
                 .find(|n| n.text_range().start() < anchor.text_range().start())
                 .or_else(|| Some(anchor));
 
-            ImportAction::add_new_use(anchor, false)
+            let add_after_anchor = anchor
+                .clone()
+                .and_then(ast::Attr::cast)
+                .map(|attr| attr.kind() == ast::AttrKind::Inner)
+                .unwrap_or(false);
+            ImportAction::add_new_use(anchor, add_after_anchor)
         }
     }
 }
@@ -962,4 +967,26 @@ mod foo {
     ",
         );
     }
+
+    #[test]
+    fn inserts_imports_after_inner_attributes() {
+        check_assist(
+            replace_qualified_name_with_use,
+            "
+#![allow(dead_code)]
+
+fn main() {
+    std::fmt::Debug<|>
+}
+    ",
+            "
+#![allow(dead_code)]
+use std::fmt::Debug;
+
+fn main() {
+    Debug<|>
+}
+    ",
+        );
+    }
 }
diff --git a/crates/ra_cli/Cargo.toml b/crates/ra_cli/Cargo.toml
index bcd408421..53d4876f6 100644
--- a/crates/ra_cli/Cargo.toml
+++ b/crates/ra_cli/Cargo.toml
@@ -6,8 +6,10 @@ authors = ["rust-analyzer developers"]
 publish = false
 
 [dependencies]
+itertools = "0.8.0"
 pico-args = "0.3.0"
 env_logger = { version = "0.7.1", default-features = false }
+rand = { version = "0.7.0", features = ["small_rng"] }
 
 ra_syntax = { path = "../ra_syntax" }
 ra_ide = { path = "../ra_ide" }
diff --git a/crates/ra_cli/src/analysis_bench.rs b/crates/ra_cli/src/analysis_bench.rs
index 5485a38ff..4835a68ce 100644
--- a/crates/ra_cli/src/analysis_bench.rs
+++ b/crates/ra_cli/src/analysis_bench.rs
@@ -2,6 +2,7 @@
 
 use std::{
     path::{Path, PathBuf},
+    str::FromStr,
     sync::Arc,
     time::Instant,
 };
@@ -14,12 +15,35 @@ use ra_ide::{Analysis, AnalysisChange, AnalysisHost, FilePosition, LineCol};
 
 use crate::Result;
 
+pub(crate) struct Position {
+    path: PathBuf,
+    line: u32,
+    column: u32,
+}
+
+impl FromStr for Position {
+    type Err = Box<dyn std::error::Error + Send + Sync>;
+    fn from_str(s: &str) -> Result<Self> {
+        let (path_line, column) = rsplit_at_char(s, ':')?;
+        let (path, line) = rsplit_at_char(path_line, ':')?;
+        Ok(Position { path: path.into(), line: line.parse()?, column: column.parse()? })
+    }
+}
+
+fn rsplit_at_char(s: &str, c: char) -> Result<(&str, &str)> {
+    let idx = s.rfind(':').ok_or_else(|| format!("no `{}` in {}", c, s))?;
+    Ok((&s[..idx], &s[idx + 1..]))
+}
+
 pub(crate) enum Op {
     Highlight { path: PathBuf },
-    Complete { path: PathBuf, line: u32, column: u32 },
+    Complete(Position),
+    GotoDef(Position),
 }
 
 pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
+    ra_prof::init();
+
     let start = Instant::now();
     eprint!("loading: ");
     let (mut host, roots) = ra_batch::load_cargo(path)?;
@@ -29,7 +53,7 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
     let file_id = {
         let path = match &op {
             Op::Highlight { path } => path,
-            Op::Complete { path, .. } => path,
+            Op::Complete(pos) | Op::GotoDef(pos) => &pos.path,
         };
         let path = std::env::current_dir()?.join(path).canonicalize()?;
         roots
@@ -49,7 +73,7 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
             .ok_or_else(|| format!("Can't find {:?}", path))?
     };
 
-    match op {
+    match &op {
         Op::Highlight { .. } => {
             let res = do_work(&mut host, file_id, |analysis| {
                 analysis.diagnostics(file_id).unwrap();
@@ -59,16 +83,30 @@ pub(crate) fn run(verbose: bool, path: &Path, op: Op) -> Result<()> {
                 println!("\n{}", res);
             }
         }
-        Op::Complete { line, column, .. } => {
+        Op::Complete(pos) | Op::GotoDef(pos) => {
+            let is_completion = match op {
+                Op::Complete(..) => true,
+                _ => false,
+            };
+
             let offset = host
                 .analysis()
                 .file_line_index(file_id)?
-                .offset(LineCol { line, col_utf16: column });
+                .offset(LineCol { line: pos.line - 1, col_utf16: pos.column });
             let file_postion = FilePosition { file_id, offset };
 
-            let res = do_work(&mut host, file_id, |analysis| analysis.completions(file_postion));
-            if verbose {
-                println!("\n{:#?}", res);
+            if is_completion {
+                let res =
+                    do_work(&mut host, file_id, |analysis| analysis.completions(file_postion));
+                if verbose {
+                    println!("\n{:#?}", res);
+                }
+            } else {
+                let res =
+                    do_work(&mut host, file_id, |analysis| analysis.goto_definition(file_postion));
+                if verbose {
+                    println!("\n{:#?}", res);
+                }
             }
         }
     }
diff --git a/crates/ra_cli/src/analysis_stats.rs b/crates/ra_cli/src/analysis_stats.rs
index 833235bff..6d2dd34c6 100644
--- a/crates/ra_cli/src/analysis_stats.rs
+++ b/crates/ra_cli/src/analysis_stats.rs
@@ -2,6 +2,9 @@
 
 use std::{collections::HashSet, fmt::Write, path::Path, time::Instant};
 
+use itertools::Itertools;
+use rand::{seq::SliceRandom, thread_rng};
+
 use hir::{
     db::{DefDatabase, HirDatabase},
     AssocItem, Crate, HasSource, HirDisplay, ModuleDef,
@@ -19,6 +22,7 @@ pub fn run(
     path: &Path,
     only: Option<&str>,
     with_deps: bool,
+    randomize: bool,
 ) -> Result<()> {
     let db_load_time = Instant::now();
     let (mut host, roots) = ra_batch::load_cargo(path)?;
@@ -41,7 +45,11 @@ pub fn run(
             })
             .collect::<HashSet<_>>();
 
-    for krate in Crate::all(db) {
+    let mut krates = Crate::all(db);
+    if randomize {
+        krates.shuffle(&mut thread_rng());
+    }
+    for krate in krates {
         let module = krate.root_module(db).expect("crate without root module");
         let file_id = module.definition_source(db).file_id;
         if members.contains(&db.file_source_root(file_id.original_file(db))) {
@@ -50,6 +58,10 @@ pub fn run(
         }
     }
 
+    if randomize {
+        visit_queue.shuffle(&mut thread_rng());
+    }
+
     println!("Crates in this dir: {}", num_crates);
     let mut num_decls = 0;
     let mut funcs = Vec::new();
@@ -79,10 +91,14 @@ pub fn run(
     println!("Total functions: {}", funcs.len());
     println!("Item Collection: {:?}, {}", analysis_time.elapsed(), ra_prof::memory_usage());
 
+    if randomize {
+        funcs.shuffle(&mut thread_rng());
+    }
+
     let inference_time = Instant::now();
     let mut bar = match verbosity {
-        Verbosity::Verbose | Verbosity::Normal => ProgressReport::new(funcs.len() as u64),
-        Verbosity::Quiet => ProgressReport::hidden(),
+        Verbosity::Quiet | Verbosity::Spammy => ProgressReport::hidden(),
+        _ => ProgressReport::new(funcs.len() as u64),
     };
 
     bar.tick();
@@ -92,7 +108,20 @@ pub fn run(
     let mut num_type_mismatches = 0;
     for f in funcs {
         let name = f.name(db);
-        let mut msg = format!("processing: {}", name);
+        let full_name = f
+            .module(db)
+            .path_to_root(db)
+            .into_iter()
+            .rev()
+            .filter_map(|it| it.name(db))
+            .chain(Some(f.name(db)))
+            .join("::");
+        if let Some(only_name) = only {
+            if name.to_string() != only_name && full_name != only_name {
+                continue;
+            }
+        }
+        let mut msg = format!("processing: {}", full_name);
         if verbosity.is_verbose() {
             let src = f.source(db);
             let original_file = src.file_id.original_file(db);
@@ -100,15 +129,15 @@ pub fn run(
             let syntax_range = src.value.syntax().text_range();
             write!(msg, " ({:?} {})", path, syntax_range).unwrap();
         }
-        bar.set_message(&msg);
-        if let Some(only_name) = only {
-            if name.to_string() != only_name {
-                continue;
-            }
+        if verbosity.is_spammy() {
+            bar.println(format!("{}", msg));
         }
+        bar.set_message(&msg);
         let f_id = FunctionId::from(f);
         let body = db.body(f_id.into());
         let inference_result = db.infer(f_id.into());
+        let (previous_exprs, previous_unknown, previous_partially_unknown) =
+            (num_exprs, num_exprs_unknown, num_exprs_partially_unknown);
         for (expr_id, _) in body.exprs.iter() {
             let ty = &inference_result[expr_id];
             num_exprs += 1;
@@ -125,6 +154,33 @@ pub fn run(
                     num_exprs_partially_unknown += 1;
                 }
             }
+            if only.is_some() && verbosity.is_spammy() {
+                // in super-verbose mode for just one function, we print every single expression
+                let (_, sm) = db.body_with_source_map(f_id.into());
+                let src = sm.expr_syntax(expr_id);
+                if let Some(src) = src {
+                    let original_file = src.file_id.original_file(db);
+                    let line_index = host.analysis().file_line_index(original_file).unwrap();
+                    let text_range = src.value.either(
+                        |it| it.syntax_node_ptr().range(),
+                        |it| it.syntax_node_ptr().range(),
+                    );
+                    let (start, end) = (
+                        line_index.line_col(text_range.start()),
+                        line_index.line_col(text_range.end()),
+                    );
+                    bar.println(format!(
+                        "{}:{}-{}:{}: {}",
+                        start.line + 1,
+                        start.col_utf16,
+                        end.line + 1,
+                        end.col_utf16,
+                        ty.display(db)
+                    ));
+                } else {
+                    bar.println(format!("unknown location: {}", ty.display(db)));
+                }
+            }
             if let Some(mismatch) = inference_result.type_mismatch_for_expr(expr_id) {
                 num_type_mismatches += 1;
                 if verbosity.is_verbose() {
@@ -164,6 +220,15 @@ pub fn run(
                 }
             }
         }
+        if verbosity.is_spammy() {
+            bar.println(format!(
+                "In {}: {} exprs, {} unknown, {} partial",
+                full_name,
+                num_exprs - previous_exprs,
+                num_exprs_unknown - previous_unknown,
+                num_exprs_partially_unknown - previous_partially_unknown
+            ));
+        }
         bar.inc(1);
     }
     bar.finish_and_clear();
diff --git a/crates/ra_cli/src/main.rs b/crates/ra_cli/src/main.rs
index 806612c2c..750cbab86 100644
--- a/crates/ra_cli/src/main.rs
+++ b/crates/ra_cli/src/main.rs
@@ -16,6 +16,7 @@ type Result<T> = std::result::Result<T, Box<dyn Error + Send + Sync>>;
 
 #[derive(Clone, Copy)]
 pub enum Verbosity {
+    Spammy,
     Verbose,
     Normal,
     Quiet,
@@ -24,7 +25,13 @@ pub enum Verbosity {
 impl Verbosity {
     fn is_verbose(self) -> bool {
         match self {
-            Verbosity::Verbose => true,
+            Verbosity::Verbose | Verbosity::Spammy => true,
+            _ => false,
+        }
+    }
+    fn is_spammy(self) -> bool {
+        match self {
+            Verbosity::Spammy => true,
             _ => false,
         }
     }
@@ -86,14 +93,18 @@ fn main() -> Result<()> {
                 return Ok(());
             }
             let verbosity = match (
+                matches.contains(["-vv", "--spammy"]),
                 matches.contains(["-v", "--verbose"]),
                 matches.contains(["-q", "--quiet"]),
             ) {
-                (false, false) => Verbosity::Normal,
-                (false, true) => Verbosity::Quiet,
-                (true, false) => Verbosity::Verbose,
-                (true, true) => Err("Invalid flags: -q conflicts with -v")?,
+                (true, _, true) => Err("Invalid flags: -q conflicts with -vv")?,
+                (true, _, false) => Verbosity::Spammy,
+                (false, false, false) => Verbosity::Normal,
+                (false, false, true) => Verbosity::Quiet,
+                (false, true, false) => Verbosity::Verbose,
+                (false, true, true) => Err("Invalid flags: -q conflicts with -v")?,
             };
+            let randomize = matches.contains("--randomize");
             let memory_usage = matches.contains("--memory-usage");
             let only: Option<String> = matches.opt_value_from_str(["-o", "--only"])?;
             let with_deps: bool = matches.contains("--with-deps");
@@ -111,6 +122,7 @@ fn main() -> Result<()> {
                 path.as_ref(),
                 only.as_ref().map(String::as_ref),
                 with_deps,
+                randomize,
             )?;
         }
         "analysis-bench" => {
@@ -120,25 +132,16 @@ fn main() -> Result<()> {
             }
             let verbose = matches.contains(["-v", "--verbose"]);
             let path: String = matches.opt_value_from_str("--path")?.unwrap_or_default();
-            let highlight_path = matches.opt_value_from_str("--highlight")?;
-            let complete_path = matches.opt_value_from_str("--complete")?;
-            if highlight_path.is_some() && complete_path.is_some() {
-                panic!("either --highlight or --complete must be set, not both")
-            }
-            let op = if let Some(path) = highlight_path {
-                let path: String = path;
-                analysis_bench::Op::Highlight { path: path.into() }
-            } else if let Some(path_line_col) = complete_path {
-                let path_line_col: String = path_line_col;
-                let (path_line, column) = rsplit_at_char(path_line_col.as_str(), ':')?;
-                let (path, line) = rsplit_at_char(path_line, ':')?;
-                analysis_bench::Op::Complete {
-                    path: path.into(),
-                    line: line.parse()?,
-                    column: column.parse()?,
-                }
-            } else {
-                panic!("either --highlight or --complete must be set")
+            let highlight_path: Option<String> = matches.opt_value_from_str("--highlight")?;
+            let complete_path: Option<String> = matches.opt_value_from_str("--complete")?;
+            let goto_def_path: Option<String> = matches.opt_value_from_str("--goto-def")?;
+            let op = match (highlight_path, complete_path, goto_def_path) {
+                (Some(path), None, None) => analysis_bench::Op::Highlight { path: path.into() },
+                (None, Some(position), None) => analysis_bench::Op::Complete(position.parse()?),
+                (None, None, Some(position)) => analysis_bench::Op::GotoDef(position.parse()?),
+                _ => panic!(
+                    "exactly one of  `--highlight`, `--complete` or `--goto-def` must be set"
+                ),
             };
             matches.finish().or_else(handle_extra_flags)?;
             analysis_bench::run(verbose, path.as_ref(), op)?;
@@ -171,8 +174,3 @@ fn read_stdin() -> Result<String> {
     std::io::stdin().read_to_string(&mut buff)?;
     Ok(buff)
 }
-
-fn rsplit_at_char(s: &str, c: char) -> Result<(&str, &str)> {
-    let idx = s.rfind(':').ok_or_else(|| format!("no `{}` in {}", c, s))?;
-    Ok((&s[..idx], &s[idx + 1..]))
-}
diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 4d9641728..a56b8ab04 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -10,9 +10,9 @@ use hir_def::{
     per_ns::PerNs,
     resolver::HasResolver,
     type_ref::{Mutability, TypeRef},
-    AdtId, ConstId, DefWithBodyId, EnumId, FunctionId, GenericDefId, HasModule, ImplId,
-    LocalEnumVariantId, LocalModuleId, LocalStructFieldId, Lookup, ModuleId, StaticId, StructId,
-    TraitId, TypeAliasId, TypeParamId, UnionId,
+    AdtId, AssocContainerId, ConstId, DefWithBodyId, EnumId, FunctionId, GenericDefId, HasModule,
+    ImplId, LocalEnumVariantId, LocalModuleId, LocalStructFieldId, Lookup, ModuleId, StaticId,
+    StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
 };
 use hir_expand::{
     diagnostics::DiagnosticSink,
@@ -25,7 +25,10 @@ use hir_ty::{
 };
 use ra_db::{CrateId, Edition, FileId};
 use ra_prof::profile;
-use ra_syntax::ast::{self, AttrsOwner};
+use ra_syntax::{
+    ast::{self, AttrsOwner},
+    AstNode,
+};
 
 use crate::{
     db::{DefDatabase, HirDatabase},
@@ -119,7 +122,9 @@ impl_froms!(
     BuiltinType
 );
 
-pub use hir_def::{attr::Attrs, item_scope::ItemInNs, visibility::Visibility, AssocItemId};
+pub use hir_def::{
+    attr::Attrs, item_scope::ItemInNs, visibility::Visibility, AssocItemId, AssocItemLoc,
+};
 use rustc_hash::FxHashSet;
 
 impl Module {
@@ -639,17 +644,49 @@ pub struct MacroDef {
     pub(crate) id: MacroDefId,
 }
 
+/// Invariant: `inner.as_assoc_item(db).is_some()`
+/// We do not actively enforce this invariant.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub enum AssocItem {
     Function(Function),
     Const(Const),
     TypeAlias(TypeAlias),
 }
-// FIXME: not every function, ... is actually an assoc item. maybe we should make
-// sure that you can only turn actual assoc items into AssocItems. This would
-// require not implementing From, and instead having some checked way of
-// casting them, and somehow making the constructors private, which would be annoying.
-impl_froms!(AssocItem: Function, Const, TypeAlias);
+pub enum AssocItemContainer {
+    Trait(Trait),
+    ImplBlock(ImplBlock),
+}
+pub trait AsAssocItem {
+    fn as_assoc_item(self, db: &impl DefDatabase) -> Option<AssocItem>;
+}
+
+impl AsAssocItem for Function {
+    fn as_assoc_item(self, db: &impl DefDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::Function, self.id)
+    }
+}
+impl AsAssocItem for Const {
+    fn as_assoc_item(self, db: &impl DefDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::Const, self.id)
+    }
+}
+impl AsAssocItem for TypeAlias {
+    fn as_assoc_item(self, db: &impl DefDatabase) -> Option<AssocItem> {
+        as_assoc_item(db, AssocItem::TypeAlias, self.id)
+    }
+}
+fn as_assoc_item<ID, DEF, CTOR, AST>(db: &impl DefDatabase, ctor: CTOR, id: ID) -> Option<AssocItem>
+where
+    ID: Lookup<Data = AssocItemLoc<AST>>,
+    DEF: From<ID>,
+    CTOR: FnOnce(DEF) -> AssocItem,
+    AST: AstNode,
+{
+    match id.lookup(db).container {
+        AssocContainerId::TraitId(_) | AssocContainerId::ImplId(_) => Some(ctor(DEF::from(id))),
+        AssocContainerId::ContainerId(_) => None,
+    }
+}
 
 impl AssocItem {
     pub fn module(self, db: &impl DefDatabase) -> Module {
@@ -659,6 +696,18 @@ impl AssocItem {
             AssocItem::TypeAlias(t) => t.module(db),
         }
     }
+    pub fn container(self, db: &impl DefDatabase) -> AssocItemContainer {
+        let container = match self {
+            AssocItem::Function(it) => it.id.lookup(db).container,
+            AssocItem::Const(it) => it.id.lookup(db).container,
+            AssocItem::TypeAlias(it) => it.id.lookup(db).container,
+        };
+        match container {
+            AssocContainerId::TraitId(id) => AssocItemContainer::Trait(id.into()),
+            AssocContainerId::ImplId(id) => AssocItemContainer::ImplBlock(id.into()),
+            AssocContainerId::ContainerId(_) => panic!("invalid AssocItem"),
+        }
+    }
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
@@ -769,6 +818,7 @@ impl TypeParam {
     }
 }
 
+// FIXME: rename from `ImplBlock` to `Impl`
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ImplBlock {
     pub(crate) id: ImplId,
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index e1c7b7a20..5cd965f7a 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -39,10 +39,10 @@ mod has_source;
 
 pub use crate::{
     code_model::{
-        Adt, AssocItem, AttrDef, Const, Crate, CrateDependency, DefWithBody, Docs, Enum,
-        EnumVariant, FieldSource, Function, GenericDef, HasAttrs, HasVisibility, ImplBlock, Local,
-        MacroDef, Module, ModuleDef, ScopeDef, Static, Struct, StructField, Trait, Type, TypeAlias,
-        TypeParam, Union, VariantDef,
+        Adt, AsAssocItem, AssocItem, AssocItemContainer, AttrDef, Const, Crate, CrateDependency,
+        DefWithBody, Docs, Enum, EnumVariant, FieldSource, Function, GenericDef, HasAttrs,
+        HasVisibility, ImplBlock, Local, MacroDef, Module, ModuleDef, ScopeDef, Static, Struct,
+        StructField, Trait, Type, TypeAlias, TypeParam, Union, VariantDef,
     },
     has_source::HasSource,
     source_analyzer::{PathResolution, ScopeEntryWithSyntax, SourceAnalyzer},
diff --git a/crates/ra_hir/src/source_analyzer.rs b/crates/ra_hir/src/source_analyzer.rs
index bb9a35c5d..94d5b4cfd 100644
--- a/crates/ra_hir/src/source_analyzer.rs
+++ b/crates/ra_hir/src/source_analyzer.rs
@@ -15,11 +15,9 @@ use hir_def::{
     },
     expr::{ExprId, PatId},
     resolver::{self, resolver_for_scope, Resolver, TypeNs, ValueNs},
-    DefWithBodyId, TraitId,
-};
-use hir_expand::{
-    hygiene::Hygiene, name::AsName, AstId, HirFileId, InFile, MacroCallId, MacroCallKind,
+    AsMacroCall, DefWithBodyId, TraitId,
 };
+use hir_expand::{hygiene::Hygiene, name::AsName, HirFileId, InFile, MacroCallId};
 use hir_ty::{InEnvironment, InferenceResult, TraitEnvironment};
 use ra_syntax::{
     ast::{self, AstNode},
@@ -363,12 +361,10 @@ impl SourceAnalyzer {
         db: &impl HirDatabase,
         macro_call: InFile<&ast::MacroCall>,
     ) -> Option<Expansion> {
-        let def = self.resolve_macro_call(db, macro_call)?.id;
-        let ast_id = AstId::new(
-            macro_call.file_id,
-            db.ast_id_map(macro_call.file_id).ast_id(macro_call.value),
-        );
-        Some(Expansion { macro_call_id: def.as_call_id(db, MacroCallKind::FnLike(ast_id)) })
+        let macro_call_id = macro_call.as_call_id(db, |path| {
+            self.resolver.resolve_path_as_macro(db, &path).map(|it| it.into())
+        })?;
+        Some(Expansion { macro_call_id })
     }
 }
 
diff --git a/crates/ra_hir_def/Cargo.toml b/crates/ra_hir_def/Cargo.toml
index 1efa00fe0..6b9be9948 100644
--- a/crates/ra_hir_def/Cargo.toml
+++ b/crates/ra_hir_def/Cargo.toml
@@ -14,6 +14,7 @@ rustc-hash = "1.0"
 either = "1.5"
 anymap = "0.12"
 drop_bomb = "0.1.4"
+itertools = "0.8.2"
 
 ra_arena = { path = "../ra_arena" }
 ra_db = { path = "../ra_db" }
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index 142c52d35..010d35e55 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -7,9 +7,7 @@ use std::{mem, ops::Index, sync::Arc};
 
 use drop_bomb::DropBomb;
 use either::Either;
-use hir_expand::{
-    ast_id_map::AstIdMap, hygiene::Hygiene, AstId, HirFileId, InFile, MacroCallKind, MacroDefId,
-};
+use hir_expand::{ast_id_map::AstIdMap, hygiene::Hygiene, AstId, HirFileId, InFile, MacroDefId};
 use ra_arena::{map::ArenaMap, Arena};
 use ra_prof::profile;
 use ra_syntax::{ast, AstNode, AstPtr};
@@ -23,7 +21,7 @@ use crate::{
     nameres::CrateDefMap,
     path::{ModPath, Path},
     src::HasSource,
-    DefWithBodyId, HasModule, Lookup, ModuleId,
+    AsMacroCall, DefWithBodyId, HasModule, Lookup, ModuleId,
 };
 
 pub(crate) struct Expander {
@@ -51,30 +49,26 @@ impl Expander {
         db: &DB,
         macro_call: ast::MacroCall,
     ) -> Option<(Mark, T)> {
-        let ast_id = AstId::new(
-            self.current_file_id,
-            db.ast_id_map(self.current_file_id).ast_id(&macro_call),
-        );
-
-        if let Some(path) = macro_call.path().and_then(|path| self.parse_mod_path(path)) {
-            if let Some(def) = self.resolve_path_as_macro(db, &path) {
-                let call_id = def.as_call_id(db, MacroCallKind::FnLike(ast_id));
-                let file_id = call_id.as_file();
-                if let Some(node) = db.parse_or_expand(file_id) {
-                    if let Some(expr) = T::cast(node) {
-                        log::debug!("macro expansion {:#?}", expr.syntax());
-
-                        let mark = Mark {
-                            file_id: self.current_file_id,
-                            ast_id_map: mem::take(&mut self.ast_id_map),
-                            bomb: DropBomb::new("expansion mark dropped"),
-                        };
-                        self.hygiene = Hygiene::new(db, file_id);
-                        self.current_file_id = file_id;
-                        self.ast_id_map = db.ast_id_map(file_id);
-
-                        return Some((mark, expr));
-                    }
+        let macro_call = InFile::new(self.current_file_id, &macro_call);
+
+        if let Some(call_id) =
+            macro_call.as_call_id(db, |path| self.resolve_path_as_macro(db, &path))
+        {
+            let file_id = call_id.as_file();
+            if let Some(node) = db.parse_or_expand(file_id) {
+                if let Some(expr) = T::cast(node) {
+                    log::debug!("macro expansion {:#?}", expr.syntax());
+
+                    let mark = Mark {
+                        file_id: self.current_file_id,
+                        ast_id_map: mem::take(&mut self.ast_id_map),
+                        bomb: DropBomb::new("expansion mark dropped"),
+                    };
+                    self.hygiene = Hygiene::new(db, file_id);
+                    self.current_file_id = file_id;
+                    self.ast_id_map = db.ast_id_map(file_id);
+
+                    return Some((mark, expr));
                 }
             }
         }
@@ -99,10 +93,6 @@ impl Expander {
         Path::from_src(path, &self.hygiene)
     }
 
-    fn parse_mod_path(&mut self, path: ast::Path) -> Option<ModPath> {
-        ModPath::from_src(path, &self.hygiene)
-    }
-
     fn resolve_path_as_macro(&self, db: &impl DefDatabase, path: &ModPath) -> Option<MacroDefId> {
         self.crate_def_map
             .resolve_path(db, self.module.local_id, path, BuiltinShadowMode::Other)
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index e656f9a41..1fc892362 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -8,7 +8,7 @@ use ra_arena::Arena;
 use ra_syntax::{
     ast::{
         self, ArgListOwner, ArrayExprKind, LiteralKind, LoopBodyOwner, ModuleItemOwner, NameOwner,
-        TypeAscriptionOwner,
+        SlicePatComponents, TypeAscriptionOwner,
     },
     AstNode, AstPtr,
 };
@@ -164,9 +164,9 @@ where
                             let match_expr = self.collect_expr_opt(condition.expr());
                             let placeholder_pat = self.missing_pat();
                             let arms = vec![
-                                MatchArm { pats: vec![pat], expr: then_branch, guard: None },
+                                MatchArm { pat, expr: then_branch, guard: None },
                                 MatchArm {
-                                    pats: vec![placeholder_pat],
+                                    pat: placeholder_pat,
                                     expr: else_branch.unwrap_or_else(|| self.empty_block()),
                                     guard: None,
                                 },
@@ -203,8 +203,8 @@ where
                             let placeholder_pat = self.missing_pat();
                             let break_ = self.alloc_expr_desugared(Expr::Break { expr: None });
                             let arms = vec![
-                                MatchArm { pats: vec![pat], expr: body, guard: None },
-                                MatchArm { pats: vec![placeholder_pat], expr: break_, guard: None },
+                                MatchArm { pat, expr: body, guard: None },
+                                MatchArm { pat: placeholder_pat, expr: break_, guard: None },
                             ];
                             let match_expr =
                                 self.alloc_expr_desugared(Expr::Match { expr: match_expr, arms });
@@ -250,7 +250,7 @@ where
                     match_arm_list
                         .arms()
                         .map(|arm| MatchArm {
-                            pats: arm.pats().map(|p| self.collect_pat(p)).collect(),
+                            pat: self.collect_pat_opt(arm.pat()),
                             expr: self.collect_expr_opt(arm.expr()),
                             guard: arm
                                 .guard()
@@ -587,11 +587,16 @@ where
                 let path = p.path().and_then(|path| self.expander.parse_path(path));
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
+            ast::Pat::OrPat(p) => {
+                let pats = p.pats().map(|p| self.collect_pat(p)).collect();
+                Pat::Or(pats)
+            }
+            ast::Pat::ParenPat(p) => return self.collect_pat_opt(p.pat()),
             ast::Pat::TuplePat(p) => {
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::Tuple(args)
             }
-            ast::Pat::PlaceholderPat(_) => Pat::Wild,
+            ast::Pat::PlaceholderPat(_) | ast::Pat::DotDotPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
                 let path = p.path().and_then(|path| self.expander.parse_path(path));
                 let record_field_pat_list =
@@ -616,12 +621,20 @@ where
 
                 Pat::Record { path, args: fields }
             }
+            ast::Pat::SlicePat(p) => {
+                let SlicePatComponents { prefix, slice, suffix } = p.components();
+
+                Pat::Slice {
+                    prefix: prefix.into_iter().map(|p| self.collect_pat(p)).collect(),
+                    slice: slice.map(|p| self.collect_pat(p)),
+                    suffix: suffix.into_iter().map(|p| self.collect_pat(p)).collect(),
+                }
+            }
 
             // FIXME: implement
-            ast::Pat::DotDotPat(_) => Pat::Missing,
             ast::Pat::BoxPat(_) => Pat::Missing,
             ast::Pat::LiteralPat(_) => Pat::Missing,
-            ast::Pat::SlicePat(_) | ast::Pat::RangePat(_) => Pat::Missing,
+            ast::Pat::RangePat(_) => Pat::Missing,
         };
         let ptr = AstPtr::new(&pat);
         self.alloc_pat(pattern, Either::Left(ptr))
diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
index a63552327..a58a7b21f 100644
--- a/crates/ra_hir_def/src/body/scope.rs
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -158,9 +158,7 @@ fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope
             compute_expr_scopes(*expr, body, scopes, scope);
             for arm in arms {
                 let scope = scopes.new_scope(scope);
-                for pat in &arm.pats {
-                    scopes.add_bindings(body, scope, *pat);
-                }
+                scopes.add_bindings(body, scope, arm.pat);
                 scopes.set_scope(arm.expr, scope);
                 compute_expr_scopes(arm.expr, body, scopes, scope);
             }
@@ -194,7 +192,7 @@ mod tests {
         let (off, code) = extract_offset(code);
         let code = {
             let mut buf = String::new();
-            let off = u32::from(off) as usize;
+            let off = off.to_usize();
             buf.push_str(&code[..off]);
             buf.push_str("marker");
             buf.push_str(&code[off..]);
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index a75ef9970..9707c5527 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -202,7 +202,7 @@ pub enum Array {
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MatchArm {
-    pub pats: Vec<PatId>,
+    pub pat: PatId,
     pub guard: Option<ExprId>,
     pub expr: ExprId,
 }
@@ -382,6 +382,7 @@ pub enum Pat {
     Missing,
     Wild,
     Tuple(Vec<PatId>),
+    Or(Vec<PatId>),
     Record {
         path: Option<Path>,
         args: Vec<RecordFieldPat>,
@@ -393,7 +394,7 @@ pub enum Pat {
     },
     Slice {
         prefix: Vec<PatId>,
-        rest: Option<PatId>,
+        slice: Option<PatId>,
         suffix: Vec<PatId>,
     },
     Path(Path),
@@ -420,12 +421,12 @@ impl Pat {
             Pat::Bind { subpat, .. } => {
                 subpat.iter().copied().for_each(f);
             }
-            Pat::Tuple(args) | Pat::TupleStruct { args, .. } => {
+            Pat::Or(args) | Pat::Tuple(args) | Pat::TupleStruct { args, .. } => {
                 args.iter().copied().for_each(f);
             }
             Pat::Ref { pat, .. } => f(*pat),
-            Pat::Slice { prefix, rest, suffix } => {
-                let total_iter = prefix.iter().chain(rest.iter()).chain(suffix.iter());
+            Pat::Slice { prefix, slice, suffix } => {
+                let total_iter = prefix.iter().chain(slice.iter()).chain(suffix.iter());
                 total_iter.copied().for_each(f);
             }
             Pat::Record { args, .. } => {
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index feb3a300d..aa0b558b8 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -46,7 +46,10 @@ mod marks;
 
 use std::hash::Hash;
 
-use hir_expand::{ast_id_map::FileAstId, AstId, HirFileId, InFile, MacroDefId};
+use hir_expand::{
+    ast_id_map::FileAstId, db::AstDatabase, hygiene::Hygiene, AstId, HirFileId, InFile,
+    MacroCallId, MacroCallKind, MacroDefId,
+};
 use ra_arena::{impl_arena_id, RawId};
 use ra_db::{impl_intern_key, salsa, CrateId};
 use ra_syntax::{ast, AstNode};
@@ -413,3 +416,61 @@ impl HasModule for StaticLoc {
         self.container.module(db)
     }
 }
+
+/// A helper trait for converting to MacroCallId
+pub trait AsMacroCall {
+    fn as_call_id(
+        &self,
+        db: &(impl db::DefDatabase + AstDatabase),
+        resolver: impl Fn(path::ModPath) -> Option<MacroDefId>,
+    ) -> Option<MacroCallId>;
+}
+
+impl AsMacroCall for InFile<&ast::MacroCall> {
+    fn as_call_id(
+        &self,
+        db: &(impl db::DefDatabase + AstDatabase),
+        resolver: impl Fn(path::ModPath) -> Option<MacroDefId>,
+    ) -> Option<MacroCallId> {
+        let ast_id = AstId::new(self.file_id, db.ast_id_map(self.file_id).ast_id(self.value));
+        let h = Hygiene::new(db, self.file_id);
+        let path = path::ModPath::from_src(self.value.path()?, &h)?;
+
+        AstIdWithPath::new(ast_id.file_id, ast_id.value, path).as_call_id(db, resolver)
+    }
+}
+
+/// Helper wrapper for `AstId` with `ModPath`
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct AstIdWithPath<T: ast::AstNode> {
+    pub ast_id: AstId<T>,
+    pub path: path::ModPath,
+}
+
+impl<T: ast::AstNode> AstIdWithPath<T> {
+    pub fn new(file_id: HirFileId, ast_id: FileAstId<T>, path: path::ModPath) -> AstIdWithPath<T> {
+        AstIdWithPath { ast_id: AstId::new(file_id, ast_id), path }
+    }
+}
+
+impl AsMacroCall for AstIdWithPath<ast::MacroCall> {
+    fn as_call_id(
+        &self,
+        db: &impl AstDatabase,
+        resolver: impl Fn(path::ModPath) -> Option<MacroDefId>,
+    ) -> Option<MacroCallId> {
+        let def = resolver(self.path.clone())?;
+        Some(def.as_call_id(db, MacroCallKind::FnLike(self.ast_id.clone())))
+    }
+}
+
+impl AsMacroCall for AstIdWithPath<ast::ModuleItem> {
+    fn as_call_id(
+        &self,
+        db: &impl AstDatabase,
+        resolver: impl Fn(path::ModPath) -> Option<MacroDefId>,
+    ) -> Option<MacroCallId> {
+        let def = resolver(self.path.clone())?;
+        Some(def.as_call_id(db, MacroCallKind::Attr(self.ast_id.clone())))
+    }
+}
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 6352c71ef..51c65a5d7 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -7,7 +7,7 @@ use hir_expand::{
     builtin_derive::find_builtin_derive,
     builtin_macro::find_builtin_macro,
     name::{name, AsName, Name},
-    HirFileId, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind,
+    HirFileId, MacroCallId, MacroDefId, MacroDefKind,
 };
 use ra_cfg::CfgOptions;
 use ra_db::{CrateId, FileId};
@@ -25,8 +25,9 @@ use crate::{
     path::{ImportAlias, ModPath, PathKind},
     per_ns::PerNs,
     visibility::Visibility,
-    AdtId, AstId, ConstLoc, ContainerId, EnumLoc, EnumVariantId, FunctionLoc, ImplLoc, Intern,
-    LocalModuleId, ModuleDefId, ModuleId, StaticLoc, StructLoc, TraitLoc, TypeAliasLoc, UnionLoc,
+    AdtId, AsMacroCall, AstId, AstIdWithPath, ConstLoc, ContainerId, EnumLoc, EnumVariantId,
+    FunctionLoc, ImplLoc, Intern, LocalModuleId, ModuleDefId, ModuleId, StaticLoc, StructLoc,
+    TraitLoc, TypeAliasLoc, UnionLoc,
 };
 
 pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> CrateDefMap {
@@ -99,11 +100,16 @@ struct ImportDirective {
 #[derive(Clone, Debug, Eq, PartialEq)]
 struct MacroDirective {
     module_id: LocalModuleId,
-    ast_id: AstId<ast::MacroCall>,
-    path: ModPath,
+    ast_id: AstIdWithPath<ast::MacroCall>,
     legacy: Option<MacroCallId>,
 }
 
+#[derive(Clone, Debug, Eq, PartialEq)]
+struct DeriveDirective {
+    module_id: LocalModuleId,
+    ast_id: AstIdWithPath<ast::ModuleItem>,
+}
+
 /// Walks the tree of module recursively
 struct DefCollector<'a, DB> {
     db: &'a DB,
@@ -112,7 +118,7 @@ struct DefCollector<'a, DB> {
     unresolved_imports: Vec<ImportDirective>,
     resolved_imports: Vec<ImportDirective>,
     unexpanded_macros: Vec<MacroDirective>,
-    unexpanded_attribute_macros: Vec<(LocalModuleId, AstId<ast::ModuleItem>, ModPath)>,
+    unexpanded_attribute_macros: Vec<DeriveDirective>,
     mod_dirs: FxHashMap<LocalModuleId, ModDir>,
     cfg_options: &'a CfgOptions,
 }
@@ -146,7 +152,7 @@ where
                 ReachedFixedPoint::Yes => break,
                 ReachedFixedPoint::No => i += 1,
             }
-            if i == 1000 {
+            if i == 10000 {
                 log::error!("name resolution is stuck");
                 break;
             }
@@ -515,16 +521,16 @@ where
                 return false;
             }
 
-            let resolved_res = self.def_map.resolve_path_fp_with_macro(
-                self.db,
-                ResolveMode::Other,
-                directive.module_id,
-                &directive.path,
-                BuiltinShadowMode::Module,
-            );
-
-            if let Some(def) = resolved_res.resolved_def.take_macros() {
-                let call_id = def.as_call_id(self.db, MacroCallKind::FnLike(directive.ast_id));
+            if let Some(call_id) = directive.ast_id.as_call_id(self.db, |path| {
+                let resolved_res = self.def_map.resolve_path_fp_with_macro(
+                    self.db,
+                    ResolveMode::Other,
+                    directive.module_id,
+                    &path,
+                    BuiltinShadowMode::Module,
+                );
+                resolved_res.resolved_def.take_macros()
+            }) {
                 resolved.push((directive.module_id, call_id));
                 res = ReachedFixedPoint::No;
                 return false;
@@ -532,12 +538,11 @@ where
 
             true
         });
-        attribute_macros.retain(|(module_id, ast_id, path)| {
-            let resolved_res = self.resolve_attribute_macro(path);
-
-            if let Some(def) = resolved_res {
-                let call_id = def.as_call_id(self.db, MacroCallKind::Attr(*ast_id));
-                resolved.push((*module_id, call_id));
+        attribute_macros.retain(|directive| {
+            if let Some(call_id) =
+                directive.ast_id.as_call_id(self.db, |path| self.resolve_attribute_macro(&path))
+            {
+                resolved.push((directive.module_id, call_id));
                 res = ReachedFixedPoint::No;
                 return false;
             }
@@ -833,20 +838,22 @@ where
                 };
                 let path = ModPath::from_tt_ident(ident);
 
-                let ast_id = AstId::new(self.file_id, def.kind.ast_id());
-                self.def_collector.unexpanded_attribute_macros.push((self.module_id, ast_id, path));
+                let ast_id = AstIdWithPath::new(self.file_id, def.kind.ast_id(), path);
+                self.def_collector
+                    .unexpanded_attribute_macros
+                    .push(DeriveDirective { module_id: self.module_id, ast_id });
             }
         }
     }
 
     fn collect_macro(&mut self, mac: &raw::MacroData) {
-        let ast_id = AstId::new(self.file_id, mac.ast_id);
+        let mut ast_id = AstIdWithPath::new(self.file_id, mac.ast_id, mac.path.clone());
 
         // Case 0: builtin macros
         if mac.builtin {
             if let Some(name) = &mac.name {
                 let krate = self.def_collector.def_map.krate;
-                if let Some(macro_id) = find_builtin_macro(name, krate, ast_id) {
+                if let Some(macro_id) = find_builtin_macro(name, krate, ast_id.ast_id) {
                     self.def_collector.define_macro(
                         self.module_id,
                         name.clone(),
@@ -862,7 +869,7 @@ where
         if is_macro_rules(&mac.path) {
             if let Some(name) = &mac.name {
                 let macro_id = MacroDefId {
-                    ast_id: Some(ast_id),
+                    ast_id: Some(ast_id.ast_id),
                     krate: Some(self.def_collector.def_map.krate),
                     kind: MacroDefKind::Declarative,
                 };
@@ -872,15 +879,13 @@ where
         }
 
         // Case 2: try to resolve in legacy scope and expand macro_rules
-        if let Some(macro_def) = mac.path.as_ident().and_then(|name| {
-            self.def_collector.def_map[self.module_id].scope.get_legacy_macro(&name)
+        if let Some(macro_call_id) = ast_id.as_call_id(self.def_collector.db, |path| {
+            path.as_ident().and_then(|name| {
+                self.def_collector.def_map[self.module_id].scope.get_legacy_macro(&name)
+            })
         }) {
-            let macro_call_id =
-                macro_def.as_call_id(self.def_collector.db, MacroCallKind::FnLike(ast_id));
-
             self.def_collector.unexpanded_macros.push(MacroDirective {
                 module_id: self.module_id,
-                path: mac.path.clone(),
                 ast_id,
                 legacy: Some(macro_call_id),
             });
@@ -890,14 +895,12 @@ where
 
         // Case 3: resolve in module scope, expand during name resolution.
         // We rewrite simple path `macro_name` to `self::macro_name` to force resolve in module scope only.
-        let mut path = mac.path.clone();
-        if path.is_ident() {
-            path.kind = PathKind::Super(0);
+        if ast_id.path.is_ident() {
+            ast_id.path.kind = PathKind::Super(0);
         }
 
         self.def_collector.unexpanded_macros.push(MacroDirective {
             module_id: self.module_id,
-            path,
             ast_id,
             legacy: None,
         });
diff --git a/crates/ra_hir_def/src/resolver.rs b/crates/ra_hir_def/src/resolver.rs
index 05cf4646a..e2b228e80 100644
--- a/crates/ra_hir_def/src/resolver.rs
+++ b/crates/ra_hir_def/src/resolver.rs
@@ -542,11 +542,7 @@ impl Resolver {
 
     fn push_generic_params_scope(self, db: &impl DefDatabase, def: GenericDefId) -> Resolver {
         let params = db.generic_params(def);
-        if params.types.is_empty() {
-            self
-        } else {
-            self.push_scope(Scope::GenericParams { def, params })
-        }
+        self.push_scope(Scope::GenericParams { def, params })
     }
 
     fn push_impl_block_scope(self, impl_block: ImplId) -> Resolver {
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 7cf3b59a7..9506f2e1c 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -323,11 +323,18 @@ impl<T: Clone> InFile<&T> {
     }
 }
 
+impl<T> InFile<Option<T>> {
+    pub fn transpose(self) -> Option<InFile<T>> {
+        let value = self.value?;
+        Some(InFile::new(self.file_id, value))
+    }
+}
+
 impl InFile<SyntaxNode> {
-    pub fn ancestors_with_macros<'a>(
+    pub fn ancestors_with_macros(
         self,
-        db: &'a impl crate::db::AstDatabase,
-    ) -> impl Iterator<Item = InFile<SyntaxNode>> + 'a {
+        db: &impl crate::db::AstDatabase,
+    ) -> impl Iterator<Item = InFile<SyntaxNode>> + '_ {
         std::iter::successors(Some(self), move |node| match node.value.parent() {
             Some(parent) => Some(node.with_value(parent)),
             None => {
@@ -338,6 +345,15 @@ impl InFile<SyntaxNode> {
     }
 }
 
+impl InFile<SyntaxToken> {
+    pub fn ancestors_with_macros(
+        self,
+        db: &impl crate::db::AstDatabase,
+    ) -> impl Iterator<Item = InFile<SyntaxNode>> + '_ {
+        self.map(|it| it.parent()).ancestors_with_macros(db)
+    }
+}
+
 impl<N: AstNode> InFile<N> {
     pub fn descendants<T: AstNode>(self) -> impl Iterator<Item = InFile<T>> {
         self.value.syntax().descendants().filter_map(T::cast).map(move |n| self.with_value(n))
diff --git a/crates/ra_hir_ty/src/display.rs b/crates/ra_hir_ty/src/display.rs
index d1ff85f0f..14e089cf4 100644
--- a/crates/ra_hir_ty/src/display.rs
+++ b/crates/ra_hir_ty/src/display.rs
@@ -2,7 +2,12 @@
 
 use std::fmt;
 
-use crate::db::HirDatabase;
+use crate::{
+    db::HirDatabase, utils::generics, ApplicationTy, CallableDef, FnSig, GenericPredicate,
+    Obligation, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
+};
+use hir_def::{generics::TypeParamProvenance, AdtId, AssocContainerId, Lookup};
+use hir_expand::name::Name;
 
 pub struct HirFormatter<'a, 'b, DB> {
     pub db: &'a DB,
@@ -97,3 +102,369 @@ where
         })
     }
 }
+
+const TYPE_HINT_TRUNCATION: &str = "…";
+
+impl HirDisplay for &Ty {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        HirDisplay::hir_fmt(*self, f)
+    }
+}
+
+impl HirDisplay for ApplicationTy {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        match self.ctor {
+            TypeCtor::Bool => write!(f, "bool")?,
+            TypeCtor::Char => write!(f, "char")?,
+            TypeCtor::Int(t) => write!(f, "{}", t)?,
+            TypeCtor::Float(t) => write!(f, "{}", t)?,
+            TypeCtor::Str => write!(f, "str")?,
+            TypeCtor::Slice => {
+                let t = self.parameters.as_single();
+                write!(f, "[{}]", t.display(f.db))?;
+            }
+            TypeCtor::Array => {
+                let t = self.parameters.as_single();
+                write!(f, "[{}; _]", t.display(f.db))?;
+            }
+            TypeCtor::RawPtr(m) => {
+                let t = self.parameters.as_single();
+                write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
+            }
+            TypeCtor::Ref(m) => {
+                let t = self.parameters.as_single();
+                let ty_display = if f.omit_verbose_types() {
+                    t.display_truncated(f.db, f.max_size)
+                } else {
+                    t.display(f.db)
+                };
+                write!(f, "&{}{}", m.as_keyword_for_ref(), ty_display)?;
+            }
+            TypeCtor::Never => write!(f, "!")?,
+            TypeCtor::Tuple { .. } => {
+                let ts = &self.parameters;
+                if ts.len() == 1 {
+                    write!(f, "({},)", ts[0].display(f.db))?;
+                } else {
+                    write!(f, "(")?;
+                    f.write_joined(&*ts.0, ", ")?;
+                    write!(f, ")")?;
+                }
+            }
+            TypeCtor::FnPtr { .. } => {
+                let sig = FnSig::from_fn_ptr_substs(&self.parameters);
+                write!(f, "fn(")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, ") -> {}", sig.ret().display(f.db))?;
+            }
+            TypeCtor::FnDef(def) => {
+                let sig = f.db.callable_item_signature(def).subst(&self.parameters);
+                let name = match def {
+                    CallableDef::FunctionId(ff) => f.db.function_data(ff).name.clone(),
+                    CallableDef::StructId(s) => f.db.struct_data(s).name.clone(),
+                    CallableDef::EnumVariantId(e) => {
+                        let enum_data = f.db.enum_data(e.parent);
+                        enum_data.variants[e.local_id].name.clone()
+                    }
+                };
+                match def {
+                    CallableDef::FunctionId(_) => write!(f, "fn {}", name)?,
+                    CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {
+                        write!(f, "{}", name)?
+                    }
+                }
+                if self.parameters.len() > 0 {
+                    let generics = generics(f.db, def.into());
+                    let (parent_params, self_param, type_params, _impl_trait_params) =
+                        generics.provenance_split();
+                    let total_len = parent_params + self_param + type_params;
+                    // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
+                    if total_len > 0 {
+                        write!(f, "<")?;
+                        f.write_joined(&self.parameters.0[..total_len], ", ")?;
+                        write!(f, ">")?;
+                    }
+                }
+                write!(f, "(")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, ") -> {}", sig.ret().display(f.db))?;
+            }
+            TypeCtor::Adt(def_id) => {
+                let name = match def_id {
+                    AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
+                    AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
+                    AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
+                };
+                write!(f, "{}", name)?;
+                if self.parameters.len() > 0 {
+                    write!(f, "<")?;
+
+                    let mut non_default_parameters = Vec::with_capacity(self.parameters.len());
+                    let parameters_to_write = if f.omit_verbose_types() {
+                        match self
+                            .ctor
+                            .as_generic_def()
+                            .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
+                            .filter(|defaults| !defaults.is_empty())
+                        {
+                            Option::None => self.parameters.0.as_ref(),
+                            Option::Some(default_parameters) => {
+                                for (i, parameter) in self.parameters.iter().enumerate() {
+                                    match (parameter, default_parameters.get(i)) {
+                                        (&Ty::Unknown, _) | (_, None) => {
+                                            non_default_parameters.push(parameter.clone())
+                                        }
+                                        (_, Some(default_parameter))
+                                            if parameter != default_parameter =>
+                                        {
+                                            non_default_parameters.push(parameter.clone())
+                                        }
+                                        _ => (),
+                                    }
+                                }
+                                &non_default_parameters
+                            }
+                        }
+                    } else {
+                        self.parameters.0.as_ref()
+                    };
+
+                    f.write_joined(parameters_to_write, ", ")?;
+                    write!(f, ">")?;
+                }
+            }
+            TypeCtor::AssociatedType(type_alias) => {
+                let trait_ = match type_alias.lookup(f.db).container {
+                    AssocContainerId::TraitId(it) => it,
+                    _ => panic!("not an associated type"),
+                };
+                let trait_name = f.db.trait_data(trait_).name.clone();
+                let name = f.db.type_alias_data(type_alias).name.clone();
+                write!(f, "{}::{}", trait_name, name)?;
+                if self.parameters.len() > 0 {
+                    write!(f, "<")?;
+                    f.write_joined(&*self.parameters.0, ", ")?;
+                    write!(f, ">")?;
+                }
+            }
+            TypeCtor::Closure { .. } => {
+                let sig = self.parameters[0]
+                    .callable_sig(f.db)
+                    .expect("first closure parameter should contain signature");
+                let return_type_hint = sig.ret().display(f.db);
+                if sig.params().is_empty() {
+                    write!(f, "|| -> {}", return_type_hint)?;
+                } else if f.omit_verbose_types() {
+                    write!(f, "|{}| -> {}", TYPE_HINT_TRUNCATION, return_type_hint)?;
+                } else {
+                    write!(f, "|")?;
+                    f.write_joined(sig.params(), ", ")?;
+                    write!(f, "| -> {}", return_type_hint)?;
+                };
+            }
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for ProjectionTy {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        let trait_name = f.db.trait_data(self.trait_(f.db)).name.clone();
+        write!(f, "<{} as {}", self.parameters[0].display(f.db), trait_name,)?;
+        if self.parameters.len() > 1 {
+            write!(f, "<")?;
+            f.write_joined(&self.parameters[1..], ", ")?;
+            write!(f, ">")?;
+        }
+        write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
+        Ok(())
+    }
+}
+
+impl HirDisplay for Ty {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        match self {
+            Ty::Apply(a_ty) => a_ty.hir_fmt(f)?,
+            Ty::Projection(p_ty) => p_ty.hir_fmt(f)?,
+            Ty::Placeholder(id) => {
+                let generics = generics(f.db, id.parent);
+                let param_data = &generics.params.types[id.local_id];
+                match param_data.provenance {
+                    TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
+                        write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
+                    }
+                    TypeParamProvenance::ArgumentImplTrait => {
+                        write!(f, "impl ")?;
+                        let bounds = f.db.generic_predicates_for_param(*id);
+                        let substs = Substs::type_params_for_generics(&generics);
+                        write_bounds_like_dyn_trait(
+                            &bounds.iter().map(|b| b.clone().subst(&substs)).collect::<Vec<_>>(),
+                            f,
+                        )?;
+                    }
+                }
+            }
+            Ty::Bound(idx) => write!(f, "?{}", idx)?,
+            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
+                match self {
+                    Ty::Dyn(_) => write!(f, "dyn ")?,
+                    Ty::Opaque(_) => write!(f, "impl ")?,
+                    _ => unreachable!(),
+                };
+                write_bounds_like_dyn_trait(&predicates, f)?;
+            }
+            Ty::Unknown => write!(f, "{{unknown}}")?,
+            Ty::Infer(..) => write!(f, "_")?,
+        }
+        Ok(())
+    }
+}
+
+fn write_bounds_like_dyn_trait(
+    predicates: &[GenericPredicate],
+    f: &mut HirFormatter<impl HirDatabase>,
+) -> fmt::Result {
+    // Note: This code is written to produce nice results (i.e.
+    // corresponding to surface Rust) for types that can occur in
+    // actual Rust. It will have weird results if the predicates
+    // aren't as expected (i.e. self types = $0, projection
+    // predicates for a certain trait come after the Implemented
+    // predicate for that trait).
+    let mut first = true;
+    let mut angle_open = false;
+    for p in predicates.iter() {
+        match p {
+            GenericPredicate::Implemented(trait_ref) => {
+                if angle_open {
+                    write!(f, ">")?;
+                }
+                if !first {
+                    write!(f, " + ")?;
+                }
+                // We assume that the self type is $0 (i.e. the
+                // existential) here, which is the only thing that's
+                // possible in actual Rust, and hence don't print it
+                write!(f, "{}", f.db.trait_data(trait_ref.trait_).name.clone())?;
+                if trait_ref.substs.len() > 1 {
+                    write!(f, "<")?;
+                    f.write_joined(&trait_ref.substs[1..], ", ")?;
+                    // there might be assoc type bindings, so we leave the angle brackets open
+                    angle_open = true;
+                }
+            }
+            GenericPredicate::Projection(projection_pred) => {
+                // in types in actual Rust, these will always come
+                // after the corresponding Implemented predicate
+                if angle_open {
+                    write!(f, ", ")?;
+                } else {
+                    write!(f, "<")?;
+                    angle_open = true;
+                }
+                let name =
+                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name.clone();
+                write!(f, "{} = ", name)?;
+                projection_pred.ty.hir_fmt(f)?;
+            }
+            GenericPredicate::Error => {
+                if angle_open {
+                    // impl Trait<X, {error}>
+                    write!(f, ", ")?;
+                } else if !first {
+                    // impl Trait + {error}
+                    write!(f, " + ")?;
+                }
+                p.hir_fmt(f)?;
+            }
+        }
+        first = false;
+    }
+    if angle_open {
+        write!(f, ">")?;
+    }
+    Ok(())
+}
+
+impl TraitRef {
+    fn hir_fmt_ext(&self, f: &mut HirFormatter<impl HirDatabase>, use_as: bool) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        self.substs[0].hir_fmt(f)?;
+        if use_as {
+            write!(f, " as ")?;
+        } else {
+            write!(f, ": ")?;
+        }
+        write!(f, "{}", f.db.trait_data(self.trait_).name.clone())?;
+        if self.substs.len() > 1 {
+            write!(f, "<")?;
+            f.write_joined(&self.substs[1..], ", ")?;
+            write!(f, ">")?;
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for TraitRef {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        self.hir_fmt_ext(f, false)
+    }
+}
+
+impl HirDisplay for &GenericPredicate {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        HirDisplay::hir_fmt(*self, f)
+    }
+}
+
+impl HirDisplay for GenericPredicate {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        if f.should_truncate() {
+            return write!(f, "{}", TYPE_HINT_TRUNCATION);
+        }
+
+        match self {
+            GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
+            GenericPredicate::Projection(projection_pred) => {
+                write!(f, "<")?;
+                projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
+                write!(
+                    f,
+                    ">::{} = {}",
+                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
+                    projection_pred.ty.display(f.db)
+                )?;
+            }
+            GenericPredicate::Error => write!(f, "{{error}}")?,
+        }
+        Ok(())
+    }
+}
+
+impl HirDisplay for Obligation {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
+        match self {
+            Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db)),
+            Obligation::Projection(proj) => write!(
+                f,
+                "Normalize({} => {})",
+                proj.projection_ty.display(f.db),
+                proj.ty.display(f.db)
+            ),
+        }
+    }
+}
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 3c9c02d03..39d8bc0ca 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -165,12 +165,14 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::Match { expr, arms } => {
                 let input_ty = self.infer_expr(*expr, &Expectation::none());
 
-                let mut result_ty = self.table.new_maybe_never_type_var();
+                let mut result_ty = if arms.len() == 0 {
+                    Ty::simple(TypeCtor::Never)
+                } else {
+                    self.table.new_type_var()
+                };
 
                 for arm in arms {
-                    for &pat in &arm.pats {
-                        let _pat_ty = self.infer_pat(pat, &input_ty, BindingMode::default());
-                    }
+                    let _pat_ty = self.infer_pat(arm.pat, &input_ty, BindingMode::default());
                     if let Some(guard_expr) = arm.guard {
                         self.infer_expr(
                             guard_expr,
diff --git a/crates/ra_hir_ty/src/infer/pat.rs b/crates/ra_hir_ty/src/infer/pat.rs
index e7283f24c..a5dfdf6c4 100644
--- a/crates/ra_hir_ty/src/infer/pat.rs
+++ b/crates/ra_hir_ty/src/infer/pat.rs
@@ -82,6 +82,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
         let is_non_ref_pat = match &body[pat] {
             Pat::Tuple(..)
+            | Pat::Or(..)
             | Pat::TupleStruct { .. }
             | Pat::Record { .. }
             | Pat::Range { .. }
@@ -126,6 +127,17 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
             }
+            Pat::Or(ref pats) => {
+                if let Some((first_pat, rest)) = pats.split_first() {
+                    let ty = self.infer_pat(*first_pat, expected, default_bm);
+                    for pat in rest {
+                        self.infer_pat(*pat, expected, default_bm);
+                    }
+                    ty
+                } else {
+                    Ty::Unknown
+                }
+            }
             Pat::Ref { pat, mutability } => {
                 let expectation = match expected.as_reference() {
                     Some((inner_ty, exp_mut)) => {
diff --git a/crates/ra_hir_ty/src/infer/unify.rs b/crates/ra_hir_ty/src/infer/unify.rs
index fe05642ae..1dc842f40 100644
--- a/crates/ra_hir_ty/src/infer/unify.rs
+++ b/crates/ra_hir_ty/src/infer/unify.rs
@@ -249,6 +249,8 @@ impl InferenceTable {
         match (ty1, ty2) {
             (Ty::Unknown, _) | (_, Ty::Unknown) => true,
 
+            (Ty::Placeholder(p1), Ty::Placeholder(p2)) if *p1 == *p2 => true,
+
             (Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2)))
             | (Ty::Infer(InferTy::IntVar(tv1)), Ty::Infer(InferTy::IntVar(tv2)))
             | (Ty::Infer(InferTy::FloatVar(tv1)), Ty::Infer(InferTy::FloatVar(tv2)))
diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs
index c5fe18c85..571579cc4 100644
--- a/crates/ra_hir_ty/src/lib.rs
+++ b/crates/ra_hir_ty/src/lib.rs
@@ -41,13 +41,12 @@ mod marks;
 
 use std::ops::Deref;
 use std::sync::Arc;
-use std::{fmt, iter, mem};
+use std::{iter, mem};
 
 use hir_def::{
-    expr::ExprId, generics::TypeParamProvenance, type_ref::Mutability, AdtId, AssocContainerId,
-    DefWithBodyId, GenericDefId, HasModule, Lookup, TraitId, TypeAliasId, TypeParamId,
+    expr::ExprId, type_ref::Mutability, AdtId, AssocContainerId, DefWithBodyId, GenericDefId,
+    HasModule, Lookup, TraitId, TypeAliasId, TypeParamId,
 };
-use hir_expand::name::Name;
 use ra_db::{impl_intern_key, salsa, CrateId};
 
 use crate::{
@@ -55,7 +54,7 @@ use crate::{
     primitive::{FloatTy, IntTy, Uncertain},
     utils::{generics, make_mut_slice, Generics},
 };
-use display::{HirDisplay, HirFormatter};
+use display::HirDisplay;
 
 pub use autoderef::autoderef;
 pub use infer::{do_infer_query, InferTy, InferenceResult};
@@ -291,7 +290,7 @@ pub enum Ty {
     /// {}` when we're type-checking the body of that function. In this
     /// situation, we know this stands for *some* type, but don't know the exact
     /// type.
-    Param(TypeParamId),
+    Placeholder(TypeParamId),
 
     /// A bound type variable. This is used in various places: when representing
     /// some polymorphic type like the type of function `fn f<T>`, the type
@@ -365,7 +364,7 @@ impl Substs {
 
     /// Return Substs that replace each parameter by itself (i.e. `Ty::Param`).
     pub(crate) fn type_params_for_generics(generic_params: &Generics) -> Substs {
-        Substs(generic_params.iter().map(|(id, _)| Ty::Param(id)).collect())
+        Substs(generic_params.iter().map(|(id, _)| Ty::Placeholder(id)).collect())
     }
 
     /// Return Substs that replace each parameter by itself (i.e. `Ty::Param`).
@@ -813,7 +812,7 @@ impl TypeWalk for Ty {
                     p.walk(f);
                 }
             }
-            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
+            Ty::Placeholder { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
         }
         f(self);
     }
@@ -831,374 +830,8 @@ impl TypeWalk for Ty {
                     p.walk_mut_binders(f, binders + 1);
                 }
             }
-            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
+            Ty::Placeholder { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
         }
         f(self, binders);
     }
 }
-
-const TYPE_HINT_TRUNCATION: &str = "…";
-
-impl HirDisplay for &Ty {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        HirDisplay::hir_fmt(*self, f)
-    }
-}
-
-impl HirDisplay for ApplicationTy {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        if f.should_truncate() {
-            return write!(f, "{}", TYPE_HINT_TRUNCATION);
-        }
-
-        match self.ctor {
-            TypeCtor::Bool => write!(f, "bool")?,
-            TypeCtor::Char => write!(f, "char")?,
-            TypeCtor::Int(t) => write!(f, "{}", t)?,
-            TypeCtor::Float(t) => write!(f, "{}", t)?,
-            TypeCtor::Str => write!(f, "str")?,
-            TypeCtor::Slice => {
-                let t = self.parameters.as_single();
-                write!(f, "[{}]", t.display(f.db))?;
-            }
-            TypeCtor::Array => {
-                let t = self.parameters.as_single();
-                write!(f, "[{}; _]", t.display(f.db))?;
-            }
-            TypeCtor::RawPtr(m) => {
-                let t = self.parameters.as_single();
-                write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
-            }
-            TypeCtor::Ref(m) => {
-                let t = self.parameters.as_single();
-                let ty_display = if f.omit_verbose_types() {
-                    t.display_truncated(f.db, f.max_size)
-                } else {
-                    t.display(f.db)
-                };
-                write!(f, "&{}{}", m.as_keyword_for_ref(), ty_display)?;
-            }
-            TypeCtor::Never => write!(f, "!")?,
-            TypeCtor::Tuple { .. } => {
-                let ts = &self.parameters;
-                if ts.len() == 1 {
-                    write!(f, "({},)", ts[0].display(f.db))?;
-                } else {
-                    write!(f, "(")?;
-                    f.write_joined(&*ts.0, ", ")?;
-                    write!(f, ")")?;
-                }
-            }
-            TypeCtor::FnPtr { .. } => {
-                let sig = FnSig::from_fn_ptr_substs(&self.parameters);
-                write!(f, "fn(")?;
-                f.write_joined(sig.params(), ", ")?;
-                write!(f, ") -> {}", sig.ret().display(f.db))?;
-            }
-            TypeCtor::FnDef(def) => {
-                let sig = f.db.callable_item_signature(def).subst(&self.parameters);
-                let name = match def {
-                    CallableDef::FunctionId(ff) => f.db.function_data(ff).name.clone(),
-                    CallableDef::StructId(s) => f.db.struct_data(s).name.clone(),
-                    CallableDef::EnumVariantId(e) => {
-                        let enum_data = f.db.enum_data(e.parent);
-                        enum_data.variants[e.local_id].name.clone()
-                    }
-                };
-                match def {
-                    CallableDef::FunctionId(_) => write!(f, "fn {}", name)?,
-                    CallableDef::StructId(_) | CallableDef::EnumVariantId(_) => {
-                        write!(f, "{}", name)?
-                    }
-                }
-                if self.parameters.len() > 0 {
-                    let generics = generics(f.db, def.into());
-                    let (parent_params, self_param, type_params, _impl_trait_params) =
-                        generics.provenance_split();
-                    let total_len = parent_params + self_param + type_params;
-                    // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
-                    if total_len > 0 {
-                        write!(f, "<")?;
-                        f.write_joined(&self.parameters.0[..total_len], ", ")?;
-                        write!(f, ">")?;
-                    }
-                }
-                write!(f, "(")?;
-                f.write_joined(sig.params(), ", ")?;
-                write!(f, ") -> {}", sig.ret().display(f.db))?;
-            }
-            TypeCtor::Adt(def_id) => {
-                let name = match def_id {
-                    AdtId::StructId(it) => f.db.struct_data(it).name.clone(),
-                    AdtId::UnionId(it) => f.db.union_data(it).name.clone(),
-                    AdtId::EnumId(it) => f.db.enum_data(it).name.clone(),
-                };
-                write!(f, "{}", name)?;
-                if self.parameters.len() > 0 {
-                    write!(f, "<")?;
-
-                    let mut non_default_parameters = Vec::with_capacity(self.parameters.len());
-                    let parameters_to_write = if f.omit_verbose_types() {
-                        match self
-                            .ctor
-                            .as_generic_def()
-                            .map(|generic_def_id| f.db.generic_defaults(generic_def_id))
-                            .filter(|defaults| !defaults.is_empty())
-                        {
-                            Option::None => self.parameters.0.as_ref(),
-                            Option::Some(default_parameters) => {
-                                for (i, parameter) in self.parameters.iter().enumerate() {
-                                    match (parameter, default_parameters.get(i)) {
-                                        (&Ty::Unknown, _) | (_, None) => {
-                                            non_default_parameters.push(parameter.clone())
-                                        }
-                                        (_, Some(default_parameter))
-                                            if parameter != default_parameter =>
-                                        {
-                                            non_default_parameters.push(parameter.clone())
-                                        }
-                                        _ => (),
-                                    }
-                                }
-                                &non_default_parameters
-                            }
-                        }
-                    } else {
-                        self.parameters.0.as_ref()
-                    };
-
-                    f.write_joined(parameters_to_write, ", ")?;
-                    write!(f, ">")?;
-                }
-            }
-            TypeCtor::AssociatedType(type_alias) => {
-                let trait_ = match type_alias.lookup(f.db).container {
-                    AssocContainerId::TraitId(it) => it,
-                    _ => panic!("not an associated type"),
-                };
-                let trait_name = f.db.trait_data(trait_).name.clone();
-                let name = f.db.type_alias_data(type_alias).name.clone();
-                write!(f, "{}::{}", trait_name, name)?;
-                if self.parameters.len() > 0 {
-                    write!(f, "<")?;
-                    f.write_joined(&*self.parameters.0, ", ")?;
-                    write!(f, ">")?;
-                }
-            }
-            TypeCtor::Closure { .. } => {
-                let sig = self.parameters[0]
-                    .callable_sig(f.db)
-                    .expect("first closure parameter should contain signature");
-                let return_type_hint = sig.ret().display(f.db);
-                if sig.params().is_empty() {
-                    write!(f, "|| -> {}", return_type_hint)?;
-                } else if f.omit_verbose_types() {
-                    write!(f, "|{}| -> {}", TYPE_HINT_TRUNCATION, return_type_hint)?;
-                } else {
-                    write!(f, "|")?;
-                    f.write_joined(sig.params(), ", ")?;
-                    write!(f, "| -> {}", return_type_hint)?;
-                };
-            }
-        }
-        Ok(())
-    }
-}
-
-impl HirDisplay for ProjectionTy {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        if f.should_truncate() {
-            return write!(f, "{}", TYPE_HINT_TRUNCATION);
-        }
-
-        let trait_name = f.db.trait_data(self.trait_(f.db)).name.clone();
-        write!(f, "<{} as {}", self.parameters[0].display(f.db), trait_name,)?;
-        if self.parameters.len() > 1 {
-            write!(f, "<")?;
-            f.write_joined(&self.parameters[1..], ", ")?;
-            write!(f, ">")?;
-        }
-        write!(f, ">::{}", f.db.type_alias_data(self.associated_ty).name)?;
-        Ok(())
-    }
-}
-
-impl HirDisplay for Ty {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        if f.should_truncate() {
-            return write!(f, "{}", TYPE_HINT_TRUNCATION);
-        }
-
-        match self {
-            Ty::Apply(a_ty) => a_ty.hir_fmt(f)?,
-            Ty::Projection(p_ty) => p_ty.hir_fmt(f)?,
-            Ty::Param(id) => {
-                let generics = generics(f.db, id.parent);
-                let param_data = &generics.params.types[id.local_id];
-                match param_data.provenance {
-                    TypeParamProvenance::TypeParamList | TypeParamProvenance::TraitSelf => {
-                        write!(f, "{}", param_data.name.clone().unwrap_or_else(Name::missing))?
-                    }
-                    TypeParamProvenance::ArgumentImplTrait => {
-                        write!(f, "impl ")?;
-                        let bounds = f.db.generic_predicates_for_param(*id);
-                        let substs = Substs::type_params_for_generics(&generics);
-                        write_bounds_like_dyn_trait(
-                            &bounds.iter().map(|b| b.clone().subst(&substs)).collect::<Vec<_>>(),
-                            f,
-                        )?;
-                    }
-                }
-            }
-            Ty::Bound(idx) => write!(f, "?{}", idx)?,
-            Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
-                match self {
-                    Ty::Dyn(_) => write!(f, "dyn ")?,
-                    Ty::Opaque(_) => write!(f, "impl ")?,
-                    _ => unreachable!(),
-                };
-                write_bounds_like_dyn_trait(&predicates, f)?;
-            }
-            Ty::Unknown => write!(f, "{{unknown}}")?,
-            Ty::Infer(..) => write!(f, "_")?,
-        }
-        Ok(())
-    }
-}
-
-fn write_bounds_like_dyn_trait(
-    predicates: &[GenericPredicate],
-    f: &mut HirFormatter<impl HirDatabase>,
-) -> fmt::Result {
-    // Note: This code is written to produce nice results (i.e.
-    // corresponding to surface Rust) for types that can occur in
-    // actual Rust. It will have weird results if the predicates
-    // aren't as expected (i.e. self types = $0, projection
-    // predicates for a certain trait come after the Implemented
-    // predicate for that trait).
-    let mut first = true;
-    let mut angle_open = false;
-    for p in predicates.iter() {
-        match p {
-            GenericPredicate::Implemented(trait_ref) => {
-                if angle_open {
-                    write!(f, ">")?;
-                }
-                if !first {
-                    write!(f, " + ")?;
-                }
-                // We assume that the self type is $0 (i.e. the
-                // existential) here, which is the only thing that's
-                // possible in actual Rust, and hence don't print it
-                write!(f, "{}", f.db.trait_data(trait_ref.trait_).name.clone())?;
-                if trait_ref.substs.len() > 1 {
-                    write!(f, "<")?;
-                    f.write_joined(&trait_ref.substs[1..], ", ")?;
-                    // there might be assoc type bindings, so we leave the angle brackets open
-                    angle_open = true;
-                }
-            }
-            GenericPredicate::Projection(projection_pred) => {
-                // in types in actual Rust, these will always come
-                // after the corresponding Implemented predicate
-                if angle_open {
-                    write!(f, ", ")?;
-                } else {
-                    write!(f, "<")?;
-                    angle_open = true;
-                }
-                let name =
-                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name.clone();
-                write!(f, "{} = ", name)?;
-                projection_pred.ty.hir_fmt(f)?;
-            }
-            GenericPredicate::Error => {
-                if angle_open {
-                    // impl Trait<X, {error}>
-                    write!(f, ", ")?;
-                } else if !first {
-                    // impl Trait + {error}
-                    write!(f, " + ")?;
-                }
-                p.hir_fmt(f)?;
-            }
-        }
-        first = false;
-    }
-    if angle_open {
-        write!(f, ">")?;
-    }
-    Ok(())
-}
-
-impl TraitRef {
-    fn hir_fmt_ext(&self, f: &mut HirFormatter<impl HirDatabase>, use_as: bool) -> fmt::Result {
-        if f.should_truncate() {
-            return write!(f, "{}", TYPE_HINT_TRUNCATION);
-        }
-
-        self.substs[0].hir_fmt(f)?;
-        if use_as {
-            write!(f, " as ")?;
-        } else {
-            write!(f, ": ")?;
-        }
-        write!(f, "{}", f.db.trait_data(self.trait_).name.clone())?;
-        if self.substs.len() > 1 {
-            write!(f, "<")?;
-            f.write_joined(&self.substs[1..], ", ")?;
-            write!(f, ">")?;
-        }
-        Ok(())
-    }
-}
-
-impl HirDisplay for TraitRef {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        self.hir_fmt_ext(f, false)
-    }
-}
-
-impl HirDisplay for &GenericPredicate {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        HirDisplay::hir_fmt(*self, f)
-    }
-}
-
-impl HirDisplay for GenericPredicate {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        if f.should_truncate() {
-            return write!(f, "{}", TYPE_HINT_TRUNCATION);
-        }
-
-        match self {
-            GenericPredicate::Implemented(trait_ref) => trait_ref.hir_fmt(f)?,
-            GenericPredicate::Projection(projection_pred) => {
-                write!(f, "<")?;
-                projection_pred.projection_ty.trait_ref(f.db).hir_fmt_ext(f, true)?;
-                write!(
-                    f,
-                    ">::{} = {}",
-                    f.db.type_alias_data(projection_pred.projection_ty.associated_ty).name,
-                    projection_pred.ty.display(f.db)
-                )?;
-            }
-            GenericPredicate::Error => write!(f, "{{error}}")?,
-        }
-        Ok(())
-    }
-}
-
-impl HirDisplay for Obligation {
-    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
-        match self {
-            Obligation::Trait(tr) => write!(f, "Implements({})", tr.display(f.db)),
-            Obligation::Projection(proj) => write!(
-                f,
-                "Normalize({} => {})",
-                proj.projection_ty.display(f.db),
-                proj.ty.display(f.db)
-            ),
-        }
-    }
-}
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index c68c5852b..6a2aded02 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -14,9 +14,9 @@ use hir_def::{
     path::{GenericArg, Path, PathSegment, PathSegments},
     resolver::{HasResolver, Resolver, TypeNs},
     type_ref::{TypeBound, TypeRef},
-    AdtId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule, ImplId,
-    LocalStructFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
-    VariantId,
+    AdtId, AssocContainerId, ConstId, EnumId, EnumVariantId, FunctionId, GenericDefId, HasModule,
+    ImplId, LocalStructFieldId, Lookup, StaticId, StructId, TraitId, TypeAliasId, TypeParamId,
+    UnionId, VariantId,
 };
 use ra_arena::map::ArenaMap;
 use ra_db::CrateId;
@@ -152,7 +152,7 @@ impl Ty {
                                     data.provenance == TypeParamProvenance::ArgumentImplTrait
                                 })
                                 .nth(idx as usize)
-                                .map_or(Ty::Unknown, |(id, _)| Ty::Param(id));
+                                .map_or(Ty::Unknown, |(id, _)| Ty::Placeholder(id));
                             param
                         } else {
                             Ty::Unknown
@@ -270,7 +270,7 @@ impl Ty {
                 let generics =
                     generics(ctx.db, ctx.resolver.generic_def().expect("generics in scope"));
                 match ctx.type_param_mode {