14 files changed, 1149 insertions, 199 deletions

diff --git a/crates/ide/src/annotations.rs b/crates/ide/src/annotations.rs
index 2e8e82b70..72492f826 100644
--- a/crates/ide/src/annotations.rs
+++ b/crates/ide/src/annotations.rs
@@ -1,12 +1,13 @@
-use hir::Semantics;
+use either::Either;
+use hir::{HasSource, Semantics};
 use ide_db::{
-    base_db::{FileId, FilePosition, FileRange, SourceDatabase},
-    RootDatabase, SymbolKind,
+    base_db::{FileId, FilePosition, FileRange},
+    helpers::visit_file_defs,
+    RootDatabase,
 };
-use syntax::TextRange;
+use syntax::{ast::NameOwner, AstNode, TextRange, TextSize};
 
 use crate::{
-    file_structure::file_structure,
     fn_references::find_all_methods,
     goto_implementation::goto_implementation,
     references::find_all_refs,
@@ -75,39 +76,56 @@ pub(crate) fn annotations(
         }
     }
 
-    file_structure(&db.parse(file_id).tree())
-        .into_iter()
-        .filter(|node| {
-            matches!(
-                node.kind,
-                SymbolKind::Trait
-                    | SymbolKind::Struct
-                    | SymbolKind::Enum
-                    | SymbolKind::Union
-                    | SymbolKind::Const
-            )
-        })
-        .for_each(|node| {
-            if config.annotate_impls && node.kind != SymbolKind::Const {
+    visit_file_defs(&Semantics::new(db), file_id, &mut |def| match def {
+        Either::Left(def) => {
+            let node = match def {
+                hir::ModuleDef::Const(konst) => {
+                    konst.source(db).and_then(|node| range_and_position_of(&node.value))
+                }
+                hir::ModuleDef::Trait(trait_) => {
+                    trait_.source(db).and_then(|node| range_and_position_of(&node.value))
+                }
+                hir::ModuleDef::Adt(hir::Adt::Struct(strukt)) => {
+                    strukt.source(db).and_then(|node| range_and_position_of(&node.value))
+                }
+                hir::ModuleDef::Adt(hir::Adt::Enum(enum_)) => {
+                    enum_.source(db).and_then(|node| range_and_position_of(&node.value))
+                }
+                hir::ModuleDef::Adt(hir::Adt::Union(union)) => {
+                    union.source(db).and_then(|node| range_and_position_of(&node.value))
+                }
+                _ => None,
+            };
+            let (offset, range) = match node {
+                Some(node) => node,
+                None => return,
+            };
+
+            if config.annotate_impls && !matches!(def, hir::ModuleDef::Const(_)) {
                 annotations.push(Annotation {
-                    range: node.node_range,
+                    range,
                     kind: AnnotationKind::HasImpls {
-                        position: FilePosition { file_id, offset: node.navigation_range.start() },
+                        position: FilePosition { file_id, offset },
                         data: None,
                     },
                 });
             }
-
             if config.annotate_references {
                 annotations.push(Annotation {
-                    range: node.node_range,
+                    range,
                     kind: AnnotationKind::HasReferences {
-                        position: FilePosition { file_id, offset: node.navigation_range.start() },
+                        position: FilePosition { file_id, offset },
                         data: None,
                     },
                 });
             }
-        });
+
+            fn range_and_position_of(node: &dyn NameOwner) -> Option<(TextSize, TextRange)> {
+                Some((node.name()?.syntax().text_range().start(), node.syntax().text_range()))
+            }
+        }
+        Either::Right(_) => (),
+    });
 
     if config.annotate_method_references {
         annotations.extend(find_all_methods(db, file_id).into_iter().map(|method| Annotation {
@@ -934,4 +952,19 @@ mod tests {
             "#]],
         );
     }
+
+    #[test]
+    fn test_no_annotations_outside_module_tree() {
+        check(
+            r#"
+//- /foo.rs
+struct Foo;
+//- /lib.rs
+// this file comes last since `check` checks the first file only
+"#,
+            expect![[r#"
+                []
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index fe32f39b6..22697a537 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -6,6 +6,7 @@
 
 mod fixes;
 mod field_shorthand;
+mod unlinked_file;
 
 use std::cell::RefCell;
 
@@ -22,6 +23,7 @@ use syntax::{
     SyntaxNode, SyntaxNodePtr, TextRange,
 };
 use text_edit::TextEdit;
+use unlinked_file::UnlinkedFile;
 
 use crate::{FileId, Label, SourceChange};
 
@@ -156,6 +158,18 @@ pub(crate) fn diagnostics(
                 .with_code(Some(d.code())),
             );
         })
+        .on::<UnlinkedFile, _>(|d| {
+            // Override severity and mark as unused.
+            res.borrow_mut().push(
+                Diagnostic::hint(
+                    sema.diagnostics_display_range(d.display_source()).range,
+                    d.message(),
+                )
+                .with_unused(true)
+                .with_fix(d.fix(&sema))
+                .with_code(Some(d.code())),
+            );
+        })
         .on::<hir::diagnostics::UnresolvedProcMacro, _>(|d| {
             // Use more accurate position if available.
             let display_range = d
@@ -197,9 +211,13 @@ pub(crate) fn diagnostics(
             );
         });
 
-    if let Some(m) = sema.to_module_def(file_id) {
-        m.diagnostics(db, &mut sink);
-    };
+    match sema.to_module_def(file_id) {
+        Some(m) => m.diagnostics(db, &mut sink),
+        None => {
+            sink.push(UnlinkedFile { file_id, node: SyntaxNodePtr::new(&parse.tree().syntax()) });
+        }
+    }
+
     drop(sink);
     res.into_inner()
 }
@@ -307,6 +325,17 @@ mod tests {
         );
     }
 
+    /// Checks that there's a diagnostic *without* fix at `$0`.
+    fn check_no_fix(ra_fixture: &str) {
+        let (analysis, file_position) = fixture::position(ra_fixture);
+        let diagnostic = analysis
+            .diagnostics(&DiagnosticsConfig::default(), file_position.file_id)
+            .unwrap()
+            .pop()
+            .unwrap();
+        assert!(diagnostic.fix.is_none(), "got a fix when none was expected: {:?}", diagnostic);
+    }
+
     /// Takes a multi-file input fixture with annotated cursor position and checks that no diagnostics
     /// apply to the file containing the cursor.
     pub(crate) fn check_no_diagnostics(ra_fixture: &str) {
@@ -975,4 +1004,132 @@ impl TestStruct {
 
         check_fix(input, expected);
     }
+
+    #[test]
+    fn unlinked_file_prepend_first_item() {
+        cov_mark::check!(unlinked_file_prepend_before_first_item);
+        check_fix(
+            r#"
+//- /main.rs
+fn f() {}
+//- /foo.rs
+$0
+"#,
+            r#"
+mod foo;
+
+fn f() {}
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_append_mod() {
+        cov_mark::check!(unlinked_file_append_to_existing_mods);
+        check_fix(
+            r#"
+//- /main.rs
+//! Comment on top
+
+mod preexisting;
+
+mod preexisting2;
+
+struct S;
+
+mod preexisting_bottom;)
+//- /foo.rs
+$0
+"#,
+            r#"
+//! Comment on top
+
+mod preexisting;
+
+mod preexisting2;
+mod foo;
+
+struct S;
+
+mod preexisting_bottom;)
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_insert_in_empty_file() {
+        cov_mark::check!(unlinked_file_empty_file);
+        check_fix(
+            r#"
+//- /main.rs
+//- /foo.rs
+$0
+"#,
+            r#"
+mod foo;
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_old_style_modrs() {
+        check_fix(
+            r#"
+//- /main.rs
+mod submod;
+//- /submod/mod.rs
+// in mod.rs
+//- /submod/foo.rs
+$0
+"#,
+            r#"
+// in mod.rs
+mod foo;
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_new_style_mod() {
+        check_fix(
+            r#"
+//- /main.rs
+mod submod;
+//- /submod.rs
+//- /submod/foo.rs
+$0
+"#,
+            r#"
+mod foo;
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_with_cfg_off() {
+        cov_mark::check!(unlinked_file_skip_fix_when_mod_already_exists);
+        check_no_fix(
+            r#"
+//- /main.rs
+#[cfg(never)]
+mod foo;
+
+//- /foo.rs
+$0
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_with_cfg_on() {
+        check_no_diagnostics(
+            r#"
+//- /main.rs
+#[cfg(not(never))]
+mod foo;
+
+//- /foo.rs
+"#,
+        );
+    }
 }
diff --git a/crates/ide/src/diagnostics/unlinked_file.rs b/crates/ide/src/diagnostics/unlinked_file.rs
new file mode 100644
index 000000000..c5741bf6b
--- /dev/null
+++ b/crates/ide/src/diagnostics/unlinked_file.rs
@@ -0,0 +1,156 @@
+//! Diagnostic emitted for files that aren't part of any crate.
+
+use hir::{
+    db::DefDatabase,
+    diagnostics::{Diagnostic, DiagnosticCode},
+    InFile,
+};
+use ide_db::{
+    base_db::{FileId, FileLoader, SourceDatabase, SourceDatabaseExt},
+    source_change::SourceChange,
+    RootDatabase,
+};
+use syntax::{
+    ast::{self, ModuleItemOwner, NameOwner},
+    AstNode, SyntaxNodePtr,
+};
+use text_edit::TextEdit;
+
+use crate::Fix;
+
+use super::fixes::DiagnosticWithFix;
+
+#[derive(Debug)]
+pub(crate) struct UnlinkedFile {
+    pub(crate) file_id: FileId,
+    pub(crate) node: SyntaxNodePtr,
+}
+
+impl Diagnostic for UnlinkedFile {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("unlinked-file")
+    }
+
+    fn message(&self) -> String {
+        "file not included in module tree".to_string()
+    }
+
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile::new(self.file_id.into(), self.node.clone())
+    }
+
+    fn as_any(&self) -> &(dyn std::any::Any + Send + 'static) {
+        self
+    }
+}
+
+impl DiagnosticWithFix for UnlinkedFile {
+    fn fix(&self, sema: &hir::Semantics<RootDatabase>) -> Option<Fix> {
+        // If there's an existing module that could add a `mod` item to include the unlinked file,
+        // suggest that as a fix.
+
+        let source_root = sema.db.source_root(sema.db.file_source_root(self.file_id));
+        let our_path = source_root.path_for_file(&self.file_id)?;
+        let module_name = our_path.name_and_extension()?.0;
+
+        // Candidates to look for:
+        // - `mod.rs` in the same folder
+        //   - we also check `main.rs` and `lib.rs`
+        // - `$dir.rs` in the parent folder, where `$dir` is the directory containing `self.file_id`
+        let parent = our_path.parent()?;
+        let mut paths =
+            vec![parent.join("mod.rs")?, parent.join("main.rs")?, parent.join("lib.rs")?];
+
+        // `submod/bla.rs` -> `submod.rs`
+        if let Some(newmod) = (|| {
+            let name = parent.name_and_extension()?.0;
+            parent.parent()?.join(&format!("{}.rs", name))
+        })() {
+            paths.push(newmod);
+        }
+
+        for path in &paths {
+            if let Some(parent_id) = source_root.file_for_path(path) {
+                for krate in sema.db.relevant_crates(*parent_id).iter() {
+                    let crate_def_map = sema.db.crate_def_map(*krate);
+                    for (_, module) in crate_def_map.modules() {
+                        if module.origin.is_inline() {
+                            // We don't handle inline `mod parent {}`s, they use different paths.
+                            continue;
+                        }
+
+                        if module.origin.file_id() == Some(*parent_id) {
+                            return make_fix(sema.db, *parent_id, module_name, self.file_id);
+                        }
+                    }
+                }
+            }
+        }
+
+        None
+    }
+}
+
+fn make_fix(
+    db: &RootDatabase,
+    parent_file_id: FileId,
+    new_mod_name: &str,
+    added_file_id: FileId,
+) -> Option<Fix> {
+    fn is_outline_mod(item: &ast::Item) -> bool {
+        matches!(item, ast::Item::Module(m) if m.item_list().is_none())
+    }
+
+    let mod_decl = format!("mod {};", new_mod_name);
+    let ast: ast::SourceFile = db.parse(parent_file_id).tree();
+
+    let mut builder = TextEdit::builder();
+
+    // If there's an existing `mod m;` statement matching the new one, don't emit a fix (it's
+    // probably `#[cfg]`d out).
+    for item in ast.items() {
+        if let ast::Item::Module(m) = item {
+            if let Some(name) = m.name() {
+                if m.item_list().is_none() && name.to_string() == new_mod_name {
+                    cov_mark::hit!(unlinked_file_skip_fix_when_mod_already_exists);
+                    return None;
+                }
+            }
+        }
+    }
+
+    // If there are existing `mod m;` items, append after them (after the first group of them, rather).
+    match ast
+        .items()
+        .skip_while(|item| !is_outline_mod(item))
+        .take_while(|item| is_outline_mod(item))
+        .last()
+    {
+        Some(last) => {
+            cov_mark::hit!(unlinked_file_append_to_existing_mods);
+            builder.insert(last.syntax().text_range().end(), format!("\n{}", mod_decl));
+        }
+        None => {
+            // Prepend before the first item in the file.
+            match ast.items().next() {
+                Some(item) => {
+                    cov_mark::hit!(unlinked_file_prepend_before_first_item);
+                    builder.insert(item.syntax().text_range().start(), format!("{}\n\n", mod_decl));
+                }
+                None => {
+                    // No items in the file, so just append at the end.
+                    cov_mark::hit!(unlinked_file_empty_file);
+                    builder.insert(ast.syntax().text_range().end(), format!("{}\n", mod_decl));
+                }
+            }
+        }
+    }
+
+    let edit = builder.finish();
+    let trigger_range = db.parse(added_file_id).tree().syntax().text_range();
+    Some(Fix::new(
+        &format!("Insert `{}`", mod_decl),
+        SourceChange::from_text_edit(parent_file_id, edit),
+        trigger_range,
+    ))
+}
diff --git a/crates/ide/src/file_structure.rs b/crates/ide/src/file_structure.rs
index 26793bdb4..9f879a66e 100644
--- a/crates/ide/src/file_structure.rs
+++ b/crates/ide/src/file_structure.rs
@@ -1,7 +1,8 @@
 use ide_db::SymbolKind;
 use syntax::{
     ast::{self, AttrsOwner, GenericParamsOwner, NameOwner},
-    match_ast, AstNode, SourceFile, SyntaxNode, TextRange, WalkEvent,
+    match_ast, AstNode, AstToken, NodeOrToken, SourceFile, SyntaxNode, SyntaxToken, TextRange,
+    WalkEvent,
 };
 
 #[derive(Debug, Clone)]
@@ -10,11 +11,17 @@ pub struct StructureNode {
     pub label: String,
     pub navigation_range: TextRange,
     pub node_range: TextRange,
-    pub kind: SymbolKind,
+    pub kind: StructureNodeKind,
     pub detail: Option<String>,
     pub deprecated: bool,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
+pub enum StructureNodeKind {
+    SymbolKind(SymbolKind),
+    Region,
+}
+
 // Feature: File Structure
 //
 // Provides a tree of the symbols defined in the file. Can be used to
@@ -32,34 +39,46 @@ pub(crate) fn file_structure(file: &SourceFile) -> Vec<StructureNode> {
     let mut res = Vec::new();
     let mut stack = Vec::new();
 
-    for event in file.syntax().preorder() {
+    for event in file.syntax().preorder_with_tokens() {
         match event {
-            WalkEvent::Enter(node) => {
+            WalkEvent::Enter(NodeOrToken::Node(node)) => {
                 if let Some(mut symbol) = structure_node(&node) {
                     symbol.parent = stack.last().copied();
                     stack.push(res.len());
                     res.push(symbol);
                 }
             }
-            WalkEvent::Leave(node) => {
+            WalkEvent::Leave(NodeOrToken::Node(node)) => {
                 if structure_node(&node).is_some() {
                     stack.pop().unwrap();
                 }
             }
+            WalkEvent::Enter(NodeOrToken::Token(token)) => {
+                if let Some(mut symbol) = structure_token(token) {
+                    symbol.parent = stack.last().copied();
+                    stack.push(res.len());
+                    res.push(symbol);
+                }
+            }
+            WalkEvent::Leave(NodeOrToken::Token(token)) => {
+                if structure_token(token).is_some() {
+                    stack.pop().unwrap();
+                }
+            }
         }
     }
     res
 }
 
 fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
-    fn decl<N: NameOwner + AttrsOwner>(node: N, kind: SymbolKind) -> Option<StructureNode> {
+    fn decl<N: NameOwner + AttrsOwner>(node: N, kind: StructureNodeKind) -> Option<StructureNode> {
         decl_with_detail(&node, None, kind)
     }
 
     fn decl_with_type_ref<N: NameOwner + AttrsOwner>(
         node: &N,
         type_ref: Option<ast::Type>,
-        kind: SymbolKind,
+        kind: StructureNodeKind,
     ) -> Option<StructureNode> {
         let detail = type_ref.map(|type_ref| {
             let mut detail = String::new();
@@ -72,7 +91,7 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
     fn decl_with_detail<N: NameOwner + AttrsOwner>(
         node: &N,
         detail: Option<String>,
-        kind: SymbolKind,
+        kind: StructureNodeKind,
     ) -> Option<StructureNode> {
         let name = node.name()?;
 
@@ -120,18 +139,18 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
                     collapse_ws(ret_type.syntax(), &mut detail);
                 }
 
-                decl_with_detail(&it, Some(detail), SymbolKind::Function)
+                decl_with_detail(&it, Some(detail), StructureNodeKind::SymbolKind(SymbolKind::Function))
             },
-            ast::Struct(it) => decl(it, SymbolKind::Struct),
-            ast::Union(it) => decl(it, SymbolKind::Union),
-            ast::Enum(it) => decl(it, SymbolKind::Enum),
-            ast::Variant(it) => decl(it, SymbolKind::Variant),
-            ast::Trait(it) => decl(it, SymbolKind::Trait),
-            ast::Module(it) => decl(it, SymbolKind::Module),
-            ast::TypeAlias(it) => decl_with_type_ref(&it, it.ty(), SymbolKind::TypeAlias),
-            ast::RecordField(it) => decl_with_type_ref(&it, it.ty(), SymbolKind::Field),
-            ast::Const(it) => decl_with_type_ref(&it, it.ty(), SymbolKind::Const),
-            ast::Static(it) => decl_with_type_ref(&it, it.ty(), SymbolKind::Static),
+            ast::Struct(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Struct)),
+            ast::Union(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Union)),
+            ast::Enum(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Enum)),
+            ast::Variant(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Variant)),
+            ast::Trait(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Trait)),
+            ast::Module(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Module)),
+            ast::TypeAlias(it) => decl_with_type_ref(&it, it.ty(), StructureNodeKind::SymbolKind(SymbolKind::TypeAlias)),
+            ast::RecordField(it) => decl_with_type_ref(&it, it.ty(), StructureNodeKind::SymbolKind(SymbolKind::Field)),
+            ast::Const(it) => decl_with_type_ref(&it, it.ty(), StructureNodeKind::SymbolKind(SymbolKind::Const)),
+            ast::Static(it) => decl_with_type_ref(&it, it.ty(), StructureNodeKind::SymbolKind(SymbolKind::Static)),
             ast::Impl(it) => {
                 let target_type = it.self_ty()?;
                 let target_trait = it.trait_();
@@ -147,18 +166,38 @@ fn structure_node(node: &SyntaxNode) -> Option<StructureNode> {
                     label,
                     navigation_range: target_type.syntax().text_range(),
                     node_range: it.syntax().text_range(),
-                    kind: SymbolKind::Impl,
+                    kind: StructureNodeKind::SymbolKind(SymbolKind::Impl),
                     detail: None,
                     deprecated: false,
                 };
                 Some(node)
             },
-            ast::MacroRules(it) => decl(it, SymbolKind::Macro),
+            ast::MacroRules(it) => decl(it, StructureNodeKind::SymbolKind(SymbolKind::Macro)),
             _ => None,
         }
     }
 }
 
+fn structure_token(token: SyntaxToken) -> Option<StructureNode> {
+    if let Some(comment) = ast::Comment::cast(token) {
+        let text = comment.text().trim();
+
+        if let Some(region_name) = text.strip_prefix("// region:").map(str::trim) {
+            return Some(StructureNode {
+                parent: None,
+                label: region_name.to_string(),
+                navigation_range: comment.syntax().text_range(),
+                node_range: comment.syntax().text_range(),
+                kind: StructureNodeKind::Region,
+                detail: None,
+                deprecated: false,
+            });
+        }
+    }
+
+    None
+}
+
 #[cfg(test)]
 mod tests {
     use expect_test::{expect, Expect};
@@ -217,6 +256,16 @@ fn obsolete() {}
 
 #[deprecated(note = "for awhile")]
 fn very_obsolete() {}
+
+// region: Some region name
+// endregion
+
+// region: dontpanic
+mod m {
+fn f() {}
+// endregion
+fn g() {}
+}
 "#,
             expect![[r#"
                 [
@@ -225,7 +274,9 @@ fn very_obsolete() {}
                         label: "Foo",
                         navigation_range: 8..11,
                         node_range: 1..26,
-                        kind: Struct,
+                        kind: SymbolKind(
+                            Struct,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -236,7 +287,9 @@ fn very_obsolete() {}
                         label: "x",
                         navigation_range: 18..19,
                         node_range: 18..24,
-                        kind: Field,
+                        kind: SymbolKind(
+                            Field,
+                        ),
                         detail: Some(
                             "i32",
                         ),
@@ -247,7 +300,9 @@ fn very_obsolete() {}
                         label: "m",
                         navigation_range: 32..33,
                         node_range: 28..158,
-                        kind: Module,
+                        kind: SymbolKind(
+                            Module,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -258,7 +313,9 @@ fn very_obsolete() {}
                         label: "bar1",
                         navigation_range: 43..47,
                         node_range: 40..52,
-                        kind: Function,
+                        kind: SymbolKind(
+                            Function,
+                        ),
                         detail: Some(
                             "fn()",
                         ),
@@ -271,7 +328,9 @@ fn very_obsolete() {}
                         label: "bar2",
                         navigation_range: 60..64,
                         node_range: 57..81,
-                        kind: Function,
+                        kind: SymbolKind(
+                            Function,
+                        ),
                         detail: Some(
                             "fn<T>(t: T) -> T",
                         ),
@@ -284,7 +343,9 @@ fn very_obsolete() {}
                         label: "bar3",
                         navigation_range: 89..93,
                         node_range: 86..156,
-                        kind: Function,
+                        kind: SymbolKind(
+                            Function,
+                        ),
                         detail: Some(
                             "fn<A, B>(a: A, b: B) -> Vec< u32 >",
                         ),
@@ -295,7 +356,9 @@ fn very_obsolete() {}
                         label: "E",
                         navigation_range: 165..166,
                         node_range: 160..180,
-                        kind: Enum,
+                        kind: SymbolKind(
+                            Enum,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -306,7 +369,9 @@ fn very_obsolete() {}
                         label: "X",
                         navigation_range: 169..170,
                         node_range: 169..170,
-                        kind: Variant,
+                        kind: SymbolKind(
+                            Variant,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -317,7 +382,9 @@ fn very_obsolete() {}
                         label: "Y",
                         navigation_range: 172..173,
                         node_range: 172..178,
-                        kind: Variant,
+                        kind: SymbolKind(
+                            Variant,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -326,7 +393,9 @@ fn very_obsolete() {}
                         label: "T",
                         navigation_range: 186..187,
                         node_range: 181..193,
-                        kind: TypeAlias,
+                        kind: SymbolKind(
+                            TypeAlias,
+                        ),
                         detail: Some(
                             "()",
                         ),
@@ -337,7 +406,9 @@ fn very_obsolete() {}
                         label: "S",
                         navigation_range: 201..202,
                         node_range: 194..213,
-                        kind: Static,
+                        kind: SymbolKind(
+                            Static,
+                        ),
                         detail: Some(
                             "i32",
                         ),
@@ -348,7 +419,9 @@ fn very_obsolete() {}
                         label: "C",
                         navigation_range: 220..221,
                         node_range: 214..232,
-                        kind: Const,
+                        kind: SymbolKind(
+                            Const,
+                        ),
                         detail: Some(
                             "i32",
                         ),
@@ -359,7 +432,9 @@ fn very_obsolete() {}
                         label: "impl E",
                         navigation_range: 239..240,
                         node_range: 234..243,
-                        kind: Impl,
+                        kind: SymbolKind(
+                            Impl,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -368,7 +443,9 @@ fn very_obsolete() {}
                         label: "impl fmt::Debug for E",
                         navigation_range: 265..266,
                         node_range: 245..269,
-                        kind: Impl,
+                        kind: SymbolKind(
+                            Impl,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -377,7 +454,9 @@ fn very_obsolete() {}
                         label: "mc",
                         navigation_range: 284..286,
                         node_range: 271..303,
-                        kind: Macro,
+                        kind: SymbolKind(
+                            Macro,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -386,7 +465,9 @@ fn very_obsolete() {}
                         label: "mcexp",
                         navigation_range: 334..339,
                         node_range: 305..356,
-                        kind: Macro,
+                        kind: SymbolKind(
+                            Macro,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -395,7 +476,9 @@ fn very_obsolete() {}
                         label: "mcexp",
                         navigation_range: 387..392,
                         node_range: 358..409,
-                        kind: Macro,
+                        kind: SymbolKind(
+                            Macro,
+                        ),
                         detail: None,
                         deprecated: false,
                     },
@@ -404,7 +487,9 @@ fn very_obsolete() {}
                         label: "obsolete",
                         navigation_range: 428..436,
                         node_range: 411..441,
-                        kind: Function,
+                        kind: SymbolKind(
+                            Function,
+                        ),
                         detail: Some(
                             "fn()",
                         ),
@@ -415,12 +500,75 @@ fn very_obsolete() {}
                         label: "very_obsolete",
                         navigation_range: 481..494,
                         node_range: 443..499,
-                        kind: Function,
+                        kind: SymbolKind(
+                            Function,
+                        ),
                         detail: Some(
                             "fn()",
                         ),
                         deprecated: true,
                     },
+                    StructureNode {
+                        parent: None,
+                        label: "Some region name",
+                        navigation_range: 501..528,
+                        node_range: 501..528,
+                        kind: Region,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: None,
+                        label: "m",
+                        navigation_range: 568..569,
+                        node_range: 543..606,
+                        kind: SymbolKind(
+                            Module,
+                        ),
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            20,
+                        ),
+                        label: "dontpanic",
+                        navigation_range: 543..563,
+                        node_range: 543..563,
+                        kind: Region,
+                        detail: None,
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            20,
+                        ),
+                        label: "f",
+                        navigation_range: 575..576,
+                        node_range: 572..581,
+                        kind: SymbolKind(
+                            Function,
+                        ),
+                        detail: Some(
+                            "fn()",
+                        ),
+                        deprecated: false,
+                    },
+                    StructureNode {
+                        parent: Some(
+                            20,
+                        ),
+                        label: "g",
+                        navigation_range: 598..599,
+                        node_range: 582..604,
+                        kind: SymbolKind(
+                            Function,
+                        ),
+                        detail: Some(
+                            "fn()",
+                        ),
+                        deprecated: false,
+                    },
                 ]
             "#]],
         );
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index abed1969e..e8f31e4b1 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -1161,4 +1161,15 @@ struct S;
 "#,
         )
     }
+
+    #[test]
+    fn goto_incomplete_field() {
+        check(
+            r#"
+struct A { a: u32 }
+         //^
+fn foo() { A { a$0: }; }
+"#,
+        )
+    }
 }
diff --git a/crates/ide/src/goto_implementation.rs b/crates/ide/src/goto_implementation.rs
index 3990305fc..f4d7c14a6 100644
--- a/crates/ide/src/goto_implementation.rs
+++ b/crates/ide/src/goto_implementation.rs
@@ -1,6 +1,9 @@
-use hir::{Crate, Impl, Semantics};
-use ide_db::RootDatabase;
-use syntax::{algo::find_node_at_offset, ast, AstNode};
+use hir::{Impl, Semantics};
+use ide_db::{
+    defs::{Definition, NameClass, NameRefClass},
+    RootDatabase,
+};
+use syntax::{ast, AstNode};
 
 use crate::{display::TryToNav, FilePosition, NavigationTarget, RangeInfo};
 
@@ -21,55 +24,42 @@ pub(crate) fn goto_implementation(
     let source_file = sema.parse(position.file_id);
     let syntax = source_file.syntax().clone();
 
-    let krate = sema.to_module_def(position.file_id)?.krate();
-
-    if let Some(nominal_def) = find_node_at_offset::<ast::Adt>(&syntax, position.offset) {
-        return Some(RangeInfo::new(
-            nominal_def.syntax().text_range(),
-            impls_for_def(&sema, &nominal_def, krate)?,
-        ));
-    } else if let Some(trait_def) = find_node_at_offset::<ast::Trait>(&syntax, position.offset) {
-        return Some(RangeInfo::new(
-            trait_def.syntax().text_range(),
-            impls_for_trait(&sema, &trait_def, krate)?,
-        ));
-    }
-
-    None
-}
-
-fn impls_for_def(
-    sema: &Semantics<RootDatabase>,
-    node: &ast::Adt,
-    krate: Crate,
-) -> Option<Vec<NavigationTarget>> {
-    let ty = match node {
-        ast::Adt::Struct(def) => sema.to_def(def)?.ty(sema.db),
-        ast::Adt::Enum(def) => sema.to_def(def)?.ty(sema.db),
-        ast::Adt::Union(def) => sema.to_def(def)?.ty(sema.db),
+    let node = sema.find_node_at_offset_with_descend(&syntax, position.offset)?;
+    let def = match &node {
+        ast::NameLike::Name(name) => {
+            NameClass::classify(&sema, name).map(|class| class.referenced_or_defined(sema.db))
+        }
+        ast::NameLike::NameRef(name_ref) => {
+            NameRefClass::classify(&sema, name_ref).map(|class| class.referenced(sema.db))
+        }
+        ast::NameLike::Lifetime(_) => None,
+    }?;
+    let def = match def {
+        Definition::ModuleDef(def) => def,
+        _ => return None,
     };
-
-    let impls = Impl::all_in_crate(sema.db, krate);
-
-    Some(
-        impls
-            .into_iter()
-            .filter(|impl_def| ty.is_equal_for_find_impls(&impl_def.target_ty(sema.db)))
-            .filter_map(|imp| imp.try_to_nav(sema.db))
-            .collect(),
-    )
+    let navs = match def {
+        hir::ModuleDef::Trait(trait_) => impls_for_trait(&sema, trait_),
+        hir::ModuleDef::Adt(adt) => impls_for_ty(&sema, adt.ty(sema.db)),
+        hir::ModuleDef::TypeAlias(alias) => impls_for_ty(&sema, alias.ty(sema.db)),
+        hir::ModuleDef::BuiltinType(builtin) => {
+            let module = sema.to_module_def(position.file_id)?;
+            impls_for_ty(&sema, builtin.ty(sema.db, module))
+        }
+        _ => return None,
+    };
+    Some(RangeInfo { range: node.syntax().text_range(), info: navs })
 }
 
-fn impls_for_trait(
-    sema: &Semantics<RootDatabase>,
-    node: &ast::Trait,
-    krate: Crate,
-) -> Option<Vec<NavigationTarget>> {
-    let tr = sema.to_def(node)?;
-
-    let impls = Impl::for_trait(sema.db, krate, tr);
+fn impls_for_ty(sema: &Semantics<RootDatabase>, ty: hir::Type) -> Vec<NavigationTarget> {
+    Impl::all_for_type(sema.db, ty).into_iter().filter_map(|imp| imp.try_to_nav(sema.db)).collect()
+}
 
-    Some(impls.into_iter().filter_map(|imp| imp.try_to_nav(sema.db)).collect())
+fn impls_for_trait(sema: &Semantics<RootDatabase>, trait_: hir::Trait) -> Vec<NavigationTarget> {
+    Impl::all_for_trait(sema.db, trait_)
+        .into_iter()
+        .filter_map(|imp| imp.try_to_nav(sema.db))
+        .collect()
 }
 
 #[cfg(test)]
@@ -226,4 +216,48 @@ macro Copy {}
 "#,
         );
     }
+
+    #[test]
+    fn goto_implementation_type_alias() {
+        check(
+            r#"
+struct Foo;
+
+type Bar$0 = Foo;
+
+impl Foo {}
+   //^^^
+impl Bar {}
+   //^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_adt_generic() {
+        check(
+            r#"
+struct Foo$0<T>;
+
+impl<T> Foo<T> {}
+      //^^^^^^
+impl Foo<str> {}
+   //^^^^^^^^
+"#,
+        );
+    }
+
+    #[test]
+    fn goto_implementation_builtin() {
+        check(
+            r#"
+//- /lib.rs crate:main deps:core
+fn foo(_: bool$0) {{}}
+//- /libcore.rs crate:core
+#[lang = "bool"]
+impl bool {}
+   //^^^^
+"#,
+        );
+    }
 }
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 4ceb20742..16c04eeee 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -219,7 +219,7 @@ fn hint_iterator(
     let strukt = std::iter::successors(Some(ty.clone()), |ty| ty.remove_ref())
         .last()
         .and_then(|strukt| strukt.as_adt())?;
-    let krate = strukt.krate(db)?;
+    let krate = strukt.krate(db);
     if krate != famous_defs.core()? {
         return None;
     }
diff --git a/crates/ide/src/join_lines.rs b/crates/ide/src/join_lines.rs
index 20a920ddb..d571ed559 100644
--- a/crates/ide/src/join_lines.rs
+++ b/crates/ide/src/join_lines.rs
@@ -218,7 +218,7 @@ mod tests {
         let result = join_lines(&file, range);
 
         let actual = {
-            let mut actual = before.to_string();
+            let mut actual = before;
             result.apply(&mut actual);
             actual
         };
@@ -622,7 +622,7 @@ fn foo() {
         let parse = SourceFile::parse(&before);
         let result = join_lines(&parse.tree(), sel);
         let actual = {
-            let mut actual = before.to_string();
+            let mut actual = before;
             result.apply(&mut actual);
             actual
         };
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index d1a250d48..662da5a96 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -71,7 +71,7 @@ pub use crate::{
     diagnostics::{Diagnostic, DiagnosticsConfig, Fix, Severity},
     display::navigation_target::NavigationTarget,
     expand_macro::ExpandedMacro,
-    file_structure::StructureNode,
+    file_structure::{StructureNode, StructureNodeKind},
     folding_ranges::{Fold, FoldKind},
     hover::{HoverAction, HoverConfig, HoverGotoTypeData, HoverResult},
     inlay_hints::{InlayHint, InlayHintsConfig, InlayKind},
@@ -87,7 +87,7 @@ pub use crate::{
 pub use hir::{Documentation, Semantics};
 pub use ide_assists::{Assist, AssistConfig, AssistId, AssistKind};
 pub use ide_completion::{
-    CompletionConfig, CompletionItem, CompletionItemKind, CompletionScore, ImportEdit,
+    CompletionConfig, CompletionItem, CompletionItemKind, CompletionRelevance, ImportEdit,
     InsertTextFormat,
 };
 pub use ide_db::{
@@ -101,7 +101,7 @@ pub use ide_db::{
     search::{ReferenceAccess, SearchScope},
     source_change::{FileSystemEdit, SourceChange},
     symbol_index::Query,
-    RootDatabase,
+    RootDatabase, SymbolKind,
 };
 pub use ide_ssr::SsrError;
 pub use syntax::{TextRange, TextSize};
@@ -447,6 +447,15 @@ impl Analysis {
         self.with_db(|db| runnables::runnables(db, file_id))
     }
 
+    /// Returns the set of tests for the given file position.
+    pub fn related_tests(
+        &self,
+        position: FilePosition,
+        search_scope: Option<SearchScope>,
+    ) -> Cancelable<Vec<Runnable>> {
+        self.with_db(|db| runnables::related_tests(db, position, search_scope))
+    }
+
     /// Computes syntax highlighting for the given file
     pub fn highlight(&self, file_id: FileId) -> Cancelable<Vec<HlRange>> {
         self.with_db(|db| syntax_highlighting::highlight(db, file_id, None, false))
diff --git a/crates/ide/src/parent_module.rs b/crates/ide/src/parent_module.rs
index 03d71b380..22b0d6ecb 100644
--- a/crates/ide/src/parent_module.rs
+++ b/crates/ide/src/parent_module.rs
@@ -1,6 +1,7 @@
 use hir::Semantics;
 use ide_db::base_db::{CrateId, FileId, FilePosition};
 use ide_db::RootDatabase;
+use itertools::Itertools;
 use syntax::{
     algo::find_node_at_offset,
     ast::{self, AstNode},
@@ -18,8 +19,7 @@ use crate::NavigationTarget;
 // | VS Code | **Rust Analyzer: Locate parent module**
 // |===
 
-/// This returns `Vec` because a module may be included from several places. We
-/// don't handle this case yet though, so the Vec has length at most one.
+/// This returns `Vec` because a module may be included from several places.
 pub(crate) fn parent_module(db: &RootDatabase, position: FilePosition) -> Vec<NavigationTarget> {
     let sema = Semantics::new(db);
     let source_file = sema.parse(position.file_id);
@@ -37,27 +37,23 @@ pub(crate) fn parent_module(db: &RootDatabase, position: FilePosition) -> Vec<Na
         }
     }
 
-    let module = match module {
-        Some(module) => sema.to_def(&module),
-        None => sema.to_module_def(position.file_id),
-    };
-    let module = match module {
-        None => return Vec::new(),
-        Some(it) => it,
-    };
-    let nav = NavigationTarget::from_module_to_decl(db, module);
-    vec![nav]
+    match module {
+        Some(module) => sema
+            .to_def(&module)
+            .into_iter()
+            .map(|module| NavigationTarget::from_module_to_decl(db, module))
+            .collect(),
+        None => sema
+            .to_module_defs(position.file_id)
+            .map(|module| NavigationTarget::from_module_to_decl(db, module))
+            .collect(),
+    }
 }
 
 /// Returns `Vec` for the same reason as `parent_module`
 pub(crate) fn crate_for(db: &RootDatabase, file_id: FileId) -> Vec<CrateId> {
     let sema = Semantics::new(db);
-    let module = match sema.to_module_def(file_id) {
-        Some(it) => it,
-        None => return Vec::new(),
-    };
-    let krate = module.krate();
-    vec![krate.into()]
+    sema.to_module_defs(file_id).map(|module| module.krate().into()).unique().collect()
 }
 
 #[cfg(test)]
@@ -67,11 +63,13 @@ mod tests {
     use crate::fixture;
 
     fn check(ra_fixture: &str) {
-        let (analysis, position, expected) = fixture::nav_target_annotation(ra_fixture);
-        let mut navs = analysis.parent_module(position).unwrap();
-        assert_eq!(navs.len(), 1);
-        let nav = navs.pop().unwrap();
-        assert_eq!(expected, FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() });
+        let (analysis, position, expected) = fixture::annotations(ra_fixture);
+        let navs = analysis.parent_module(position).unwrap();
+        let navs = navs
+            .iter()
+            .map(|nav| FileRange { file_id: nav.file_id, range: nav.focus_or_full_range() })
+            .collect::<Vec<_>>();
+        assert_eq!(expected.into_iter().map(|(fr, _)| fr).collect::<Vec<_>>(), navs);
     }
 
     #[test]
@@ -120,15 +118,46 @@ mod foo {
     }
 
     #[test]
-    fn test_resolve_crate_root() {
-        let (analysis, file_id) = fixture::file(
+    fn test_resolve_multi_parent_module() {
+        check(
             r#"
 //- /main.rs
 mod foo;
+  //^^^
+#[path = "foo.rs"]
+mod bar;
+  //^^^
+//- /foo.rs
+$0
+"#,
+        );
+    }
+
+    #[test]
+    fn test_resolve_crate_root() {
+        let (analysis, file_id) = fixture::file(
+            r#"
 //- /foo.rs
 $0
+//- /main.rs
+mod foo;
 "#,
         );
         assert_eq!(analysis.crate_for(file_id).unwrap().len(), 1);
     }
+
+    #[test]
+    fn test_resolve_multi_parent_crate() {
+        let (analysis, file_id) = fixture::file(
+            r#"
+//- /baz.rs
+$0
+//- /foo.rs crate:foo
+mod baz;
+//- /bar.rs crate:bar
+mod baz;
+"#,
+        );
+        assert_eq!(analysis.crate_for(file_id).unwrap().len(), 2);
+    }
 }
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
index fef70533d..ec7c7686d 100644
--- a/crates/ide/src/references.rs
+++ b/crates/ide/src/references.rs
@@ -29,7 +29,7 @@ use crate::{display::TryToNav, FilePosition, NavigationTarget};
 
 #[derive(Debug, Clone)]
 pub struct ReferenceSearchResult {
-    pub declaration: Declaration,
+    pub declaration: Option<Declaration>,
     pub references: FxHashMap<FileId, Vec<(TextRange, Option<ReferenceAccess>)>>,
 }
 
@@ -91,10 +91,10 @@ pub(crate) fn find_all_refs(
             _ => {}
         }
     }
-    let nav = def.try_to_nav(sema.db)?;
-    let decl_range = nav.focus_or_full_range();
-
-    let declaration = Declaration { nav, access: decl_access(&def, &syntax, decl_range) };
+    let declaration = def.try_to_nav(sema.db).map(|nav| {
+        let decl_range = nav.focus_or_full_range();
+        Declaration { nav, access: decl_access(&def, &syntax, decl_range) }
+    });
     let references = usages
         .into_iter()
         .map(|(file_id, refs)| {
@@ -1004,8 +1004,7 @@ impl Foo {
         let refs = analysis.find_all_refs(pos, search_scope).unwrap().unwrap();
 
         let mut actual = String::new();
-        {
-            let decl = refs.declaration;
+        if let Some(decl) = refs.declaration {
             format_to!(actual, "{}", decl.nav.debug_render());
             if let Some(access) = decl.access {
                 format_to!(actual, " {:?}", access)
@@ -1258,4 +1257,17 @@ fn main() {
             "#]],
         );
     }
+
+    #[test]
+    fn test_primitives() {
+        check(
+            r#"
+fn foo(_: bool) -> bo$0ol { true }
+"#,
+            expect![[r#"
+                FileId(0) 10..14
+                FileId(0) 19..23
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/references/rename.rs b/crates/ide/src/references/rename.rs
index 1e378279d..5340b638a 100644
--- a/crates/ide/src/references/rename.rs
+++ b/crates/ide/src/references/rename.rs
@@ -510,7 +510,8 @@ fn source_edit_from_def(
     def: Definition,
     new_name: &str,
 ) -> RenameResult<(FileId, TextEdit)> {
-    let nav = def.try_to_nav(sema.db).unwrap();
+    let nav =
+        def.try_to_nav(sema.db).ok_or_else(|| format_err!("No references found at position"))?;
 
     let mut replacement_text = String::new();
     let mut repl_range = nav.focus_or_full_range();
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index 280565563..0c7a8fbf8 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -1,10 +1,19 @@
 use std::fmt;
 
+use ast::NameOwner;
 use cfg::CfgExpr;
-use hir::{AsAssocItem, HasAttrs, HasSource, Semantics};
+use either::Either;
+use hir::{AsAssocItem, HasAttrs, HasSource, HirDisplay, Semantics};
 use ide_assists::utils::test_related_attribute;
-use ide_db::{defs::Definition, RootDatabase, SymbolKind};
+use ide_db::{
+    base_db::{FilePosition, FileRange},
+    defs::Definition,
+    helpers::visit_file_defs,
+    search::SearchScope,
+    RootDatabase, SymbolKind,
+};
 use itertools::Itertools;
+use rustc_hash::FxHashSet;
 use syntax::{
     ast::{self, AstNode, AttrsOwner},
     match_ast, SyntaxNode,
@@ -12,17 +21,17 @@ use syntax::{
 
 use crate::{
     display::{ToNav, TryToNav},
-    FileId, NavigationTarget,
+    references, FileId, NavigationTarget,
 };
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct Runnable {
     pub nav: NavigationTarget,
     pub kind: RunnableKind,
     pub cfg: Option<CfgExpr>,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub enum TestId {
     Name(String),
     Path(String),
@@ -37,7 +46,7 @@ impl fmt::Display for TestId {
     }
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub enum RunnableKind {
     Test { test_id: TestId, attr: TestAttr },
     TestMod { path: String },
@@ -95,49 +104,129 @@ impl Runnable {
 // |===
 pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
     let sema = Semantics::new(db);
-    let module = match sema.to_module_def(file_id) {
-        None => return Vec::new(),
-        Some(it) => it,
-    };
 
     let mut res = Vec::new();
-    runnables_mod(&sema, &mut res, module);
+    visit_file_defs(&sema, file_id, &mut |def| match def {
+        Either::Left(def) => {
+            let runnable = match def {
+                hir::ModuleDef::Module(it) => runnable_mod(&sema, it),
+                hir::ModuleDef::Function(it) => runnable_fn(&sema, it),
+                _ => None,
+            };
+            res.extend(runnable.or_else(|| module_def_doctest(&sema, def)))
+        }
+        Either::Right(impl_) => {
+            res.extend(impl_.items(db).into_iter().filter_map(|assoc| match assoc {
+                hir::AssocItem::Function(it) => {
+                    runnable_fn(&sema, it).or_else(|| module_def_doctest(&sema, it.into()))
+                }
+                hir::AssocItem::Const(it) => module_def_doctest(&sema, it.into()),
+                hir::AssocItem::TypeAlias(it) => module_def_doctest(&sema, it.into()),
+            }))
+        }
+    });
     res
 }
 
-fn runnables_mod(sema: &Semantics<RootDatabase>, acc: &mut Vec<Runnable>, module: hir::Module) {
-    acc.extend(module.declarations(sema.db).into_iter().filter_map(|def| {
-        let runnable = match def {
-            hir::ModuleDef::Module(it) => runnable_mod(&sema, it),
-            hir::ModuleDef::Function(it) => runnable_fn(&sema, it),
-            _ => None,
-        };
-        runnable.or_else(|| module_def_doctest(&sema, def))
-    }));
+// Feature: Related Tests
+//
+// Provides a sneak peek of all tests where the current item is used.
+//
+// The simplest way to use this feature is via the context menu:
+//  - Right-click on the selected item. The context menu opens.
+//  - Select **Peek related tests**
+//
+// |===
+// | Editor  | Action Name
+//
+// | VS Code | **Rust Analyzer: Peek related tests**
+// |===
+pub(crate) fn related_tests(
+    db: &RootDatabase,
+    position: FilePosition,
+    search_scope: Option<SearchScope>,
+) -> Vec<Runnable> {
+    let sema = Semantics::new(db);
+    let mut res: FxHashSet<Runnable> = FxHashSet::default();
 
-    acc.extend(module.impl_defs(sema.db).into_iter().flat_map(|it| it.items(sema.db)).filter_map(
-        |def| match def {
-            hir::AssocItem::Function(it) => {
-                runnable_fn(&sema, it).or_else(|| module_def_doctest(&sema, it.into()))
-            }
-            hir::AssocItem::Const(it) => module_def_doctest(&sema, it.into()),
-            hir::AssocItem::TypeAlias(it) => module_def_doctest(&sema, it.into()),
-        },
-    ));
-
-    for def in module.declarations(sema.db) {
-        if let hir::ModuleDef::Module(submodule) = def {
-            match submodule.definition_source(sema.db).value {
-                hir::ModuleSource::Module(_) => runnables_mod(sema, acc, submodule),
-                hir::ModuleSource::SourceFile(_) => {
-                    cov_mark::hit!(dont_recurse_in_outline_submodules)
+    find_related_tests(&sema, position, search_scope, &mut res);
+
+    res.into_iter().collect_vec()
+}
+
+fn find_related_tests(
+    sema: &Semantics<RootDatabase>,
+    position: FilePosition,
+    search_scope: Option<SearchScope>,
+    tests: &mut FxHashSet<Runnable>,
+) {
+    if let Some(refs) = references::find_all_refs(&sema, position, search_scope) {
+        for (file_id, refs) in refs.references {
+            let file = sema.parse(file_id);
+            let file = file.syntax();
+            let functions = refs.iter().filter_map(|(range, _)| {
+                let token = file.token_at_offset(range.start()).next()?;
+                let token = sema.descend_into_macros(token);
+                let syntax = token.parent();
+                syntax.ancestors().find_map(ast::Fn::cast)
+            });
+
+            for fn_def in functions {
+                if let Some(runnable) = as_test_runnable(&sema, &fn_def) {
+                    // direct test
+                    tests.insert(runnable);
+                } else if let Some(module) = parent_test_module(&sema, &fn_def) {
+                    // indirect test
+                    find_related_tests_in_module(sema, &fn_def, &module, tests);
                 }
-                hir::ModuleSource::BlockExpr(_) => {} // inner items aren't runnable
             }
         }
     }
 }
 
+fn find_related_tests_in_module(
+    sema: &Semantics<RootDatabase>,
+    fn_def: &ast::Fn,
+    parent_module: &hir::Module,
+    tests: &mut FxHashSet<Runnable>,
+) {
+    if let Some(fn_name) = fn_def.name() {
+        let mod_source = parent_module.definition_source(sema.db);
+        let range = match mod_source.value {
+            hir::ModuleSource::Module(m) => m.syntax().text_range(),
+            hir::ModuleSource::BlockExpr(b) => b.syntax().text_range(),
+            hir::ModuleSource::SourceFile(f) => f.syntax().text_range(),
+        };
+
+        let file_id = mod_source.file_id.original_file(sema.db);
+        let mod_scope = SearchScope::file_range(FileRange { file_id, range });
+        let fn_pos = FilePosition { file_id, offset: fn_name.syntax().text_range().start() };
+        find_related_tests(sema, fn_pos, Some(mod_scope), tests)
+    }
+}
+
+fn as_test_runnable(sema: &Semantics<RootDatabase>, fn_def: &ast::Fn) -> Option<Runnable> {
+    if test_related_attribute(&fn_def).is_some() {
+        let function = sema.to_def(fn_def)?;
+        runnable_fn(sema, function)
+    } else {
+        None
+    }
+}
+
+fn parent_test_module(sema: &Semantics<RootDatabase>, fn_def: &ast::Fn) -> Option<hir::Module> {
+    fn_def.syntax().ancestors().find_map(|node| {
+        let module = ast::Module::cast(node)?;
+        let module = sema.to_def(&module)?;
+
+        if has_test_function_or_multiple_test_submodules(sema, &module) {
+            Some(module)
+        } else {
+            None
+        }
+    })
+}
+
 pub(crate) fn runnable_fn(sema: &Semantics<RootDatabase>, def: hir::Function) -> Option<Runnable> {
     let func = def.source(sema.db)?;
     let name_string = def.name(sema.db).to_string();
@@ -234,11 +323,21 @@ fn module_def_doctest(sema: &Semantics<RootDatabase>, def: hir::ModuleDef) -> Op
             // FIXME: this also looks very wrong
             if let Some(assoc_def) = assoc_def {
                 if let hir::AssocItemContainer::Impl(imp) = assoc_def.container(sema.db) {
-                    if let Some(adt) = imp.target_ty(sema.db).as_adt() {
-                        let name = adt.name(sema.db).to_string();
+                    let ty = imp.target_ty(sema.db);
+                    if let Some(adt) = ty.as_adt() {
+                        let name = adt.name(sema.db);
                         let idx = path.rfind(':').map_or(0, |idx| idx + 1);
                         let (prefix, suffix) = path.split_at(idx);
-                        return format!("{}{}::{}", prefix, name, suffix);
+                        let mut ty_params = ty.type_parameters().peekable();
+                        let params = if ty_params.peek().is_some() {
+                            format!(
+                                "<{}>",
+                                ty_params.format_with(", ", |ty, cb| cb(&ty.display(sema.db)))
+                            )
+                        } else {
+                            String::new()
+                        };
+                        return format!("{}{}{}::{}", prefix, name, params, suffix);
                     }
                 }
             }
@@ -256,7 +355,7 @@ fn module_def_doctest(sema: &Semantics<RootDatabase>, def: hir::ModuleDef) -> Op
     Some(res)
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct TestAttr {
     pub ignore: bool,
 }
@@ -349,6 +448,12 @@ mod tests {
         );
     }
 
+    fn check_tests(ra_fixture: &str, expect: Expect) {
+        let (analysis, position) = fixture::position(ra_fixture);
+        let tests = analysis.related_tests(position, None).unwrap();
+        expect.assert_debug_eq(&tests);
+    }
+
     #[test]
     fn test_runnables() {
         check(
@@ -1056,7 +1161,6 @@ mod tests {
 
     #[test]
     fn dont_recurse_in_outline_submodules() {
-        cov_mark::check!(dont_recurse_in_outline_submodules);
         check(
             r#"
 //- /lib.rs
@@ -1074,4 +1178,261 @@ mod tests {
             "#]],
         );
     }
+
+    #[test]
+    fn find_no_tests() {
+        check_tests(
+            r#"
+//- /lib.rs
+fn foo$0() {  };
+"#,
+            expect![[r#"
+                []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn find_direct_fn_test() {
+        check_tests(
+            r#"
+//- /lib.rs
+fn foo$0() { };
+
+mod tests {
+    #[test]
+    fn foo_test() {
+        super::foo()
+    }
+}
+"#,
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                0,
+                            ),
+                            full_range: 31..85,
+                            focus_range: 46..54,
+                            name: "foo_test",
+                            kind: Function,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "tests::foo_test",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg: None,
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn find_direct_struct_test() {
+        check_tests(
+            r#"
+//- /lib.rs
+struct Fo$0o;
+fn foo(arg: &Foo) { };
+
+mod tests {
+    use super::*;
+
+    #[test]
+    fn foo_test() {
+        foo(Foo);
+    }
+}
+"#,
+            expect![[r#"
+            [
+                Runnable {
+                    nav: NavigationTarget {
+                        file_id: FileId(
+                            0,
+                        ),
+                        full_range: 71..122,
+                        focus_range: 86..94,
+                        name: "foo_test",
+                        kind: Function,
+                    },
+                    kind: Test {
+                        test_id: Path(
+                            "tests::foo_test",
+                        ),
+                        attr: TestAttr {
+                            ignore: false,
+                        },
+                    },
+                    cfg: None,
+                },
+            ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn find_indirect_fn_test() {
+        check_tests(
+            r#"
+//- /lib.rs
+fn foo$0() { };
+
+mod tests {
+    use super::foo;
+
+    fn check1() {
+        check2()
+    }
+
+    fn check2() {
+        foo()
+    }
+
+    #[test]
+    fn foo_test() {
+        check1()
+    }
+}
+"#,
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                0,
+                            ),
+                            full_range: 133..183,
+                            focus_range: 148..156,
+                            name: "foo_test",
+                            kind: Function,
+                        },
+                        kind: Test {
+                            test_id: Path(
+                                "tests::foo_test",
+                            ),
+                            attr: TestAttr {
+                                ignore: false,
+                            },
+                        },
+                        cfg: None,
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn tests_are_unique() {
+        check_tests(
+            r#"
+//- /lib.rs
+fn foo$0() { };
+
+mod tests {
+    use super::foo;
+
+    #[test]
+    fn foo_test() {
+        foo();
+        foo();
+    }
+
+    #[test]
+    fn foo2_test() {
+        foo();
+        foo();
+    }
+
+}
+"#,
+            expect![[r#"
+            [
+                Runnable {
+                    nav: NavigationTarget {
+                        file_id: FileId(
+                            0,
+                        ),
+                        full_range: 52..115,
+                        focus_range: 67..75,
+                        name: "foo_test",
+                        kind: Function,
+                    },
+                    kind: Test {
+                        test_id: Path(
+                            "tests::foo_test",
+                        ),
+                        attr: TestAttr {
+                            ignore: false,
+                        },
+                    },
+                    cfg: None,
+                },
+                Runnable {
+                    nav: NavigationTarget {
+                        file_id: FileId(
+                            0,
+                        ),
+                        full_range: 121..185,
+                        focus_range: 136..145,
+                        name: "foo2_test",
+                        kind: Function,
+                    },
+                    kind: Test {
+                        test_id: Path(
+                            "tests::foo2_test",
+                        ),
+                        attr: TestAttr {
+                            ignore: false,
+                        },
+                    },
+                    cfg: None,
+                },
+            ]
+            "#]],
+        );
+    }
+
+    #[test]
+    fn doc_test_type_params() {
+        check(
+            r#"
+//- /lib.rs
+$0
+struct Foo<T, U>;
+
+impl<T, U> Foo<T, U> {
+    /// ```rust
+    /// ````
+    fn t() {}
+}
+"#,
+            &[&DOCTEST],
+            expect![[r#"
+                [
+                    Runnable {
+                        nav: NavigationTarget {
+                            file_id: FileId(
+                                0,
+                            ),
+                            full_range: 47..85,
+                            name: "t",
+                        },
+                        kind: DocTest {
+                            test_id: Path(
+                                "Foo<T, U>::t",
+                            ),
+                        },
+                        cfg: None,
+                    },
+                ]
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide/src/typing.rs b/crates/ide/src/typing.rs
index e3c3aebac..a718faf63 100644
--- a/crates/ide/src/typing.rs
+++ b/crates/ide/src/typing.rs
@@ -145,9 +145,8 @@ mod tests {
     use super::*;
 
     fn do_type_char(char_typed: char, before: &str) -> Option<String> {
-        let (offset, before) = extract_offset(before);
+        let (offset, mut before) = extract_offset(before);
         let edit = TextEdit::insert(offset, char_typed.to_string());
-        let mut before = before.to_string();
         edit.apply(&mut before);
         let parse = SourceFile::parse(&before);
         on_char_typed_inner(&parse.tree(), offset, char_typed).map(|it| {