8 files changed, 207 insertions, 52 deletions

diff --git a/crates/ra_ide/src/completion.rs b/crates/ra_ide/src/completion.rs
index c378c2c62..a27e0fc15 100644
--- a/crates/ra_ide/src/completion.rs
+++ b/crates/ra_ide/src/completion.rs
@@ -33,6 +33,23 @@ pub use crate::completion::completion_item::{
     CompletionItem, CompletionItemKind, InsertTextFormat,
 };
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct CompletionOptions {
+    pub enable_postfix_completions: bool,
+    pub add_call_parenthesis: bool,
+    pub add_call_argument_snippets: bool,
+}
+
+impl Default for CompletionOptions {
+    fn default() -> Self {
+        CompletionOptions {
+            enable_postfix_completions: true,
+            add_call_parenthesis: true,
+            add_call_argument_snippets: true,
+        }
+    }
+}
+
 /// Main entry point for completion. We run completion as a two-phase process.
 ///
 /// First, we look at the position and collect a so-called `CompletionContext.
@@ -55,8 +72,12 @@ pub use crate::completion::completion_item::{
 /// `foo` *should* be present among the completion variants. Filtering by
 /// identifier prefix/fuzzy match should be done higher in the stack, together
 /// with ordering of completions (currently this is done by the client).
-pub(crate) fn completions(db: &RootDatabase, position: FilePosition) -> Option<Completions> {
-    let ctx = CompletionContext::new(db, position)?;
+pub(crate) fn completions(
+    db: &RootDatabase,
+    position: FilePosition,
+    opts: &CompletionOptions,
+) -> Option<Completions> {
+    let ctx = CompletionContext::new(db, position, opts)?;
 
     let mut acc = Completions::default();
 
diff --git a/crates/ra_ide/src/completion/complete_dot.rs b/crates/ra_ide/src/completion/complete_dot.rs
index f275305e2..d8f6f0d9d 100644
--- a/crates/ra_ide/src/completion/complete_dot.rs
+++ b/crates/ra_ide/src/completion/complete_dot.rs
@@ -718,4 +718,35 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn test_method_completion_3547() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+            struct HashSet<T> {}
+            impl<T> HashSet<T> {
+                pub fn the_method(&self) {}
+            }
+            fn foo() {
+                let s: HashSet<_>;
+                s.<|>
+            }
+            ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_method()",
+                source_range: [201; 201),
+                delete: [201; 201),
+                insert: "the_method()$0",
+                kind: Method,
+                lookup: "the_method",
+                detail: "pub fn the_method(&self)",
+            },
+        ]
+        "###
+        );
+    }
 }
diff --git a/crates/ra_ide/src/completion/complete_postfix.rs b/crates/ra_ide/src/completion/complete_postfix.rs
index 65ecea125..6d000548d 100644
--- a/crates/ra_ide/src/completion/complete_postfix.rs
+++ b/crates/ra_ide/src/completion/complete_postfix.rs
@@ -12,7 +12,7 @@ use crate::{
 };
 
 pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
-    if !ctx.db.feature_flags.get("completion.enable-postfix") {
+    if !ctx.options.enable_postfix_completions {
         return;
     }
 
diff --git a/crates/ra_ide/src/completion/complete_trait_impl.rs b/crates/ra_ide/src/completion/complete_trait_impl.rs
index 18a1d2995..2bf654a57 100644
--- a/crates/ra_ide/src/completion/complete_trait_impl.rs
+++ b/crates/ra_ide/src/completion/complete_trait_impl.rs
@@ -34,7 +34,7 @@
 use hir::{self, Docs, HasSource};
 use ra_assists::utils::get_missing_impl_items;
 use ra_syntax::{
-    ast::{self, edit},
+    ast::{self, edit, ImplDef},
     AstNode, SyntaxKind, SyntaxNode, TextRange,
 };
 use ra_text_edit::TextEdit;
@@ -47,22 +47,22 @@ use crate::{
 };
 
 pub(crate) fn complete_trait_impl(acc: &mut Completions, ctx: &CompletionContext) {
-    let trigger = ctx.token.ancestors().find(|p| match p.kind() {
-        SyntaxKind::FN_DEF
-        | SyntaxKind::TYPE_ALIAS_DEF
-        | SyntaxKind::CONST_DEF
-        | SyntaxKind::BLOCK_EXPR => true,
-        _ => false,
-    });
-
-    let impl_def = trigger
-        .as_ref()
-        .and_then(|node| node.parent())
-        .and_then(|node| node.parent())
-        .and_then(ast::ImplDef::cast);
-
-    if let (Some(trigger), Some(impl_def)) = (trigger, impl_def) {
+    if let Some((trigger, impl_def)) = completion_match(ctx) {
         match trigger.kind() {
+            SyntaxKind::NAME_REF => {
+                get_missing_impl_items(&ctx.sema, &impl_def).iter().for_each(|item| match item {
+                    hir::AssocItem::Function(fn_item) => {
+                        add_function_impl(&trigger, acc, ctx, &fn_item)
+                    }
+                    hir::AssocItem::TypeAlias(type_item) => {
+                        add_type_alias_impl(&trigger, acc, ctx, &type_item)
+                    }
+                    hir::AssocItem::Const(const_item) => {
+                        add_const_impl(&trigger, acc, ctx, &const_item)
+                    }
+                })
+            }
+
             SyntaxKind::FN_DEF => {
                 for missing_fn in get_missing_impl_items(&ctx.sema, &impl_def).iter().filter_map(
                     |item| match item {
@@ -101,6 +101,21 @@ pub(crate) fn complete_trait_impl(acc: &mut Completions, ctx: &CompletionContext
     }
 }
 
+fn completion_match(ctx: &CompletionContext) -> Option<(SyntaxNode, ImplDef)> {
+    let (trigger, impl_def_offset) = ctx.token.ancestors().find_map(|p| match p.kind() {
+        SyntaxKind::FN_DEF
+        | SyntaxKind::TYPE_ALIAS_DEF
+        | SyntaxKind::CONST_DEF
+        | SyntaxKind::BLOCK_EXPR => Some((p, 2)),
+        SyntaxKind::NAME_REF => Some((p, 5)),
+        _ => None,
+    })?;
+    let impl_def = (0..impl_def_offset - 1)
+        .try_fold(trigger.parent()?, |t, _| t.parent())
+        .and_then(ast::ImplDef::cast)?;
+    Some((trigger, impl_def))
+}
+
 fn add_function_impl(
     fn_def_node: &SyntaxNode,
     acc: &mut Completions,
@@ -210,6 +225,103 @@ mod tests {
     }
 
     #[test]
+    fn name_ref_function_type_const() {
+        let completions = complete(
+            r"
+            trait Test {
+                type TestType;
+                const TEST_CONST: u16;
+                fn test();
+            }
+
+            struct T1;
+
+            impl Test for T1 {
+                t<|>
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "const TEST_CONST: u16 = ",
+                source_range: [209; 210),
+                delete: [209; 210),
+                insert: "const TEST_CONST: u16 = ",
+                kind: Const,
+                lookup: "TEST_CONST",
+            },
+            CompletionItem {
+                label: "fn test()",
+                source_range: [209; 210),
+                delete: [209; 210),
+                insert: "fn test() {}",
+                kind: Function,
+                lookup: "test",
+            },
+            CompletionItem {
+                label: "type TestType = ",
+                source_range: [209; 210),
+                delete: [209; 210),
+                insert: "type TestType = ",
+                kind: TypeAlias,
+                lookup: "TestType",
+            },
+        ]
+        "###);
+    }
+
+    #[test]
+    fn no_nested_fn_completions() {
+        let completions = complete(
+            r"
+            trait Test {
+                fn test();
+                fn test2();
+            }
+
+            struct T1;
+
+            impl Test for T1 {
+                fn test() {
+                    t<|>
+                }
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"[]"###);
+    }
+
+    #[test]
+    fn name_ref_single_function() {
+        let completions = complete(
+            r"
+            trait Test {
+                fn test();
+            }
+
+            struct T1;
+
+            impl Test for T1 {
+                t<|>
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "fn test()",
+                source_range: [139; 140),
+                delete: [139; 140),
+                insert: "fn test() {}",
+                kind: Function,
+                lookup: "test",
+            },
+        ]
+        "###);
+    }
+
+    #[test]
     fn single_function() {
         let completions = complete(
             r"
diff --git a/crates/ra_ide/src/completion/completion_context.rs b/crates/ra_ide/src/completion/completion_context.rs
index 40535c09e..3646fb8dc 100644
--- a/crates/ra_ide/src/completion/completion_context.rs
+++ b/crates/ra_ide/src/completion/completion_context.rs
@@ -11,7 +11,7 @@ use ra_syntax::{
 };
 use ra_text_edit::AtomTextEdit;
 
-use crate::FilePosition;
+use crate::{completion::CompletionOptions, FilePosition};
 
 /// `CompletionContext` is created early during completion to figure out, where
 /// exactly is the cursor, syntax-wise.
@@ -19,6 +19,7 @@ use crate::FilePosition;
 pub(crate) struct CompletionContext<'a> {
     pub(super) sema: Semantics<'a, RootDatabase>,
     pub(super) db: &'a RootDatabase,
+    pub(super) options: &'a CompletionOptions,
     pub(super) offset: TextUnit,
     /// The token before the cursor, in the original file.
     pub(super) original_token: SyntaxToken,
@@ -57,6 +58,7 @@ impl<'a> CompletionContext<'a> {
     pub(super) fn new(
         db: &'a RootDatabase,
         position: FilePosition,
+        options: &'a CompletionOptions,
     ) -> Option<CompletionContext<'a>> {
         let sema = Semantics::new(db);
 
@@ -80,6 +82,7 @@ impl<'a> CompletionContext<'a> {
         let mut ctx = CompletionContext {
             sema,
             db,
+            options,
             original_token,
             token,
             offset: position.offset,
diff --git a/crates/ra_ide/src/completion/completion_item.rs b/crates/ra_ide/src/completion/completion_item.rs
index 19bbb2517..1d14e9636 100644
--- a/crates/ra_ide/src/completion/completion_item.rs
+++ b/crates/ra_ide/src/completion/completion_item.rs
@@ -321,14 +321,18 @@ impl Into<Vec<CompletionItem>> for Completions {
 
 #[cfg(test)]
 pub(crate) fn do_completion(code: &str, kind: CompletionKind) -> Vec<CompletionItem> {
-    use crate::completion::completions;
-    use crate::mock_analysis::{analysis_and_position, single_file_with_position};
+    use crate::{
+        completion::{completions, CompletionOptions},
+        mock_analysis::{analysis_and_position, single_file_with_position},
+    };
+
     let (analysis, position) = if code.contains("//-") {
         analysis_and_position(code)
     } else {
         single_file_with_position(code)
     };
-    let completions = completions(&analysis.db, position).unwrap();
+    let options = CompletionOptions::default();
+    let completions = completions(&analysis.db, position, &options).unwrap();
     let completion_items: Vec<CompletionItem> = completions.into();
     let mut kind_completions: Vec<CompletionItem> =
         completion_items.into_iter().filter(|c| c.completion_kind == kind).collect();
diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
index aada4d025..3dc56e4a3 100644
--- a/crates/ra_ide/src/completion/presentation.rs
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -104,10 +104,7 @@ impl Completions {
         };
 
         // Add `<>` for generic types
-        if ctx.is_path_type
-            && !ctx.has_type_args
-            && ctx.db.feature_flags.get("completion.insertion.add-call-parenthesis")
-        {
+        if ctx.is_path_type && !ctx.has_type_args && ctx.options.add_call_parenthesis {
             let has_non_default_type_params = match resolution {
                 ScopeDef::ModuleDef(Adt(it)) => it.has_non_default_type_params(ctx.db),
                 ScopeDef::ModuleDef(TypeAlias(it)) => it.has_non_default_type_params(ctx.db),
@@ -212,21 +209,14 @@ impl Completions {
                 .detail(function_signature.to_string());
 
         // If not an import, add parenthesis automatically.
-        if ctx.use_item_syntax.is_none()
-            && !ctx.is_call
-            && ctx.db.feature_flags.get("completion.insertion.add-call-parenthesis")
-        {
+        if ctx.use_item_syntax.is_none() && !ctx.is_call && ctx.options.add_call_parenthesis {
             tested_by!(inserts_parens_for_function_calls);
 
             let (snippet, label) = if params.is_empty() || has_self_param && params.len() == 1 {
                 (format!("{}()$0", name), format!("{}()", name))
             } else {
                 builder = builder.trigger_call_info();
-                let snippet = if ctx
-                    .db
-                    .feature_flags
-                    .get("completion.insertion.add-argument-snippets")
-                {
+                let snippet = if ctx.options.add_call_argument_snippets {
                     let to_skip = if has_self_param { 1 } else { 0 };
                     let function_params_snippet = join(
                         function_signature.parameter_names.iter().skip(to_skip).enumerate().map(
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index c60e86aea..9f45003d3 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -62,7 +62,7 @@ use crate::display::ToNav;
 pub use crate::{
     assists::{Assist, AssistId},
     call_hierarchy::CallItem,
-    completion::{CompletionItem, CompletionItemKind, InsertTextFormat},
+    completion::{CompletionItem, CompletionItemKind, CompletionOptions, InsertTextFormat},
     diagnostics::Severity,
     display::{file_structure, FunctionSignature, NavigationTarget, StructureNode},
     expand_macro::ExpandedMacro,
@@ -84,7 +84,6 @@ pub use ra_db::{
 };
 pub use ra_ide_db::{
     change::{AnalysisChange, LibraryData},
-    feature_flags::FeatureFlags,
     line_index::{LineCol, LineIndex},
     line_index_utils::translate_offset_with_edit,
     search::SearchScope,
@@ -131,13 +130,13 @@ pub struct AnalysisHost {
 
 impl Default for AnalysisHost {
     fn default() -> AnalysisHost {
-        AnalysisHost::new(None, FeatureFlags::default())
+        AnalysisHost::new(None)
     }
 }
 
 impl AnalysisHost {
-    pub fn new(lru_capcity: Option<usize>, feature_flags: FeatureFlags) -> AnalysisHost {
-        AnalysisHost { db: RootDatabase::new(lru_capcity, feature_flags) }
+    pub fn new(lru_capacity: Option<usize>) -> AnalysisHost {
+        AnalysisHost { db: RootDatabase::new(lru_capacity) }
     }
     /// Returns a snapshot of the current state, which you can query for
     /// semantic information.
@@ -145,10 +144,6 @@ impl AnalysisHost {
         Analysis { db: self.db.snapshot() }
     }
 
-    pub fn feature_flags(&self) -> &FeatureFlags {
-        &self.db.feature_flags
-    }
-
     /// Applies changes to the current state of the world. If there are
     /// outstanding snapshots, they will be canceled.
     pub fn apply_change(&mut self, change: AnalysisChange) {
@@ -224,11 +219,6 @@ impl Analysis {
         (host.analysis(), file_id)
     }
 
-    /// Features for Analysis.
-    pub fn feature_flags(&self) -> &FeatureFlags {
-        &self.db.feature_flags
-    }
-
     /// Debug info about the current state of the analysis.
     pub fn status(&self) -> Cancelable<String> {
         self.with_db(|db| status::status(&*db))
@@ -450,8 +440,12 @@ impl Analysis {
     }
 
     /// Computes completions at the given position.
-    pub fn completions(&self, position: FilePosition) -> Cancelable<Option<Vec<CompletionItem>>> {
-        self.with_db(|db| completion::completions(db, position).map(Into::into))
+    pub fn completions(
+        &self,
+        position: FilePosition,
+        options: &CompletionOptions,
+    ) -> Cancelable<Option<Vec<CompletionItem>>> {
+        self.with_db(|db| completion::completions(db, position, options).map(Into::into))
     }
 
     /// Computes assists (aka code actions aka intentions) for the given