6 files changed, 171 insertions, 18 deletions

diff --git a/Cargo.lock b/Cargo.lock
index cf88c4e17..7fecee1b5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -775,9 +775,9 @@ dependencies = [
 
 [[package]]
 name = "lsp-types"
-version = "0.81.0"
+version = "0.82.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e02724627e9ef8ba91f461ebc01d48aebbd13a4b7c9dc547a0a2890f53e2171"
+checksum = "db895abb8527cf59e3de893ab2acf52cf904faeb65e60ea6f373e11fe86464e8"
 dependencies = [
  "base64",
  "bitflags",
diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index 849c8f6d0..a2a166e0a 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -709,11 +709,23 @@ impl Function {
     }
 
     pub fn params(self, db: &dyn HirDatabase) -> Vec<Param> {
+        let resolver = self.id.resolver(db.upcast());
+        let ctx = hir_ty::TyLoweringContext::new(db, &resolver);
+        let environment = TraitEnvironment::lower(db, &resolver);
         db.function_data(self.id)
             .params
             .iter()
             .skip(if self.self_param(db).is_some() { 1 } else { 0 })
-            .map(|_| Param { _ty: () })
+            .map(|type_ref| {
+                let ty = Type {
+                    krate: self.id.lookup(db.upcast()).container.module(db.upcast()).krate,
+                    ty: InEnvironment {
+                        value: Ty::from_hir_ext(&ctx, type_ref).0,
+                        environment: environment.clone(),
+                    },
+                };
+                Param { ty }
+            })
             .collect()
     }
 
@@ -742,15 +754,21 @@ impl From<Mutability> for Access {
     }
 }
 
+pub struct Param {
+    ty: Type,
+}
+
+impl Param {
+    pub fn ty(&self) -> &Type {
+        &self.ty
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct SelfParam {
     func: FunctionId,
 }
 
-pub struct Param {
-    _ty: (),
-}
-
 impl SelfParam {
     pub fn access(self, db: &dyn HirDatabase) -> Access {
         let func_data = db.function_data(self.func);
@@ -1276,6 +1294,14 @@ impl Type {
         )
     }
 
+    pub fn remove_ref(&self) -> Option<Type> {
+        if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Ref(_), .. }) = self.ty.value {
+            self.ty.value.substs().map(|substs| self.derived(substs[0].clone()))
+        } else {
+            None
+        }
+    }
+
     pub fn is_unknown(&self) -> bool {
         matches!(self.ty.value, Ty::Unknown)
     }
diff --git a/crates/ide/src/completion/completion_context.rs b/crates/ide/src/completion/completion_context.rs
index 161f59c1e..671b13328 100644
--- a/crates/ide/src/completion/completion_context.rs
+++ b/crates/ide/src/completion/completion_context.rs
@@ -1,7 +1,7 @@
 //! FIXME: write short doc here
 
 use base_db::SourceDatabase;
-use hir::{Semantics, SemanticsScope, Type};
+use hir::{Local, ScopeDef, Semantics, SemanticsScope, Type};
 use ide_db::RootDatabase;
 use syntax::{
     algo::{find_covering_element, find_node_at_offset},
@@ -91,6 +91,7 @@ pub(crate) struct CompletionContext<'a> {
     pub(super) impl_as_prev_sibling: bool,
     pub(super) is_match_arm: bool,
     pub(super) has_item_list_or_source_file_parent: bool,
+    pub(super) locals: Vec<(String, Local)>,
 }
 
 impl<'a> CompletionContext<'a> {
@@ -119,6 +120,12 @@ impl<'a> CompletionContext<'a> {
             original_file.syntax().token_at_offset(position.offset).left_biased()?;
         let token = sema.descend_into_macros(original_token.clone());
         let scope = sema.scope_at_offset(&token.parent(), position.offset);
+        let mut locals = vec![];
+        scope.process_all_names(&mut |name, scope| {
+            if let ScopeDef::Local(local) = scope {
+                locals.push((name.to_string(), local));
+            }
+        });
         let mut ctx = CompletionContext {
             sema,
             scope,
@@ -167,6 +174,7 @@ impl<'a> CompletionContext<'a> {
             if_is_prev: false,
             is_match_arm: false,
             has_item_list_or_source_file_parent: false,
+            locals,
         };
 
         let mut original_file = original_file.syntax().clone();
diff --git a/crates/ide/src/completion/presentation.rs b/crates/ide/src/completion/presentation.rs
index 24c507f9b..987cbfa7a 100644
--- a/crates/ide/src/completion/presentation.rs
+++ b/crates/ide/src/completion/presentation.rs
@@ -191,6 +191,17 @@ impl Completions {
         func: hir::Function,
         local_name: Option<String>,
     ) {
+        fn add_arg(arg: &str, ty: &Type, ctx: &CompletionContext) -> String {
+            if let Some(derefed_ty) = ty.remove_ref() {
+                for (name, local) in ctx.locals.iter() {
+                    if name == arg && local.ty(ctx.db) == derefed_ty {
+                        return (if ty.is_mutable_reference() { "&mut " } else { "&" }).to_string()
+                            + &arg.to_string();
+                    }
+                }
+            }
+            arg.to_string()
+        };
         let name = local_name.unwrap_or_else(|| func.name(ctx.db).to_string());
         let ast_node = func.source(ctx.db).value;
 
@@ -205,12 +216,20 @@ impl Completions {
                 .set_deprecated(is_deprecated(func, ctx.db))
                 .detail(function_declaration(&ast_node));
 
+        let params_ty = func.params(ctx.db);
         let params = ast_node
             .param_list()
             .into_iter()
             .flat_map(|it| it.params())
-            .flat_map(|it| it.pat())
-            .map(|pat| pat.to_string().trim_start_matches('_').into())
+            .zip(params_ty)
+            .flat_map(|(it, param_ty)| {
+                if let Some(pat) = it.pat() {
+                    let name = pat.to_string();
+                    let arg = name.trim_start_matches("mut ").trim_start_matches('_');
+                    return Some(add_arg(arg, param_ty.ty(), ctx));
+                }
+                None
+            })
             .collect();
 
         builder = builder.add_call_parens(ctx, name, Params::Named(params));
@@ -864,6 +883,106 @@ fn main() { foo(${1:foo}, ${2:bar}, ${3:ho_ge_})$0 }
     }
 
     #[test]
+    fn insert_ref_when_matching_local_in_scope() {
+        check_edit(
+            "ref_arg",
+            r#"
+struct Foo {}
+fn ref_arg(x: &Foo) {}
+fn main() {
+    let x = Foo {};
+    ref_ar<|>
+}
+"#,
+            r#"
+struct Foo {}
+fn ref_arg(x: &Foo) {}
+fn main() {
+    let x = Foo {};
+    ref_arg(${1:&x})$0
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn insert_mut_ref_when_matching_local_in_scope() {
+        check_edit(
+            "ref_arg",
+            r#"
+struct Foo {}
+fn ref_arg(x: &mut Foo) {}
+fn main() {
+    let x = Foo {};
+    ref_ar<|>
+}
+"#,
+            r#"
+struct Foo {}
+fn ref_arg(x: &mut Foo) {}
+fn main() {
+    let x = Foo {};
+    ref_arg(${1:&mut x})$0
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn insert_ref_when_matching_local_in_scope_for_method() {
+        check_edit(
+            "apply_foo",
+            r#"
+struct Foo {}
+struct Bar {}
+impl Bar {
+    fn apply_foo(&self, x: &Foo) {}
+}
+
+fn main() {
+    let x = Foo {};
+    let y = Bar {};
+    y.<|>
+}
+"#,
+            r#"
+struct Foo {}
+struct Bar {}
+impl Bar {
+    fn apply_foo(&self, x: &Foo) {}
+}
+
+fn main() {
+    let x = Foo {};
+    let y = Bar {};
+    y.apply_foo(${1:&x})$0
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn trim_mut_keyword_in_func_completion() {
+        check_edit(
+            "take_mutably",
+            r#"
+fn take_mutably(mut x: &i32) {}
+
+fn main() {
+    take_m<|>
+}
+"#,
+            r#"
+fn take_mutably(mut x: &i32) {}
+
+fn main() {
+    take_mutably(${1:x})$0
+}
+"#,
+        );
+    }
+
+    #[test]
     fn inserts_parens_for_tuple_enums() {
         mark::check!(inserts_parens_for_tuple_enums);
         check_edit(
diff --git a/crates/rust-analyzer/Cargo.toml b/crates/rust-analyzer/Cargo.toml
index 0fbb9cb0d..631ffc4a7 100644
--- a/crates/rust-analyzer/Cargo.toml
+++ b/crates/rust-analyzer/Cargo.toml
@@ -21,7 +21,7 @@ env_logger = { version = "0.7.1", default-features = false }
 itertools = "0.9.0"
 jod-thread = "0.1.0"
 log = "0.4.8"
-lsp-types = { version = "0.81.0", features = ["proposed"] }
+lsp-types = { version = "0.82.0", features = ["proposed"] }
 parking_lot = "0.11.0"
 pico-args = "0.3.1"
 oorandom = "11.1.2"
diff --git a/crates/rust-analyzer/src/caps.rs b/crates/rust-analyzer/src/caps.rs
index de4bc2813..c589afeaf 100644
--- a/crates/rust-analyzer/src/caps.rs
+++ b/crates/rust-analyzer/src/caps.rs
@@ -5,7 +5,7 @@ use lsp_types::{
     CallHierarchyServerCapability, ClientCapabilities, CodeActionKind, CodeActionOptions,
     CodeActionProviderCapability, CodeLensOptions, CompletionOptions,
     DocumentOnTypeFormattingOptions, FoldingRangeProviderCapability, HoverProviderCapability,
-    ImplementationProviderCapability, RenameOptions, RenameProviderCapability, SaveOptions,
+    ImplementationProviderCapability, OneOf, RenameOptions, SaveOptions,
     SelectionRangeProviderCapability, SemanticTokensFullOptions, SemanticTokensLegend,
     SemanticTokensOptions, ServerCapabilities, SignatureHelpOptions, TextDocumentSyncCapability,
     TextDocumentSyncKind, TextDocumentSyncOptions, TypeDefinitionProviderCapability,
@@ -42,16 +42,16 @@ pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabiliti
             work_done_progress_options: WorkDoneProgressOptions { work_done_progress: None },
         }),
         declaration_provider: None,
-        definition_provider: Some(true),
+        definition_provider: Some(OneOf::Left(true)),
         type_definition_provider: Some(TypeDefinitionProviderCapability::Simple(true)),
         implementation_provider: Some(ImplementationProviderCapability::Simple(true)),
-        references_provider: Some(true),
-        document_highlight_provider: Some(true),
-        document_symbol_provider: Some(true),
+        references_provider: Some(OneOf::Left(true)),
+        document_highlight_provider: Some(OneOf::Left(true)),
+        document_symbol_provider: Some(OneOf::Left(true)),
         workspace_symbol_provider: Some(true),
         code_action_provider: Some(code_action_provider),
         code_lens_provider: Some(CodeLensOptions { resolve_provider: Some(true) }),
-        document_formatting_provider: Some(true),
+        document_formatting_provider: Some(OneOf::Left(true)),
         document_range_formatting_provider: None,
         document_on_type_formatting_provider: Some(DocumentOnTypeFormattingOptions {
             first_trigger_character: "=".to_string(),
@@ -60,7 +60,7 @@ pub fn server_capabilities(client_caps: &ClientCapabilities) -> ServerCapabiliti
         selection_range_provider: Some(SelectionRangeProviderCapability::Simple(true)),
         semantic_highlighting: None,
         folding_range_provider: Some(FoldingRangeProviderCapability::Simple(true)),
-        rename_provider: Some(RenameProviderCapability::Options(RenameOptions {
+        rename_provider: Some(OneOf::Right(RenameOptions {
             prepare_provider: Some(true),
             work_done_progress_options: WorkDoneProgressOptions { work_done_progress: None },
         })),