Place cursor correctly when completing assoc fns with self

Author: matklad

crates/completion/src/completions/qualified_path.rs

@@ -353,10 +353,10 @@ impl S {
 fn foo() { let _ = S::<|> }
 "#,
             expect![[r#"
-                ct C   const C: i32 = 42;
-                ta T   type T = i32;
-                fn a() fn a()
-                me b() fn b(&self)
+                ct C    const C: i32 = 42;
+                ta T    type T = i32;
+                fn a()  fn a()
+                me b(…) fn b(&self)
             "#]],
         );
     }
@@ -503,14 +503,14 @@ trait Sub: Super {
 fn foo<T: Sub>() { T::<|> }
 "#,
             expect![[r#"
-                ct C2          const C2: ();
-                ct CONST       const CONST: u8;
-                ta SubTy       type SubTy;
-                ta Ty          type Ty;
-                fn func()      fn func()
-                me method()    fn method(&self)
-                fn subfunc()   fn subfunc()
-                me submethod() fn submethod(&self)
+                ct C2           const C2: ();
+                ct CONST        const CONST: u8;
+                ta SubTy        type SubTy;
+                ta Ty           type Ty;
+                fn func()       fn func()
+                me method(…)    fn method(&self)
+                fn subfunc()    fn subfunc()
+                me submethod(…) fn submethod(&self)
             "#]],
         );
     }
@@ -543,14 +543,14 @@ impl<T> Sub for Wrap<T> {
 }
 "#,
             expect![[r#"
-                ct C2          const C2: () = ();
-                ct CONST       const CONST: u8 = 0;
-                ta SubTy       type SubTy;
-                ta Ty          type Ty;
-                fn func()      fn func()
-                me method()    fn method(&self)
-                fn subfunc()   fn subfunc()
-                me submethod() fn submethod(&self)
+                ct C2           const C2: () = ();
+                ct CONST        const CONST: u8 = 0;
+                ta SubTy        type SubTy;
+                ta Ty           type Ty;
+                fn func()       fn func()
+                me method(…)    fn method(&self)
+                fn subfunc()    fn subfunc()
+                me submethod(…) fn submethod(&self)
             "#]],
         );
     }

crates/completion/src/render/builder_ext.rs

@@ -5,6 +5,7 @@ use test_utils::mark;
 
 use crate::{item::Builder, CompletionContext};
 
+#[derive(Debug)]
 pub(super) enum Params {
     Named(Vec<String>),
     Anonymous(usize),

crates/completion/src/render/function.rs

@@ -2,6 +2,7 @@
 
 use hir::{HasSource, Type};
 use syntax::{ast::Fn, display::function_declaration};
+use test_utils::mark;
 
 use crate::{
     item::{CompletionItem, CompletionItemKind, CompletionKind, ImportToAdd},
@@ -67,24 +68,32 @@ impl<'a> FunctionRender<'a> {
     }
 
     fn params(&self) -> Params {
+        let ast_params = match self.ast_node.param_list() {
+            Some(it) => it,
+            None => return Params::Named(Vec::new()),
+        };
+
+        let mut params_pats = Vec::new();
         let params_ty = if self.ctx.completion.dot_receiver.is_some() {
             self.func.method_params(self.ctx.db()).unwrap_or_default()
         } else {
+            if let Some(s) = ast_params.self_param() {
+                mark::hit!(parens_for_method_call_as_assoc_fn);
+                params_pats.push(Some(s.to_string()));
+            }
             self.func.assoc_fn_params(self.ctx.db())
         };
-        let params = self
-            .ast_node
-            .param_list()
+        params_pats
+            .extend(ast_params.params().into_iter().map(|it| it.pat().map(|it| it.to_string())));
+
+        let params = params_pats
             .into_iter()
-            .flat_map(|it| it.params())
             .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(self.add_arg(arg, param_ty.ty()));
-                }
-                None
+            .flat_map(|(pat, param_ty)| {
+                let pat = pat?;
+                let name = pat.to_string();
+                let arg = name.trim_start_matches("mut ").trim_start_matches('_');
+                Some(self.add_arg(arg, param_ty.ty()))
             })
             .collect();
         Params::Named(params)
@@ -176,6 +185,28 @@ fn bar(s: &S) {
         );
     }
 
+    #[test]
+    fn parens_for_method_call_as_assoc_fn() {
+        mark::check!(parens_for_method_call_as_assoc_fn);
+        check_edit(
+            "foo",
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::f<|> }
+"#,
+            r#"
+struct S;
+impl S {
+    fn foo(&self) {}
+}
+fn main() { S::foo(${1:&self})$0 }
+"#,
+        );
+    }
+
     #[test]
     fn suppress_arg_snippets() {
         mark::check!(suppress_arg_snippets);

crates/hir/src/code_model.rs

@@ -806,6 +806,7 @@ impl From<Mutability> for Access {
     }
 }
 
+#[derive(Debug)]
 pub struct Param {
     ty: Type,
 }