Auto merge of rust-lang#12901 - Veykril:completion-trait-expr, r=Veykril

fix: Don't complete marker traits in expression position

cc rust-lang/rust-analyzer#12196

Author: bors

crates/ide-completion/src/completions/expr.rs

@@ -202,10 +202,21 @@ pub(crate) fn complete_expr_path(
                     }
                 }
             }
-            ctx.process_all_names(&mut |name, def| {
-                if scope_def_applicable(def) {
-                    acc.add_path_resolution(ctx, path_ctx, name, def);
+            ctx.process_all_names(&mut |name, def| match def {
+                ScopeDef::ModuleDef(hir::ModuleDef::Trait(t)) => {
+                    let assocs = t.items_with_supertraits(ctx.db);
+                    match &*assocs {
+                        // traits with no assoc items are unusable as expressions since
+                        // there is no associated item path that can be constructed with them
+                        [] => (),
+                        // FIXME: Render the assoc item with the trait qualified
+                        &[_item] => acc.add_path_resolution(ctx, path_ctx, name, def),
+                        // FIXME: Append `::` to the thing here, since a trait on its own won't work
+                        [..] => acc.add_path_resolution(ctx, path_ctx, name, def),
+                    }
                 }
+                _ if scope_def_applicable(def) => acc.add_path_resolution(ctx, path_ctx, name, def),
+                _ => (),
             });
 
             if is_func_update.is_none() {

crates/ide-completion/src/render.rs

@@ -1347,7 +1347,6 @@ fn main() {
                 fn main() []
                 fn foo(…) []
                 md core []
-                tt Sized []
             "#]],
         )
     }
@@ -1394,7 +1393,6 @@ fn main() {
                 fn main() []
                 fn foo(…) []
                 md core []
-                tt Sized []
             "#]],
         )
     }
@@ -1492,7 +1490,6 @@ fn main() {
                 fn &bar() [type]
                 fn foo(…) []
                 md core []
-                tt Sized []
             "#]],
         )
     }

crates/ide-completion/src/tests/expression.rs

@@ -44,7 +44,6 @@ fn baz() {
             st Record
             st Tuple
             st Unit
-            tt Trait
             un Union
             ev TupleV(…)     TupleV(u32)
             bt u32
@@ -137,7 +136,6 @@ impl Unit {
             st Record
             st Tuple
             st Unit
-            tt Trait
             tp TypeParam
             un Union
             ev TupleV(…)    TupleV(u32)

crates/ide-completion/src/tests/record.rs

@@ -167,7 +167,6 @@ fn main() {
             st Foo
             st Foo {…}              Foo { foo1: u32, foo2: u32 }
             tt Default
-            tt Sized
             bt u32
             kw crate::
             kw self::