Auto merge of #18005 - rami3l:fix/for-completion-in-impl, r=Veykril

fix(ide-completion): fix handling of `for` in `impl T for A` in function body

Closes #17787.

src/tools/rust-analyzer/crates/ide-completion/src/completions/keyword.rs

@@ -150,6 +150,68 @@ fn foo(a: A) { a.$0 }
         );
     }
 
+    #[test]
+    fn for_in_impl() {
+        check_edit(
+            "for",
+            r#"
+struct X;
+impl X $0 {}
+"#,
+            r#"
+struct X;
+impl X for $0 {}
+"#,
+        );
+        check_edit(
+            "for",
+            r#"
+fn foo() {
+    struct X;
+    impl X $0 {}
+}
+"#,
+            r#"
+fn foo() {
+    struct X;
+    impl X for $0 {}
+}
+"#,
+        );
+        check_edit(
+            "for",
+            r#"
+fn foo() {
+    struct X;
+    impl X $0
+}
+"#,
+            r#"
+fn foo() {
+    struct X;
+    impl X for $0
+}
+"#,
+        );
+        check_edit(
+            "for",
+            r#"
+fn foo() {
+    struct X;
+    impl X { fn bar() { $0 } }
+}
+"#,
+            r#"
+fn foo() {
+    struct X;
+    impl X { fn bar() { for $1 in $2 {
+    $0
+} } }
+}
+"#,
+        );
+    }
+
     #[test]
     fn let_semi() {
         cov_mark::check!(let_semi);

src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs

@@ -1132,10 +1132,18 @@ fn classify_name_ref(
             ast::PathType(it) => make_path_kind_type(it.into()),
             ast::PathExpr(it) => {
                 if let Some(p) = it.syntax().parent() {
-                    if ast::ExprStmt::can_cast(p.kind()) {
-                        if let Some(kind) = inbetween_body_and_decl_check(p) {
-                            return Some(make_res(NameRefKind::Keyword(kind)));
-                        }
+                    let p_kind = p.kind();
+                    // The syntax node of interest, for which we want to check whether
+                    // it is sandwiched between an item decl signature and its body.
+                    let probe = if ast::ExprStmt::can_cast(p_kind) {
+                        Some(p)
+                    } else if ast::StmtList::can_cast(p_kind) {
+                        Some(it.syntax().clone())
+                    } else {
+                        None
+                    };
+                    if let Some(kind) = probe.and_then(inbetween_body_and_decl_check) {
+                        return Some(make_res(NameRefKind::Keyword(kind)));
                     }
                 }
 
@@ -1199,7 +1207,13 @@ fn classify_name_ref(
                     }
                 }
             },
-            ast::RecordExpr(it) => make_path_kind_expr(it.into()),
+            ast::RecordExpr(it) => {
+                // A record expression in this position is usually a result of parsing recovery, so check that
+                if let Some(kind) = inbetween_body_and_decl_check(it.syntax().clone()) {
+                    return Some(make_res(NameRefKind::Keyword(kind)));
+                }
+                make_path_kind_expr(it.into())
+            },
             _ => return None,
         }
     };