Fix completion of HashMap::new

The `ty` function in code_model returned the type with placeholders for type
parameters. That's nice for printing, but not good for completion, because
placeholders won't unify with anything else: So the type we got for `HashMap`
was `HashMap<K, V, T>`, which doesn't unify with `HashMap<?, ?, RandomState>`,
so the `new` method wasn't shown.

Now we instead return `HashMap<{unknown}, {unknown}, {unknown}>`, which does
unify with the impl type. Maybe we should just expose this properly as variables
though, i.e. we'd return something like `exists<type, type, type> HashMap<?0,
?1, ?2>` (in Chalk notation). It'll make the API more complicated, but harder to
misuse. (And it would handle cases like `type TypeAlias<T> = HashMap<T, T>` more
correctly.)

1 files changed, 14 insertions, 0 deletions

diff --git a/crates/ra_ide/src/call_info.rs b/crates/ra_ide/src/call_info.rs
index 2b35a3803..39d09a07f 100644
--- a/crates/ra_ide/src/call_info.rs
+++ b/crates/ra_ide/src/call_info.rs
@@ -544,6 +544,20 @@ fn main() {
     }
 
     #[test]
+    fn generic_struct() {
+        let info = call_info(
+            r#"
+struct TS<T>(T);
+fn main() {
+    let s = TS(<|>);
+}"#,
+        );
+
+        assert_eq!(info.label(), "struct TS<T>(T) -> TS");
+        assert_eq!(info.active_parameter, Some(0));
+    }
+
+    #[test]
     #[should_panic]
     fn cant_call_named_structs() {
         let _ = call_info(