Merge #8945

8945: fix: Make expected type work in more situations r=flodiebold a=flodiebold

Also makes call info show the correct types for generic methods.

![2021-05-23-182952_1134x616_scrot](https://user-images.githubusercontent.com/906069/119269023-dd5a5b00-bbf5-11eb-993a-b6e122c3b9a6.png)
![2021-05-23-183117_922x696_scrot](https://user-images.githubusercontent.com/906069/119269025-dfbcb500-bbf5-11eb-983c-fc415b8428e0.png)


Co-authored-by: Florian Diebold <[email protected]>

2 files changed, 5 insertions, 9 deletions

diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 53c4ee9da..d1f113e7f 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -181,7 +181,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         for (id, expr) in body.exprs.iter() {
             if let Expr::MethodCall { receiver, .. } = expr {
                 let function_id = match self.infer.method_resolution(id) {
-                    Some(id) => id,
+                    Some((id, _)) => id,
                     None => continue,
                 };
 
@@ -239,15 +239,11 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                     return;
                 }
 
-                // FIXME: note that we erase information about substs here. This
-                // is not right, but, luckily, doesn't matter as we care only
-                // about the number of params
-                let callee = match self.infer.method_resolution(call_id) {
-                    Some(callee) => callee,
+                let (callee, subst) = match self.infer.method_resolution(call_id) {
+                    Some(it) => it,
                     None => return,
                 };
-                let sig =
-                    db.callable_item_signature(callee.into()).into_value_and_skipped_binders().0;
+                let sig = db.callable_item_signature(callee.into()).substitute(&Interner, &subst);
 
                 (sig, args)
             }
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index ed97dc0e3..5d13bddea 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -105,7 +105,7 @@ fn walk_unsafe(
         Expr::MethodCall { .. } => {
             if infer
                 .method_resolution(current)
-                .map(|func| db.function_data(func).is_unsafe())
+                .map(|(func, _)| db.function_data(func).is_unsafe())
                 .unwrap_or(false)
             {
                 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });