Normalize all types when finishing inference

The new solver does not eagerly normalize, but things after inference expect types to be normalized. rustc does the same.

Also, I'm afraid other things in r-a don't expect results of the solver to be unnormalized. We'll need to handle that.

2 files changed, 29 insertions, 0 deletions

diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
index a709aebfa9c..bb4782bd419 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
@@ -621,6 +621,9 @@ impl<'a> InferenceTable<'a> {
     where
         T: HasInterner<Interner = Interner> + TypeFoldable<Interner>,
     {
+        let t = self.resolve_with_fallback(t, &|_, _, d, _| d);
+        let t = self.normalize_associated_types_in(t);
+        // Resolve again, because maybe normalization inserted infer vars.
         self.resolve_with_fallback(t, &|_, _, d, _| d)
     }
 
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
index 059f4ad32a5..20190fbc045 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
@@ -24,3 +24,29 @@ impl<'a> IntoIterator for &'a Grid {
         "#]],
     );
 }
+
+#[test]
+fn normalization() {
+    check_infer(
+        r#"
+//- minicore: iterator, iterators
+fn main() {
+    _ = [0i32].into_iter().filter_map(|_n| Some(1i32));
+}
+    "#,
+        expect![[r#"
+            10..69 '{     ...2)); }': ()
+            16..17 '_': FilterMap<IntoIter<i32, 1>, impl FnMut(i32) -> Option<i32>>
+            16..66 '_ = [0...1i32))': ()
+            20..26 '[0i32]': [i32; 1]
+            20..38 '[0i32]...iter()': IntoIter<i32, 1>
+            20..66 '[0i32]...1i32))': FilterMap<IntoIter<i32, 1>, impl FnMut(i32) -> Option<i32>>
+            21..25 '0i32': i32
+            50..65 '|_n| Some(1i32)': impl FnMut(i32) -> Option<i32>
+            51..53 '_n': i32
+            55..59 'Some': fn Some<i32>(i32) -> Option<i32>
+            55..65 'Some(1i32)': Option<i32>
+            60..64 '1i32': i32
+        "#]],
+    );
+}