From e14e7ffa34bf9a458681fe7490ac2d51b02ff908 Mon Sep 17 00:00:00 2001
From: Florian Diebold <flodiebold@gmail.com>
Date: Sun, 16 Feb 2020 12:57:19 +0100
Subject: Fix coercion of &T to itself
The autoderef coercion logic did not handle matching placeholders. This led to
some type mismatches.
---
crates/ra_hir_ty/src/infer/unify.rs | 2 ++
crates/ra_hir_ty/src/tests/coercion.rs | 22 ++++++++++++++++++++++
2 files changed, 24 insertions(+)
(limited to 'crates')
diff --git a/crates/ra_hir_ty/src/infer/unify.rs b/crates/ra_hir_ty/src/infer/unify.rs
index fe05642ae..1dc842f40 100644
--- a/crates/ra_hir_ty/src/infer/unify.rs
+++ b/crates/ra_hir_ty/src/infer/unify.rs
@@ -249,6 +249,8 @@ impl InferenceTable {
match (ty1, ty2) {
(Ty::Unknown, _) | (_, Ty::Unknown) => true,
+ (Ty::Placeholder(p1), Ty::Placeholder(p2)) if *p1 == *p2 => true,
+
(Ty::Infer(InferTy::TypeVar(tv1)), Ty::Infer(InferTy::TypeVar(tv2)))
| (Ty::Infer(InferTy::IntVar(tv1)), Ty::Infer(InferTy::IntVar(tv2)))
| (Ty::Infer(InferTy::FloatVar(tv1)), Ty::Infer(InferTy::FloatVar(tv2)))
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index fc5ef36a5..42330b269 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -526,3 +526,25 @@ fn test() {
"###
);
}
+
+#[test]
+fn coerce_placeholder_ref() {
+ // placeholders should unify, even behind references
+ assert_snapshot!(
+ infer_with_mismatches(r#"
+struct S<T> { t: T }
+impl<TT> S<TT> {
+ fn get(&self) -> &TT {
+ &self.t
+ }
+}
+"#, true),
+ @r###"
+ [51; 55) 'self': &S<TT>
+ [64; 87) '{ ... }': &TT
+ [74; 81) '&self.t': &TT
+ [75; 79) 'self': &S<TT>
+ [75; 81) 'self.t': TT
+ "###
+ );
+}
--
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