From 5b05209744ce7dcd15f814482babbfd163553b57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lauren=C8=9Biu=20Nicola?= <lnicola@dend.ro>
Date: Tue, 18 Feb 2020 13:26:00 +0200
Subject: Exclude methods from non-parameter types introduced by generic
 constraints

---
 crates/ra_hir_ty/src/method_resolution.rs       | 17 +++++++++++------
 crates/ra_hir_ty/src/tests/method_resolution.rs | 23 +++++++++++++++++++++++
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/crates/ra_hir_ty/src/method_resolution.rs b/crates/ra_hir_ty/src/method_resolution.rs
index 964acdb09..988d83af5 100644
--- a/crates/ra_hir_ty/src/method_resolution.rs
+++ b/crates/ra_hir_ty/src/method_resolution.rs
@@ -377,12 +377,17 @@ fn iterate_trait_method_candidates<T>(
 ) -> Option<T> {
     // if ty is `impl Trait` or `dyn Trait`, the trait doesn't need to be in scope
     let inherent_trait = self_ty.value.inherent_trait().into_iter();
-    // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
-    let traits_from_env = env
-        .trait_predicates_for_self_ty(&self_ty.value)
-        .map(|tr| tr.trait_)
-        .flat_map(|t| all_super_traits(db, t));
-    let traits = inherent_trait.chain(traits_from_env).chain(traits_in_scope.iter().copied());
+    let env_traits = if let Ty::Placeholder(_) = self_ty.value {
+        // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
+        env.trait_predicates_for_self_ty(&self_ty.value)
+            .map(|tr| tr.trait_)
+            .flat_map(|t| all_super_traits(db, t))
+            .collect()
+    } else {
+        Vec::new()
+    };
+    let traits =
+        inherent_trait.chain(env_traits.into_iter()).chain(traits_in_scope.iter().copied());
     'traits: for t in traits {
         let data = db.trait_data(t);
 
diff --git a/crates/ra_hir_ty/src/tests/method_resolution.rs b/crates/ra_hir_ty/src/tests/method_resolution.rs
index 1f767d324..644d59e17 100644
--- a/crates/ra_hir_ty/src/tests/method_resolution.rs
+++ b/crates/ra_hir_ty/src/tests/method_resolution.rs
@@ -1007,6 +1007,29 @@ fn test() { foo.call()<|>; }
     );
 }
 
+#[test]
+fn method_resolution_non_parameter_type() {
+    let t = type_at(
+        r#"
+//- /main.rs
+mod a {
+    pub trait Foo {
+        fn foo(&self);
+    }
+}
+
+struct Wrapper<T>(T);
+fn foo<T>(t: Wrapper<T>)
+where
+    Wrapper<T>: a::Foo,
+{
+    t.foo()<|>;
+}
+"#,
+    );
+    assert_eq!(t, "{unknown}");
+}
+
 #[test]
 fn method_resolution_slow() {
     // this can get quite slow if we set the solver size limit too high
-- 
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