[clang] In ExprRequirement building, treat OverloadExpr as dependent (PR #66683)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

<details>
<summary>Changes</summary>

As reported in #<!-- -->66612, we aren't correctly treating the placeholder expression type correctly, so we ended up trying to get a reference version of it, and this resulted in an assertion, since the placeholder type cannot have a reference added.

Fixes: #<!-- -->66612

---
Full diff: https://github.com/llvm/llvm-project/pull/66683.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaExprCXX.cpp (+2-1) 
- (modified) clang/test/SemaTemplate/concepts.cpp (+17) 


``````````diff
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index bb4ef065d5c72aa..77289595972e3cf 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -9063,7 +9063,8 @@ Sema::BuildExprRequirement(
     concepts::ExprRequirement::ReturnTypeRequirement ReturnTypeRequirement) {
   auto Status = concepts::ExprRequirement::SS_Satisfied;
   ConceptSpecializationExpr *SubstitutedConstraintExpr = nullptr;
-  if (E->isInstantiationDependent() || ReturnTypeRequirement.isDependent())
+  if (E->isInstantiationDependent() || E->getType()->isPlaceholderType() ||
+      ReturnTypeRequirement.isDependent())
     Status = concepts::ExprRequirement::SS_Dependent;
   else if (NoexceptLoc.isValid() && canThrow(E) == CanThrowResult::CT_Can)
     Status = concepts::ExprRequirement::SS_NoexceptNotMet;
diff --git a/clang/test/SemaTemplate/concepts.cpp b/clang/test/SemaTemplate/concepts.cpp
index 891b45aa5789296..68050e0f09e248a 100644
--- a/clang/test/SemaTemplate/concepts.cpp
+++ b/clang/test/SemaTemplate/concepts.cpp
@@ -1031,3 +1031,20 @@ void test() {
     fff(42UL); // expected-error {{no matching function}}
 }
 }
+
+namespace GH66612 {
+  template<typename C>
+    auto end(C c) ->int;
+
+  template <typename T>
+    concept Iterator = true;
+
+  template <typename CT>
+    concept Container = requires(CT b) {
+        { end } -> Iterator; // #66612GH_END
+    };
+
+  static_assert(Container<int>);// expected-error{{static assertion failed}}
+  // expected-note at -1{{because 'int' does not satisfy 'Container'}}
+  // expected-note@#66612GH_END{{because 'end' would be invalid: reference to overloaded function could not be resolved; did you mean to call it?}}
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/66683