[clang] Fix assertion failure during operator overload resolution. (PR #98671)

[Daniel M. Katz via cfe-commits]

https://github.com/katzdm updated https://github.com/llvm/llvm-project/pull/98671

>From 47db72077258ebe086059f116bbf7fb32c184c8d Mon Sep 17 00:00:00 2001
From: Dan Katz <katzdm at gmail.com>
Date: Fri, 12 Jul 2024 13:57:33 -0400
Subject: [PATCH] Fix assertion failure during operator overload resolution.

---
 clang/lib/Sema/SemaConcept.cpp |  3 ++-
 clang/test/SemaCXX/PR98671.cpp | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/SemaCXX/PR98671.cpp

diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 202dd86c67f62..f94fb8be20e07 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -1519,7 +1519,8 @@ bool Sema::IsAtLeastAsConstrained(NamedDecl *D1,
     auto IsExpectedEntity = [](const FunctionDecl *FD) {
       FunctionDecl::TemplatedKind Kind = FD->getTemplatedKind();
       return Kind == FunctionDecl::TK_NonTemplate ||
-             Kind == FunctionDecl::TK_FunctionTemplate;
+             Kind == FunctionDecl::TK_FunctionTemplate ||
+             Kind == FunctionDecl::TK_FunctionTemplateSpecialization;
     };
     const auto *FD2 = dyn_cast<FunctionDecl>(D2);
     (void)IsExpectedEntity;
diff --git a/clang/test/SemaCXX/PR98671.cpp b/clang/test/SemaCXX/PR98671.cpp
new file mode 100644
index 0000000000000..696b750759854
--- /dev/null
+++ b/clang/test/SemaCXX/PR98671.cpp
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only %s -verify
+
+struct S {
+  operator int();
+
+  template <typename T>
+  operator T();
+};
+
+
+// Ensure that no assertion is raised when overload resolution fails while
+// choosing between an operator function template and an operator function.
+constexpr auto r = &S::operator int;
+// expected-error at -1 {{initializer of type '<overloaded function type>'}}