[Clang][Sema] fix deducing auto& from const int in template parameters is impossible in partial specializations

Author: huqizhi

clang/lib/Sema/SemaTemplateDeduction.cpp

@@ -649,6 +649,7 @@ static bool IsPossiblyOpaquelyQualifiedTypeInternal(const Type *T) {
   case Type::PackIndexing:
   case Type::UnresolvedUsing:
   case Type::TemplateTypeParm:
+  case Type::Auto:
     return true;
 
   case Type::ConstantArray:

clang/test/SemaTemplate/PR77189.cpp

@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -fsyntax-only -std=c++17 -verify %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++20 -verify %s
+// expected-no-diagnostics
+
+struct false_type {
+	static constexpr bool value = false;
+};
+
+struct true_type {
+	static constexpr bool value = true;
+};
+
+template <auto& Value, int>
+struct test : false_type {};
+
+template <auto& Value>
+struct test<Value, 0> : true_type {};
+
+int main() {
+    static constexpr int v = 42;
+    static_assert(test<v, 0>::value);
+}