[clang] c34aa78 - [Clang][Sema] fix deducing auto& from const int in template parameters is impossible in partial specializations (#79733)

[via cfe-commits]

Author: Qizhi Hu
Date: 2024-01-29T06:42:52+08:00
New Revision: c34aa784f8867517315d8ef32a8038ee9dbb7165

URL: https://github.com/llvm/llvm-project/commit/c34aa784f8867517315d8ef32a8038ee9dbb7165
DIFF: https://github.com/llvm/llvm-project/commit/c34aa784f8867517315d8ef32a8038ee9dbb7165.diff

LOG: [Clang][Sema] fix deducing auto& from const int in template parameters is impossible in partial specializations (#79733)

Fix [issue](https://github.com/llvm/llvm-project/issues/77189)
AutoType is possible cv qualified.

Co-authored-by: huqizhi <836744285 at qq.com>

Added: 
    clang/test/SemaTemplate/PR77189.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaTemplateDeduction.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 254e0a9cb72979d..2aa8fea4ad67c02 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -130,6 +130,9 @@ Bug Fixes to C++ Support
 - Fixed a bug where variables referenced by requires-clauses inside
   nested generic lambdas were not properly injected into the constraint scope.
   (`#73418 <https://github.com/llvm/llvm-project/issues/73418>`_)
+- Fixed deducing auto& from const int in template parameters of partial
+  specializations.
+  (`#77189 <https://github.com/llvm/llvm-project/issues/77189>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

diff  --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 25e58f7bdd953d1..f08577febcd3e80 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/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:

diff  --git a/clang/test/SemaTemplate/PR77189.cpp b/clang/test/SemaTemplate/PR77189.cpp
new file mode 100644
index 000000000000000..1e9cc7984163c06
--- /dev/null
+++ b/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);
+}