https://github.com/GeorgeKA updated
https://github.com/llvm/llvm-project/pull/133806
>From dd978982b2ab41d3d2a55abb448e653a80158ecd Mon Sep 17 00:00:00 2001
From: George Asante <gkasa...@gmail.com>
Date: Mon, 31 Mar 2025 17:41:20 -0400
Subject: [PATCH 1/2] Add warning message for C++17 alias template CTAD
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 13 ++++++++++---
clang/lib/Sema/SemaInit.cpp | 4 +++-
clang/test/SemaCXX/cxx17-compat.cpp | 2 +-
.../cxx1z-class-template-argument-deduction.cpp | 4 ++--
4 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index c77cde297dc32..6f71628f19a4a 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8444,9 +8444,16 @@ let CategoryName = "Lambda Issue" in {
"C++ standards before C++20">, InGroup<CXXPre20Compat>, DefaultIgnore;
// C++20 class template argument deduction for alias templates.
- def warn_cxx17_compat_ctad_for_alias_templates : Warning<
- "class template argument deduction for alias templates is incompatible with "
- "C++ standards before C++20">, InGroup<CXXPre20Compat>, DefaultIgnore;
+ def warn_cxx17_compat_ctad_for_alias_templates
+ : Warning<"class template argument deduction for alias templates is "
+ "incompatible with "
+ "C++ standards before C++20">,
+ InGroup<CXXPre20Compat>,
+ DefaultIgnore;
+ def ext_ctad_for_alias_templates_cxx20
+ : ExtWarn<"class template argument deduction for alias templates is a "
+ "C++20 extension">,
+ InGroup<CXX20>;
}
def err_return_in_captured_stmt : Error<
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index cea121d576c5c..7229cd42f85d0 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -9896,7 +9896,9 @@ QualType
Sema::DeduceTemplateSpecializationFromInitializer(
if (auto *AliasTemplate = dyn_cast_or_null<TypeAliasTemplateDecl>(
TemplateName.getAsTemplateDecl())) {
Diag(Kind.getLocation(),
- diag::warn_cxx17_compat_ctad_for_alias_templates);
+ getLangOpts().CPlusPlus20
+ ? diag::warn_cxx17_compat_ctad_for_alias_templates
+ : diag::ext_ctad_for_alias_templates_cxx20);
LookupTemplateDecl = AliasTemplate;
auto UnderlyingType = AliasTemplate->getTemplatedDecl()
->getUnderlyingType()
diff --git a/clang/test/SemaCXX/cxx17-compat.cpp
b/clang/test/SemaCXX/cxx17-compat.cpp
index 54ea3384022d4..81b3e1fde5493 100644
--- a/clang/test/SemaCXX/cxx17-compat.cpp
+++ b/clang/test/SemaCXX/cxx17-compat.cpp
@@ -137,7 +137,7 @@ template<typename T> struct A { A(T); };
template<typename T> using B = A<T>;
B b = {1};
#if __cplusplus <= 201703L
- // FIXME: diagnose as well
+ // expected-warning@-2 {{class template argument deduction for alias
templates is a C++20 extension}}
#else
// expected-warning@-4 {{class template argument deduction for alias
templates is incompatible with C++ standards before C++20}}
#endif
diff --git a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
index 9aaa13d7ac41a..a7d740e66ba63 100644
--- a/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
+++ b/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp
@@ -113,9 +113,9 @@ namespace dependent {
};
template<typename T> void f() {
typename T::X tx = 0;
- typename T::Y ty = 0;
+ typename T::Y ty = 0; // expected-warning {{class template argument
deduction for alias templates is a C++20 extension}}
}
- template void f<B>();
+ template void f<B>(); // expected-note {{in instantiation of function
template specialization 'dependent::f<dependent::B>' requested here}}
template<typename T> struct C { C(T); };
template<typename T> C(T) -> C<T>;
>From c48c4a60c1ed8aebff27bf8a7bb108dd3a9ad3ef Mon Sep 17 00:00:00 2001
From: George Asante <gkasa...@gmail.com>
Date: Mon, 31 Mar 2025 18:38:06 -0400
Subject: [PATCH 2/2] Switched to using multiclasses for both messages
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 14 ++------------
clang/lib/Sema/SemaInit.cpp | 4 ++--
2 files changed, 4 insertions(+), 14 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td
b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 6f71628f19a4a..79389eebd81f1 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -49,6 +49,8 @@ defm constexpr_ctor_missing_init : CXX20Compat<
defm adl_only_template_id : CXX20Compat<
"use of function template name with no prior declaration in function call "
"with explicit template arguments is">;
+defm ctad_for_alias_templates
+ : CXX20Compat<"class template argument deduction for alias templates is">;
// C++23 compatibility with C++20 and earlier.
defm constexpr_static_var : CXX23Compat<
@@ -8442,18 +8444,6 @@ let CategoryName = "Lambda Issue" in {
def warn_cxx17_compat_lambda_def_ctor_assign : Warning<
"%select{default construction|assignment}0 of lambda is incompatible with "
"C++ standards before C++20">, InGroup<CXXPre20Compat>, DefaultIgnore;
-
- // C++20 class template argument deduction for alias templates.
- def warn_cxx17_compat_ctad_for_alias_templates
- : Warning<"class template argument deduction for alias templates is "
- "incompatible with "
- "C++ standards before C++20">,
- InGroup<CXXPre20Compat>,
- DefaultIgnore;
- def ext_ctad_for_alias_templates_cxx20
- : ExtWarn<"class template argument deduction for alias templates is a "
- "C++20 extension">,
- InGroup<CXX20>;
}
def err_return_in_captured_stmt : Error<
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 7229cd42f85d0..a7e09f851214a 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -9897,8 +9897,8 @@ QualType
Sema::DeduceTemplateSpecializationFromInitializer(
TemplateName.getAsTemplateDecl())) {
Diag(Kind.getLocation(),
getLangOpts().CPlusPlus20
- ? diag::warn_cxx17_compat_ctad_for_alias_templates
- : diag::ext_ctad_for_alias_templates_cxx20);
+ ? diag::compat_cxx20_ctad_for_alias_templates
+ : diag::compat_pre_cxx20_ctad_for_alias_templates);
LookupTemplateDecl = AliasTemplate;
auto UnderlyingType = AliasTemplate->getTemplatedDecl()
->getUnderlyingType()
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