[clang] [clang] Create new warning group for deprecation of '-fno-relaxed-template-template-args' (PR #92324)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Matheus Izvekov (mizvekov)

<details>
<summary>Changes</summary>

This allows the warning to be disabled in isolation, as it helps when treating them as errors.

---
Full diff: https://github.com/llvm/llvm-project/pull/92324.diff


5 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2-1) 
- (modified) clang/include/clang/Basic/DiagnosticDriverKinds.td (+3) 
- (modified) clang/include/clang/Basic/DiagnosticGroups.td (+2) 
- (modified) clang/lib/Driver/ToolChains/Clang.cpp (+7-3) 
- (modified) clang/test/Driver/frelaxed-template-template-args.cpp (+3-1) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ae699ebfc6038..8f847a4376247 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -51,7 +51,8 @@ C++ Specific Potentially Breaking Changes
 - The behavior controlled by the `-frelaxed-template-template-args` flag is now
   on by default, and the flag is deprecated. Until the flag is finally removed,
   it's negative spelling can be used to obtain compatibility with previous
-  versions of clang.
+  versions of clang. The deprecation warning for the negative spelling can be
+  disabled with `-Wno-deprecated-no-relaxed-template-template-args`.
 
 - Clang now rejects pointer to member from parenthesized expression in unevaluated context such as ``decltype(&(foo::bar))``. (#GH40906).
 
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 9781fcaa4ff5e..9d97a75f696f6 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -436,6 +436,9 @@ def warn_drv_clang_unsupported : Warning<
   "the clang compiler does not support '%0'">;
 def warn_drv_deprecated_arg : Warning<
   "argument '%0' is deprecated%select{|, use '%2' instead}1">, InGroup<Deprecated>;
+def warn_drv_deprecated_arg_no_relaxed_template_template_args : Warning<
+  "argument '-fno-relaxed-template-template-args' is deprecated">,
+  InGroup<DeprecatedNoRelaxedTemplateTemplateArgs>;
 def warn_drv_deprecated_custom : Warning<
   "argument '%0' is deprecated, %1">, InGroup<Deprecated>;
 def warn_drv_assuming_mfloat_abi_is : Warning<
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index 2beb1d45124b4..4cb4f3d999f7a 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -104,6 +104,7 @@ def EnumConversion : DiagGroup<"enum-conversion",
                                [EnumEnumConversion,
                                 EnumFloatConversion,
                                 EnumCompareConditional]>;
+def DeprecatedNoRelaxedTemplateTemplateArgs : DiagGroup<"deprecated-no-relaxed-template-template-args">;
 def ObjCSignedCharBoolImplicitIntConversion :
   DiagGroup<"objc-signed-char-bool-implicit-int-conversion">;
 def Shorten64To32 : DiagGroup<"shorten-64-to-32">;
@@ -228,6 +229,7 @@ def Deprecated : DiagGroup<"deprecated", [DeprecatedAnonEnumEnumConversion,
                                           DeprecatedLiteralOperator,
                                           DeprecatedPragma,
                                           DeprecatedRegister,
+                                          DeprecatedNoRelaxedTemplateTemplateArgs,
                                           DeprecatedThisCapture,
                                           DeprecatedType,
                                           DeprecatedVolatile,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 42feb1650574e..c3e6d563f3bd2 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7253,10 +7253,14 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (Arg *A =
           Args.getLastArg(options::OPT_frelaxed_template_template_args,
                           options::OPT_fno_relaxed_template_template_args)) {
-    D.Diag(diag::warn_drv_deprecated_arg)
-        << A->getAsString(Args) << /*hasReplacement=*/false;
-    if (A->getOption().matches(options::OPT_fno_relaxed_template_template_args))
+    if (A->getOption().matches(
+            options::OPT_fno_relaxed_template_template_args)) {
+      D.Diag(diag::warn_drv_deprecated_arg_no_relaxed_template_template_args);
       CmdArgs.push_back("-fno-relaxed-template-template-args");
+    } else {
+      D.Diag(diag::warn_drv_deprecated_arg)
+          << A->getAsString(Args) << /*hasReplacement=*/false;
+    }
   }
 
   // -fsized-deallocation is off by default, as it is an ABI-breaking change for
diff --git a/clang/test/Driver/frelaxed-template-template-args.cpp b/clang/test/Driver/frelaxed-template-template-args.cpp
index 57fc4e3da6e5d..7a7fd6f0bbc8f 100644
--- a/clang/test/Driver/frelaxed-template-template-args.cpp
+++ b/clang/test/Driver/frelaxed-template-template-args.cpp
@@ -1,7 +1,9 @@
 // RUN: %clang -fsyntax-only -### %s 2>&1 | FileCheck --check-prefix=CHECK-DEF %s
 // RUN: %clang -fsyntax-only -frelaxed-template-template-args %s 2>&1 | FileCheck --check-prefix=CHECK-ON %s
 // RUN: %clang -fsyntax-only -fno-relaxed-template-template-args %s 2>&1 | FileCheck --check-prefix=CHECK-OFF %s
+// RUN: %clang -fsyntax-only -fno-relaxed-template-template-args -Wno-deprecated-no-relaxed-template-template-args %s 2>&1 | FileCheck --check-prefix=CHECK-DIS --allow-empty %s
 
 // CHECK-DEF-NOT: "-cc1"{{.*}} "-fno-relaxed-template-template-args"
 // CHECK-ON:  warning: argument '-frelaxed-template-template-args' is deprecated [-Wdeprecated]
-// CHECK-OFF: warning: argument '-fno-relaxed-template-template-args' is deprecated [-Wdeprecated]
+// CHECK-OFF: warning: argument '-fno-relaxed-template-template-args' is deprecated [-Wdeprecated-no-relaxed-template-template-args]
+// CHECK-DIS-NOT: warning: argument '-fno-relaxed-template-template-args' is deprecated

``````````

</details>


https://github.com/llvm/llvm-project/pull/92324