[clang] Revert default behavior change of P0522R0 implementation (#91811)

This partially reverts b86e099.

Just the default is changed back, on the Driver side.
No Frontend changes.
The positive spelling of the flag is undeprecated.

No documentation changes or changelog entries because we plan to revert
this revert as soon as #62529
is fixed.

Author: mizvekov

clang/lib/Driver/ToolChains/Clang.cpp

@@ -7249,15 +7249,15 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.addOptOutFlag(CmdArgs, options::OPT_fassume_unique_vtables,
                      options::OPT_fno_assume_unique_vtables);
 
-  // -frelaxed-template-template-args is deprecated.
-  if (Arg *A =
-          Args.getLastArg(options::OPT_frelaxed_template_template_args,
-                          options::OPT_fno_relaxed_template_template_args)) {
+  // -fno-relaxed-template-template-args is deprecated.
+  if (Arg *A = Args.getLastArg(options::OPT_frelaxed_template_template_args,
+                               options::OPT_fno_relaxed_template_template_args);
+      A &&
+      A->getOption().matches(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))
-      CmdArgs.push_back("-fno-relaxed-template-template-args");
-  }
+  else
+    CmdArgs.push_back("-fno-relaxed-template-template-args");
 
   // -fsized-deallocation is off by default, as it is an ABI-breaking change for
   // most platforms.

clang/test/Driver/frelaxed-template-template-args.cpp

@@ -1,5 +1,7 @@
-// RUN: %clang -fsyntax-only -frelaxed-template-template-args %s 2>&1 | FileCheck --check-prefix=CHECK-ON %s
+// 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 --allow-empty %s
 // RUN: %clang -fsyntax-only -fno-relaxed-template-template-args %s 2>&1 | FileCheck --check-prefix=CHECK-OFF %s
 
-// CHECK-ON:  warning: argument '-frelaxed-template-template-args' is deprecated [-Wdeprecated]
+// CHECK-DEF: "-cc1"{{.*}} "-fno-relaxed-template-template-args"
+// CHECK-ON-NOT: warning: argument '-frelaxed-template-template-args' is deprecated [-Wdeprecated]
 // CHECK-OFF: warning: argument '-fno-relaxed-template-template-args' is deprecated [-Wdeprecated]