[clang] [clang-tools-extra] [libcxx] [clang] Enable sized deallocation by default in C++14 onwards (PR #83774)

[Pengcheng Wang via cfe-commits]

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@@ -7238,10 +7238,15 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   Args.addOptInFlag(CmdArgs, options::OPT_frelaxed_template_template_args,
                     options::OPT_fno_relaxed_template_template_args);
 
-  // -fsized-deallocation is off by default, as it is an ABI-breaking change for
-  // most platforms.
-  Args.addOptInFlag(CmdArgs, options::OPT_fsized_deallocation,
-                    options::OPT_fno_sized_deallocation);
+  // -fsized-deallocation is on by default in C++14 onwards and otherwise off
+  // by default.
+  if (Arg *A = Args.getLastArg(options::OPT_fsized_deallocation,
+                               options::OPT_fno_sized_deallocation)) {
+    if (A->getOption().matches(options::OPT_fno_sized_deallocation))
+      CmdArgs.push_back("-fno-sized-deallocation");
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wangpc-pp wrote:

I don't know if I understand correctly, but I think we need both clang and cc1 options for `sized_deallocation`. Please see `aligned_allocation` case, which is the same as `sized_deallocation`:
https://github.com/llvm/llvm-project/blob/24e8c6a09b7d226dbe706aeae7aebf479a1e5087/clang/include/clang/Driver/Options.td#L3355-L3358
And there are a lot of tests assumed we have cc1 options `-fno-sized-deallocation` and `-fsized-deallocation` like [`clang/test/SemaCXX/builtin-operator-new-delete.cpp`](https://github.com/llvm/llvm-project/blob/main/clang/test/SemaCXX/builtin-operator-new-delete.cpp).

https://github.com/llvm/llvm-project/pull/83774