[clang] Default to -fno-sized-deallocation for AIX (#97076)

Some `libc++` LIT test cases and user code define their own version of
`operator delete` that are not sized. With `-fno-sized-deallocation`,
destructors call the non-sized `operator delete` and it will be resolved
to the user defined version. However, with `-fsized-deallocation`,
destructors will call the sized `operator delete` which will be resolved
to the weak definition in `libc++abi` because the user code does not
define the corresponding sized version. The `libc++abi` sized `operator
delete` in turn calls the non-sized version of `operator delete` of the
same shared object inside `libc++abi` instead of the user defined
version on AIX because runtime linking is not the default for AIX and
therefore, fails the tests or user code. This patch sets
`-fno-sized-deallocation` as the default for AIX if neither
`-fsize-deallocation` nor `-fno-sized-deallocation` is explicitly set,
similar to what is done for ZOS.

Author: xingxue-ibm

clang/lib/Driver/ToolChains/AIX.cpp

@@ -551,6 +551,12 @@ void AIX::addClangTargetOptions(
   if (Args.hasFlag(options::OPT_fxl_pragma_pack,
                    options::OPT_fno_xl_pragma_pack, true))
     CC1Args.push_back("-fxl-pragma-pack");
+
+  // Pass "-fno-sized-deallocation" only when the user hasn't manually enabled
+  // or disabled sized deallocations.
+  if (!Args.getLastArgNoClaim(options::OPT_fsized_deallocation,
+                              options::OPT_fno_sized_deallocation))
+    CC1Args.push_back("-fno-sized-deallocation");
 }
 
 void AIX::addProfileRTLibs(const llvm::opt::ArgList &Args,

clang/unittests/StaticAnalyzer/CallEventTest.cpp

@@ -76,7 +76,12 @@ TEST(CXXDeallocatorCall, SimpleDestructor) {
     }
   )",
                                                          Diags));
+#if defined(_AIX) || defined(__MVS__)
+  // AIX and ZOS default to -fno-sized-deallocation.
+  EXPECT_EQ(Diags, "test.CXXDeallocator: NumArgs: 1\n");
+#else
   EXPECT_EQ(Diags, "test.CXXDeallocator: NumArgs: 2\n");
+#endif
 }
 
 } // namespace