From 33171df9cc7f6560dea7b0b162ab51ff97417468 Mon Sep 17 00:00:00 2001
From: Leonard Chan <leonardchan@google.com>
Date: Thu, 4 Aug 2022 22:56:32 +0000
Subject: [PATCH] Revert "[clang][Darwin] Always set the default C++ Standard
 Library to libc++"

This reverts commit c5ccb78ade8136134e0ca9dde64de97f913f0f8c.

We're seeing darwin-stdlib.cpp fail on our linux, mac, and windows
builders:
https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8806821020552676065/overview
---
 clang/lib/Driver/ToolChains/Darwin.cpp     |  7 ++++++-
 clang/test/Driver/darwin-iphone-defaults.m |  2 +-
 clang/test/Driver/darwin-stdlib.cpp        | 15 +++++++++------
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
index 7e3fc62..bada811 100644
--- a/clang/lib/Driver/ToolChains/Darwin.cpp
+++ b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -896,7 +896,12 @@ types::ID MachO::LookupTypeForExtension(StringRef Ext) const {
 bool MachO::HasNativeLLVMSupport() const { return true; }
 
 ToolChain::CXXStdlibType Darwin::GetDefaultCXXStdlibType() const {
-  // Always use libc++ by default
+  // Use libstdc++ on old targets (OSX < 10.9 and iOS < 7)
+  if ((isTargetMacOSBased() && isMacosxVersionLT(10, 9)) ||
+      (isTargetIOSBased() && isIPhoneOSVersionLT(7, 0)))
+    return ToolChain::CST_Libstdcxx;
+
+  // On all other targets, use libc++
   return ToolChain::CST_Libcxx;
 }
 
diff --git a/clang/test/Driver/darwin-iphone-defaults.m b/clang/test/Driver/darwin-iphone-defaults.m
index 79d3bc8..ec9507f 100644
--- a/clang/test/Driver/darwin-iphone-defaults.m
+++ b/clang/test/Driver/darwin-iphone-defaults.m
@@ -1,4 +1,4 @@
-// RUN: %clang -target i386-apple-darwin -miphoneos-version-min=5.0 -arch armv7 -stdlib=platform -flto -S -o - %s | FileCheck %s
+// RUN: %clang -target i386-apple-darwin9 -miphoneos-version-min=3.0 -arch armv7 -stdlib=platform -flto -S -o - %s | FileCheck %s
 
 // CHECK: @f0() [[F0:#[0-9]+]]
 // CHECK: @__f0_block_invoke
diff --git a/clang/test/Driver/darwin-stdlib.cpp b/clang/test/Driver/darwin-stdlib.cpp
index d15eb19..0538a42 100644
--- a/clang/test/Driver/darwin-stdlib.cpp
+++ b/clang/test/Driver/darwin-stdlib.cpp
@@ -2,10 +2,13 @@
 // than the platform default. (see https://llvm.org/bugs/show_bug.cgi?id=30548)
 // XFAIL: default-cxx-stdlib-set
 
-// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch arm64 -miphoneos-version-min=7.0 %s -### 2>&1 | FileCheck %s
-// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -mmacosx-version-min=10.9 %s -### 2>&1 | FileCheck %s
-// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch armv7s -miphoneos-version-min=7.0 %s -### 2>&1 | FileCheck %s
-// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch armv7k %s -### 2>&1 | FileCheck %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch arm64 -miphoneos-version-min=7.0 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBCXX
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -mmacosx-version-min=10.8 -Wno-stdlibcxx-not-found %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBSTDCXX
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -mmacosx-version-min=10.9 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBCXX
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch armv7s -miphoneos-version-min=6.1 -Wno-stdlibcxx-not-found %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBSTDCXX
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch armv7s -miphoneos-version-min=7.0 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBCXX
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %S/Inputs/darwin_toolchain_tree/bin/ -arch armv7k %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-LIBCXX
 
-// CHECK: "-stdlib=libc++"
-// CHECK-NOT: "-stdlib=libstdc++"
+// CHECK-LIBCXX: "-stdlib=libc++"
+// CHECK-LIBSTDCXX-NOT: -stdlib=libc++
+// CHECK-LIBSTDCXX-NOT: -stdlib=libstdc++
-- 
2.7.4