From be78c416c070a8a87fe8f449a717c5a7b800f683 Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Sun, 30 Jul 2017 21:17:41 +0200
Subject: [PATCH 2/8] Allow overriding stdlib under MacOS

---
 mkspecs/common/clang-mac.conf | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/mkspecs/common/clang-mac.conf b/mkspecs/common/clang-mac.conf
index cbae2e6262..bdf855fed2 100644
--- a/mkspecs/common/clang-mac.conf
+++ b/mkspecs/common/clang-mac.conf
@@ -6,8 +6,20 @@ QMAKE_OBJCXXFLAGS_USE_PRECOMPILE = $$QMAKE_CFLAGS_USE_PRECOMPILE
 
 QMAKE_XCODE_GCC_VERSION = com.apple.compilers.llvm.clang.1_0
 
-QMAKE_CXXFLAGS += -stdlib=libc++
-QMAKE_LFLAGS   += -stdlib=libc++
+# Use libc++ by default under MacOS/Clang
+isEmpty(QMAKE_MACOSX_STDLIB) {
+    QMAKE_MACOSX_STDLIB = libc++
+}
+isEqual(QMAKE_MACOSX_STDLIB, libstdc++) {
+    # To enable libstdc++, passing -stdlib=XXX is not enough - at least under osxcross the stdheaders are otherwise not found
+    # It is also required to disable GCC extensions by defining __STRICT_ANSI__ because not all GCC extensions are supported by Clang
+    QMAKE_CXXFLAGS += -D__STRICT_ANSI__ -foc-use-gcc-libstdc++
+    QMAKE_LFLAGS   += -D__STRICT_ANSI__ -foc-use-gcc-libstdc++
+} else {
+    QMAKE_CXXFLAGS += -stdlib=$${QMAKE_MACOSX_STDLIB}
+    QMAKE_LFLAGS   += -stdlib=$${QMAKE_MACOSX_STDLIB}
+}
+
 QMAKE_AR_LTCG  = libtool -static -o
 
 QMAKE_CFLAGS_APPLICATION_EXTENSION  = -fapplication-extension
-- 
2.13.4

