From fc3f7d36fba17a49f01a0d82c72c0c8d84a40bdf Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Thu, 12 Apr 2018 20:07:38 +0000
Subject: [PATCH] [MinGW] Look for libc++ headers in a triplet prefixed path as
 well

This makes it consistent with libstdc++ and the other default
include directories.

If these headers are found in both locations and one isn't a
symlink to the other, this will cause errors due to libc++ headers
having wrapper headers for some standard C headers, wrappers that
do #include_next the actual one.

If the same libc++ standard C wrapper header exists in more than one
include directory before the real system one, the header include
guard will stop it from doing another #include_next to pick up the
real one, breaking things.

As this is a rather uncommon situation, this should be acceptable
and toolchain maintainers can adapt accordingly if necessary.

Also simplify some of the existing code with a local variable.

Differential Revision: https://reviews.llvm.org/D45500

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@329946 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Driver/ToolChains/MinGW.cpp | 9 ++++++---
 test/Driver/mingw.cpp           | 4 ++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/lib/Driver/ToolChains/MinGW.cpp b/lib/Driver/ToolChains/MinGW.cpp
index db83ac6fa7..8e59fd126a 100644
--- a/lib/Driver/ToolChains/MinGW.cpp
+++ b/lib/Driver/ToolChains/MinGW.cpp
@@ -453,11 +453,14 @@ void toolchains::MinGW::AddClangCXXStdlibIncludeArgs(
       DriverArgs.hasArg(options::OPT_nostdincxx))
     return;
 
+  StringRef Slash = llvm::sys::path::get_separator();
+
   switch (GetCXXStdlibType(DriverArgs)) {
   case ToolChain::CST_Libcxx:
+    addSystemInclude(DriverArgs, CC1Args, Base + Arch + Slash + "include" +
+                                              Slash + "c++" + Slash + "v1");
     addSystemInclude(DriverArgs, CC1Args,
-                     Base + "include" + llvm::sys::path::get_separator() +
-                         "c++" + llvm::sys::path::get_separator() + "v1");
+                     Base + "include" + Slash + "c++" + Slash + "v1");
     break;
 
   case ToolChain::CST_Libstdcxx:
@@ -472,7 +475,7 @@ void toolchains::MinGW::AddClangCXXStdlibIncludeArgs(
     llvm::sys::path::append(CppIncludeBases[3], "include", "c++");
     for (auto &CppIncludeBase : CppIncludeBases) {
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase);
-      CppIncludeBase += llvm::sys::path::get_separator();
+      CppIncludeBase += Slash;
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase + Arch);
       addSystemInclude(DriverArgs, CC1Args, CppIncludeBase + "backward");
     }
diff --git a/test/Driver/mingw.cpp b/test/Driver/mingw.cpp
index 4e25c1dfa0..216ad65362 100644
--- a/test/Driver/mingw.cpp
+++ b/test/Driver/mingw.cpp
@@ -3,6 +3,10 @@
 // CHECK_MINGW_CLANG_TREE: "{{.*}}/Inputs/mingw_clang_tree/mingw32{{/|\\\\}}include"
 
 
+// RUN: %clang -target i686-windows-gnu -rtlib=platform -stdlib=libc++ -c -### --sysroot=%S/Inputs/mingw_clang_tree/mingw32 %s 2>&1 | FileCheck -check-prefix=CHECK_MINGW_CLANG_TREE_LIBCXX %s
+// CHECK_MINGW_CLANG_TREE_LIBCXX: "{{.*}}/Inputs/mingw_clang_tree/mingw32{{/|\\\\}}i686-w64-mingw32{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
+
+
 // RUN: %clang -target i686-pc-windows-gnu -rtlib=platform -stdlib=libstdc++ -c -### --sysroot=%S/Inputs/mingw_mingw_org_tree/mingw %s 2>&1 | FileCheck -check-prefix=CHECK_MINGW_ORG_TREE %s
 // CHECK_MINGW_ORG_TREE: "{{.*}}/Inputs/mingw_mingw_org_tree/mingw{{/|\\\\}}lib{{/|\\\\}}gcc{{/|\\\\}}mingw32{{/|\\\\}}4.8.1{{/|\\\\}}include{{/|\\\\}}c++"
 // CHECK_MINGW_ORG_TREE: "{{.*}}/Inputs/mingw_mingw_org_tree/mingw{{/|\\\\}}lib{{/|\\\\}}gcc{{/|\\\\}}mingw32{{/|\\\\}}4.8.1{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}mingw32"
-- 
2.40.0