[driver] Conditionally include installed libc++ headers for Android

[smeenai]

Summary

https://reviews.llvm.org/D71154 prevented Clang from search for libc++
headers installed alongside the driver when targeting Android. The
motivation was the NDK's use of a different libc++ inline namespace
(__ndk1 instead of the standard __1), which made regular libc++
headers incompatible with the NDK's libc++ library.

Since then, libc++ has gained the ability to install its __config_site
header (which controls the inline namespace, among other things) to a
per-target include directory, which enables per-target customizations.
If this directory is present, the user has expressly built libc++ for
Android, and we should use those headers.

The motivation is that, with the current setup, if a user builds their
own libc++ for Android, they'll use the library they built themselves
but the NDK's headers instead of their own, which is surprising at best
and can cause all sorts of problems (e.g. if you built your own libc++
with a different ABI configuration). It's important to match the headers
and libraries in that scenario, and checking for an Android per-target
include directory lets us do so without regressing the original scenario
which https://reviews.llvm.org/D71154 was addressing.

While I'm here, switch to using sys::path::append instead of slashes
directly, to get system path separators on Windows, which is consistent
with how library paths are constructed (and that consistency will be
important in a follow-up, where we use a common search function for the
include and library path construction).

(As an aside, one of the motivations for https://reviews.llvm.org/D71154
was to support targeting both Android and Apple platforms, which
expected libc++ headers to be provided by the toolcain at the time.
Apple has since switched to including libc++ headers in the platform SDK
instead of in the toolchain, so that specific motivation no longer
applies either.)

[rprichard]

This change looks like an improvement to me. The NDK currently puts the libc++ headers into the sysroot, but putting it in the usual toolchain include location seems better.

clang/lib/Driver/ToolChains/Gnu.cpp

3108

Will the Target here have an Android API level suffix?

[smeenai]

clang/lib/Driver/ToolChains/Gnu.cpp

3108

Yup, it will. D159293 and D158476 are the follow-ups to address that. The first one makes this call-site use the current fallback logic in the driver, and the second one extends that fallback logic to look for the next newest available API level if you don't have headers/libraries for the current API level.

[glandium]

This + D159293 works great for me. Thanks a bunch. (I'm not a reviewer, though)

[smeenai]

Rebase to avoid pre-existing CI failure

[smeenai]

In D159292#4632389, @rprichard wrote:

This change looks like an improvement to me. The NDK currently puts the libc++ headers into the sysroot, but putting it in the usual toolchain include location seems better.

Are you comfortable accepting this, or should I ping other reviewers? :)

[smeenai]

Ping.

[rprichard]

In D159292#4646096, @smeenai wrote:

Ping.

I asked a couple of other people at Google to take a look at the patches. Someone should get to it next week I think?

[smeenai]

In D159292#4646811, @rprichard wrote:

In D159292#4646096, @smeenai wrote:

Ping.

I asked a couple of other people at Google to take a look at the patches. Someone should get to it next week I think?

Thank you!

[phosek]

LGTM

clang/lib/Driver/ToolChains/Gnu.cpp

 
 void
 Generic_GCC::addLibCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                    llvm::opt::ArgStringList &CC1Args) const {
   const Driver &D = getDriver();
   std::string SysRoot = computeSysRoot();
   std::string Target = getTripleString();
 
-  auto AddIncludePath = [&](std::string Path) {
+  auto AddIncludePath = [&](StringRef Path, bool TargetDirRequired = false) {
     std::string Version = detectLibcxxVersion(Path);
     if (Version.empty())
       return false;
 
     // First add the per-target include path if it exists.
-    std::string TargetDir = Path + "/" + Target + "/c++/" + Version;
+    SmallString<128> TargetDir(Path);
+    llvm::sys::path::append(TargetDir, Target, "c++", Version);
     if (D.getVFS().exists(TargetDir))
       addSystemInclude(DriverArgs, CC1Args, TargetDir);
+    else if (TargetDirRequired)
+      return false;
 
     // Second add the generic one.
-    addSystemInclude(DriverArgs, CC1Args, Path + "/c++/" + Version);
+    SmallString<128> GenericDir(Path);
+    llvm::sys::path::append(GenericDir, "c++", Version);
+    addSystemInclude(DriverArgs, CC1Args, GenericDir);
     return true;
   };
 
-  // Android never uses the libc++ headers installed alongside the toolchain,
-  // which are generally incompatible with the NDK libraries anyway.
-  if (!getTriple().isAndroid())
-    if (AddIncludePath(getDriver().Dir + "/../include"))
-      return;
+  // Android only uses the libc++ headers installed alongside the toolchain if
+  // they contain an Android-specific target include path, otherwise they're
+  // incompatible with the NDK libraries.
+  SmallString<128> DriverIncludeDir(getDriver().Dir);
+  llvm::sys::path::append(DriverIncludeDir, "..", "include");
+  if (AddIncludePath(DriverIncludeDir,
+                     /*TargetDirRequired=*/getTriple().isAndroid()))
   // If this is a development, non-installed, clang, libcxx will
   // not be found at ../include/c++ but it likely to be found at
   // one of the following two locations:
-  if (AddIncludePath(concat(SysRoot, "/usr/local/include")))
+  SmallString<128> UsrLocalIncludeDir(SysRoot);
+  llvm::sys::path::append(UsrLocalIncludeDir, "usr", "local", "include");
+  if (AddIncludePath(UsrLocalIncludeDir))
     return;
-  if (AddIncludePath(concat(SysRoot, "/usr/include")))
+  SmallString<128> UsrIncludeDir(SysRoot);
+  llvm::sys::path::append(UsrIncludeDir, "usr", "include");
+  if (AddIncludePath(UsrIncludeDir))
     return;
 }
 
 bool Generic_GCC::addLibStdCXXIncludePaths(Twine IncludeDir, StringRef Triple,
                                            Twine IncludeSuffix,
                                            const llvm::opt::ArgList &DriverArgs,
                                            llvm::opt::ArgStringList &CC1Args,
                                            bool DetectDebian) const {

clang/test/Driver/android-installed-libcxx.cpp

+// Check that we only find libc++ in the installation directory when it contains
+// an Android-specific include directory.
+
+// RUN: mkdir -p %t1/bin
+// RUN: mkdir -p %t1/include/c++/v1
+// RUN: mkdir -p %t1/sysroot
+// RUN: %clang -target aarch64-none-linux-android -ccc-install-dir %t1/bin \
+// RUN:   --sysroot=%t1/sysroot -stdlib=libc++ -fsyntax-only \
+// RUN:   %s -### 2>&1 | FileCheck %s
+// CHECK-NOT: "-internal-isystem" "{{.*}}v1"
+
+// RUN: mkdir -p %t2/bin
+// RUN: mkdir -p %t2/include/c++/v1
+// RUN: mkdir -p %t2/sysroot
+// RUN: mkdir -p %t2/include/aarch64-none-linux-android/c++/v1
+
+// RUN: %clang -target aarch64-none-linux-android -ccc-install-dir %/t2/bin \
+// RUN:   --sysroot=%t2/sysroot -stdlib=libc++ -fsyntax-only \
+// RUN:   %s -### 2>&1 | FileCheck --check-prefix=ANDROID-DIR -DDIR=%/t2/bin %s
+
+// ANDROID-DIR: "-internal-isystem" "[[DIR]][[SEP:/|\\\\]]..[[SEP]]include[[SEP]]aarch64-none-linux-android[[SEP]]c++[[SEP]]v1"
+// ANDROID-DIR-SAME: "-internal-isystem" "[[DIR]][[SEP]]..[[SEP]]include[[SEP]]c++[[SEP]]v1"

clang/test/Driver/android-ndk-standalone.cpp

 // Test header and library paths when Clang is used with Android standalone
 // toolchain.
 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=arm-linux-androideabi21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck  %s
 // CHECK: "-cc1"
 // CHECK: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
-// CHECK: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
 // CHECK: "-internal-isystem" "{{.*}}/sysroot/usr/local/include"
 // CHECK: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/arm-linux-androideabi"
 // CHECK: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a/thumb"
 // CHECK-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a"

 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=armv7a-none-linux-androideabi21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck  --check-prefix=CHECK-ARMV7 %s
 // CHECK-ARMV7: "-cc1"
 // CHECK-ARMV7: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
-// CHECK-ARMV7: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-ARMV7: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-ARMV7: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
 // CHECK-ARMV7: "-internal-isystem" "{{.*}}/sysroot/usr/local/include"
 // CHECK-ARMV7: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/arm-linux-androideabi"
 // CHECK-ARMV7: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-ARMV7: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-ARMV7: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-ARMV7-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a/thumb"
 // CHECK-ARMV7-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/thumb"

 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=arm-linux-androideabi21 \
 // RUN:     -mthumb \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck  --check-prefix=CHECK-THUMB %s
 // CHECK-THUMB: "-cc1"
 // CHECK-THUMB: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
-// CHECK-THUMB: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-THUMB: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-THUMB: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
 // CHECK-THUMB: "-internal-isystem" "{{.*}}/sysroot/usr/local/include"
 // CHECK-THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/arm-linux-androideabi"
 // CHECK-THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-THUMB: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-THUMB-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a/thumb"
 // CHECK-THUMB-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a"

 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=arm-linux-androideabi21 \
 // RUN:     -march=armv7-a -mthumb \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck  --check-prefix=CHECK-ARMV7THUMB %s
 // CHECK-ARMV7THUMB: "-cc1"
 // CHECK-ARMV7THUMB: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
-// CHECK-ARMV7THUMB: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-ARMV7THUMB: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-ARMV7THUMB: "-internal-isystem" "[[RESOURCE_DIR]]{{(/|\\\\)}}include"
 // CHECK-ARMV7THUMB: "-internal-isystem" "{{.*}}/sysroot/usr/local/include"
 // CHECK-ARMV7THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/arm-linux-androideabi"
 // CHECK-ARMV7THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-ARMV7THUMB: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-ARMV7THUMB: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-ARMV7THUMB-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/thumb"
 // CHECK-ARMV7THUMB-NOT: "-L{{.*}}/lib/gcc/arm-linux-androideabi/4.9/armv7-a"

 // RUN:   | FileCheck  --check-prefix=CHECK-ARMV7THUMB %s
 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=aarch64-linux-android21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck --check-prefix=CHECK-AARCH64 %s
 // CHECK-AARCH64: "-cc1"
-// CHECK-AARCH64: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-AARCH64: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-AARCH64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/aarch64-linux-android"
 // CHECK-AARCH64: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-AARCH64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-AARCH64: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-AARCH64: "-L{{.*}}/lib/gcc/aarch64-linux-android/4.9"
 // CHECK-AARCH64: "-L{{.*}}/sysroot/usr/lib/aarch64-linux-android/21"
 // CHECK-AARCH64: "-L{{.*}}/sysroot/usr/lib/aarch64-linux-android"
 // CHECK-AARCH64: "-L{{.*}}/lib/gcc/aarch64-linux-android/4.9/../../../../aarch64-linux-android/lib"
 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=arm64-linux-android21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck --check-prefix=CHECK-ARM64 %s
 // CHECK-ARM64: "-cc1"
-// CHECK-ARM64: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-ARM64: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-ARM64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/aarch64-linux-android"
 // CHECK-ARM64: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-ARM64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-ARM64: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-ARM64: "-L{{.*}}/lib/gcc/aarch64-linux-android/4.9"
 // CHECK-ARM64: "-L{{.*}}/sysroot/usr/lib/aarch64-linux-android/21"
 // CHECK-ARM64: "-L{{.*}}/sysroot/usr/lib/aarch64-linux-android"
 // CHECK-ARM64: "-L{{.*}}/lib/gcc/aarch64-linux-android/4.9/../../../../aarch64-linux-android/lib"
 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=i686-linux-android21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck --check-prefix=CHECK-I686 %s
 // CHECK-I686: "-cc1"
-// CHECK-I686: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-I686: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-I686: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/i686-linux-android"
 // CHECK-I686: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-I686: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-I686: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-I686: "-L{{.*}}/lib/gcc/i686-linux-android/4.9"
 // CHECK-I686: "-L{{.*}}/sysroot/usr/lib/i686-linux-android/21"
 // CHECK-I686: "-L{{.*}}/sysroot/usr/lib/i686-linux-android"
 // CHECK-I686: "-L{{.*}}/lib/gcc/i686-linux-android/4.9/../../../../i686-linux-android/lib"
 //
 // RUN: %clang -### %s 2>&1 \
 // RUN:     --target=x86_64-linux-android21 \
 // RUN:     --gcc-toolchain=%S/Inputs/basic_android_ndk_tree \
 // RUN:     --sysroot=%S/Inputs/basic_android_ndk_tree/sysroot \
 // RUN:   | FileCheck --check-prefix=CHECK-X86_64 %s
 // CHECK-X86_64: "-cc1"
-// CHECK-X86_64: "-internal-isystem" "{{.*}}/include/c++/v1"
+// CHECK-X86_64: "-internal-isystem" "{{.*}}{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-X86_64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include/x86_64-linux-android"
 // CHECK-X86_64: "-internal-externc-isystem" "{{.*}}/sysroot/include"
 // CHECK-X86_64: "-internal-externc-isystem" "{{.*}}/sysroot/usr/include"
 // CHECK-X86_64: "{{.*}}ld{{(.exe)?}}" "--sysroot=[[SYSROOT:[^"]+]]"
 // CHECK-X86_64: "-L{{.*}}/lib/gcc/x86_64-linux-android/4.9"
 // CHECK-X86_64: "-L{{.*}}/sysroot/usr/lib/x86_64-linux-android/21"
 // CHECK-X86_64: "-L{{.*}}/sysroot/usr/lib/x86_64-linux-android"
 // CHECK-X86_64: "-L{{.*}}/lib/gcc/x86_64-linux-android/4.9/../../../../x86_64-linux-android/lib"

clang/test/Driver/android-no-installed-libcxx.cpp

-// Check that we don't find the libc++ in the installation directory when
-// targeting Android.
-
-// RUN: mkdir -p %t/bin
-// RUN: mkdir -p %t/include/c++/v1
-// RUN: mkdir -p %t/sysroot
-// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
-// RUN:   --sysroot=%t/sysroot -stdlib=libc++ -fsyntax-only \
-// RUN:   %s -### 2>&1 | FileCheck %s
-// CHECK-NOT: "-internal-isystem" "{{.*}}v1"

clang/test/Driver/linux-header-search.cpp

 // General tests that the header search paths detected by the driver and passed
 // to CC1 are sane.
 //
 // Test a simulated installation of libc++ on Linux, both through sysroot and
 // the installation path of Clang.
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-SYSROOT %s
 // CHECK-BASIC-LIBCXX-SYSROOT: "-cc1"
 // CHECK-BASIC-LIBCXX-SYSROOT: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/x86_64-unknown-linux-gnu/c++/v1"
-// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP:/|\\\\]]usr[[SEP]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v1"
+// CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP]]usr[[SEP]]include[[SEP]]c++[[SEP]]v1"
 // CHECK-BASIC-LIBCXX-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 
 // Test include paths when the sysroot path ends with `/`.
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree/ \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-SYSROOT-SLASH %s
 // CHECK-BASIC-LIBCXX-SYSROOT-SLASH: "-cc1"
 // CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-isysroot" "[[SYSROOT:[^"]+/]]"
-// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/include/x86_64-unknown-linux-gnu/c++/v1"
-// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/include/c++/v1"
+// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr[[SEP:/|\\\\]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v1"
+// CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr[[SEP]]include[[SEP]]c++[[SEP]]v1"
 // CHECK-BASIC-LIBCXX-SYSROOT-SLASH-SAME: "-internal-isystem" "[[SYSROOT]]usr/local/include"
 
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxx_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXX-INSTALL %s
 // CHECK-BASIC-LIBCXX-INSTALL: "-cc1"
 // CHECK-BASIC-LIBCXX-INSTALL: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/x86_64-unknown-linux-gnu/c++/v1"
-// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v1"
+// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin[[SEP:/|\\\\]]..[[SEP]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v1"
+// CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin[[SEP]]..[[SEP]]include[[SEP]]c++[[SEP]]v1"
 // CHECK-BASIC-LIBCXX-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 //
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxxv2_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXXV2-SYSROOT %s
 // CHECK-BASIC-LIBCXXV2-SYSROOT: "-cc1"
 // CHECK-BASIC-LIBCXXV2-SYSROOT: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/x86_64-unknown-linux-gnu/c++/v2"
-// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v2"
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP:/|\\\\]]usr[[SEP]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v2"
+// CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP]]usr[[SEP]]include[[SEP]]c++[[SEP]]v2"
 // CHECK-BASIC-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxxv2_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxxv2_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBCXXV2-INSTALL %s
 // CHECK-BASIC-LIBCXXV2-INSTALL: "-cc1"
 // CHECK-BASIC-LIBCXXV2-INSTALL: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/x86_64-unknown-linux-gnu/c++/v2"
-// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin/../include/c++/v2"
+// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin[[SEP:/|\\\\]]..[[SEP]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v2"
+// CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/bin[[SEP]]..[[SEP]]include[[SEP]]c++[[SEP]]v2"
 // CHECK-BASIC-LIBCXXV2-INSTALL: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 
 // Test Linux with libstdc++ when the sysroot path ends with `/`.
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libstdc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \

 // RUN:     -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libstdcxx_libcxxv2_tree \
 // RUN:     --gcc-toolchain="" \
 // RUN:   | FileCheck --check-prefix=CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT %s
 // CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-cc1"
 // CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/x86_64-unknown-linux-gnu/c++/v2"
-// CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v2"
+// CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP:/|\\\\]]usr[[SEP]]include[[SEP]]x86_64-unknown-linux-gnu[[SEP]]c++[[SEP]]v2"
+// CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]][[SEP]]usr[[SEP]]include[[SEP]]c++[[SEP]]v2"
 // CHECK-BASIC-LIBSTDCXX-LIBCXXV2-SYSROOT: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 
 // Test Gentoo's weirdness both before and after they changed it in their GCC
 // 4.6.4 release.
 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu -stdlib=libstdc++ \
 // RUN:     --sysroot=%S/Inputs/gentoo_linux_gcc_4.6.2_tree \
 // RUN:     --gcc-toolchain="" \

clang/test/Driver/linux-musl-header-search.cpp

 // RUN: %clang -### %s -fsyntax-only 2>&1 \
 // RUN:     --target=x86_64-linux-musl -stdlib=libc++ \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree --gcc-toolchain= \
 // RUN:   | FileCheck --check-prefix=CHECK-X86-64-LIBCXX %s
 
 // RESOURCE_DIR/include comes after /usr/include on linux-musl.
 // This is different from a glibc-based distribution.
 // CHECK-X86-64-LIBCXX: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
 // CHECK-X86-64-LIBCXX: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-X86-64-LIBCXX: "-internal-isystem" "[[SYSROOT]]/usr/include/c++/v1"
+// CHECK-X86-64-LIBCXX: "-internal-isystem" "[[SYSROOT]]{{/|\\\\}}usr{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-X86-64-LIBCXX: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 // CHECK-X86-64-LIBCXX: "-internal-externc-isystem" "[[SYSROOT]]/usr/include"
 // CHECK-X86-64-LIBCXX: "-internal-isystem" "[[RESOURCE_DIR]]{{/|\\\\}}include"
 
 // RUN: %clang -### %s -fsyntax-only -nobuiltininc 2>&1 \
 // RUN:     --target=x86_64-linux-musl \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_tree/usr/bin \
 // RUN:     -resource-dir=%S/Inputs/resource_dir \

clang/test/Driver/linux-per-target-runtime-dir.c

 // RUN: %clangxx -x c++ %s -### -o %t.o 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -stdlib=libc++ \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:     -ccc-install-dir %S/Inputs/basic_linux_libcxx_tree/usr/bin \
 // RUN:     --gcc-toolchain="" \
 // RUN:     --sysroot=%S/Inputs/basic_linux_libcxx_tree \
 // RUN:   | FileCheck --check-prefix=CHECK-PER-TARGET-RUNTIME %s
 // CHECK-PER-TARGET-RUNTIME: "-cc1"
 // CHECK-PER-TARGET-RUNTIME: "-resource-dir" "[[RESDIR:[^"]*]]"
 // CHECK-PER-TARGET-RUNTIME: "-isysroot" "[[SYSROOT:[^"]+]]"
-// CHECK-PER-TARGET-RUNTIME: "-internal-isystem" "{{.*}}/../include/c++/v1"
+// CHECK-PER-TARGET-RUNTIME: "-internal-isystem" "{{.*}}{{/|\\\\}}..{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
 // CHECK-PER-TARGET-RUNTIME: "-internal-isystem" "[[SYSROOT]]/usr/local/include"
 // CHECK-PER-TARGET-RUNTIME: "--sysroot=[[SYSROOT]]"
 // CHECK-PER-TARGET-RUNTIME: "-L{{.*}}{{/|\\\\}}..{{/|\\\\}}lib{{/|\\\\}}x86_64-unknown-linux-gnu"
 
 // RUN: %clang -rtlib=compiler-rt -print-libgcc-file-name 2>&1 \
 // RUN:     --target=x86_64-unknown-linux-gnu \
 // RUN:     -resource-dir=%S/Inputs/resource_dir_with_per_target_subdir \
 // RUN:   | FileCheck --check-prefix=CHECK-CLANGRT-X8664 %s