[Driver] Introduce -stdlib++-isystem

There are times when we wish to explicitly control the C++ standard
library search paths used by the driver. For example, when we're
building against the Android NDK, we might want to use the NDK's C++
headers (which have a custom inline namespace) even if we have C++
headers installed next to the driver. We might also be building against
a non-standard directory layout and wanting to specify the C++ standard
library include directories explicitly.

We could accomplish this by passing -nostdinc++ and adding an explicit
-isystem for our custom search directories. However, users of our
toolchain may themselves want to use -nostdinc++ and a custom C++ search
path (libc++'s build does this, for example), and our added -isystem
won't respect the -nostdinc++, leading to multiple C++ header
directories on the search path, which causes build failures.

Add a new driver option -stdlib++-isystem to support this use case.
Passing this option suppresses adding the default C++ library include
paths in the driver, and it also respects -nostdinc++ to allow users to
still override the C++ library paths themselves.

It's a bit unfortunate that we end up with both -stdlib++-isystem and
-cxx-isystem, but their semantics differ significantly. -cxx-isystem is
unaffected by -nostdinc++ and is added to the end of the search path
(which is not appropriate for C++ standard library headers, since they
often #include_next into other system headers), while -stdlib++-isystem
respects -nostdinc++, is added to the beginning of the search path, and
suppresses the default C++ library include paths.

Differential Revision: https://reviews.llvm.org/D64089

llvm-svn: 367982

1 files changed, 53 insertions, 0 deletions

diff --git a/clang/test/Driver/stdlibxx-isystem.cpp b/clang/test/Driver/stdlibxx-isystem.cpp
new file mode 100644
index 00000000000..cf7535ff423
--- /dev/null
+++ b/clang/test/Driver/stdlibxx-isystem.cpp
@@ -0,0 +1,53 @@
+// Backslash escaping makes matching against the installation directory fail on
+// Windows. Temporarily disable the test there until we add an option to print
+// the installation directory unescaped.
+// UNSUPPORTED: system-windows
+
+// By default, we should search for libc++ next to the driver.
+// RUN: mkdir -p %t/bin
+// RUN: mkdir -p %t/include/c++/v1
+// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
+// RUN:   -stdlib=libc++ -fsyntax-only %s -### 2>&1 | \
+// RUN:   FileCheck -check-prefix=LIBCXX %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %t/bin \
+// RUN:   -stdlib=libc++ -fsyntax-only %s -### 2>&1 | \
+// RUN:   FileCheck -check-prefix=LIBCXX %s
+// LIBCXX: InstalledDir: [[INSTALLDIR:.+$]]
+// LIBCXX: "-internal-isystem" "[[INSTALLDIR]]/../include/c++/v1"
+
+// Passing -stdlib++-isystem should suppress the default search.
+// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -stdlib=libc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=NODEFAULT %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -stdlib=libc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=NODEFAULT %s
+// NODEFAULT: InstalledDir: [[INSTALLDIR:.+$]]
+// NODEFAULT-NOT: "-internal-isystem" "[[INSTALLDIR]]/../include/c++/v1"
+
+// And we should add it as an -internal-isystem.
+// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -stdlib=libc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=INCPATH %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -stdlib=libc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=INCPATH %s
+// INCPATH: "-internal-isystem" "/tmp/foo" "-internal-isystem" "/tmp/bar"
+
+// We shouldn't pass the -stdlib++-isystem to cc1.
+// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp -stdlib=libc++ -fsyntax-only %s -### 2>&1 | \
+// RUN:   FileCheck -check-prefix=NOCC1 %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp -stdlib=libc++ -fsyntax-only %s -### 2>&1 | \
+// RUN:   FileCheck -check-prefix=NOCC1 %s
+// NOCC1-NOT: "-stdlib++-isystem" "/tmp"
+
+// It should respect -nostdinc++.
+// RUN: %clang -target aarch64-linux-android -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -nostdinc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=NOSTDINCXX %s
+// RUN: %clang -target x86_64-apple-darwin -ccc-install-dir %t/bin \
+// RUN:   -stdlib++-isystem /tmp/foo -stdlib++-isystem /tmp/bar -nostdinc++ \
+// RUN:   -fsyntax-only %s -### 2>&1 | FileCheck -check-prefix=NOSTDINCXX %s
+// NOSTDINCXX-NOT: "-internal-isystem" "/tmp/foo" "-internal-isystem" "/tmp/bar"