With `%/t`, we can now compare `-###` output against the installtion dir
without backslash escaping getting in the way. Having to check against
the doubled-up backslashes is ugly, but it's the pattern used in lots of
tests (including for things like debug info where an `-###` alternative
that didn't escape backslashes wouldn't help).
A drive-by change in 53c98d85a8a609552448043d5512e70313b1eb1b made
-stdlib++-isystem be suppressed by -nostdinc and -nostdlibinc in
addition to -nostdinc++. However, that's contrary to the intent of the
flag. It's common to provide your own C++ headers (e.g. when building
libc++ by itself or as a compiler-rt dependency) but rely on the system
C headers, and having -stdlib++-isystem only look at -nostdinc++ allows
us to customize both the C header path (via -nostdinc or -nostdlibinc)
and the C++ header path (via -stdlib++-isystem) at the toolchain level
but still let users of the toolchain provide their own C++ headers. Add
a comment explaining the rationale to make it clearer.
This follows GCC. Having libstdc++/libc++ include paths is not useful
anyway because libstdc++/libc++ header files cannot find features.h.
While here, suppress -stdlib++-isystem with -nostdlibinc.
Fixed the test case to set --sysroot, which lets it succeed in the case where
a directory named "/usr/include/c++/v1" or "/usr/local/include/c++/v1" exists.
Original commit message:
> The NDK uses a separate set of libc++ headers in the sysroot. Any headers
> in the installation directory are not going to work on Android, not least
> because they use a different name for the inline namespace (std::__1 instead
> of std::__ndk1).
>
> This effectively makes it impossible to produce a single toolchain that is
> capable of targeting both Android and another platform that expects libc++
> headers to be installed in the installation directory, such as Mac.
>
> In order to allow this scenario to work, stop looking for headers in the
> install directory on Android.
Differential Revision: https://reviews.llvm.org/D71154
The NDK uses a separate set of libc++ headers in the sysroot. Any headers
in the installation directory are not going to work on Android, not least
because they use a different name for the inline namespace (std::__1 instead
of std::__ndk1).
This effectively makes it impossible to produce a single toolchain that is
capable of targeting both Android and another platform that expects libc++
headers to be installed in the installation directory, such as Mac.
In order to allow this scenario to work, stop looking for headers in the
install directory on Android.
Differential Revision: https://reviews.llvm.org/D71154
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
