linux: update header used for major macro

[compnerd]

Newer versions of glibc indicate that they intend to move the major
macro from sys/types.h to sys/sysmacros.h. Add a check for the
header and include that earlier to ensure that the macro is provided by
the newer header when available/possible. This avoids an unnecessary
warning from the system headers.

[compnerd]

CC: @das @dgrove-oss

[compnerd]

Since I put this up on a weekend, a gentle ping during the work week!

[das]

FWIW the reason for the name change of the autotools-generate header was to avoid overwriting the manually maintained config/config.h header for Darwin (and getting it to show up as changed in git etc).

it looks like the same thing was replicated with the CMake build system, so only #include <config/config_ac.h> should be needed here ?

[compnerd]

WFM, I'll adjust that.

[atrick]

swift-corelibs-libdispatch/os/linux_base.h:16:10: fatal error: 'config/config_ac.h' file not found
#include <config/config_ac.h>
^

[das]

huh, we have
AC_CONFIG_HEADER([config/config_ac.h])
in configure.ac to generate that header (we really don't want config/config.h to be used on Linux since that is the static Darwin config).

Or Is the issue that that header is not getting installed ?
we can't use it from os/linux_base.h in that case (at least not from that path, it could be installed into os/ alongside linux_base.h, probably with a different name like linux_config.h)

@atrick do you have a full build log ? was the above issue when building a dependent project or when building libdispatch itself ?

[das]

looks like it is the latter, from 3138:

[554/850] Building CXX object tools/SourceKit/lib/Support/CMakeFiles/SourceKitSupport.dir/Concurrency-libdispatch.cpp.o
FAILED: tools/SourceKit/lib/Support/CMakeFiles/SourceKitSupport.dir/Concurrency-libdispatch.cpp.o 
/usr/bin/clang++   -DCMARK_STATIC_DEFINE -DGTEST_HAS_RTTI=0 -D_DEBUG -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Itools/SourceKit/lib/Support -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift/tools/SourceKit/lib/Support -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift/tools/SourceKit/include -Iinclude -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift/include -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/llvm/include -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/buildbot_incremental/llvm-linux-x86_64/include -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/buildbot_incremental/llvm-linux-x86_64/tools/clang/include -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/llvm/tools/clang/include -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/cmark/src -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/buildbot_incremental/cmark-linux-x86_64/src -I/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift-corelibs-libdispatch -Wno-unknown-warning-option -Werror=unguarded-availability-new -fno-stack-protector -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -Werror=date-time -std=c++11 -fcolor-diagnostics -ffunction-sections -fdata-sections -Werror=switch -Wdocumentation -Wimplicit-fallthrough -Wunreachable-code -Woverloaded-virtual -DOBJC_OLD_DISPATCH_PROTOTYPES=0 -O3    -UNDEBUG  -fno-exceptions -fno-rtti -target x86_64-unknown-linux-gnu -O2 -g0 -UNDEBUG -fblocks -MMD -MT tools/SourceKit/lib/Support/CMakeFiles/SourceKitSupport.dir/Concurrency-libdispatch.cpp.o -MF tools/SourceKit/lib/Support/CMakeFiles/SourceKitSupport.dir/Concurrency-libdispatch.cpp.o.d -o tools/SourceKit/lib/Support/CMakeFiles/SourceKitSupport.dir/Concurrency-libdispatch.cpp.o -c /home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift/tools/SourceKit/lib/Support/Concurrency-libdispatch.cpp
In file included from /home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift/tools/SourceKit/lib/Support/Concurrency-libdispatch.cpp:19:
In file included from /home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift-corelibs-libdispatch/dispatch/dispatch.h:30:
/home/buildnode/disk2/workspace/oss-swift-incremental-RA-linux-ubuntu-14_04/swift-corelibs-libdispatch/os/linux_base.h:16:10: fatal error: 'config/config_ac.h' file not found
#include <config/config_ac.h>
         ^

probably the simplest option is to just wrap this new header include in __has_include(<sys/sysmacros.h>)
instead of a configure-generated define

[das]

the existing HAVE_SYS_CDEFS_H case almost certainly has the same issue and should be fixed the same way

[compnerd]

Okay, Ill create a new PR to change it over.