Expect cxx_variadic_templates to implement N2555.
N2555 is essentially a bugfix and predates most compiler releases which
aimed to experimentally support variadic templates.
Record the availability of this feature for GNU 4.8 on (UNIX AND
NOT APPLE) only. In the future, availability can be recorded for
earlier GNU, for other platforms and for other compilers. Initially
the affected configurations are as restricted as possible to allow
for easy testing while extending the features vector in only one
dimension.
The error message when using the set_property API directly is not
very good, but follow up commits will provide origin debugging of
the property and a target_compile_features command which will
provide a configure-time backtrace when possible.
As CMAKE_ROOT_FIND_PATH can be a list, a new CMAKE_SYSROOT is
introduced, which is never a list.
The contents of this variable is passed to supporting compilers
as --sysroot. It is also accounted for when processing implicit
link directories reported by the compiler, and when generating
RPATH information.
Clang can compile code, but uses the gcc tools for other tasks such
as linking. The -gcc-toolchain option can be used for that, but
generalize so that other compilers can be treated the same.
If such a location is specified, use it as a hint for finding
the binutils executables.
For clang, this allows passing -target <triple> to the compiler, and
for qcc, -V<arch> using toolchain files containing something like
set(triple arm-linux-gnueabihf)
set(CMAKE_C_COMPILER "/usr/bin/clang")
set(CMAKE_C_COMPILER_TARGET ${triple})
set(CMAKE_CXX_COMPILER "/usr/bin/clang++")
set(CMAKE_CXX_COMPILER_TARGET ${triple})
or
set(arch gcc_ntoarmv7le)
set(CMAKE_C_COMPILER /opt/qnx650/host/linux/x86/usr/bin/qcc)
set(CMAKE_C_COMPILER_TARGET ${arch})
set(CMAKE_CXX_COMPILER /opt/qnx650/host/linux/x86/usr/bin/QCC)
set(CMAKE_CXX_COMPILER_TARGET ${arch})
Both clang and qcc are inherently cross compiler( driver)s.
When cross-compiling with clang, use the CMAKE_${lang}_COMPILER_TARGET
as the _CMAKE_TOOLCHAIN_PREFIX to find the appropriate binutils.
When cross-compiling with QNX qcc, use the CMAKE_${lang}_COMPILER_TARGET
to set the appropriate _CMAKE_TOOLCHAIN_PREFIX.
1763c31 Set policy CMP0025 to NEW while building CMake itself
aa53ee5 Add policy CMP0025 for Apple Clang compiler id compatibility
ab65862 Clang: Add separate "AppleClang" compiler id
Apple distributes their own Clang build with their own version numbers
that differ from upstream Clang. Use the __apple_build_version__ symbol
to identify the Apple Clang compiler and report the Apple Build Version
as the fourth version component in CMAKE_<LANG>_COMPILER_VERSION. Add
Compiler/AppleClang-<lang> and Platform/Darwin-AppleClang-<lang> modules
that simply include the upstream equivalents.
Fix comparisons of CMAKE_<LANG>_COMPILER_ID to Clang in CMake's own
source and tests to account for AppleClang.
Teach the compiler identification preprocessor tests to report when
Clang simulates MSVC, and what version. If not MSVC, assume GNU.
Teach compiler information modules Clang-(C|CXX) to recognize when Clang
simulates MSVC and skip loading the GNU information.
Teach the Windows-MSVC platform information to recognize when it is
loaded as the simulated compiler and use that version information
instead of the real compiler's (different) version scheme.
Add platform modules Windows-Clang-(C|CXX) and support module
Windows-Clang to load either Windows-MSVC or Windows-GNU and wrap
the corresponding information macros.
For clang, this allows passing -target <triple> to the compiler, and
for qcc, -V<arch> using toolchain files containing something like
set(triple arm-linux-gnueabihf)
set(CMAKE_C_COMPILER "/usr/bin/clang")
set(CMAKE_C_COMPILER_TARGET ${triple})
set(CMAKE_CXX_COMPILER "/usr/bin/clang++")
set(CMAKE_CXX_COMPILER_TARGET ${triple})
or
set(arch gcc_ntoarmv7le)
set(CMAKE_C_COMPILER /opt/qnx650/host/linux/x86/usr/bin/qcc)
set(CMAKE_C_COMPILER_TARGET ${arch})
set(CMAKE_CXX_COMPILER /opt/qnx650/host/linux/x86/usr/bin/QCC)
set(CMAKE_CXX_COMPILER_TARGET ${arch})
Both clang and qcc are inherently cross compiler( driver)s.
As CMAKE_ROOT_FIND_PATH can be a list, a new CMAKE_SYSROOT is
introduced, which is never a list.
The contents of this variable is passed to supporting compilers
as --sysroot. It is also accounted for when processing implicit
link directories reported by the compiler, and when generating
RPATH information.
This corresponds to the g++ and clang++
option -fvisibility-inlines-hidden on linux. On Windows with MinGW,
this corresponds to -fno-keep-inline-dllexport. That option is
not supported by clang currently.
This is initialized by CMAKE_<LANG>_VISIBILITY_PRESET. The target
property is used as the operand to the -fvisibility= compile option
with GNU compilers and clang.
In GNU.cmake, -isystem is not used if APPLE is set. However, Clang has
pretty much always supported -isystem, so we should always use it.
In the future, GNU.cmake should do a version check to see if -isystem is
supported.
According to XL C/C++ V9.0 documentation the default for -qpic/-qnopic
is platform-dependent. It won't hurt to add the option on platforms
where it is the default, so always add it when we want position
independent code.
The GNU compiler information file tests for GNU >= 3.4 because earlier
versions do not have the flag. The version number test is not valid for
Clang compiler versions, but we know Clang supports the flag.
While Clang presents an almost identical interface to GNU there will be
some differences. Split the compiler information modules to allow
separate rules for Clang. Start by loading the GNU rules but leave a
place to add Clang-specific information.
Previously, it was inconsistent in that some platforms/compilers
had this flag for the RelWithDebInfo configuration and some didn't.
This fixes issue #11366.
Stephen Kelly
Nils Gladitz
Peter Kümmel
Brad King
Alex Neundorf
Ben Boeckel
Neil Carlson
David Cole
Clinton Stimpson