Revert commit v3.7.0-rc1~266^2 (Xcode: Obey SYSTEM keyword for includes,
2015-08-31). It worked for C, C++, and Swift but not for GNU Assembly
files for which Xcode has no property to set flags.
Closes: #16449
CMake used to put all header search paths into HEADER_SEARCH_PATHS
attribute. Unfortunately this attribute does not support to declare
a search path as a system include.
As a hack one could add a -isystem /path to the cflags but then include
ordering is not deterministic. A better approach was chosen with this
patch by not filling HEADER_SEARCH_PATHS at all and to populate
the C, C++, and Fortran flags directly. The include paths used by
Xcode should be now identical to the ones used by Unix Makefiles and
Ninja generator.
Create a `CMAKE_<LANG>_STANDARD_INCLUDE_DIRECTORIES` variable to specify
system include directories for for `<LANG>` compiler command lines.
This plays a role for include directories as the existing
`CMAKE_<LANG>_STANDARD_LIBRARIES` variable does for link libraries.
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.
Exclude Ninja and Xcode from the CMP0021 test
They do not behave the same as the makefile generator with
relative paths.
Don't overwrite the header file for in-source builds.
Unlike other target properties, this does not have a corresponding
non-INTERFACE variant.
This allows propagation of system attribute on include directories
from link dependents.
Eliminate callers of cmMakefile::GetIncludeDirectories.
All callers of GetIncludeDirectories should go through the local generator
object.
Only the local generator calls cmTarget::GetIncludeDirectories directly.
Gregor Jasny
Daniel Pfeifer
Brad King
Stephen Kelly
Bill Hoffman