Because not all compilers under test support the existing 'activation
features', add another test to ensure that compilers which support
both static_assert and nullptr behave as expected in this test.
The purpose of the feature listing in these tests is to make other
features from the same feature set (eg "C++11 features") available.
The compilers under test until now have supported these 'activation
features', but MSVC does not. Use the cxx_static_assert feature
instead to activate the feature set.
The tests below test the presence of both cxx_final and cxx_override,
only one of which is supported by MSVC. The test is in part intended
to verify that the COMPILE_FEATURES genex supports multiple arguments
and allows users to define names for groups of features (Clang already
calls cxx_final and cxx_override 'override control' as a group). Keep
the test, and allow the expectation to be set as appropriate.
Clang 3.4 uses C99 by default, and Clang 3.6 uses C11 by default:
http://thread.gmane.org/gmane.comp.compilers.clang.devel/39379
GNU 4.9 uses C90 by default, and GNU 5.0 uses C11 by default:
https://gcc.gnu.org/gcc-5/changes.html
Test that the default compiler settings result in the expected dialect
macros being defined for both C and CXX. Remove the unused main.c
file from the CompileFeatures unit test.
Allow setting build properties based on the features available
for a target. The availability of features is determined at
generate-time by evaluating the link implementation.
Ensure that the <LANG>_STANDARD determined while evaluating
COMPILE_FEATURES in the link implementation is not lower than that
provided by the INTERFACE of the link implementation. This is
similar to handling of transitive properties such as
POSITION_INDEPENDENT_CODE.
Add properties and variables corresponding to CXX equivalents.
Add features for c_function_prototypes (C90), c_restrict (C99),
c_variadic_macros (C99) and c_static_assert (C11). This feature
set can be extended later.
Add a <PREFIX>_RESTRICT symbol define to WriteCompilerDetectionHeader
to conditionally represent the c_restrict feature.
Remove the use of check_cxx_source_compiles which is now just getting in
the way.
Blacklist the cxx_alignof feature in the test with GNU 4.7. The test
file compiles, but it is documented as available first in GNU 4.8.
Extend the interface of the target_compile_features command with
PUBLIC and INTERFACE keywords. Populate the INTERFACE_COMPILER_FEATURES
target property if they are set. Consume the INTERFACE_COMPILER_FEATURES
target property from linked dependent targets to determine the final
required compiler features and the compile flag, if needed.
Use the same pattern of origin-debugging which is used for other
build properties.
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.
Stephen Kelly
Brad King