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CMake: Don't assume that -fvisibility=hidden is supported outside Windows. 

The original code was good enough for supporting GNU/Linux
and a few others but it wasn't very portable.
This commit is contained in:
Lasse Collin 2023-10-15 02:20:47 +03:00
parent 34a48239ed
commit a338f62471
1 changed files with 24 additions and 4 deletions
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28
CMakeLists.txt
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@ -862,10 +862,30 @@ if(HAVE_IMMINTRIN_H)
tuklib_add_definition_if(liblzma HAVE_USABLE_CLMUL)
endif()
# Support -fvisiblity=hidden when building shared liblzma.
# These lines do nothing on Windows (even under Cygwin).
# HAVE_VISIBILITY should always be defined to 0 or 1.
if(BUILD_SHARED_LIBS)
# Symbol visibility support:
#
# The C_VISIBILITY_PRESET property takes care of adding the compiler
# option -fvisibility=hidden (or equivalent) if and only if it is supported.
#
# HAVE_VISIBILITY indicates if __attribute__((__visibility__("default")))
# is supported. HAVE_VISIBILITY is ignored on Windows and Cygwin in
# the C code so we don't need to handle that here. HAVE_VISIBILITY
# should always be defined to 0 or 1.
#
# CMake's GenerateExportHeader module is too fancy since liblzma already
# has the necessary macros. Instead, check CMake's internal variable
# CMAKE_C_COMPILE_OPTIONS_VISIBILITY (it's the C-specific variant of
# CMAKE_<LANG>_COMPILE_OPTIONS_VISIBILITY) which contains the string or
# substring "-fvisibility=" when that compiler option is supported (due to
# the possibility of substring, we use MATCHES instead of STREQUAL). It's
# empty or unset when visibility isn't supported.
#
# NOTE: CMake 3.27 doesn't support other visibility mechanisms. For example,
# SolarisStudio ("SunPro") has the option -xldscope=hidden and uses __global
# instead of GNU C's __attribute__ to mark exported symbols. Autotools-based
# build doesn't support -xldscope=hidden either.
if(BUILD_SHARED_LIBS
AND CMAKE_C_COMPILE_OPTIONS_VISIBILITY MATCHES "-fvisibility=")
set_target_properties(liblzma PROPERTIES C_VISIBILITY_PRESET hidden)
target_compile_definitions(liblzma PRIVATE HAVE_VISIBILITY=1)
else()