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

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The original code was good enough for supporting GNU/Linux
and a few others but it wasn't very portable.

CMake doesn't support Solaris Studio's -xldscope=hidden.
If it ever does, things should still work with this commit
as Solaris Studio supports not only its own __global but also
the GNU C __attribute__((visibility("default"))). Support for the
attribute was added in 2007 to Sun Studio 12 compiler version 5.9.
This commit is contained in:
Lasse Collin 2024-02-19 13:38:42 +02:00
parent 2ced9d34be
commit b0d1422b60
1 changed files with 22 additions and 4 deletions
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26
CMakeLists.txt
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@ -1144,10 +1144,28 @@ if(ALLOW_ARM64_CRC32)
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 should always be defined to 0 or 1. It tells liblzma
# if __attribute__((__visibility__("default")))
# and __attribute__((__visibility__("hidden"))) are supported.
# Those are useful only when the compiler supports -fvisibility=hidden
# or such option so HAVE_VISIBILITY should be 1 only when both option and
# the attribute support are present. HAVE_VISIBILITY is ignored on Windows
# and Cygwin by the liblzma C code; __declspec(dllexport) is used instead.
#
# 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 compiler
# command line option for visibility support. It's empty or unset when
# visibility isn't supported. (It was added to CMake 2.8.12 in the commit
# 0e9f4bc00c6b26f254e74063e4026ac33b786513 in 2013.) This way we don't
# set HAVE_VISIBILITY to 1 when visibility isn't actually supported.
if(BUILD_SHARED_LIBS AND CMAKE_C_COMPILE_OPTIONS_VISIBILITY)
set_target_properties(liblzma PROPERTIES C_VISIBILITY_PRESET hidden)
target_compile_definitions(liblzma PRIVATE HAVE_VISIBILITY=1)
else()