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Fix C/C++ standards being unset for VVVVVV target if CMake is >= 3.1.3 

So, it turns out we weren't quite done fighting CMake yet...

To accommodate #869 (and actually also #272), the C standard was raised
from C90 to C99. This turned out to require a bit of a fight with the
CentOS CI's CMake version to get it to set the flags we wanted (and to
not overwrite them later). Eventually the fix was to move the block
that sets the standards to later in the file, which was done in
24353a54bb.

As it apparently turns out, if your CMake is at least 3.1.3 and
`CMAKE_<LANG>_STANDARD` is used instead of the workaround, the standard
setting now has an effect on the third party libraries, but not on
VVVVVV itself. The cause is (probably) the phrase "if it is set when a
target is created" in the CMake documentation - the
`CMAKE_<LANG>_STANDARD` values have to come before the VVVVVV target is
defined. In other words, the compiler's default C/C++ standard will be
used, probably something like C17 and C++17. As I can confirm with
`__cplusplus` and `__STDC_VERSION__` with my recent-enough CMake. If I
force the pre-3.1.3 workaround to be used, everything is compiled with
C99/C++98 as expected; and the `-fno-exceptions` `-fno-rtti` flags
appear everywhere regardless of version.

So my fix is to make the CMakeLists a little less complex by
simplifying away the `CMAKE_<LANG>_STANDARD` and
`CMAKE_<LANG>_EXTENSIONS`, and always using the workaround regardless
of CMake version. There's nothing wrong with the workaround, the same
thing is also done for `-fno-exceptions` `-fno-rtti`, and it's good to
have a less complicated CMakeLists that doesn't do different and
unexpected things for different versions.
This commit is contained in:
Dav999-v 2022-03-22 20:50:49 +01:00 committed by Misa Elizabeth Kai
parent 24353a54bb
commit c61c4fab6f
1 changed files with 8 additions and 20 deletions
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28
desktop_version/CMakeLists.txt
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@ -248,27 +248,9 @@ if(MSVC)
target_compile_options(VVVVVV PRIVATE /wd4244)
endif()
if(${CMAKE_VERSION} VERSION_LESS "3.1.3")
message(WARNING "Your CMake version is too old; using workaround")
if(MSVC)
# MSVC doesn't have /std:c99 or /std:c++98 switches!
else()
string(REGEX REPLACE "-std=[a-z0-9]+" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
string(REGEX REPLACE "-std=[a-z0-9+]+" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++98")
endif()
else()
set(CMAKE_C_STANDARD 99)
set(CMAKE_C_EXTENSIONS OFF)
set(CMAKE_CXX_STANDARD 98)
set(CMAKE_CXX_EXTENSIONS OFF)
endif()
if(MSVC)
# MSVC doesn't have /std:c99 or /std:c++98 switches!
# Disable exceptions
string(REGEX REPLACE "/EH[a-z]+" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc")
@ -277,6 +259,12 @@ if(MSVC)
string(REPLACE "/GR" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /GR-")
else()
string(REGEX REPLACE "-std=[a-z0-9]+" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
string(REGEX REPLACE "-std=[a-z0-9+]+" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++98")
# Disable exceptions
string(REPLACE "-fexceptions" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions")