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Avoid using C++14 to build CMake if cstdio breaks 

The GNU 4.8 standard library's cstdio header is not aware that C++14
honors C11's removal of "gets" from stdio.h and results in an error:

  /.../include/c++/4.8/cstdio:120:11: error: no member named 'gets' in the global namespace

Detect this problematic case and default to using C++11 instead of
C++14 for building CMake itself.
This commit is contained in:
Brad King 2015-05-08 11:04:21 -04:00
parent 6831f91a6c
commit 3307e10fc4
3 changed files with 41 additions and 1 deletions
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7
CMakeLists.txt
View File

@ -41,7 +41,12 @@ if(NOT DEFINED CMAKE_C_STANDARD AND NOT CMake_NO_C_STANDARD)
set(CMAKE_C_STANDARD 11)
endif()
if(NOT DEFINED CMAKE_CXX_STANDARD AND NOT CMake_NO_CXX_STANDARD)
set(CMAKE_CXX_STANDARD 14)
include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx14_cstdio.cmake)
if(NOT CMake_CXX14_CSTDIO_BROKEN)
set(CMAKE_CXX_STANDARD 14)
else()
set(CMAKE_CXX_STANDARD 11)
endif()
endif()
# option to set the internal encoding of CMake to UTF-8

33
Source/Checks/cm_cxx14_cstdio.cmake Normal file
View File

@ -0,0 +1,33 @@
set(CMake_CXX14_CSTDIO_BROKEN 0)
if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang" AND CMAKE_CXX14_STANDARD_COMPILE_OPTION)
if(NOT DEFINED CMake_CXX14_CSTDIO_WORKS)
message(STATUS "Checking if compiler supports C++14 cstdio")
try_compile(CMake_CXX14_CSTDIO_WORKS
${CMAKE_CURRENT_BINARY_DIR}
${CMAKE_CURRENT_LIST_DIR}/cm_cxx14_cstdio.cpp
CMAKE_FLAGS -DCMAKE_CXX_STANDARD=14
OUTPUT_VARIABLE OUTPUT
)
if(CMake_CXX14_CSTDIO_WORKS AND "${OUTPUT}" MATCHES "error: no member named.*gets.*in the global namespace")
set_property(CACHE CMake_CXX14_CSTDIO_WORKS PROPERTY VALUE 0)
endif()
if(CMake_CXX14_CSTDIO_WORKS)
message(STATUS "Checking if compiler supports C++14 cstdio - yes")
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
"Determining if compiler supports C++14 cstdio passed with the following output:\n"
"${OUTPUT}\n"
"\n"
)
else()
message(STATUS "Checking if compiler supports C++14 cstdio - no")
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if compiler supports C++14 cstdio failed with the following output:\n"
"${OUTPUT}\n"
"\n"
)
endif()
endif()
if(NOT CMake_CXX14_CSTDIO_WORKS)
set(CMake_CXX14_CSTDIO_BROKEN 1)
endif()
endif()

2
Source/Checks/cm_cxx14_cstdio.cpp Normal file
View File

@ -0,0 +1,2 @@
#include <cstdio>
int main() { return 0; }