为什么指定-std=gnu++11时使用C++98？ [复制]

Question

我正在尝试编译一个应用程序，并在CMakeLists.txt 中添加了这些行

option(DISPLAY "Display images and steps" OFF)
option(TESTS "Build tests too" OFF)

if (DISPLAY)
set(CMAKE_CXX_FLAGS "-g -Wall -std=gnu++11 -DDISPLAY_IMGS")
else()
set(CMAKE_CXX_FLAGS "-g -Wall -std=gnu++11")
endif()

（这些行在文件的开头）我收到这样的错误：

In function ‘int main(int, char**)’:
error: in C++98 ‘featuresTypes’ must be initialized by constructor, not by ‘{...}’

谁能告诉我为什么这样做？事实上，在 KDevelop 中构建它可以正常工作，但是在终端中构建它（$ cmake .. 和 $ make），它会给出错误。

---

VERBOSE=1 说：

/usr/bin/cmake -H/home/xxx/proj/prj1 -B/home/xxx/proj/prj1/build --check-build-system CMakeFiles/Makefile.cmake 0
/usr/bin/cmake -E cmake_progress_start /home/xxx/proj/prj1/build/CMakeFiles /home/xxx/proj/prj1/build/CMakeFiles/progress.marks
make -f CMakeFiles/Makefile2 all
make[1]: Entering directory `/home/xxx/proj/prj1/build'
make -f CMakeFiles/prj1.dir/build.make CMakeFiles/prj1.dir/depend
make[2]: Entering directory `/home/xxx/proj/prj1/build'
cd /home/xxx/proj/prj1/build && /usr/bin/cmake -E cmake_depends "Unix Makefiles" /home/xxx/proj/prj1 /home/xxx/proj/prj1 /home/xxx/proj/prj1/build /home/xxx/proj/prj1/build /home/xxx/proj/prj1/build/CMakeFiles/prj1.dir/DependInfo.cmake --color=
Dependee "/home/xxx/proj/prj1/build/CMakeFiles/optimisation.dir/DependInfo.cmake" is newer than depender "/home/xxx/proj/prj1/build/CMakeFiles/prj1.dir/depend.internal".
Dependee "/home/xxx/proj/prj1/build/CMakeFiles/CMakeDirectoryInformation.cmake" is newer than depender "/home/xxx/proj/prj1/build/CMakeFiles/prj1.dir/depend.internal".
Scanning dependencies of target optimisation
make[2]: Leaving directory `/home/xxx/proj/prj1/build'
make -f CMakeFiles/optimisation.dir/build.make CMakeFiles/prj1.dir/build
make[2]: Entering directory `/home/xxx/proj/prj1/build'
/usr/bin/cmake -E cmake_progress_report /home/xxx/proj/prj1/build/CMakeFiles 1
[ 12%] Building CXX object CMakeFiles/prj1.dir/src/cpp/main.cpp.o
/usr/bin/c++    -I/usr/local/include/opencv -I/usr/local/include -I/home/xxx/proj/prj1/src/hpp    -o CMakeFiles/prj1.dir/src/cpp/main.cpp.o -c /home/xxx/proj/prj1/src/cpp/main.cpp
/home/xxx/proj/prj1/src/cpp/main.cpp: In function ‘int main(int, char**)’:
/home/xxx/proj/prj1/src/cpp/main.cpp:99:33: error: in C++98 ‘featuresTypes’ must be initialized by constructor, not by ‘{...}’

它应该怎么做？

Answer 1

您的标志根本没有进入构建命令。因此，您要么尝试在 CMakeLists.txt 中的 project 行之前设置这些标志，要么在之后包含一些覆盖它们的东西。

您可能应该将它们移动到任何 project 行和包含之后，并将它们附加到当前值，因为最后一个标志获胜。

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -Wall -std=gnu++11")
if (DISPLAY)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDISPLAY_IMGS")
endif()