CMake can't find pthread
By Gabriel Cooper •
pthreads works on the system:
$ gcc -o what what.c
/tmp/ccI6m52b.o: In function `main':
what.c:(.text+0x37): undefined reference to `pthread_create'
what.c:(.text+0x48): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status
$ gcc -pthread -o what what.c
$ ./what
In the thread.However, when I run cmake with the following bare-bones CMakeLists.txt:
cmake_minimum_required(VERSION 2.8.6)
FIND_PACKAGE (Threads)The output is:
-- Could NOT find Threads (missing: Threads_FOUND)What gives? Error log states:
/usr/bin/cc -std=c11 -D_GNU_SOURCE -Wall -Wextra -Wpointer-arith -Wundef -Wvla -Wwrite-strings -Werror -Wno-error=extra -Wno-error=deprecated-declarations -Wno-error=sign-compare -Wno-error=strict-aliasing -Wno-error=type-limits -Wno-unused-parameter -Wno-error=unused-variable -Wno-error=undef -Wno-error=uninitialized -Wlogical-op -Wno-error=maybe-uninitialized -Waggregate-return -Wnested-externs -Wold-style-definition -Wstrict-prototypes -march=native -o CMakeFiles/ -c /mnt/shared/fooproj/build/release/CMakeFiles/CMakeTmp/CheckIncludeFiles.c
/mnt/shared/fooproj/build/release/CMakeFiles/CMakeTmp/CheckIncludeFiles.c:5:5: error: function declaration isn’t a prototype [-Werror=strict-prototypes] int main(){return 0;} ^
/mnt/shared/fooproj/build/release/CMakeFiles/CMakeTmp/CheckIncludeFiles.c: In function ‘main’:
/mnt/shared/fooproj/build/release/CMakeFiles/CMakeTmp/CheckIncludeFiles.c:5:5: error: old-style function definition [-Werror=old-style-definition]
cc1: all warnings being treated as errors
[...]
Source:
/* */
#include <pthread.h>
int main(){return 0;}1 Answer
I have answered this question on StackOverflow.
Short answer: it's a CMake bug which I have reported and offered a patch.
