From d4e551a90b6bf6ea4e18fa408f40f39df6ad6fb4 Mon Sep 17 00:00:00 2001
From: Steffen Dettmer <steffen.dettmer@gmail.com>
Date: Mon, 7 Aug 2017 15:30:33 +0200
Subject: FindThreads: Drop try_run to improve cross-compiling support
Use `try_compile` instead of `try_run`. It is not clear why `try_run`
was ever needed, and it does not work during cross-compiling.
Update the check's source file to remove code associated with actually
running things. Also remove the ancient `__CLASSIC_C__` code path and
use a simple `int main(void)` as in `Modules/CheckIncludeFile.c.in`.
Fixes: #16920
---
Modules/CheckForPthreads.c | 40 +++++++---------------------------------
Modules/FindThreads.cmake | 15 ++++-----------
2 files changed, 11 insertions(+), 44 deletions(-)
diff --git a/Modules/CheckForPthreads.c b/Modules/CheckForPthreads.c
index 6fc6f26..e70ceb1 100644
--- a/Modules/CheckForPthreads.c
+++ b/Modules/CheckForPthreads.c
@@ -1,41 +1,15 @@
#include <pthread.h>
-#include <stdio.h>
-#include <unistd.h>
-void* runner(void*);
-
-int res = 0;
-#ifdef __CLASSIC_C__
-int main()
-{
- int ac;
- char* av[];
-#else
-int main(int ac, char* av[])
+void* start_routine(void* args)
{
-#endif
- pthread_t tid[2];
- pthread_create(&tid[0], 0, runner, (void*)1);
- pthread_create(&tid[1], 0, runner, (void*)2);
-
-#if defined(__BEOS__) && !defined(__ZETA__) /* (no usleep on BeOS 5.) */
- usleep(1); /* for strange behavior on single-processor sun */
-#endif
-
- pthread_join(tid[0], 0);
- pthread_join(tid[1], 0);
- if (ac > 1000) {
- return *av[0];
- }
- return res;
+ return args;
}
-void* runner(void* args)
+int main(void)
{
- int cc;
- for (cc = 0; cc < 10; cc++) {
- printf("%p CC: %d\n", args, cc);
- }
- res++;
+ /* This is a compile and link test, no code to actually run things. */
+ pthread_t thread;
+ pthread_create(&thread, 0, start_routine, 0);
+ pthread_join(thread, 0);
return 0;
}
diff --git a/Modules/FindThreads.cmake b/Modules/FindThreads.cmake
index 2c6a58b..a0148dd 100644
--- a/Modules/FindThreads.cmake
+++ b/Modules/FindThreads.cmake
@@ -86,23 +86,16 @@ macro(_check_pthreads_flag)
set(_threads_src ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindThreads/CheckForPthreads.cxx)
configure_file(${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c "${_threads_src}" COPYONLY)
endif()
- try_run(THREADS_PTHREAD_ARG THREADS_HAVE_PTHREAD_ARG
+ try_compile(THREADS_HAVE_PTHREAD_ARG
${CMAKE_BINARY_DIR}
${_threads_src}
CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
- COMPILE_OUTPUT_VARIABLE OUTPUT)
+ OUTPUT_VARIABLE OUTPUT)
unset(_threads_src)
if(THREADS_HAVE_PTHREAD_ARG)
- if(THREADS_PTHREAD_ARG STREQUAL "2")
- set(Threads_FOUND TRUE)
- message(STATUS "Check if compiler accepts -pthread - yes")
- else()
- message(STATUS "Check if compiler accepts -pthread - no")
- file(APPEND
- ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
- "Determining if compiler accepts -pthread returned ${THREADS_PTHREAD_ARG} instead of 2. The compiler had the following output:\n${OUTPUT}\n\n")
- endif()
+ set(Threads_FOUND TRUE)
+ message(STATUS "Check if compiler accepts -pthread - yes")
else()
message(STATUS "Check if compiler accepts -pthread - no")
file(APPEND
--
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