deps: new dep "proj" fails to compile

[knz]

/data/home/kena/src/go/src/github.com/cockroachdb/cockroach/c-deps/proj/src/pj_mutex.c:130:48: error: use of undeclared identifier 'PTHREAD_MUTEX_RECURSIVE_NP'; did you mean 'PTHREAD_MUTEX_RECURSIVE'?
        pthread_mutexattr_settype(&mutex_attr, PTHREAD_MUTEX_RECURSIVE_NP);
                                               ^~~~~~~~~~~~~~~~~~~~~~~~~~
                                               PTHREAD_MUTEX_RECURSIVE
/usr/include/pthread.h:132:2: note: 'PTHREAD_MUTEX_RECURSIVE' declared here
        PTHREAD_MUTEX_RECURSIVE         = 2,    /* Recursive mutex */
        ^

nb: the _NP variants are obsolete as far as I can see

[knz]

I'm confused because there's a conditional just before

#ifdef HAVE_PTHREAD_MUTEX_RECURSIVE

and my system most definitely has PTHREAD_MUTEX_RECURSIVE

Is the build perhaps forgetting to run the configure script?

[knz]

ok I found what's amiss

on my system, PTHREAD_MUTEX_RECURSIVE is an enum tag,

and CMake mistakenly tries to identify its availability using the following C code:

int main(int argc, char** argv)
{
  (void)argv;
#ifndef PTHREAD_MUTEX_RECURSIVE
  return ((int*)(&PTHREAD_MUTEX_RECURSIVE))[argc];
#else
  (void)argc;
  return 0;
#endif 
}

ie it assumes that something is either a macro or an lvalue, and it doesn't consider enum tags.

This is a bug in the CMake implementation, or perhaps even the CMakefile itself.

For comparison, here's how RocksDB does it:

CHECK_CXX_SOURCE_COMPILES("
#include <pthread.h>
int main() {
  (void) PTHREAD_MUTEX_ADAPTIVE_NP;
}
" HAVE_PTHREAD_MUTEX_ADAPTIVE_NP)
if(HAVE_PTHREAD_MUTEX_ADAPTIVE_NP)
  add_definitions(-DROCKSDB_PTHREAD_ADAPTIVE_MUTEX)
endif()

which is much better

[knz]

I could send a PR to manually edit CMakeLists.txt with the fix, however how do I guarantee that the fix remains if we ever bump the dependency?

[knz]

(Instructions as to where's the upstream bug tracker so I can file the upstream issue are welcome)

[knz]

For reference the following diff fixes it:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cde21f0c..5c7e7b51 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,9 +60,15 @@ find_package (Threads)

 include(CheckIncludeFiles)
 include(CheckSymbolExists)
-CHECK_SYMBOL_EXISTS(PTHREAD_MUTEX_RECURSIVE pthread.h HAVE_PTHREAD_MUTEX_RECURSIVE_DEFN)
-if (HAVE_PTHREAD_MUTEX_RECURSIVE_DEFN)
-    add_definitions(-DHAVE_PTHREAD_MUTEX_RECURSIVE=1)
+
+CHECK_C_SOURCE_COMPILES("
+#include <pthread.h>
+int main() {
+  (void) PTHREAD_MUTEX_RECURSIVE;
+}
+" HAVE_PTHREAD_MUTEX_RECURSIVE)
+if(HAVE_PTHREAD_MUTEX_RECURSIVE)
+  add_definitions(-DHAVE_PTHREAD_MUTEX_RECURSIVE=1)
 endif()

 boost_report_value(PROJ_PLATFORM_NAME)

[otan]

we're pinned to an older version of PROJ (tracker here: https://github.com/OSGeo/PROJ) at 4.9.3, so not sure if they'll care. you can file a bug there.

we'll probably have to fork this to make this work for you. i'll set that up shortly.