With CMAKE_TRY_COMPILE_TARGET_TYPE set to STATIC_LIBRARY, the try_compile()
(which is used by check_c_source_compiles()) will build static library
instead of executable. This avoids linking additional libraries in and thus
speeds up those checks a little.
This commit also avoids #3743 (GSSAPI build errors) on itself with cmake
3.6 or above. That issue was fixed separately for all versions.
Ref: #3744
There were several -Wunused warnings and one duplicate macro definition.
The EXTRA_DEFINES variable of the CurlCheckCSources macro was being
abused ("__unused1\n#undef inline\n#define __unused2", seriously?) to
insert extra C code. Avoid this broken abstraction and use cmake's
check_c_source_compiles directly (works fine with CMake 2.8, maybe
even cmake 2.6).
After cleaning up all related variables (EXTRA_DEFINES,
HEADER_INCLUDES, auxiliary headers_hack), also remove a duplicate
add_headers_include macro and remove duplicate header additions before
the struct timeval check.
Oh, and now the code is converted to use CheckCSourceRuns and
CheckCSourceCompiles, the two curl-specific helpers can be removed.
Unfortunately, the cmake output is now slightly more verbose. Before:
Performing Test int send(int, const void *, size_t, int) (curl_cv_func_send_test)
Performing Test int send(int, const void *, size_t, int) (curl_cv_func_send_test) - Failed
Since check_c_source_compiles prints the varname, now you see:
Performing Test curl_cv_func_send_test
Performing Test curl_cv_func_send_test - Failed
Tested: int send(int, const void *, size_t, int)
Compared cmake output with each other using vimdiff, no functional
differences were found. Tested with GCC 4.9.1 and Clang 3.5.0.
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
