1# - Try to find how to link to the standard math library, if anything at all is needed to do.
2# On most platforms this is automatic, but for example it's not automatic on QNX.
3#
4# Once done this will define
5#
6#  STANDARD_MATH_LIBRARY_FOUND - we found how to successfully link to the standard math library
7#  STANDARD_MATH_LIBRARY - the name of the standard library that one has to link to.
8#                            -- this will be left empty if it's automatic (most platforms).
9#                            -- this will be set to "m" on platforms where one must explicitly
10#                               pass the "-lm" linker flag.
11#
12# Copyright (c) 2010 Benoit Jacob <jacob.benoit.1@gmail.com>
13# Redistribution and use is allowed according to the terms of the 2-clause BSD license.
14
15
16include(CheckCXXSourceCompiles)
17
18# a little test program for c++ math functions.
19# notice the std:: is required on some platforms such as QNX
20
21set(find_standard_math_library_test_program
22"#include<cmath>
23int main() { std::sin(0.0); std::log(0.0f); }")
24
25# first try compiling/linking the test program without any linker flags
26
27set(CMAKE_REQUIRED_FLAGS "")
28set(CMAKE_REQUIRED_LIBRARIES "")
29CHECK_CXX_SOURCE_COMPILES(
30  "${find_standard_math_library_test_program}"
31  standard_math_library_linked_to_automatically
32)
33
34if(standard_math_library_linked_to_automatically)
35
36  # the test program linked successfully without any linker flag.
37  set(STANDARD_MATH_LIBRARY "")
38  set(STANDARD_MATH_LIBRARY_FOUND TRUE)
39
40else()
41
42  # the test program did not link successfully without any linker flag.
43  # This is a very uncommon case that so far we only saw on QNX. The next try is the
44  # standard name 'm' for the standard math library.
45
46  set(CMAKE_REQUIRED_LIBRARIES "m")
47  CHECK_CXX_SOURCE_COMPILES(
48    "${find_standard_math_library_test_program}"
49    standard_math_library_linked_to_as_m)
50
51  if(standard_math_library_linked_to_as_m)
52
53    # the test program linked successfully when linking to the 'm' library
54    set(STANDARD_MATH_LIBRARY "m")
55    set(STANDARD_MATH_LIBRARY_FOUND TRUE)
56
57  else()
58
59    # the test program still doesn't link successfully
60    set(STANDARD_MATH_LIBRARY_FOUND FALSE)
61
62  endif()
63
64endif()
65