cart-elc

Source code for CART-ELC
git clone git://git.laack.co/cart-elc.git
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FindStandardMathLibrary.cmake (2482B)

      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 #               2020 Susi Lehtola <susi.lehtola@gmail.com>
     14 # Redistribution and use is allowed according to the terms of the 2-clause BSD license.
     15 
     16 
     17 include(CheckCXXSourceCompiles)
     18 
     19 # a little test program for c++ math functions.
     20 # notice the std:: is required on some platforms such as QNX
     21 # notice the (void) is required if -Wall (-Wunused-value) is added to CMAKE_CXX_FLAG
     22 
     23 # We read in the arguments from standard input to avoid the compiler optimizing away the calls
     24 set(find_standard_math_library_test_program
     25 "
     26 #include<cmath>
     27 int main(int argc, char **){
     28   return int(std::sin(double(argc)) + std::log(double(argc)));
     29 }")
     30 
     31 # first try compiling/linking the test program without any linker flags
     32 
     33 set(CMAKE_REQUIRED_FLAGS "")
     34 set(CMAKE_REQUIRED_LIBRARIES "")
     35 CHECK_CXX_SOURCE_COMPILES(
     36   "${find_standard_math_library_test_program}"
     37   standard_math_library_linked_to_automatically
     38 )
     39 
     40 if(standard_math_library_linked_to_automatically)
     41 
     42   # the test program linked successfully without any linker flag.
     43   set(STANDARD_MATH_LIBRARY "")
     44   set(STANDARD_MATH_LIBRARY_FOUND TRUE)
     45 
     46 else()
     47 
     48   # the test program did not link successfully without any linker flag.
     49   # This is a very uncommon case that so far we only saw on QNX. The next try is the
     50   # standard name 'm' for the standard math library.
     51 
     52   set(CMAKE_REQUIRED_LIBRARIES "m")
     53   CHECK_CXX_SOURCE_COMPILES(
     54     "${find_standard_math_library_test_program}"
     55     standard_math_library_linked_to_as_m)
     56 
     57   if(standard_math_library_linked_to_as_m)
     58 
     59     # the test program linked successfully when linking to the 'm' library
     60     set(STANDARD_MATH_LIBRARY "m")
     61     set(STANDARD_MATH_LIBRARY_FOUND TRUE)
     62 
     63   else()
     64 
     65     # the test program still doesn't link successfully
     66     set(STANDARD_MATH_LIBRARY_FOUND FALSE)
     67 
     68   endif()
     69 
     70 endif()