rationalize ISO_Fortran_binding.h check

Author: scivision

CMakeLists.txt

@@ -29,7 +29,9 @@ endif()
 if(ffilesystem_fortran)
   enable_language(Fortran)
 
-  include(cmake/iso_fortran_binding.cmake)
+  if(ffilesystem_iso_fortran_binding)
+    include(cmake/iso_fortran_binding.cmake)
+  endif()
 endif()
 
 # --- RPATH handling for transitive dependencies

cmake/iso_fortran_binding.cmake

@@ -1,48 +1,57 @@
-if(ffilesystem_iso_fortran_binding)
-  if(CMAKE_C_COMPILER_ID STREQUAL "AppleClang" AND CMAKE_Fortran_COMPILER_ID STREQUAL "LLVMFlang")
-    find_program(brew_exe NAMES brew)
-    if(brew_exe)
-      execute_process(COMMAND ${brew_exe} --prefix flang
-      OUTPUT_VARIABLE flang_prefix
-      OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET)
-    endif()
-    find_path(ffilesystem_ISO_Fortran_binding_path NAMES ISO_Fortran_binding.h
-    HINTS ${flang_prefix}/include
-    PATH_SUFFIXES flang)
-    if(ffilesystem_ISO_Fortran_binding_path)
-      set(CMAKE_REQUIRED_INCLUDES ${ffilesystem_ISO_Fortran_binding_path})
+# AppleClang needs a hint to find Flang ISO_Fortran_binding.h since they are distinct compiler vendors
+if(NOT DEFINED ffilesystem_ISO_Fortran_binding_path AND
+    CMAKE_C_COMPILER_ID STREQUAL "AppleClang" AND CMAKE_Fortran_COMPILER_ID STREQUAL "LLVMFlang")
+
+
+  set(_flang_ifb_hint)
+
+  find_program(brew_exe NAMES brew)
+  if(brew_exe)
+    execute_process(COMMAND ${brew_exe} --prefix flang
+    OUTPUT_VARIABLE flang_prefix
+    OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_QUIET
+    RESULT_VARIABLE _ret
+    )
+    if(_ret EQUAL 0)
+      set(_flang_ifb_hint HINTS ${flang_prefix}/include NO_DEFAULT_PATH)
     endif()
   endif()
 
-  check_include_file("ISO_Fortran_binding.h" ffilesystem_ifb_ok)
-  if(ffilesystem_ifb_ok)
-    if(NOT DEFINED ffilesystem_HAVE_ISO_FORTRAN_BINDING)
-
-      message(CHECK_START "checking that ISO_Fortran_binding.h is usable for <string> interoperability")
-
-      try_run(ffilesystem_ifb_run ffilesystem_ifb_build
-      SOURCES ${CMAKE_CURRENT_LIST_DIR}/ifb.c ${CMAKE_CURRENT_LIST_DIR}/ifb.f90
-      CMAKE_FLAGS -DINCLUDE_DIRECTORIES=${CMAKE_REQUIRED_INCLUDES}
-      COMPILE_OUTPUT_VARIABLE _ifb_build
-      RUN_OUTPUT_STDOUT_VARIABLE _ifb_code
-      RUN_OUTPUT_STDERR_VARIABLE _ifb_error
-      )
-
-      string(STRIP "${_ifb_code}" _ifb_code)
-      string(STRIP "${_ifb_error}" _ifb_error)
-
-      if(NOT ffilesystem_ifb_build)
-        message(CHECK_FAIL "failed to compile ISO_Fortran_binding.h ${ffilesystem_ifb_build}
-        ${_ifb_build}")
-      elseif(NOT ffilesystem_ifb_run EQUAL 0)
-        message(CHECK_FAIL "failed to test ISO_Fortran_binding.h ${ffilesystem_ifb_run}
-        ${_ifb_code}
-         ${_ifb_error}")
-      else()
-        set(ffilesystem_HAVE_ISO_FORTRAN_BINDING true CACHE STRING "ISO_Fortran_binding.h test code")
-        message(CHECK_PASS "OK: ${_ifb_code}")
-      endif()
+  find_path(ffilesystem_ISO_Fortran_binding_path
+  NAMES ISO_Fortran_binding.h
+  ${_ifb_hint}
+  PATH_SUFFIXES flang
+  )
 
-    endif()
+  if(ffilesystem_ISO_Fortran_binding_path)
+    set(CMAKE_REQUIRED_INCLUDES ${ffilesystem_ISO_Fortran_binding_path})
+  endif()
+endif()
+
+check_include_file("ISO_Fortran_binding.h" ffilesystem_ifb_ok)
+if(ffilesystem_ifb_ok AND NOT DEFINED ffilesystem_HAVE_ISO_FORTRAN_BINDING)
+  message(CHECK_START "check ISO_Fortran_binding.h for C++ <string> interoperability")
+
+  try_run(ffilesystem_ifb_run ffilesystem_ifb_build
+  SOURCES ${CMAKE_CURRENT_LIST_DIR}/ifb.c ${CMAKE_CURRENT_LIST_DIR}/ifb.f90
+  CMAKE_FLAGS -DINCLUDE_DIRECTORIES=${CMAKE_REQUIRED_INCLUDES}
+  COMPILE_OUTPUT_VARIABLE _ifb_build
+  RUN_OUTPUT_STDOUT_VARIABLE _ifb_code
+  RUN_OUTPUT_STDERR_VARIABLE _ifb_error
+  )
+
+  string(STRIP "${_ifb_code}" _ifb_code)
+  string(STRIP "${_ifb_error}" _ifb_error)
+
+  if(NOT ffilesystem_ifb_build)
+    message(CHECK_FAIL "failed to compile ISO_Fortran_binding.h ${ffilesystem_ifb_build}
+    ${_ifb_build}")
+  elseif(NOT ffilesystem_ifb_run EQUAL 0)
+    message(CHECK_FAIL "failed to run with ISO_Fortran_binding.h ${ffilesystem_ifb_run}
+    ${_ifb_code}
+    ${_ifb_error}")
+  else()
+    set(ffilesystem_HAVE_ISO_FORTRAN_BINDING true CACHE STRING "ISO_Fortran_binding.h test code")
+    message(CHECK_PASS "OK")
   endif()
 endif()

cmake/stdcpp.cmake

@@ -29,7 +29,7 @@ if(ffilesystem_stdcpp_run EQUAL 0)
       message(VERBOSE "GNU libstdc++ ${ffilesystem_stdcpp_version} is new enough to not need -lstdc++")
     endif()
   else()
-    message(VERBOSE "Did not determine GNU libstdc++ version ${ffilesystem_stdcpp_version}")
+    message(VERBOSE "libstdc++ version ${ffilesystem_stdcpp_version}")
   endif()
 endif()