[Fortran/gfortran] support environment flags in compile tests

[tblah]

Summary

Adding extra flags to compile tests is useful for testing out new
features (e.g. -flang-experimental-hlfir) or increasing test coverage
(e.g. running optimisation passes).

[tarunprabhu]

Fortran/gfortran/CMakeLists.txt

346

Instead of creating a separate env_fflags variable, it is probably better to add it to the fflags variable. That was what that local variable was intended for. Thanks for fixing the oversight.

It'll have to be added in 4 places:

• gfortran_add_compile_tests_from_tests
• gfortran_add_compile_tests
• gfortran_add_execute_tests_from_tests
• gfortran_add_execute_tests

[tblah]

Append to fflags

[tblah]

Fortran/gfortran/CMakeLists.txt

346

Thanks for taking a look

I think I still have to define env_fflags so that fflags is not overwritten. But I now append to fflags in the next line.

Thanks for the pointers. gfortran_add_compile_tests* both call gfortran_add_compile_test, where my change is so those are both covered.

gfortran_add_execute_tests* compile using a cmake generated rule. CMake already respects CMAKE_Fortran_FLAGS: https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_FLAGS.html

[tarunprabhu]

Thanks for the changes. LGTM.

[tblah]

Bugfix. Appologies for the mistake and the delay fixing it - I've been
ill for a few days.

Fortran/gfortran/CMakeLists.txt

function(gfortran_add_compile_test expect_error main others fflags ldflags)
   gfortran_unique_target_name("${PREFIX_COMPILE}" "${main}" target)
   gfortran_make_working_dir("${target}" working_dir)
 
   # The output of the compilation of the test file. This may contain warnings
   # and error messages. If the compilation succeeded without any warnings or
   # other diagnostics, it will be empty.
   set(out ${target}.out)
 
+  # Add the CMake-wide environment variable CMAKE_Fortran_FLAGS
+  # CMake escapes spaces. To really get a space (between arguments) use a ;
+  string(REPLACE " " ";" fflags ${fflags} ";" ${CMAKE_Fortran_FLAGS})
+
   add_custom_command(
     OUTPUT ${out}
     COMMAND ${CMAKE_COMMAND}
     -DCMD="${CMAKE_Fortran_COMPILER};-c;${fflags};${ldflags};${others};${main}"
     -DALWAYS_SAVE_DIAGS=OFF
     -DWORKING_DIRECTORY=${working_dir}
     -DOUTPUT_FILE=${out}
     -P ${COMPILE_SCRIPT_BIN}