bug: C preprocessor does not propagate directives to executables

Fixes #774

Author: gnikit

src/fpm_targets.f90

@@ -29,7 +29,7 @@ module fpm_targets
 use fpm_model
 use fpm_environment, only: get_os_type, OS_WINDOWS, OS_MACOS
 use fpm_filesystem, only: dirname, join_path, canon_path
-use fpm_strings, only: string_t, operator(.in.), string_cat, fnv_1a, resize
+use fpm_strings, only: string_t, operator(.in.), string_cat, fnv_1a, resize, lower, str_ends_with
 use fpm_compiler, only: get_macros
 implicit none
 
@@ -189,7 +189,7 @@ subroutine build_target_list(targets,model)
  !> The package model from which to construct the target list
  type(fpm_model_t), intent(inout), target :: model
 
- integer :: i, j, n_source
+ integer :: i, j, n_source, exe_type
  character(:), allocatable :: xsuffix, exe_dir
  logical :: with_lib
 
@@ -268,7 +268,15 @@ subroutine build_target_list(targets,model)
 
  case (FPM_UNIT_PROGRAM)
 
- call add_target(targets,package=model%packages(j)%name,type = FPM_TARGET_OBJECT,&
+ if (str_ends_with(lower(sources(i)%file_name), [".c"])) then
+ exe_type = FPM_TARGET_C_OBJECT
+ else if (str_ends_with(lower(sources(i)%file_name), [".cpp", ".cc "])) then
+ exe_type = FPM_TARGET_CPP_OBJECT
+ else ! Default to a Fortran object
+ exe_type = FPM_TARGET_OBJECT
+ end if
+
+ call add_target(targets,package=model%packages(j)%name,type = exe_type,&
  output_name = get_object_name(sources(i)), &
  source = sources(i) &
  )