[flang] included sources are parsing separately

[foxtran]

With the following code:

      subroutine test(
#include "args.f"
      end

And args.f:

     $arg)
      integer :: arg

flang-new gives the following message:

error: Could not scan test.f
./test.f:1:22: error: Unmatched '('
        subroutine test(
                       ^
./args.f:1:6: warning: Statement should not begin with a continuation line
       $arg)
       ^
./test.f:2:1: warning: included here
  #include "args.f"
  ^^^^^^^^^^^^^^^^^
./args.f:1:10: error: Unmatched ')'
       $arg)
           ^
./test.f:2:1: error: included here
  #include "args.f"
  ^^^^^^^^^^^^^^^^^

It happens because each source and include files are tokenizing separately, without full context.

[llvmbot]

@llvm/issue-subscribers-flang-frontend

Author: None (foxtran)

With the following code: ```fortran subroutine test( #include "args.f" end ``` And `args.f`: ```fortran $arg) integer :: arg ```

flang-new gives the following message:

error: Could not scan test.f
./test.f:1:22: error: Unmatched '('
        subroutine test(
                       ^
./args.f:1:6: warning: Statement should not begin with a continuation line
       $arg)
       ^
./test.f:2:1: warning: included here
  #include "args.f"
  ^^^^^^^^^^^^^^^^^
./args.f:1:10: error: Unmatched ')'
       $arg)
           ^
./test.f:2:1: error: included here
  #include "args.f"
  ^^^^^^^^^^^^^^^^^

It happens because each source and include files are tokenizing separately, without full context.

[foxtran]

I'll fix this issue. Just for your information, this bug happens in much more simple code (test2.f):

      subroutine test(
#ifdef TEST
      test)
#else
      tset)
#endif
      end

The output is:

error: Could not scan test2.f
./test2.f:1:22: error: Unmatched '('
        subroutine test(
                       ^
./test2.f:5:11: error: Unmatched ')'
        tset)
            ^

[foxtran]

Hello!

I have fixed this issue, but the patch is dirty. Looks like that running cpp preprocessor is much simpler rather having cpp preprocessor in flang frontend.

[klausler]

#95332