cpp and continuation lines

[hattom]

I ran two tests in files with cpp style preprocessor statements. In the first (which has been run through fprettify):

program test
   implicit none

   integer ::  a, b, c, e, f, g, h, i

   print *, a, b, c, d, &
#ifdef TEST
      e, f, g, h, i
#else
   e, f, g, h, i
#endif
end program test

you can see, the indentation of the e, f, ...s does not line up.

If the e, f, ... line also has a prepended ampersand, then this gives a parsing error:

$ cat test.F90
program test
   implicit none

   integer ::  a, b, c, e, f, g, h, i

   print *, a, b, c, d, &
#ifdef TEST
      & e, f, g, h, i
#else
   & e, f, g, h, i
#endif
end program test

$ fprettify test.F90 
ERROR: File test.F90, line 8
    Fatal error occured
Traceback (most recent call last):
  File "/home/me/.local/lib/python2.7/site-packages/fprettify/__init__.py", line 1584, in run
    strip_comments=args.strip_comments)
  File "/home/me/.local/lib/python2.7/site-packages/fprettify/__init__.py", line 991, in reformat_inplace
    orig_filename=filename, **kwargs)
  File "/home/me/.local/lib/python2.7/site-packages/fprettify/__init__.py", line 1093, in reformat_ffile
    lines, is_special, orig_filename, stream.line_nr)
  File "/home/me/.local/lib/python2.7/site-packages/fprettify/__init__.py", line 1337, in remove_pre_ampersands
    "Bad continuation line format", filename, line_nr)
FprettifyParseException: Bad continuation line format

I think the latter should be a valid program, although I agree that it's a slightly strange formulation.

[pseewald]

fprettify will never be fully compatible with preprocessors and may produce strange formatting - for simplicity it does not parse macros or invoke preprocessors but treats them as comments. But fprettify should always produce a correct output (correct = valid syntax) and should never fail with errors so I consider this a bug.

[Syize]

I encountered the same error with following code:

!----------------------------------------------------------------------
                          SUBROUTINE MIXLEN                            &
!----------------------------------------------------------------------
!   ******************************************************************
!   *                                                                *
!   *                   LEVEL 2.5 MIXING LENGTH                      *
!   *                                                                *
!   ******************************************************************
!
     &(LMH,U,V,T,THE,Q,CWM,Q2,Z,USTAR,CORF                             &
     &,S2,GH,RI,EL,PBLH,LPBL,LMXL,CT,LM_BL89                           &
     &,IDS,IDE,JDS,JDE,KDS,KDE                                         &
     &,IMS,IME,JMS,JME,KMS,KME                                         &
     &,ITS,ITE,JTS,JTE,KTS,KTE)

fprettify stops at this line :

!   ******************************************************************
!     *STOP AT THIS LINE*
     &(LMH,U,V,T,THE,Q,CWM,Q2,Z,USTAR,CORF                             &

After checking fprettify source code, I think it is because the function remove_pre_ampersands only checks the last line before:

m = re.search(r'(\s*)&[\s]*(?:!.*)?$', lines[pos - 1])
if not m:
    raise FprettifyParseException("Bad continuation line format", filename, line_nr)

Adding a loop to skip comments can fix this bug.

_pos = pos - 1
# skip comment line
while True:
    m = re.search(r'^\s*!', lines[_pos])
        if not m:
            break
        else:
             _pos -= 1
_pos = _pos if _pos >= 0 else 0
m = re.search(r'(\s*)&[\s]*(?:!.*)?$', lines[_pos])

[max-models]

I had the same error as @Syize, here is a minimal example of a code which doesn't work since there is a comment in the line continuation:

program mwe_bad_line_continuation
    implicit none

    real :: x, y, z

    x = 1.0
    y = 2.0

    z = x + &
        ! comment
         & y 
    print *, z
end program mwe_bad_line_continuation