[Bug preprocessor/67266] Use of "cpp -P ..." collapses multiple blank lines

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67266

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The "long runs of blank lines are discarded" part refers to the constant 8
hardcoded in the maybe_print_line_1 function.  The constant's effect can be
seen in the following test case.  The first sequence of 7 newlines is retained
while the second one of 8 newlines is compressed.

$ cat -n a.txt && gcc -dU -E -xc a.txt | cat -n
     1  line 1
     2  
     3  
     4  
     5  
     6  
     7  
     8  line 8
     9  
    10  
    11  
    12  
    13  
    14  
    15  
    16  
    17  line 17
     1  # 1 "a.txt"
     2  # 1 "<built-in>"
     3  # 1 "<command-line>"
     4  # 1 "/usr/include/stdc-predef.h" 1 3 4
     5  #undef _STDC_PREDEF_H
     6  #define __GCC_IEC_559 2
     7  #define __GCC_IEC_559_COMPLEX 2
     8  # 1 "<command-line>" 2
     9  # 1 "a.txt"
    10  line 1
    11  
    12  
    13  
    14  
    15  
    16  
    17  line 8
    18  # 17 "a.txt"
    19  line 17