[Bug preprocessor/117124] New: Header file contents get modified when macro defined before header file inclusion

[akhil.k.joyson at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117124

            Bug ID: 117124
           Summary: Header file contents get modified when macro defined
                    before header file inclusion
           Product: gcc
           Version: 11.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: akhil.k.joyson at gmail dot com
  Target Milestone: ---

Created attachment 59338
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59338&action=edit
Also try with custom header

Hi team,

If I #define with any macro which is also available in the header files, then
the header file data is also getting changed/corrupted. I was not expecting the
header file content to be modified since the header file is either from std lib
or user-defined lib.

Please check into this issue.
If required I can explain with further Images/explanations.

Regards,
Akhil