[Bug c/118820] New: [12/13/14/15 Regression] preprocessor output with #pragma inside a #pragma is incorrect

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118820

            Bug ID: 118820
           Summary: [12/13/14/15 Regression] preprocessor output with
                    #pragma inside a #pragma is incorrect
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
```
#pragma redefine_extname _Pragma ("pack(bar)")
```

When using -E we get:
```
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 0 "<command-line>" 2
# 1 "/app/example.cpp"
#pragma redefine_extname
# 1 "/app/example.cpp"
#pragma pack(bar)
# 1 "/app/example.cpp"
```

Which is wrong. The _Pragma should be spelled that way and on the same line as
the first #pragma.