toolchain/59440: tools build failures with gcc 15.1

[bad%bsd.de@localhost]

>Number:         59440
>Category:       toolchain
>Synopsis:       tools build failures with gcc 15.1
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 23 08:55:00 +0000 2025
>Originator:     Christoph Badura
>Release:        10.99.14 2025-05-20
>Organization:
The Conflicting Prototypes Foundation
>Environment:
Manjaro Linux, amd64, gcc 15.1
>Description:
Tools build errors reported by Vasyl Maksym Lanko so far:

In file included from /home/maksym/netbsd-gsoc/src/tools/texinfo/../../external/gpl2/texinfo/dist/lib/substring.c:22:
/home/maksym/netbsd-gsoc/src/tools/texinfo/../../external/gpl2/texinfo/dist/lib/system.h:123:12: error: conflicting types for 'strcasecmp'; have 'int(void)'
  123 | extern int strcasecmp ();
      |            ^~~~~~~~~~
In file included from /usr/include/string.h:462,
                 from /home/maksym/netbsd-gsoc/src/tools/texinfo/../../external/gpl2/texinfo/dist/lib/system.h:76:
/usr/include/strings.h:116:12: note: previous declaration of 'strcasecmp' with type 'int(const char *, const char *)'
  116 | extern int strcasecmp (const char *__s1, const char *__s2)
      |            ^~~~~~~~~~
/home/maksym/netbsd-gsoc/src/tools/texinfo/../../external/gpl2/texinfo/dist/lib/system.h:127:12: error: conflicting types for 'strncasecmp'; have 'int(void)'
  127 | extern int strncasecmp ();
      |            ^~~~~~~~~~~
/usr/include/strings.h:120:12: note: previous declaration of 'strncasecmp' with type 'int(const char *, const char *, long unsigned int)'
  120 | extern int strncasecmp (const char *__s1, const char *__s2, size_t __n)
      |            ^~~~~~~~~~~

*** Failed target: substring.o

And:

/home/maksym/netbsd-gsoc/src/tools/texinfo/../../external/gpl2/texinfo/dist/lib/mkstemp.c:43:10: error: too many arguments to function '__gen_tempname'; expected     0, have 2

I have warning about the same in the logs from my builds on macOS from clang.  Apparently gcc 15.1 makes these conflicts an error now.

>How-To-Repeat:
On Manjaro Linux with gcc 15.1: build.sh -m amd64 tools

>Fix:
For the first error: texinfo/dist/lib/system.h enables the prototypeless declaration because configure never checks for the declarations of strcasecmp and strncasecmp and therefore the relevant #defines aren't in config.h.

For the second error: texinfo/dist/lib/mkstemp.c has an unconditional prototypeless declaration for __gen_tempname.