Re: BUG #18995: Building with GCC 14 fails: incompatible pointer struct pam_message

PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> First, PostgreSQL 17.5 with GCC v13 builds cleaning and runs on Solaris
> 11.4, but building with GCC v14 I get the following:

> gcc -m64 -Wall -Wmissing-prototypes -Wpointer-arith
> -Wdeclaration-after-statement -Werror=vla -Wendif-labels
> -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type
> -Wshadow=compatible-local -Wformat-security -fno-strict-aliasing -fwrapv
> -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation
> -O2 -I../../../src/include -D_POSIX_PTHREAD_SEMANTICS
> -I/usr/include/libxml2 -c -o auth.o auth.c
> auth.c:101:9: error: initialization of 'int (*)(int, struct pam_message **,
> struct pam_response **, void *)' from incompatible pointer type 'int
> (*)(int, const struct pam_message **, struct pam_response **, void *)'
> [-Wincompatible-pointer-types]
> 101 | &pam_passwd_conv_proc,
> | ^
> auth.c:101:9: note: (near initialization for 'pam_passw_conv.conv')

This doesn't look like a GCC version problem, but like a discrepancy
in the PAM header files, to wit, "const" or not in the expected
signature of pam_passwd_conv_proc. Can you verify whether or not
pam_appl.h and its subsidiary headers changed?

On my Linux box I find this in /usr/include/security/_pam_types.h:

struct pam_conv {
int (*conv)(int num_msg, const struct pam_message **msg,
struct pam_response **resp, void *appdata_ptr);
void *appdata_ptr;
};

but it seems that "const" is missing in yours. I guess an alternative
theory is that it was inconsistent all along but you hadn't previously
tried to build --with-pam.

regards, tom lane