Exim-4.99 and Ubuntu 25.10

Sorry, I've just updated to Ubuntu 25.10 so didn't see this before.

I think this is a compiler problem; just reporting here for the benefit
of other Ubuntu (and possibly Debian) users who roll their own Exim.

# gcc -Werror -Wall -Wextra -Wimplicit-function-declaration -Wimplicit-int
   -Wincompatible-pointer-types -Wno-parentheses -Wno-dangling-else
   -Wno-unused-function -Wno-unused-result -Wno-address -Wno-format
   -Wno-format-truncation -Wno-format-extra-args
   -Wno-unused-but-set-variable
   -Wno-unused-variable -Wno-maybe-uninitialized
   -Wno-misleading-indentation
   -Wno-sign-compare -Wno-old-style-declaration -Wno-unused-parameter
   -Wno-empty-body -Wno-missing-field-initializers
   -Wno-implicit-fallthrough
   -c -O -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -I/usr/local/include/
   -I. rda.c
In file included from /usr/include/features.h:523,
                  from os.h:12,
                  from exim.h:38,
                  from rda.c:15:
In function ‘read’,
     inlined from ‘rda_read_string’ at rda.c:493:7:
/usr/include/x86_64-linux-gnu/bits/unistd.h:32:10: error: ‘__read_alias’
   specified size 18446744073709551615 exceeds maximum object size
   9223372036854775807 [-Werror=stringop-overflow=]
    32 |   return __glibc_fortify (read, __nbytes, sizeof (char),
       |          ^~~~~~~~~~~~~~~
/usr/include/x86_64-linux-gnu/bits/unistd-decl.h: In function
   ‘rda_read_string’:
/usr/include/x86_64-linux-gnu/bits/unistd-decl.h:29:16: note: in a call to
   function ‘__read_alias’ declared with attribute access (write_only, 2, 3)’
    29 | extern ssize_t __REDIRECT_FORTIFY (__read_alias, (int __fd,
      void *__buf,
       |                ^~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

No problem building with clang-22 or the gcc-snapshot compiler
- but `apt show gcc-snapshot` says:
    DO NOT USE THIS SNAPSHOT FOR BUILDING DEBIAN PACKAGES!

[ 18446744073709551615 = 2^64 -1 and 9223372036854775807 = 2^63 -1
   so I suspect a long / unsigned long issue somewhere in the
   compiler libraries.
]

-- 
Andrew C. Aitchison                      Kendal, UK
                    [email protected]

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