xbill, motif: fix clang build

[paparodeo]

needs backport release-24.05 tag

Description of changes

motif:
ignore benign clang errors implicit-function-declaration and incompatible-function-pointer-types

xbill depends on motif but was also broken with clang is fixed as well:
ignore implicit-function-declaration errors and regenerate autotools files so configure test programs compile with clang

https://hydra.nixos.org/build/260342733
ZHF: #309482

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[paparodeo]

Result of nixpkgs-review pr 314766 run on x86_64-darwin 1

1 package marked as broken and skipped:

• cernlib

5 packages built:

• catclock
• motif
• nedit
• snd
• xbill

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Result of nixpkgs-review pr 314766 run on x86_64-linux 1

1 package built:

• xbill

[alyssais]

Are you sure they're benign? My understanding is that they'll only be benign if all implicitly declared functions return int, and take int for all arguments (or at least an equally sized type). (There's a reason Clang has made this an error by default.)

The right way to fix this would be to make sure there aren't any implicitly defined functions. I did that for Linux in #302635, but apparently it still needs some work for macOS.

[paparodeo]

Are you sure they're benign? My understanding is that they'll only be benign if all implicitly declared functions return int, and take int for all arguments (or at least an equally sized type). (There's a reason Clang has made this an error by default.)

The right way to fix this would be to make sure there aren't any implicitly defined functions. I did that for Linux in #302635, but apparently it still needs some work for macOS.

i did build on linux with clangStdenv for motif and xbill and implicit functions are usually due to missing the string.h and the warning is also present when compiling with gcc so it doesn't seem like it is fixed on linux but has the same issue. so yes, i believe that the behaviour for gcc and clang is now identical, as they are both ignoring the error.

[edit] as for the the function definition i thought that the size of the arguments is inferred from the argument type and the return value is an int is also inferred. i'd have to verify as i've never personally written c code which relies on using implicit function definitions but promotions are similar to variadic args like printf https://en.cppreference.com/w/c/language/operator_other#Function_call

[paparodeo]

ah, i see that #302635 is still open. then closing this.