dante: fix build with clang 16

[reckenrode]

Description of changes

Fix two configure checks that fail on clang 16 due to unexpected errors:

• Undefined type uint8_t by including stdint.h; and
• Unused sa_len_ptr by incrementing the target of the pointer.

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/)
• 23.11 Release Notes (or backporting 23.05 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.

[Shados]

How are you building this against clang 16? I can successfully build pkgs.dante.override { stdenv = pkgs.clang16Stdenv; } on the parent of your commit (b9e9e44) just fine. Is the build issue somehow Darwin-specific...?

[reckenrode]

How are you building this against clang 16? I can successfully build pkgs.dante.override { stdenv = pkgs.clang16Stdenv; } on the parent of your commit (b9e9e44) just fine. Is the build issue somehow Darwin-specific...?

I’m using staging after cad1b25 was merged, updating the default LLVM to 16. The configure test fails on Darwin with the following error (from config.log):

configure:17243: checking for sa_len type
configure:17266: clang -c -g -O2 -pipe -Wall -Werror -DDEBUG=0 -D_FORTIFY_SOURCE=2 conftest.c >&5
conftest.c:88:10: error: variable 'sa_len_ptr' set but not used [-Werror,-Wunused-but-set-variable]
uint8_t *sa_len_ptr;
         ^
1 error generated.

 ...

configure:17266: clang -c -g -O2 -pipe -Wall -Werror -DDEBUG=0 -D_FORTIFY_SOURCE=2 conftest.c >&5
conftest.c:88:16: error: variable 'sa_len_ptr' set but not used [-Werror,-Wunused-but-set-variable]
unsigned char *sa_len_ptr;
               ^
1 error generated.

[toonn]

On b9e9e44 I do get a reproducable failure when trying to build dante.override { inherit (llvmPackages_16) stdenv; }:

checking for sa_len type... no
configure: WARNING: unable to obtain sa_len type, exiting
error: builder for '/nix/store/h9vpcpw4a6pb74hcv1dk5y17z9jy1877-dante-1.4.3.drv' failed with exit code 1;

With this PR it's fixed both with and without stdenv override.