Always use 0 for offsets of lib / extern union members

[HertzDevil]

Fixes #9744. See #13205 (comment). Removes the workaround in #7335.

pointerof doesn't have the same issue. Also it seems interpreter specs were broken for a while and fixed here, but I am not 100% sure.

@will @biqqles @zhangkaizhao If possible, please check whether this PR affects #13205, #12589, and #11934 (comment) respectively

[HertzDevil]

It seems the requirement for current_debug_file was dropped in LLVM 13: llvm/llvm-project@ad60802

[will]

This does look like it fixes it. I think? I wasn't able to easily get ahold of llvm 10.0.0 (the version the darwin-universal has) to try, and it seems like llvm 10.0.1 also fixes it. So it's a little unsatisfying to not be able to build with 10.0.0 to fully verify.

bash-3.2$ ~/Downloads/crystal-1.7.3-1/bin/crystal version
Crystal 1.7.3 [d61a01e18] (2023-03-07)

LLVM: 10.0.0
Default target: aarch64-apple-darwin
bash-3.2$ ~/Downloads/crystal-1.7.3-1/bin/crystal build --debug test.cr
Assertion failed: (Idx < NumElements && "Invalid element idx!"), function getElementOffset, file /var/cache/omnibus/src/llvm/llvm-10.0.0.src/include/llvm/IR/DataLayout.h, line 608.
/Users/will/Downloads/crystal-1.7.3-1/bin/crystal: line 102: 51671 Abort trap: 6           "$INSTALL_DIR/embedded/bin/crystal" "$@"

bash-3.2$ nix run .#crystal_173_llvm10 -- version
Crystal 1.7.3 [d61a01] (1970-01-01)

LLVM: 10.0.1
Default target: aarch64-apple-darwin
bash-3.2$ nix run .#crystal_173_llvm10 -- build --debug test.cr

bash-3.2$ nix run .#crystal_patch_llvm10 -- version
Crystal 1.8.0-dev [da38e4] (1970-01-01)

LLVM: 10.0.1
Default target: aarch64-apple-darwin
bash-3.2$ nix run .#crystal_patch_llvm10 -- build --debug test.cr

bash-3.2$ nix run .#crystal_patch_llvm15 -- version
Crystal 1.8.0-dev [da38e4] (1970-01-01)

LLVM: 15.0.7
Default target: aarch64-apple-darwin
bash-3.2$ nix run .#crystal_patch_llvm15 -- build --debug test.cr
bash-3.2$ nix shell .#crystal_patch_llvm10

test.cr is from your comment on my bug report

lib Foo
  union Bar
    x : Int32
    y : Int16
    z : Int8
  end
end

offsetof(Foo::Bar, @x) # => 0
offsetof(Foo::Bar, @y) # => 110689
offsetof(Foo::Bar, @z)

but it behaves the same as the crunchydata/bridge-cli project with respect to 10.0.1 also seeming to fix the issue, and only failing with the pre-compiled release on github.

flake I used to try all the llvm versions and patches

{
  inputs = {
    flake-utils.url = "github:numtide/flake-utils";

    nixpkgs-crystal = {
      url = "github:will/nixpkgs-crystal";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  description = "crystal tests";

  outputs = { self, nixpkgs, nixpkgs-crystal, flake-utils }:
    let
      systems = (builtins.attrNames nixpkgs-crystal.outputs.packages);
    in
    flake-utils.lib.eachSystem systems (system:
      let
        pkgs = nixpkgs.legacyPackages.${system};

        base = nixpkgs-crystal.packages.${system}.crystal;
        release_src = pkgs.fetchFromGitHub {
          owner = "crystal-lang";
          repo = "crystal";
          rev = "d61a01e185baf84046efce50832a97f097ba0a2f";
          hash = "sha256-ULhLGHRIZbsKhaMvNhc+W74BwNgfEjHcMnVNApWY+EE=";
        };
        patch_src = pkgs.fetchFromGitHub {
          owner = "HertzDevil";
          repo = "crystal";
          rev = "da38e42a66df7bbc2e6e5a6265f4c1f9cf3f2980";
          hash = "sha256-q4nr8qMMRDxJyJ6eURdcIsRi5dsj6ZQ18V4eXMjrr0U=";
        };

      in
      {
        packages = {
          crystal_173_llvm10 = base.override {
            llvm = pkgs.llvm_10;
            src = release_src;
          };

          crystal_patch_llvm10 = base.override {
            llvm = pkgs.llvm_10;
            src = patch_src;
          };

          crystal_patch_llvm15 = base.override {
            llvm = pkgs.llvm_15;
            src = patch_src;
          };
        };
      }
    );
}

[HertzDevil]

In that case your 10.0.1 might have had assertions disabled

[biqqles]

Thanks for the ping, this looks very promising!

Unfortunately I can't test properly for Solus as since compiling that branch (the latest release 1.7.3 works fine) results in the bundled libs not being found?

x86_64-solus-linux-g++ -c -mtune=generic -march=x86-64 -g2 -O2 -pipe -fPIC -fno-plt -D_FORTIFY_SOURCE=2 -fstack-protector-strong --param=ssp-buffer-size=32 -fasynchronous-unwind-tables -ftree-vectorize -feliminate-unused-debug-types -Wall -Wno-error -Wp,-D_REENTRANT  -o src/llvm/ext/llvm_ext.o src/llvm/ext/llvm_ext.cc -I/usr/include -std=c++14   -fno-exceptions -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS
CRYSTAL_CONFIG_BUILD_COMMIT="72a7a7da0" CRYSTAL_CONFIG_PATH=lib:/usr/lib64/crystal/src SOURCE_DATE_EPOCH="1681393377"  CRYSTAL_CONFIG_LIBRARY_PATH='$ORIGIN/../lib/crystal' ./bin/crystal build -D strict_multi_assign -D preview_overload_order --release --link-flags="-Wl,--copy-dt-needed-entries -Wl,-O1 -Wl,-z,relro -Wl,-z,now -Wl,-z,max-page-size=0x1000 -Wl,-Bsymbolic-functions -Wl,--sort-common" -Dwithout_interpreter  -o .build/crystal src/compiler/crystal.cr -D without_openssl -D without_zlib -D use_pcre2
Showing last frame. Use --error-trace for full trace.

In src/compiler/crystal/tools/doc/generator.cr:1:1

 1 | require "markd"
     ^
Error: can't find file 'markd'

If you're trying to require a shard:
- Did you remember to run `shards install`?
- Did you make sure you're running the compiler in the same directory as your shard.yml?
make: *** [Makefile:213: .build/crystal] Error 1

reply also cannot be found if I try to build with interpreter support. I can see that libs/ is populated properly via treeing it so no idea why this is suddenly happening after 1.7.3. Can bisect later if necessary.

[HertzDevil]

Does $(./bin/crystal env CRYSTAL_PATH) include the lib directory in this repository? Also apparently this was due to #13040

[biqqles]

Awesome, thank you for saving me some time, adding the lib to CRYSTAL_PATH indeed resolved it.

So the compiler specs are fixed! But unfortunately the interpreter is still not usable ☹️

$ crystal i
Crystal interpreter 1.8.0-dev [72a7a7da0] (2023-04-13).
EXPERIMENTAL SOFTWARE: if you find a bug, please consider opening an issue in
https://github.com/crystal-lang/crystal/issues/new/
crystal: /home/build/YPKG/root/llvm/build/llvm-project-14.0.6.src/llvm/include/llvm/Support/Casting.h:269: typename cast_retty<X, Y *>::ret_type llvm::cast(Y *) [X = llvm::StructType, Y = llvm::Type]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.
Aborted (core dumped)

(This is a different assertion error to, I am assuming, what this PR fixes.)

[biqqles]

@HertzDevil or @straight-shoota -- do I need to open an issue for the interpreter assertion failure or should I refocus my original report?

[straight-shoota]

This interpreter issue is tracked in #13317