weyl-pkgs — The Debuggable Universe

Every package. Every library. Every time.

RelWithDebInfo for the entire dependency closure.

No more black boxes.

Philosophy

Stock compilers. Stock C++ versions. Stock build systems.

Just the posture:

-O2                           # optimize for real
-g3 -gdwarf-5                 # symbols everywhere
-fno-omit-frame-pointer       # stack traces work
-fno-limit-debug-info         # don't truncate
hardeningDisable = [ "all" ]  # no theater
dontStrip = true              # never strip

Two Worlds

pkgs.ffmpeg        # their way
weyl-pkgs.ffmpeg   # our way

Both exist. Use whichever you need.

Build System Integration

CMake

CMAKE_BUILD_TYPE=RelWithDebInfo
CMAKE_C_FLAGS_RELWITHDEBINFO=-O2 -g3 -gdwarf-5 -DNDEBUG
CMAKE_CXX_FLAGS_RELWITHDEBINFO=-O2 -g3 -gdwarf-5 -DNDEBUG

Meson

--buildtype=debugoptimized
-Db_ndebug=true
-Ddebug=true
-Doptimization=2

Autotools

NIX_CFLAGS_COMPILE applies to everything.

Usage

In a Flake

{
  inputs.weyl-std.url = "github:weyl-ai/weyl-std";

  outputs = { self, nixpkgs, weyl-std, ... }: {
    perSystem = { system, ... }:
      let
        pkgs = import nixpkgs {
          inherit system;
          overlays = [ weyl-std.overlays.default ];
        };

        # The debuggable universe
        weyl-pkgs = import nixpkgs {
          inherit system;
          overlays = [ weyl-std.overlays.posture ];
        };
      in {
        devShells.default = pkgs.mkShell {
          packages = [
            # Your code: weyl-stdenv (clang, C++23)
            (pkgs.weyl-stdenv.mkDerivation { ... })

            # Dependencies: debuggable
            weyl-pkgs.ffmpeg
            weyl-pkgs.opencv
            weyl-pkgs.boost
          ];
        };
      };
  };
}

Debug a Crash in a Dependency

# Build with weyl-pkgs
nix build .#weyl-pkgs.ffmpeg

# Now gdb works
gdb --args ./result/bin/ffmpeg -i input.mp4 output.mkv

(gdb) bt
#0  av_frame_alloc () at libavutil/frame.c:234
#1  0x00007ffff7a12345 in decode_video () at libavcodec/decode.c:456
...

# Symbols. Line numbers. The works.

Verify the Posture

# Check a package was built with posture
nix eval '.#weyl-pkgs.ffmpeg.passthru.weyl-posture'
# => true

# Check symbols present
nm $(nix build .#weyl-pkgs.ffmpeg --print-out-paths)/lib/libavcodec.so | head

# Check not stripped
file $(nix build .#weyl-pkgs.ffmpeg --print-out-paths)/lib/libavcodec.so
# => ... not stripped

What Changes

Aspect	Stock nixpkgs	weyl-pkgs
Optimization	Varies	Always O2
Debug info	Usually none	Always g3 + DWARF5
Frame pointers	Usually omitted	Always kept
Hardening	Enabled	Disabled
Strip	Usually yes	Never
NDEBUG	Varies	Defined (asserts off)

What Doesn’t Change

Compiler (gcc/clang version)
C/C++ standard
Build system
Source code
Dependencies

Same packages. Same versions. Just debuggable.

The Fixed Point

Both pkgs and weyl-pkgs are complete nixpkgs instances.

The overlay propagates through every package, every dependency, every transitive closure.

weyl-pkgs.python311Packages.numpy
  → numpy built with posture
    → openblas built with posture
      → gfortran runtime built with posture
        → ...

All the way down.

When to Use

Use pkgs.* when:

Matching upstream builds for reproducibility
Binary cache hits matter (weyl-pkgs rebuilds everything)
Production deployment (hardening actually wanted)

Use weyl-pkgs.* when:

Debugging crashes in dependencies
Profiling (frame pointers required)
Understanding what the code actually does
Development

pkg-config Generation

Libraries without .pc files get them auto-generated:

ls $(nix build .#weyl-pkgs.somelib --print-out-paths)/lib/pkgconfig/
# => somelib.pc (auto-generated if missing)

Introspection

# View posture info
nix eval .#weyl-pkgs-info --json | jq

{
  "version": "1.0.0",
  "posture": "RelWithDebInfo",
  "optimization": "O2",
  "debug": "g3 + DWARF5",
  "frame-pointers": "always",
  "hardening": "disabled",
  "strip": "never"
}