theiphoneos1project/ld64-build

Purpose and Entry Point

This repository is a macOS build wrapper for producing a patched ld64 linker binary, ld64-objc1, with fragile Objective-C runtime support. Its operational entry point is build.sh; the repository intentionally contains only orchestration and source patches, not vendored third-party code.

Paths: build.sh, README.md

Build Orchestration

build.sh is the primary control plane. It runs interactively by default and supports automation through --non-interactive. It fetches required upstream dependencies at build time, applies this repository’s patches, and compiles the resulting linker with the active Xcode toolchain.

The script’s environment is macOS 12+ with Xcode 14+ and C++20 support. Output architecture depends on Xcode generation: older toolchains can produce universal x86_64/arm64 output, while Xcode 26+ produces arm64.

Paths: build.sh, .github/workflows/build.yml

Upstream Source Boundary

No third-party source is committed here. The build process crosses a deliberate boundary from repository-owned scripts/patches into externally fetched ld64 and related dependency sources. Reproducibility therefore depends on the fetch behavior encoded in build.sh and on availability/compatibility of upstream repositories and the installed Xcode SDK.

Paths: build.sh, README.md

Patch Layer

The Patches/ directory defines the product’s differentiating behavior: adapting ld64 to support fragile Objective-C runtime handling. Patches target linker option processing, output-file generation, LTO integration, Mach-O relocatable-file processing, and Apple dynamic-loader private declarations.

Key patch surface:

• Linker option and mode behavior: Patches/Options.cpp.patch

• Output binary/linker behavior: Patches/OutputFile.cpp.patch

• LTO file handling: Patches/lto_file.cpp.patch

• Mach-O relocatable-object handling: Patches/macho_relocatable_file.cpp.patch

• dyld-private API compatibility: Patches/dyld_priv.h.patch

• Version metadata changes: Patches/Version.inc

Produced Artifact and Runtime Boundary

The build produces ld64-objc1, a linker executable rather than a standalone application. The binary is dynamically coupled to Xcode-provided libraries, specifically libtapi.dylib and libswiftDemangle.dylib. It will fail at launch unless those libraries are reachable through its runtime loader paths.

Deployment is therefore separate from compilation: users should install the executable beside a lib/ directory containing copies of the required dylibs, or place it in an existing Xcode-compatible toolchain.

Paths: README.md, build.sh

CI and Validation Infrastructure

GitHub Actions provides the repository’s automated build environment. The workflow is the main infrastructure contract for verifying that the script, patch set, and supported macOS/Xcode environment remain compatible.

Paths: .github/workflows/build.yml, build.sh

Ownership and Licensing

Repository-owned orchestration and patches are MIT-licensed. Upstream ld64 and fetched dependencies remain under their own licenses, reinforcing the separation between this build layer and externally sourced compiler/linker code.

Paths: LICENSE, Patches/, README.md