Installation

Requirements

• Bazel 7.0+
• Bzlmod enabled (default in Bazel 7+)

Setup

Add to your MODULE.bazel:

bazel_dep(name = "rules_fortran")
git_override(
    module_name = "rules_fortran",
    remote = "https://github.com/miinso/rules_fortran.git",
    commit = "76c948c52ee3a735eb4670da885ef3907281c952",
)

The Flang toolchain registers automatically. No additional setup required.

Flang Toolchain

rules_fortran downloads prebuilt LLVM Flang binaries from miinso/flang-releases. It does not use any system-installed Fortran compiler. No apt install gfortran, no "works on my machine."

Supported Platforms

Host	Target
Linux x86_64	x86_64-unknown-linux-gnu
Linux ARM64	aarch64-unknown-linux-gnu
macOS x86_64	x86_64-apple-darwin
macOS ARM64	arm64-apple-darwin
Windows x86_64	x86_64-pc-windows-msvc

WebAssembly Cross-Compilation

All host platforms can cross-compile to wasm32-unknown-emscripten.

Each Flang release includes libflang_rt.runtime.wasm32.a, the Fortran runtime library compiled for WebAssembly. Combined with emsdk, you can compile Fortran code to run in browsers or Node.js.

See the WebAssembly example for details.

WORKSPACE

Not supported. Use Bzlmod.