Install flang with Homebrew, apt, dnf, Nix

Project links

• Homepage
• Repository

Commands and aliases

• bbc
• f18-parse-demo
• fir-lsp-server
• fir-opt
• flang
• flang-22
• flang-new
• tco

Project history

LLVM Flang lives in the monorepo under `llvm-project/flang` and is documented by the Flang team. The documentation copyright spans 2017-2026 and the current docs describe an actively developed frontend that can generate executables for a number of examples while some functionality remains missing.

The compiler architecture is documented around analysis, lowering, and object-code generation/linking. Analysis creates a decorated parse tree and symbol table, lowering converts that information into FIR, a Fortran dialect of MLIR, and later passes produce LLVM IR for the existing LLVM code-generation pipeline.

Adoption history

Flang's adoption is tied to the LLVM toolchain rather than a standalone language ecosystem. It gives LLVM distributions, package managers, and compiler users a Fortran frontend that participates in LLVM's common infrastructure.

The official docs' distinction between LLVM Flang and Classic Flang matters for users and packagers because the name has referred to more than one Fortran compiler lineage.

How it is used

Users invoke `flang` as a compiler driver for Fortran source. The docs also show developer-oriented `-fc1` and `-mmlir` commands for dumping preprocessing output, parse trees, symbol tables, FIR, MLIR pass output, and LLVM IR.

No user credentials or persistent configuration file are documented in the supplied curation or the official Flang docs.

Why package nerds care

Flang is significant because it brings Fortran into the LLVM package universe, making Fortran compilation part of the same modular compiler stack used by Clang and other LLVM frontends.

For compiler-package curators, the key nerd detail is FIR: a Fortran-specific IR layered on MLIR before conversion to LLVM IR, exposing more of the compiler pipeline than a black-box Fortran driver.

Timeline

• 2017: Flang documentation copyright begins in the official docs.
• 2020s: LLVM Flang is documented as separate from Classic Flang and under active development.
• 2026: Current docs include Flang 23 in-progress release notes and updated compiler-phase documentation.

Related projects

• Classic Flang is the separate historical compiler explicitly distinguished by the docs.
• LLVM provides the broader compiler infrastructure and monorepo.
• MLIR and FIR are central to Flang lowering before LLVM IR generation.

Sources

• https://flang.llvm.org/docs
• https://flang.llvm.org/docs/Overview.html
• https://github.com/llvm/llvm-project