Fortitude

A Fortran linter, inspired by (and built upon) Ruff. Written in Rust 🦀 and installable with Python 🐍.

Linting 72 files from the GS2 repo.

• ⚡ Blazingly fast, up to hundreds of times faster than other open-source Fortran linters.
• 🔧 Automatically fixes linter warnings.
• 📈 Over 100 rules, with many more planned.
• 📃 Multiple output formats, including SARIF and GitHub/GitLab CI.
• 🤝 Follows community best practices.
• 💪 Built on a robust tree-sitter parser.

Fortitude is developed by PlasmaFAIR, improving the sustainability of plasma science research software.

Table of Contents

For more detail, please see our documentation.

• Installation
• Usage
• Contributing
• License

Installation

Fortitude is available as fortitude-lint on PyPI:

# With uv:
uv tool install fortitude-lint@latest

# With pip:
pip install fortitude-lint

Starting with version 0.7.0, Fortitude can be installed with our standalone installers:

# On macOS and Linux:
curl -LsSf https://github.com/PlasmaFAIR/fortitude/releases/latest/download/fortitude-installer.sh | sh

# On Windows:
powershell -c "irm https://github.com/PlasmaFAIR/fortitude/releases/latest/download/fortitude-installer.psi | iex"

It can also be installed as a pure Rust project:

git clone https://github.com/PlasmaFAIR/fortitude
cd fortitude
cargo install --path crates/fortitude

Fortitude can also be installed via other package managers

Usage

Fortitude can lint your whole project under the working directory using the check command:

fortitude check

You can also call check on individual files, globs, and directories. You can configure what extensions Fortitude searches for in directories with --file-extensions:

fortitude check --file-extensions=f90,fpp

By default, Fortitude will ignore files and directories in your .gitignore. This can be disabled by setting --no-respect-gitignore. Additional excludes can be set using --extend-exclude:

# Don't check in the `benchmarks/` and `tests/` directories.
fortitude check --extend-exclude=benchmarks,tests

You can select or ignore individual rules or whole groups with --select and --ignore:

# Just check for missing `implicit none`
fortitude check --select=C001
# Also check for missing `implicit none` in interfaces
fortitude check --select=C001,C002
# Ignore all styling rules
fortitude check --ignore=S
# Only check for style rules, but ignore superfluous implicit none
fortitude check --select=S --ignore=S201
# Rules and categories can also be referred to by name
fortitude check --select=style --ignore=superfluous-implicit-none

Use --output-format=concise to get shorter output:

$ fortitude check --output-format=concise
test.f90:2:1: C111 function not contained within (sub)module or program
test.f90:5:1: S061 end statement should read 'end function double'
test.f90:7:1: C111 subroutine not contained within (sub)module or program
test.f90:8:3: C022 real has implicit kind

Use -o (or --output-file) to write the output to a file instead of printing it to the terminal. This can be combined with any --output-format:

# Write a concise report to `report.txt`
fortitude check --output-format=concise -o report.txt
# Write a SARIF report, for example to upload to GitHub code scanning
fortitude check --output-format=sarif --output-file=fortitude.sarif

The explain command can be used to get extra information about any rules:

# Print extra information for all rules
fortitude explain
# Only get information for selected rules
fortitude explain C001 C011
# Print information on all style rules
fortitude explain S
# Rules and categories can also be referred to by name
fortitude explain obsolescent superfluous-implicit-none

Use --summary to get a brief overview:

# Overview of all rules
fortitude explain --summary
# Overview of all style rules
fortitude explain style --summary

To see further commands and optional arguments, try using --help:

fortitude --help
fortitude check --help

Fixes

Fortitude can automatically fix some lint warnings, such as unnecessary implicit none statements, missing double-colons in variable declarations, and more. Just pass the --fix flag to check:

$ fortitude check --fix
fortitude: 1 files scanned.
Number of errors: 2 (2 fixed, 0 remaining)

Add --show-fixes to list each fix that was applied, grouped by file and rule:

$ fortitude check --fix --show-fixes
Fixed 1 error:
- test.f90:
    1 × S071 (missing-double-colon)

fortitude: 1 files scanned.
Number of diagnostics: 1 (1 fixed, 0 remaining)

Run fortitude explain to see which rules have fixes available.

Preview

Some fortitude rules are only available through an opt-in preview mode to give the community some time to evaluate them and provide feedback. To enable preview rules, pass the --preview flag to check,

$ fortitude check --preview

or to enable more permanently, set it in your fpm.toml:

[extra.fortitude.check]
preview = true

or fortitude.toml:

[check]
preview = true

Run fortitude explain to see which rules are in preview mode.

Configuration

Fortitude will look for either a fortitude.toml, .fortitude.toml, fpm.toml, or pyproject.toml file in the current directory, or one of its parents. If using fortitude.toml or .fortitude.toml, settings should be under the command name:

[check]
select = ["C", "E", "S"]
ignore = ["S001", "S082"]
line-length = 132
preview = true

For fpm.toml files, this has to be additionally nested under the extra.fortitude table:

[extra.fortitude.check]
select = ["C", "E", "S"]
ignore = ["S001", "S082"]
line-length = 132
preview = true

while pyproject.toml uses the tool.fortitude table:

[tool.fortitude.check]
select = ["C", "E", "S"]
ignore = ["S001", "S082"]
line-length = 132
preview = true

You can use --extend-select from the command line to select additional rules on top of those in the configuration file.

# Select correctness, error, style and obsolescent categories
fortitude check --extend-select=OB

A description of configuration options can be viewed using the config command:

# View all options under the 'check' heading
fortitude config check
# Get description of the 'extend-select' option
fortitude config check.extend-select

Editor Integration

Fortitude can be integrated into text editors and IDEs that support the Language Server Protocol (LSP), providing real-time diagnostics and code actions for applying fixes as you work.

Please see the documentation for details on setting this up for your editor.

We also have a VSCode plugin!.

pre-commit

Pre-commit hooks for Fortitude are available at fortitude-pre-commit.

Documentation

See table of rules for a list of all rules.

Contributing

Please feel free to add or suggest new rules and features! See CONTRIBUTING.md for a guide on contributing to the project. This also includes instructions for building the project from source, running tests, and linting/formatting the code. Please consult our code of conduct before contributing.

Projects Using Fortitude

More and more open-source Fortran projects are using Fortitude to help maintain their code, including:

• ADCIRC
• cp2k
• flexi
• FTorch
• MESA
• OpenFMS
• The Met Office

Show Your Support

If you've found Fortitude useful in your project, please consider adding the Fortitude badge to your README.md:

[![Fortitude](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/PlasmaFAIR/fortitude/main/docs/assets/badge/v0.json)](https://github.com/PlasmaFAIR/fortitude)

or README.rst:

.. image:: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/PlasmaFAIR/fortitude/main/docs/assets/badge/v0.json
    :target: https://github.com/PlasmaFAIR/fortitude
    :alt: Fortitude

or, as HTML:

<a href="https://github.com/PlasmaFAIR/fortitude"><img src="https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/PlasmaFAIR/fortitude/main/docs/assets/badge/v0.json" alt="Fortitude" style="max-width:100%;"></a>

License

This work is distributed under the MIT License. See LICENSE for more information.

Fortitude is inspired by, and uses parts from ruff, used under the MIT licence. See LICENSE for more information.