unmake: a makefile linter

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ABOUT

unmake is a makefile linter emphasizing portability. We target the POSIX make standard.

With unmake, you can develop practical, portable makefile scripts, such as for provisioning dev environments.

No need for more heavyweight tools like Ansible, Docker, Lua, Python, or WSL! Just good ol' make.

EXAMPLES

$ cd fixtures/parse-valid

$ unmake .
warning: ./Makefile: MAKEFILE_PRECEDENCE: lowercase Makefile to makefile for launch speed
warning: ./boilerplate-ats.mk:4: SIMPLIFY_AT: replace individual at (@) signs with .SILENT target declaration(s)
warning: ./missing-posix.mk:1: STRICT_POSIX: lead makefiles with the ".POSIX:" compliance marker, or else rename include files like *.include.mk
...

See unmake -h for more options.

See makefile for a live example of a portable dev environment provisioning script for this Rust project.

NOTABLE FEATURES

unmake applies a stricter reading of POSIX syntax than make -n. Whereas make -n may skip inactive sections depending on control flow, unmake scans each line. For example, make -n may only check instructions specific to building the default task.

In fact, the two checks complement each other. make -n checks for dry-run runtime issues. unmake checks for syntactic portability issues.

Directory recursion

unmake automatically recurses over directories.

When recursing over directories, unmake skips symlinks.

unmake's linter rules skip many implementation-specific files such as GNUmakefile.

unmake skips many machine-generated makefiles. For example, makefiles produced by autotools; Perl; and cmake when using the Unix Makefile generator (both in-source builds and out-of-source builds).

unmake skips any third party makefiles housed in subdirectories like .git, node_modules, or vendor.

To investigate makefiles in more detail, see the --debug or --inspect command line options for unmake.

PARSE ERRORS

unmake can identify low level makefile quirks, such as invalid syntax.

See SYNTAX.md for more information.

DRY RUN INTEGRITY CHECK

-n / --dry-run performs passthrough dry run validation with external make implementation tools, e.g. bmake -nf, gmake -nf, make -nf, etc.

Per POSIX, rule commands prefixed with plus (+) may continue to execute in dry run mode.

A few benefits of unmake dry run checks:

• Catch POSIX make superset parse errors (e.g. GNU and BSD)
• Catch semantic errors, such as missing target definitions
• Automatically skip common machine generated makefiles from cmake, Perl, etc.
• Less fuss than manual find \ xargs snippets
• Reduce log noise

The unmake dry run option aggressively assumes that most makefiles are buildable, top level project configurations, as opposed to make include files named like include.mk, *.include.mk, etc.

LIST MAKEFILES

-l / --list emits paths of any matching makefiles that unmake finds in the given file paths.

This is useful for feeding large make projects into external linters. Unfortunately, many linters are poorly designed, lacking directory recursion and automatic file type identification. As a stopgap, unmake can perform these duties, exporting a subset of makefiles within a large project, through xargs, to an external linter.

Like dry run, the list option automatically skips common machine generated makefiles.

When piping unmake makefile lists through xargs, we recommend adding a --print0 flag to unmake, and adding a -0 flag to xargs. This informs both programs to transfer data in null delimited form, as a precaution against errors related to any spaces in file paths.

WARNINGS

unmake can identify higher level portability recommendations for makefiles.

See WARNINGS.md for more information.

CRATE

https://crates.io/crates/unmake

API DOCUMENTATION

https://docs.rs/unmake/latest/unmake/

DOWNLOAD

https://github.com/mcandre/unmake/releases

INSTALL FROM SOURCE

$ cargo install --force --path .

RUNTIME REQUIREMENTS

(None)

Recommended

• GNU or BSD findutils
• POSIX compatible make

CONTRIBUTING

For more details on developing crit itself, see DEVELOPMENT.md.

LICENSE

BSD-2-Clause

MORE EXAMPLES

Some projects using unmake to safeguard their makefiles:

• buttery, a GIF looper
• crit, a Rust cross-compiler
• factorio, a Go cross-compiler
• octane, a MIDI forwarder
• slick, a POSIX sh syntax validator

SEE ALSO

• BSD make, a popular make implementation with BSD extensions
• cmake, a make-adjacent build system with its own portability features
• GNU make, a popular make implementation with GNU extensions
• Grunt, Node.js task runners
• invoke, a task runner for Python projects
• lake, a task runner for Lua projects
• mage, a task runner for Go projects
• ninja, a fast build system without conditionals
• nmake, a make-adjacent build system for .NET projects
• Rake, a task runner for Ruby projects
• Shake, a task runner for Haskell projects
• ShellCheck, a linter for POSIX sh family shell scripts
• slick, a POSIX sh syntax validator
• tinyrick, a task runner for Rust projects