Editing Lint (software)

{{Short description|Tool to flag poor computer code}}
{{Infobox software 
| name                   = Lint
| logo                   = 
| screenshot             = 
| screenshot size        = 
| caption                = 
| author                 = [[Stephen C. Johnson]]
| developer              = [[AT&T Bell Laboratories]]
| released               = {{Release date and age|1978|07|26}}<ref name="BellLabs"/> 
| latest release version = 
| latest release date    = 
| operating system       = [[Cross-platform]]
| language = English
| genre                  = [[List of tools for static code analysis|Static program analysis tools]]
| license                = Originally [[Proprietary software|proprietary]] [[commercial software]], now [[free software]] under a [[BSD-license|BSD-like]] license<ref>{{cite web |url=http://www.lemis.com/grog/UNIX/|publisher=lemis.com |title=UNIX is free! |date=2002-01-24}}</ref><ref>{{cite web|url=http://www.tuhs.org/Archive/Caldera-license.pdf |archive-url=https://web.archive.org/web/20090219220353/http://www.tuhs.org/Archive/Caldera-license.pdf|archive-date=February 19, 2009 |title=Dear Unix enthusiasts |last=Broderick |first=Bill |date=January 23, 2002 |publisher=[[Caldera International]]}}</ref>
| website                = 
| programming language   = [[C (programming language)|C]]
}}
'''Lint''' is the [[computer science]] term for a [[Static program analysis|static code analysis]] tool used to flag programming errors, [[Software bug|bugs]], stylistic errors and suspicious constructs.<ref>{{cite web|url=http://www.sublimelinter.com/en/v3.10.10/about.html|title=About SublimeLinter|work=The SublimeLinter Community, revision 1cecc79c|archive-url=http://web.archive.org/web/20230606032819/http://www.sublimelinter.com/en/v3.10.10/about.html |access-date=2020-03-29|archive-date=2023-06-06 }}</ref> The term originates from a [[Unix]] [[List of utility software|utility]] that examined [[C (programming language)|C language]] source code.<ref name="BellLabs">{{cite journal |last=Johnson |first=Stephen C. |author-link=Stephen C. Johnson |date=25 October 1978 |title=Lint, a C Program Checker |url=https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.56.1841 |url-status=dead |journal=Comp. Sci. Tech. Rep. |publisher=Bell Labs |pages=78–1273 |citeseerx=10.1.1.56.1841 |archive-url=https://web.archive.org/web/20220123141016/https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.56.1841&rep=rep1&type=pdf |archive-date=2022-01-23}}</ref>  A program which performs this function is also known as a "linter".

==History==
[[Stephen C. Johnson]], a computer scientist at [[Bell Labs]], came up with the term "lint" in 1978 while debugging the [[yacc]] grammar he was writing for [[C (programming language)|C]] and dealing with [[Software portability|portability]] issues stemming from porting [[Unix]] to a [[32-bit]] machine.<ref name="red"/><ref name="BellLabs"/> The term was borrowed from the word [[Lint (material)|lint]], the tiny bits of fiber and fluff shed by clothing, as the command he wrote would act like a lint trap in a clothes dryer, capturing waste fibers while leaving whole fabrics intact. In 1979, lint programming was used outside of Bell Labs for the first time, in the seventh version ([[Version 7 Unix|V7]]) of Unix.

Over the years, different versions of lint have been developed for many [[C (programming language)|C]] and [[C++]] [[compiler]]s, and while modern-day compilers have lint-like functions, lint-like tools have also advanced their capabilities. For example, Gimpel's [[PC-Lint]], introduced in 1985 and used to analyze C++ source code, is still for sale.<ref name="red">{{cite news|last1=Morris|first1=Richard|title=Stephen Curtis Johnson: Geek of the Week|url=https://www.red-gate.com/simple-talk/opinion/geek-of-the-week/stephen-curtis-johnson-geek-of-the-week/|access-date=19 January 2018|work=Red Gate Software|date=1 October 2009}}</ref>

==Overview==
In his original 1978 paper Johnson stated his reasoning in creating a separate program to detect errors, distinct from that which it analyzed: "...the general notion of having two programs is a good one" [because they concentrate on different things, thereby allowing the programmer to] "concentrate at one stage of the programming process solely on the [[algorithm]]s, [[data structure]]s, and correctness of the program, and then later retrofit, with the aid of lint, the desirable properties of universality and portability".<ref name="BellLabs"/>

== Successor linters ==
The analysis performed by lint-like tools can also be performed by an [[optimizing compiler]], which aims to generate faster code.  Even though modern [[compiler]]s have evolved to include many of lint's historical functions, lint-like tools have also evolved to detect an even wider variety of suspicious constructs. These include "warnings about syntax errors, uses of [[Undefined variable|undeclared variables]], calls to deprecated functions, spacing and formatting conventions, misuse of scope, implicit fallthrough in [[Switch statement|switch statements]], missing license headers, [and]...dangerous language features".<ref name="phab">{{cite web|title=Arcanist User Guide: Lint|url=https://secure.phabricator.com/book/phabricator/article/arcanist_lint/|website=Phabricator|access-date=19 January 2018}}</ref>

Lint-like tools are especially useful for [[Type system#DYNAMIC|dynamically typed languages]] like [[JavaScript]] and [[Python (programming language)|Python]]. Because the interpreters of such languages typically do not enforce as many and as strict rules during [[Execution (computing)|execution]], linter tools can also be used as simple [[debugger]]s for finding common errors (e.g. syntactic discrepancies) as well as hard-to-find errors such as [[heisenbug]]s (drawing attention to suspicious code as "possible errors").<ref>{{Cite web|url=https://www.thecodecampus.de/blog/eslint-customizable-javascript-linting-tool-1/|title=ESLint - Customizable JavaScript linting tool (1)|date=2015-06-09|website=theCodeCampus|language=en-US|access-date=2019-04-21}}</ref> Lint-like tools generally perform [[static code analysis|static analysis]] of source code.<ref>{{cite news|url=https://barrgroup.com/Embedded-Systems/How-To/Lint-Static-Analysis-Tool|title=How to Use Lint for Static Code Analysis|date=1 May 2002|work=Barr Group|first=Nigel| last = Jones}}</ref>

Lint-like tools have also been developed for other aspects of software development, such as enforcing grammar and style guides for given language source code.<ref>{{Citation |title=rust-lang/rustfmt |date=2025-01-20 |url=https://github.com/rust-lang/rustfmt |access-date=2025-01-21 |publisher=The Rust Programming Language}}</ref> Some tools (such as [[ESLint]]) also allow rules to be auto-fixable: a rule definition can also come with the definition of a transform that resolves the warning. Rules about style are especially likely to come with an auto-fix. If the linter is run in "fix all" mode on a file that triggers only rules about formatting, the linter will act just like a formatter.

==See also==
*[[Splint (programming tool)]]
*[[List of tools for static code analysis]]

==References==
{{Reflist}}

==Further reading==
* {{cite book|last1=Darwin|first1=Ian F.|title=Checking C Programs with Lint: C Programming Utility|date=1991|publisher=O'Reilly Media|location=United States |isbn=978-0937175309|edition=Revised|url=https://books.google.com/books?id=vweTteq3OLQC}}
* {{cite web
| url=https://man.netbsd.org/lint.1
| title=LINT(1)
| work=NetBSD General Commands Manual 
| date=2024-01-24}}

[[Category:Static program analysis tools]]
[[Category:Unix software]]
[[Category:Formerly proprietary software]]
[[Category:Software using the BSD license]]