feat(eslint-plugin): [explicit-function-return-type] add allowFunctionsWithoutTypeParameters option

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing open issue: fixes [explicit-function-return-type] Only apply to generic functions #730
• That issue was marked as accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

Adds a allowFunctionsWithoutTypeParameters option to ignore non-generic functions.

The issue is quite old but I think it makes a lot of sense to add this in. I don't often use this rule, but when I do think about it, I often mostly only want it for complex, performance-degrading types.

[typescript-eslint]

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Codecov Report

Merging #6105 (f844a55) into main (fe67b1e) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6105   +/-   ##
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  Coverage   91.28%   91.28%           
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  Files         366      366           
  Lines       12363    12365    +2     
  Branches     3617     3618    +1     
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+ Hits        11285    11287    +2     
  Misses        768      768           
  Partials      310      310           

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Impacted Files	Coverage Δ
...-plugin/src/rules/explicit-function-return-type.ts	97.82% <100.00%> (+0.09%)	⬆️

[bradzacher]

[eranhirsch]

As an avid typescript eslint fan, and someone who reads the release notes for each version, then read the linked PRs for each change, i'm missing documentation for the new flag, and it's implicit default value (i'm guessing false by reading the code). These sort of things save time when considering changing my lint config based on an update... (also, I like explicit-function-return-type...)

[bradzacher]

A lot of our docs have auto-generated bits n bobs now! So the rule page has the type and default value generated on the website, which also includes a comment with the description of the option

https://typescript-eslint.io/rules/explicit-function-return-type/#examples

But I agree - we forgot about properly documenting this - an example would be good to illustrate this what it does!

[eranhirsch]

I can't see the default value in this page, nor the option show up in the sidebar of available options. The only place the new option shows up when I search for it (via the browser's search) on that page is the options documentation itself (e.g. 1 search result on the page)

[JoshuaKGoldberg]

@eranhirsch you're right, sorry about that. Filed #6465. I look forward to seeing your pull request adding in the docs. 😄