format/no-trailing-whitespace
Severity: warning · Status: enforced · Applies to: ids/**
What
Lines must not end in spaces or tabs that have no effect.
In .htaccess and plain text that means all of it — neither format has a line-break idiom, so every trailing space is dead weight.
In Markdown it means the whitespace that cannot be doing anything: a single trailing space, a trailing tab, or whitespace on an otherwise-empty line. Two or more trailing spaces is Markdown's hard-line-break idiom, and this rule leaves it alone — see markdown/prefer-list-over-line-breaks for what to do about that instead.
Why
Trailing whitespace is invisible in most editors and reads as noise in every diff that touches the line. It is not a functional problem in these files.
The distinction Markdown gets is the point of the rule. A single trailing space in Markdown does nothing at all — a line break needs two or more — so it is pure noise. Reporting the two-space form alongside it would be wrong: those lines render as their author intended, and many of them in this repository are doing real work in maintainer blocks.
Wrong
In .htaccess, any of it:
RewriteEngine on
RewriteRule ^$ https://example.org/ [R=302,L]···In Markdown, a lone trailing space:
Contacts:·Right
RewriteEngine on
RewriteRule ^$ https://example.org/ [R=302,L]How to fix
Find it:
grep -nP '[ \t]+$' ids/my-project/.htaccessRemove it:
sed -i 's/[[:space:]]*$//' ids/my-project/.htaccessBetter still, install EditorConfig support in your editor — most modern editors have it built in, some need a plugin — and the repository's .editorconfig will handle this for you on every file you save, along with the other whitespace rules.
How to check
Run w3id-check with --rule format/no-trailing-whitespace to check this rule on its own; without it the tool runs every rule, as the pull request checks do.
node tools/check/bin/w3id-check.js --rule format/no-trailing-whitespace ids/my-projectTesting your changes covers installing the tool, and what else is worth checking by hand.