feat: add reportUnusedFallthroughComment option to no-fallthrough rule
#18188
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mdjermanovic
added
accepted
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i think we can add a correct section here with an example having a comment that doesn't permit fallthrough.
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makes sense! Added
mdjermanovic
requested changes
Mar 12, 2024
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| const isSwitchExitReachable = isAnySegmentReachable(currentCodePathSegments); | ||
| const isFallthrough = isSwitchExitReachable && (node.consequent.length > 0 || (!allowEmptyCase && hasBlankLinesBetween(node, nextToken))) && | ||
| node.parent.cases.at(-1) !== node; | ||
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| previousCase = { | ||
| node, | ||
| isSwitchExitReachable, | ||
| isFallthrough | ||
| }; |
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The state can leak across multiple switches this way:
/* eslint no-fallthrough: ["error", { "reportUnusedFallthroughComment": true }] */
switch(foo){
case 1:
doSomething();
break;
}
function f() {
switch(foo){
// falls through comment false positive
case 1:
if (a) {
throw new Error();
} else if (b) {
break;
} else {
return;
}
case 2:
break;
}
}There was a problem hiding this comment.
oh dear. And I thought I was being all clever by adding those test cases 🤦
Fixed!
mdjermanovic
changed the title
reportUnusedFallthroughComment option to no-fallthrough rule
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| { | ||
| code: ` | ||
| switch(foo){ | ||
| case 1: | ||
| doSomething(); | ||
| break; | ||
| // falls through | ||
| case 2: doSomething(); | ||
| }`, | ||
| options: [{ reportUnusedFallthroughComment: true }], | ||
| errors: [ | ||
| { | ||
| line: 6, | ||
| messageId: "unusedFallthroughComment" | ||
| } | ||
| ] | ||
| }, { |
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Can you also add a test where a fallthrough comment in a block is reported, for example:
{
code: `
switch (foo) {
case 0: {
a();
break;
// falls through
}
case 1:
b();
}`,
options: [{ reportUnusedFallthroughComment: true }],
errors: [
{
line: 6,
messageId: "unusedFallthroughComment"
}
]
},There was a problem hiding this comment.
makes sense! added
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| { | ||
| code: ` | ||
| switch(foo){ | ||
| case 1: | ||
| doSomething(); | ||
| break; | ||
| // just a comment | ||
| case 2: doSomething(); | ||
| } | ||
| `, | ||
| options: [{ reportUnusedFallthroughComment: true }] | ||
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| }, |
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Can you also add a valid test with a fallthrough comment, for example:
{
code: `
switch(foo){
case 1:
doSomething();
// falls through
case 2: doSomething();
}
`,
options: [{ reportUnusedFallthroughComment: true }]
},There was a problem hiding this comment.
makes sense! added
Co-authored-by: Milos Djermanovic <milos.djermanovic@gmail.com>
mdjermanovic
approved these changes
Mar 14, 2024
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Thanks for contributing! |
Thanks! This was fun! 🙂 |
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fixes #18182
Prerequisites checklist
What is the purpose of this pull request? (put an "X" next to an item)
[ ] Documentation update
[ ] Bug fix (template)
[ ] New rule (template)
[x] Changes an existing rule (template)
[ ] Add autofix to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:
#18182
What changes did you make? (Give an overview)
Add option (disabled by default) to report unused fallthrough comments in no-fallthrough.
Is there anything you'd like reviewers to focus on?
Changes are pretty straightforward I think.
PS this is my first PR to ESLint! very exciting