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fix(eslint-plugin): [no-unused-vars] ignore imports used only as types #9694

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merged 2 commits into from
Aug 1, 2024
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fix(eslint-plugin): [no-unused-vars] ignore imports used only as types #9694

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dd71460
fix(eslint-plugin): [no-unused-vars] ignore imports used only as types
jakebailey Aug 1, 2024
4190828
chore(eslint-plugin): [no-unused-vars] avoid extra calculation before…
jakebailey Aug 1, 2024
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17 changes: 13 additions & 4 deletions packages/eslint-plugin/src/rules/no-unused-vars.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -579,6 +579,19 @@ export default createRule<Options, MessageIds>({
for (const unusedVar of unusedVars) {
// Report the first declaration.
if (unusedVar.defs.length > 0) {
const usedOnlyAsType = unusedVar.references.some(ref =>
referenceContainsTypeQuery(ref.identifier),
);

const isImportUsedOnlyAsType =
usedOnlyAsType &&
unusedVar.defs.some(
def => def.type === DefinitionType.ImportBinding,
);
if (isImportUsedOnlyAsType) {
continue;
}

const writeReferences = unusedVar.references.filter(
ref =>
ref.isWrite() &&
Expand All @@ -589,10 +602,6 @@ export default createRule<Options, MessageIds>({
? writeReferences[writeReferences.length - 1].identifier
: unusedVar.identifiers[0];

const usedOnlyAsType = unusedVar.references.some(ref =>
referenceContainsTypeQuery(ref.identifier),
);

const messageId = usedOnlyAsType ? 'usedOnlyAsType' : 'unusedVar';

const { start } = id.loc;
Expand Down
31 changes: 10 additions & 21 deletions packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1173,6 +1173,16 @@ export type Foo = typeof foo;

export const bar = (): Foo => foo;
`,
`
import { SomeType } from 'foo';

export const value = 1234 as typeof SomeType;
`,
`
import { foo } from 'foo';

export type Bar = typeof foo;
`,
],

invalid: [
Expand Down Expand Up @@ -2256,26 +2266,5 @@ export const x = _Foo;
},
],
},
{
code: `
import { foo } from 'foo';

export type Bar = typeof foo;
`,
errors: [
{
messageId: 'usedOnlyAsType',
data: {
varName: 'foo',
action: 'defined',
additional: '',
},
line: 2,
column: 18,
endLine: 2,
endColumn: 21,
},
],
},
],
});