Jul 20, 2024 · Jul 11, 2024 · Jul 11, 2024 · Jul 16, 2024 · Jul 19, 2024 · Jul 20, 2024
diff --git a/eslint.config.mjs b/eslint.config.mjs
        { commentPattern: '.*intentional fallthrough.*' },
      ],
      'no-lonely-if': 'error',
      'no-unreachable-loop': 'error',
      'no-useless-call': 'error',
      'no-useless-computed-key': 'error',
      'no-useless-concat': 'error',
diff --git a/packages/eslint-plugin/src/rules/no-mixed-enums.ts b/packages/eslint-plugin/src/rules/no-mixed-enums.ts
          .getSymbolAtLocation(tsNode)!
          .getDeclarations()!;

        for (const declaration of declarations) {
          for (const member of (declaration as ts.EnumDeclaration).members) {
            return member.initializer
              ? tsutils.isTypeFlagSet(
                  typeChecker.getTypeAtLocation(member.initializer),
                  ts.TypeFlags.StringLike,
                )
                ? AllowedType.String
                : AllowedType.Number
              : AllowedType.Number;
          }
        }
        const [{ initializer }] = (declarations[0] as ts.EnumDeclaration)
          .members;
        return initializer &&
          tsutils.isTypeFlagSet(
            typeChecker.getTypeAtLocation(initializer),
            ts.TypeFlags.StringLike,
          )
          ? AllowedType.String
          : AllowedType.Number;
      }

      // Finally, we default to the type of the first enum member
diff --git a/packages/eslint-plugin/src/rules/no-unsafe-return.ts b/packages/eslint-plugin/src/rules/no-unsafe-return.ts
        });
      }

      for (const signature of functionType.getCallSignatures()) {
      const signature = functionType.getCallSignatures().at(0);
      if (signature) {
        const functionReturnType = signature.getReturnType();
        const result = isUnsafeAssignment(
          returnNodeType,
diff --git a/packages/eslint-plugin/tests/rules/no-unsafe-return.test.ts b/packages/eslint-plugin/tests/rules/no-unsafe-return.test.ts
        return [] as any[];
      }
    `,
    'const foo: (() => void) | undefined = () => 1;',
  ],
  invalid: [
    {
Original file line number	Diff line number	Diff line change
Expand Up		@@ -208,6 +208,7 @@ export default tseslint.config(
		{ commentPattern: '.intentional fallthrough.' },
		],
		'no-lonely-if': 'error',
		'no-unreachable-loop': 'error',
		'no-useless-call': 'error',
		'no-useless-computed-key': 'error',
		'no-useless-concat': 'error',
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -170,18 +170,15 @@ export default createRule({
		.getSymbolAtLocation(tsNode)!
		.getDeclarations()!;

		for (const declaration of declarations) {
		for (const member of (declaration as ts.EnumDeclaration).members) {
		return member.initializer
		? tsutils.isTypeFlagSet(
		typeChecker.getTypeAtLocation(member.initializer),
		ts.TypeFlags.StringLike,
		)
		? AllowedType.String
		: AllowedType.Number
		: AllowedType.Number;
		}
		}
		const [{ initializer }] = (declarations[0] as ts.EnumDeclaration)
Copy link Member Josh-CenaJul 12, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Love this because this exposes a bug (not sure if it's intentional)! Checking`declarations[0]` is almost always a bug. kirkwaiblinger and JoshuaKGoldberg reacted with heart emoji Copy link ContributorAuthor abrahamguoJul 12, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. Is this truly a bug? Is it possible for a symbol to have multiple declarations, that would be different from each other? Copy link Member Josh-CenaJul 12, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. No; if a symbol returns multiple declarations, that means these sites are merged together and should be treated as one. That's my understanding; I haven't verified it.
		.members;
		return initializer &&
		tsutils.isTypeFlagSet(
		typeChecker.getTypeAtLocation(initializer),
		ts.TypeFlags.StringLike,
		)
		? AllowedType.String
		: AllowedType.Number;
		}

		// Finally, we default to the type of the first enum member
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -166,7 +166,8 @@ export default createRule({
		});
		}

		for (const signature of functionType.getCallSignatures()) {
		const signature = functionType.getCallSignatures().at(0);
		if (signature) {
		const functionReturnType = signature.getReturnType();
		const result = isUnsafeAssignment(
		returnNodeType,
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Original file line number	Diff line number	Diff line change
Expand Up		@@ -127,6 +127,7 @@ function foo(): Set<number> {
		return [] as any[];
		}
		`,
		'const foo: (() => void) \| undefined = () => 1;',
Copy link ContributorAuthor abrahamguoJul 11, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. `functionType.getCallSignatures()` can return an empty array, but that code path was not being tested. This ensures that the code path is now covered. kirkwaiblinger reacted with heart emoji Copy link ContributorAuthor abrahamguoJul 12, 2024 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. This was brought to light because when I initially refactored the rule to assume that`getCallSignatures()[0]` was always defined, the tests passed, but the rule crashed when linting this repo, therefore showing that a test was missing. kirkwaiblinger reacted with thumbs up emoji
		],
		invalid: [
		{
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