Jan 13, 2025 · Jan 3, 2025 · Jan 7, 2025
diff --git a/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts b/packages/eslint-plugin/src/rules/no-unnecessary-condition.ts
      );
    }

    // Conditional is always necessary if it involves:
    //    `any` or `unknown` or a naked type variable
    function isConditionalAlwaysNecessary(type: ts.Type): boolean {
      return tsutils
        .unionTypeParts(type)
        .some(
          part =>
            isTypeAnyType(part) ||
            isTypeUnknownType(part) ||
            isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
        );
    }

    function isNullableMemberExpression(
      node: TSESTree.MemberExpression,
    ): boolean {

      const type = getConstrainedTypeAtLocation(services, expression);

      // Conditional is always necessary if it involves:
      //    `any` or `unknown` or a naked type variable
      if (
        tsutils
          .unionTypeParts(type)
          .some(
            part =>
              isTypeAnyType(part) ||
              isTypeUnknownType(part) ||
              isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
          )
      ) {
      if (isConditionalAlwaysNecessary(type)) {
        return;
      }
      let messageId: MessageId | null = null;
            : true;

      return (
 isTypeFlagSet(type, ts.TypeFlags.Any | ts.TypeFlags.Unknown) ||
 isConditionalAlwaysNecessary(type) ||
        (isOwnNullable && isNullableType(type))
      );
    }
diff --git a/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts b/packages/eslint-plugin/tests/rules/no-unnecessary-condition.test.ts
  return t ? 'yes' : 'no';
 }
    `,
    `
 function test<T>(arg: T, key: keyof T) {
  if (arg[key]?.toString()) {
  }
 }
    `,
    `
 function test<T>(arg: T, key: keyof T) {
  if (arg?.toString()) {
  }
 }
    `,
    `
 function test<T>(arg: T | { value: string }) {
  if (arg?.value) {
  }
 }
    `,

    // Boolean expressions
    `
Original file line number	Diff line number	Diff line change
Expand Up		@@ -304,6 +304,19 @@ export default createRule<Options, MessageId>({
		);
		}

		// Conditional is always necessary if it involves:
		// `any` or `unknown` or a naked type variable
		function isConditionalAlwaysNecessary(type: ts.Type): boolean {
		return tsutils
		.unionTypeParts(type)
		.some(
		part =>
		isTypeAnyType(part) \|\|
		isTypeUnknownType(part) \|\|
		isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
		);
		}

		function isNullableMemberExpression(
		node: TSESTree.MemberExpression,
		): boolean {
Expand DownExpand Up		@@ -370,18 +383,7 @@ export default createRule<Options, MessageId>({

		const type = getConstrainedTypeAtLocation(services, expression);

		// Conditional is always necessary if it involves:
		// `any` or `unknown` or a naked type variable
		if (
		tsutils
		.unionTypeParts(type)
		.some(
		part =>
		isTypeAnyType(part) \|\|
		isTypeUnknownType(part) \|\|
		isTypeFlagSet(part, ts.TypeFlags.TypeVariable),
		)
		) {
Copy link Member JoshuaKGoldbergJan 7, 2025 Choose a reason for hiding this comment The reason will be displayed to describe this comment to others.Learn more. [Praise] Heh, yeah, this was getting a little hard to read inline even before... ronami reacted with heart emoji
		if (isConditionalAlwaysNecessary(type)) {
		return;
		}
		let messageId: MessageId \| null = null;
Expand DownExpand Up		@@ -813,7 +815,7 @@ export default createRule<Options, MessageId>({
		: true;

		return (
		isTypeFlagSet(type, ts.TypeFlags.Any \| ts.TypeFlags.Unknown) \|\|
		isConditionalAlwaysNecessary(type) \|\|
		(isOwnNullable && isNullableType(type))
		);
		}
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -143,6 +143,24 @@ function test<T>(t: T \| []) {
		return t ? 'yes' : 'no';
		}
		`,
		`
		function test<T>(arg: T, key: keyof T) {
		if (arg[key]?.toString()) {
		}
		}
		`,
		`
		function test<T>(arg: T, key: keyof T) {
		if (arg?.toString()) {
		}
		}
		`,
		`
		function test<T>(arg: T \| { value: string }) {
		if (arg?.value) {
		}
		}
		`,

		// Boolean expressions
		`
Expand Down