Skip to content

feat(eslint-plugin): [no-unused-vars] handle comma operator for assignments, treat for-of the same as for-in #9326

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jun 25, 2024
Merged

feat(eslint-plugin): [no-unused-vars] handle comma operator for assignments, treat for-of the same as for-in #9326

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
70 changes: 48 additions & 22 deletions packages/eslint-plugin/src/util/collectUnusedVariables.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -236,20 +236,9 @@ class UnusedVarsVisitor extends Visitor {
}
}

//#endregion HELPERS

//#region VISITORS
// NOTE - This is a simple visitor - meaning it does not support selectors

protected ClassDeclaration = this.visitClass;

protected ClassExpression = this.visitClass;

protected FunctionDeclaration = this.visitFunction;

protected FunctionExpression = this.visitFunction;

protected ForInStatement(node: TSESTree.ForInStatement): void {
private visitForInForOf(
node: TSESTree.ForInStatement | TSESTree.ForOfStatement,
): void {
/**
* (Brad Zacher): I hate that this has to exist.
* But it is required for compat with the base ESLint rule.
Expand Down Expand Up @@ -298,6 +287,23 @@ class UnusedVarsVisitor extends Visitor {
this.markVariableAsUsed(idOrVariable);
}

//#endregion HELPERS

//#region VISITORS
// NOTE - This is a simple visitor - meaning it does not support selectors

protected ClassDeclaration = this.visitClass;

protected ClassExpression = this.visitClass;

protected FunctionDeclaration = this.visitFunction;

protected FunctionExpression = this.visitFunction;

protected ForInStatement = this.visitForInForOf;

protected ForOfStatement = this.visitForInForOf;

protected Identifier(node: TSESTree.Identifier): void {
const scope = this.getScope(node);
if (
Expand Down Expand Up @@ -552,6 +558,31 @@ function isUsedVariable(variable: ScopeVariable): boolean {
return false;
}

/**
* Checks whether a given node is unused expression or not.
* @param node The node itself
* @returns The node is an unused expression.
*/
function isUnusedExpression(node: TSESTree.Expression): boolean {
const parent = node.parent;

if (parent.type === AST_NODE_TYPES.ExpressionStatement) {
return true;
}

if (parent.type === AST_NODE_TYPES.SequenceExpression) {
const isLastExpression =
parent.expressions[parent.expressions.length - 1] === node;

if (!isLastExpression) {
return true;
}
return isUnusedExpression(parent);
}

return false;
}

/**
* If a given reference is left-hand side of an assignment, this gets
* the right-hand side node of the assignment.
Expand Down Expand Up @@ -594,8 +625,6 @@ function isUsedVariable(variable: ScopeVariable): boolean {

const id = ref.identifier;
const parent = id.parent;
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
const grandparent = parent.parent!;
const refScope = ref.from.variableScope;
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
const varScope = ref.resolved!.scope.variableScope;
Expand All @@ -611,7 +640,7 @@ function isUsedVariable(variable: ScopeVariable): boolean {

if (
parent.type === AST_NODE_TYPES.AssignmentExpression &&
grandparent.type === AST_NODE_TYPES.ExpressionStatement &&
isUnusedExpression(parent) &&
id === parent.left &&
!canBeUsedLater
) {
Expand Down Expand Up @@ -729,19 +758,16 @@ function isUsedVariable(variable: ScopeVariable): boolean {

const id = ref.identifier;
const parent = id.parent;
// https://github.com/typescript-eslint/typescript-eslint/issues/6225
// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
const grandparent = parent.parent!;

return (
ref.isRead() && // in RHS of an assignment for itself. e.g. `a = a + 1`
// self update. e.g. `a += 1`, `a++`
((parent.type === AST_NODE_TYPES.AssignmentExpression &&
!LOGICAL_ASSIGNMENT_OPERATORS.has(parent.operator) &&
grandparent.type === AST_NODE_TYPES.ExpressionStatement &&
isUnusedExpression(parent) &&
parent.left === id) ||
(parent.type === AST_NODE_TYPES.UpdateExpression &&
grandparent.type === AST_NODE_TYPES.ExpressionStatement) ||
isUnusedExpression(parent)) ||
(!!rhsNode &&
isInside(id, rhsNode) &&
!isInsideOfStorableFunction(id, rhsNode)))
Expand Down
Loading
Loading