webpack.StackEntry

Singly-linked stack entry that also exposes a Set-like API (has, size, iteration). Each doResolve call prepends a new StackEntry that points at the previous tip via .parent, so pushing is O(1) in time and memory. Recursion detection walks the linked list (O(n)) but the stack is typically shallow, so this is cheaper overall than cloning a Set per call.

new StackEntry(): StackEntry

Iterate entries from oldest (root) to newest (tip), matching how a Set that was populated in insertion order would iterate. Pre-seeded legacy Set<string> entries come first so error-message output stays ordered oldest-to-newest. Yields each entry as its formatted toString() form. Plugins written against the pre-5.21 Set<string> shape — e.g. [...resolveContext.stack].find(a => a.includes("module:")) — keep working unchanged because each yielded value is a plain string with all of String.prototype available natively. Resolves that never iterate the stack pay nothing; iteration costs one toString() allocation per stack frame.

has(query): boolean

Walk the linked list looking for an entry with the same request shape. Set-compatible: callers that used stack.has(entry) keep working. NOTE: kept monomorphic on purpose. An earlier draft accepted a string query too (so pre-5.21 plugins keeping their own Set<string> of seen entries could probe the live stack with the formatted form), but adding the second shape regressed doResolve's heap profile by ~1 MiB / 200 resolves on stack-churn — V8 keeps a polymorphic call-site state for parent.has(stackEntry) once has has two argument shapes. Plugins that need string membership can reach for [...stack].find(e => e.includes(formattedString)) via the String-method proxies on StackEntry instead.

toString(): string

Human-readable form used in recursion error messages, logs, and the iterator above. Not memoized: caching would require an extra slot on every StackEntry, which costs heap even on resolves that never look at the formatted form.