Microsoft/TypeScript

Give a better error message when an import isn't found but a namespace of the same name exists

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#10,464 opened on Aug 21, 2016

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 (2 comments) (0 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
BugDomain: Error MessagesEffort: ModerateHelp Wanted

Description

See #10463.

foo.d.ts

declare module foo {
    // ...
}

bar.ts

import foo = require("foo");

"foo" won't be found, but if the compiler can resolve an identifier named foo to a namespace that uses the declare module syntax, we should probably give an error like

Cannot find module 'foo'.
  A legacy-style namespace with the same name was found.
    Try changing the declaration to use quotes (e.g. 'declare module "foo"').

Contributor guide

Tech stack
typescript
Domain
developer experiencetooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript compiler internalsmodule resolutionerror message generation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
15
Research direction
Start by examining the existing error message generation in src/compiler/checker.ts for module not found errors. Then look at how namespaces are resolved and the logic in src/compiler/moduleResolver.ts. The linked issue #10463 may provide additional context. Finally, implement a check to detect if a namespace with the same name exists and produce the suggested error message.