Microsoft/TypeScript

Line break in module declaration causes compile time error

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#11,167 opened on Sep 27, 2016

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BugDomain: ParserHelp Wanted

Description

TypeScript Version: 2.0.3

A line break in the declaration of a module causes a compile time error. This could either be that the language specification isn't clear that this is illegal or a bug.

Code

// Example declaration with line break
declare module 
     my.very.long.name.foo.bar.baz.able.baker {}

Expected behavior: I don't see anything in the language specification that would make this a compile time error, so I would expect the statement to work as if declaration was all on one line, ie:

// Example declaration with line break
declare module my.very.long.name.foo.bar.baz.able.baker {}

Actual behavior:

A compile time error, in particular: (1, 9): error TS1005: ';' expected.

Contributor guide

Tech stack
typescript
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
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
basic knowledge of TypeScript compiler parsing
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate the TypeScript scanner (src/compiler/scanner.ts) or parser (src/compiler/parser.ts) to understand how line breaks are handled between 'declare' and 'module'. Compare with other declarations like 'function' or 'class'. Look for any token separation logic that might treat newline as a statement separator. The fix likely involves modifying the scanner to allow line breaks in module name tokens.
Line break in module declaration causes compile time error · Microsoft/TypeScript#11167 | Good First Issue