Disable isStartOfType's lookahead when called from isStartOfParameter #18296
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mhegazy
reviewed
Sep 7, 2017
src/compiler/parser.ts
Outdated
| @@ -2698,7 +2699,7 @@ namespace ts { | |||
| } | |||
| } | |||
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| function isStartOfType(): boolean { | |||
| function isStartOfType(disableLookahead?: boolean): boolean { | |||
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can we have a more declarative name, like inJSDocType or something?
mhegazy
reviewed
Sep 7, 2017
| var tt1 = (a, (b, c)) => a+b+c; | ||
| ~ | ||
| !!! error TS1003: Identifier expected. |
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hmm. so we had this test originally? why did not we catch this the first time around then?
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I noticed the baseline change but (1) I thought that removal of 3 errors was actually an improvement (2) didn't think it was indicative on any further problem. I also looked at the emitted code and thought it was better -- closer to what was written at least.
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well.. the new error is a parse error. so a bit worse than the 3 semantic ones.
mhegazy
approved these changes
Sep 7, 2017
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Thanks guys 👍 |
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@sandersn can you port this to release-2.5 as well |
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It's in release-2.5 now. |
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isStartOfTypehas lookahead for parenthesized types. Now that unified JSDoc parsing allows types to start parameters, this lookahead compounds with speculative arrow-function parsing's lookahead (which also cares about parentheses). Disable the lookahead whenisStartOfTypeis called fromisStartOfParameter, which was introduced with the addition of unified JSDoc parsing.Fixes #18123