Prevent detached diagnostics from running off the end of the file #55381
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typescript-bot
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Author: Team
For Milestone Bug
jakebailey
commented
Aug 15, 2023
Comment on lines
+8153
to
+8155
| if ((start + length) > sourceText.length) { | ||
| length = sourceText.length - start; | ||
| } |
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This is the actual fix.
jakebailey
commented
Aug 15, 2023
| @@ -2470,7 +2470,7 @@ namespace Parser { | |||
| if (lastError) { | |||
| addRelatedInfo( | |||
| lastError, | |||
| createDetachedDiagnostic(fileName, openPosition, 1, Diagnostics.The_parser_expected_to_find_a_1_to_match_the_0_token_here, tokenToString(openKind), tokenToString(closeKind)) | |||
| createDetachedDiagnostic(fileName, sourceText, openPosition, 1, Diagnostics.The_parser_expected_to_find_a_1_to_match_the_0_token_here, tokenToString(openKind), tokenToString(closeKind)) | |||
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This set of three detached diagnostics are the trouble; openPosition can totally be at the end of the file.
andrewbranch
approved these changes
Aug 15, 2023
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Fixes #55296
This is similar to #52450 and #53674; we can create diagnostics with hardcoded range lengths, but if the parse error starts at the end of the file, we'll crash.
I could band-aid this by special casing the one crash, but as you can see in the change, we have quite a few other places which assume it's okay to use a
length=1diagnostic, when it's possible that it may not work.So, just set the length to the maximum available (or zero) when this happens.
To make this more obvious, I've restructured things a little so that we check the ranges earlier. The stack trace in #55296 happens late because the diagnostics weren't checked until they were finally attached to the file, after parse was complete. It's possible that I could find a different way to do this that doesn't look so noisy, but I feel like this is more robust.
Realistically, I could just move
createDetachedDiagnosticintoparser.ts; it's only used there so that'd avoid some parameters. But, all of its related helpers are still in this utilities file.