Actually improve recovery when parsing bogus expressions #6319
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The crashes fixed appeared at first to be related to IfConfigStmt parsing, but are in reality symptoms of being too lax in what we accept when parsing of sub-expressions fail. Optional type annotation parsing used to propagate failures before it was patched to ‘recover’ with an AnyPattern. Instead, we’ll just hit the error path for parsing in the main expressions because what is here now isn’t a reasonable thing to return. #selector parsing assumed that the current token it was at after consuming up to a right-brace wasn’t bogus. Instead, if we’ve got here, we may as well just return a loc we know is valid: PreviousLoc.
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@slavapestov How's it look? @swift-ci please smoke test. |
CodaFi
commented
Dec 16, 2016
| @@ -661,7 +661,7 @@ ParserResult<Expr> Parser::parseExprSelector() { | |||
| if (Tok.is(tok::r_paren)) | |||
| rParenLoc = consumeToken(); | |||
| else | |||
| rParenLoc = Tok.getLoc(); | |||
| rParenLoc = PreviousLoc; | |||
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This is a touch controversial. In each case, the Verifier was smacking up against Tok.getLoc() here also being the starting location of the next declaration that got parsed since it's using a strict "x comes before y" check instead of <=. But considering nothing important uses this SourceLoc I think it should fly.
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Looks great, thanks! |
CodaFi
added a commit
to CodaFi/swift
that referenced
this pull request
Jan 4, 2017
Crashers fixed are minor logic errors: Patterns: Crash occurred when requesting the range of a created Pattern. Validity of the range should be checked before returning it to keep the entire range valid or invalid but never both. ParseExpr/ParsePattern: The same fixes as the ones provided in swiftlang#6319 CSDiag: The generic visitor needn’t look through TypeVarTypes either.
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The crashes fixed appeared at first to be related to
IfConfigStmtparsing, but are in reality symptoms of being too lax in what we accept
when parsing of sub-expressions fails.
Optional type annotation parsing used to propagate failures before it
was patched to ‘recover’ with an AnyPattern. Instead, we’ll just hit
the error path for parsing in the main expressions because what is here
now isn’t a reasonable thing to return.
#selector parsing assumed that the current token it was at after
consuming up to a right-brace wasn’t bogus. Instead, if we’ve got
here, we may as well just return a loc we know is valid:
PreviousLoc.