Dylan 53fc0614da Fix unreachable panic in parser (#19183) ... Parsing the (invalid) expression `f"{\t"i}"` caused a panic because the `TStringMiddle` character was "unreachable" due the way the parser recovered from the line continuation (it ate the t-string start). The cause of the issue is as follows: The parser begins parsing the f-string and expects to see a list of objects, essentially alternating between _interpolated elements_ and ordinary strings. It is happy to see the first left brace, but then there is a lexical error caused by the line-continuation character. So instead of the parser seeing a list of elements with just one member, it sees a list that starts like this: - Interpolated element with an invalid token, stored as a `Name` - Something else built from tokens beginning with `TStringStart` and `TStringMiddle` When it sees the `TStringStart` error recovery says "that's a list element I don't know what to do with, let's skip it". When it sees `TStringMiddle` it says "oh, that looks like the middle of _some interpolated string_ so let's try to parse it as one of the literal elements of my `FString`". Unfortunately, the function being used to parse individual list elements thinks (arguably correctly) that it's not possible to have a `TStringMiddle` sitting in your `FString`, and hits `unreachable`. Two potential ways (among many) to solve this issue are: 1. Allow a `TStringMiddle` as a valid "literal" part of an f-string during parsing (with the hope/understanding that this would only occur in an invalid context) 2. Skip the `TStringMiddle` as an "unexpected/invalid list item" in the same way that we skipped `TStringStart`. I have opted for the second approach since it seems somehow more morally correct, even though it loses more information. To implement this, the recovery context needs to know whether we are in an f-string or t-string - hence the changes to that enum. As a bonus we get slightly more specific error messages in some cases. Closes #18860		2025-07-20 22:04:14 +00:00
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snapshots	Fix unreachable panic in parser (#19183)	2025-07-20 22:04:14 +00:00
fixtures.rs	Implement template strings (#17851)	2025-05-30 15:00:56 -05:00
generate_inline_tests.rs	[syntax-errors] Start detecting compile-time syntax errors (#16106)	2025-03-21 14:45:25 -04:00