Updated string_literals.md to mitigate confusion around newline behavior
in the context of block string literals.
Addresses #2887
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Co-authored-by: jonmeow <jperkins@google.com>
Use `"` for simple string literals and `'''` for block string literals.
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
This is based on discussion on #732: that we should probably parse the invalid whitespace, then reject it as part of string validation, rather than having different parses. I worry the question of "how is this parsed" may lead to subtly unexpected results if we aren't consistent, so I'm switching the logic from the lexer to the unescape library (and also adjusting the list of rejected whitespace).
I've modified the text from the proposal slightly, focusing the overview more on a design setup, but mostly kept the details. One important thing here is I noticed that raw tab characters are disallowed -- this was a little buried before, and I've now updated the list of characters allowed in a string to exclude tabs. Additionally, I've noted `\0D` in the list of escapes as explicitly invalid.
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
T.J. Givenandjonmeow
Richard Smith
Aleksey Kladov
Jon Meow