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2024: Add reserved syntax #1652

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Nov 25, 2024
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2024: Add reserved syntax #1652

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2024: Add reserved syntax
ehuss Oct 12, 2024
35ee2a9
Add rules for reserved guards
ehuss Nov 4, 2024
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22 changes: 22 additions & 0 deletions src/tokens.md
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Expand Up @@ -887,9 +887,31 @@ r[lex.token.reserved-prefix.edition2021]
> lexes!{match"..." {}}
> ```

## Reserved guards

r[lex.token.reserved-guards]

r[lex.token.reserved-guards.syntax]
> **<sup>Lexer 2024+</sup>**\
> RESERVED_GUARDED_STRING_LITERAL : `#`<sup>+</sup> [STRING_LITERAL]\
> RESERVED_POUNDS : `#`<sup>2..</sup>

r[lex.token.reserved-guards.intro]
The reserved guards are syntax reserved for future use, and will generate a compile error if used.

r[lex.token.reserved-guards.string-literal]
The *reserved guarded string literal* is a token of one or more `U+0023` (`#`) immediately followed by a [STRING_LITERAL].

r[lex.token.reserved-guards.pounds]
The *reserved pounds* is a token of two or more `U+0023` (`#`).

r[lex.token.reserved-guards.edition2024]
> **Edition differences**: Before the 2024 edition, reserved guards are accepted by the lexer and interpreted as multiple tokens. For example, the `#"foo"#` form is interpreted as three tokens. `##` is interpreted as two tokens.

[Inferred types]: types/inferred.md
[Range patterns]: patterns.md#range-patterns
[Reference patterns]: patterns.md#reference-patterns
[STRING_LITERAL]: tokens.md#string-literals
[Subpattern binding]: patterns.md#identifier-patterns
[Wildcard patterns]: patterns.md#wildcard-pattern
[arith]: expressions/operator-expr.md#arithmetic-and-logical-binary-operators
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