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Andrew V. Teylu
c77768590d
When a macro-generating-macro captures fragment specifier tokens (like `$x:ident`) as `tt` metavariables and replays them before a keyword (like `where`), the pretty printer concatenates them into an invalid fragment specifier (e.g. `$x:identwhere` instead of `$x:ident where`). This happens because `tt` captures preserve the original token spacing. When the fragment specifier name (e.g. `ident`) was originally the last token before a closing delimiter, it retains `JointHidden` spacing. The `print_tts` function only checks `space_between` for `Spacing::Alone` tokens, so `JointHidden` tokens skip the space check entirely, causing adjacent identifier-like tokens to merge. The fix adds a check in `print_tts` to insert a space between adjacent identifier-like tokens (identifiers and keywords) regardless of the original spacing, preventing them from being concatenated into invalid tokens. This is similar to the existing `space_between` mechanism that prevents token merging for `Spacing::Alone` tokens, extended to also handle `Joint`/`JointHidden` cases where two identifier-like tokens would merge. Signed-off-by: Andrew V. Teylu <andrew.teylu@vector.com>
20 lines
591 B
Rust
20 lines
591 B
Rust
//@ pretty-mode:expanded
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//@ pp-exact:macro-fragment-specifier-whitespace.pp
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// Test that fragment specifier names in macro definitions are properly
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// separated from the following keyword/identifier token when pretty-printed.
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// This is a regression test for a bug where `$x:ident` followed by `where`
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// was pretty-printed as `$x:identwhere` (an invalid fragment specifier).
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macro_rules! outer {
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($d:tt $($params:tt)*) => {
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#[macro_export]
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macro_rules! inner {
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($($params)* where $d($rest:tt)*) => {};
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}
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};
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}
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outer!($ $x:ident);
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fn main() {}
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