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rust-lang / wg-grammar

Where the work of WG-grammar, aiming to provide a canonical grammar for Rust, resides
Apache License 2.0
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Macros #4

Open ehuss opened 6 years ago

ehuss commented 6 years ago

How exactly will macros be handled?

Will the macro part of the grammar simply indicate token trees, or should there be more to it? What needs to be addressed here?

Will the grammar's rules exactly match what the different fragment specifier types (expr, stmt, etc.) accept in rustc?

CAD97 commented 6 years ago

I think macros shouldn't be handled any special.

i.e. the grammar for macro invocation should just be $ident ! ( $tt* ).

Any more information in the grammar would require back-information for what the macro definition is.

I do think that we should try to match productions to what the macro matchers accept, though this I think would be a soft rather than hard requirement. (macros 2.0 has some room to change what are matched.)