Proving macro expansion with expandable
summary
Claim: expandable proves a declarative macro always expands to syntactically valid Rust by converting macro transcribers into state machines then into a custom VM parser. It ships as the crate "expandable" and runs via an attribute macro on a macro definition, finds real errors like using -> instead of . and emits helpful diagnostics. Current limits include a partial parser, trouble with recursive macros and macro rulesetion generation, but the prototype works end to end.
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chapters (12)
- 0:00Proving macro expansion
- 1:25Declarative macros in Rust
- 3:12Macro implementation example
- 5:22Macros need validation tools
- 7:30Defining valid macro expansion
- 8:36Language theory for macro validation
- 10:01Algorithm for macro validation
- 15:11Building interruptable parser
- 16:57Parser implementation approaches
- 18:00Demo of expandable crate
- 19:28Limitations of expandable
- 20:51Summary
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