This PR builds on https://github.com/roc-lang/roc/pull/7038, fixing some issues with the initial implementation. The PR following this one will add support for dbg in pipelines.
Use module scope instead of var store to generate idents in dbg desugar
Fix a bug in dbg expression desugaring by using the module scope to generate unique identifiers instead of the variable store.
In the initial implementation of dbg expressions we used the VarStore to generate unique identifiers for new variables created during desugaring. We should have instead used the current module's Scope, which handles identifiers within the module. Each scope has its own incrementing variable count which is independent of the shared variable store. The scope is used to generate new identifiers at other points in canonicalization, such as when assigning a global identifier to closures and expects. It's possible that the identifier generated for dbg could conflict with an identifier generated by the scope, resulting in a confusing error.
Do not display generated symbol names in error messages
When an error message reports on a symbol that was generated during canonicalization, use text like "This value" instead of "This 123 value". Generated symbols use the identifier index as the symbol name, since valid Roc variables cannot begin with a number so there's no chance of collision. We don't want to display generated symbols to the user, so when building the error message we check if the symbol's name starts with a digit.
This PR builds on https://github.com/roc-lang/roc/pull/7038, fixing some issues with the initial implementation. The PR following this one will add support for
dbgin pipelines.Use module scope instead of var store to generate idents in dbg desugar
Fix a bug in
dbgexpression desugaring by using the module scope to generate unique identifiers instead of the variable store.In the initial implementation of
dbgexpressions we used theVarStoreto generate unique identifiers for new variables created during desugaring. We should have instead used the current module'sScope, which handles identifiers within the module. Each scope has its own incrementing variable count which is independent of the shared variable store. The scope is used to generate new identifiers at other points in canonicalization, such as when assigning a global identifier to closures andexpects. It's possible that the identifier generated fordbgcould conflict with an identifier generated by the scope, resulting in a confusing error.Do not display generated symbol names in error messages
When an error message reports on a symbol that was generated during canonicalization, use text like "This value" instead of "This
123value". Generated symbols use the identifier index as the symbol name, since valid Roc variables cannot begin with a number so there's no chance of collision. We don't want to display generated symbols to the user, so when building the error message we check if the symbol's name starts with a digit.