add positional context to compiler error messages

[kkoreilly]

It would make debugging the compiler a lot easier if the error messages indicated the file and line number where they took place.

For example, instead of this error message:

failed to compile package encoding/json: failed to write declarations: failed to write function body: failed to write block statement: failed to write statement in block: failed to write assignment statement: failed to write argument: unhandled string conversion: string

It would be good to get something like this:

/Users/me/path/to/stdlib/encoding/json/marshal.go:45: failed to compile package encoding/json: failed to write declarations: failed to write function body: failed to write block statement: failed to write statement in block: failed to write assignment statement: failed to write argument: unhandled string conversion: string

[paralin]

Agreed! It should be possible to determine the location based on the AST node.

For now I recommend running with a debugger attached (either delve - https://github.com/go-delve/delve - dlv test -test.timeout 30s -test.run ^TestCompliance/if_type_assert$ ./compiler and setting a breakpoint on the location of the error you're seeing - OR use vscode with a breakpoint set and click Debug on the broken test in the tests list).

[paralin]

The current issue making this hard is we use errors.Wrap to wrap errors (each : in the error message) and therefore we don't know which AST node caused the error. The only fix I can think of at the moment is to return a custom error wrapper type with the relevant ast node included asterr.New(err, astNode) and then extract this path and prepend it when logging the error. But this would require modifying every single errors.New or fmt.Errorf of which there are thousands. I can probably get an AI to comb through it and rewrite all the errors.

[kkoreilly]

That sounds like a good idea. I will try a debugger for now as you suggested. Thanks for the information!