Parse and validate text format together #2438

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1. alexcrichton commented on Feb 6, 2026

   

   alexcrichton

   on Feb 6, 2026

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   One way to achieve half of this (sort of) is the -g (--generate-dwarf lines) flag on wasm-tools validate:

   $ cat foo.wat
   (module
     (import "" "" (func $g))
     (func $f (export "f")
       ref.func $g
       drop
     )
   )
   $ wasm-tools validate -g foo.wat
   error: ./foo.wat:4:5 function `f` failed to validate
   
   Caused by:
       0: func 1 failed to validate
       1: undeclared function reference (at offset 0x25)
   

   where validate doesn't actually emit the binary *.wasm anywhere, but with -g the text-to-binary transform inserts DWARF debugging information pointing back to the original source so the final error message has a filename/line number/column/etc.

   Now that being said the error messages still aren't great. While it's got a filename that's sort of it and it's still sort of manual figuring things out. Additionally this only works for errors in the code section, any error anywhere else doesn't have DWARF information so and invalid type, for example, wouldn't have any filename/line number printed.

   Otherwise though you're right that the spans don't have any means of making their way into the final binary except for DWARF. I think it'd be reasonable to extend that to get more errors in more places though

   👍React with 👍1Reacted by Ryan Hunt