Issue #17743 has been updated by p8 (Petrik de Heus).


Eregon (Benoit Daloze) wrote in #note-2:
> How would your format when the method takes multiple arguments?

```
from hi.rb:2:in `say_hi' called with NilClass, Numeric, String
```

> Should we show the value or just the class?

Values could possibly generate a lot of output and it might contain private data that you don't want to output.
Maybe for Boolean values showing true and false.

> I think in general this can be useful, but at the same time it's not nearly as useful as a debugger,

I agree a debugger is more useful. This would mostly be useful for finding nils.

> and it can be a significant performance overhead for JITs/VMs which would then need to collect all frames and arguments in every exception's backtrace, as well as a copy of the arguments array (instead of just [call site bci/node, called method name/target]).

I can imagine it being a performance overhead. 



----------------------------------------
Feature #17743: Show argument types in backtrace
https://bugs.ruby-lang.org/issues/17743#change-91066

* Author: p8 (Petrik de Heus)
* Status: Open
* Priority: Normal
----------------------------------------
Given the following Ruby program:
``` ruby
def say_hi(person)
  puts message(person)
end

def message(person)
  "hi: #{person.name}"
end

say_hi(nil)
```

It would be helpful if the backtrace contained the types of the argumets:
```
hi.rb:6:in `message': undefined method `name' for nil:NilClass (NoMethodError)
	from hi.rb:2:in `say_hi' called with NilClass
	from hi.rb:9:in `<main>' called with NilClass
```

Inspired by the following Twitter thread: https://twitter.com/lzsthw/status/1374350046909628423




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