[ruby-core:122576] [Ruby Misc#20968] `Array#fetch_values` unexpected method name in stack trace

Issue #20968 has been updated by Eregon (Benoit Daloze).


@mame Here is an example bug due to this change, based on the `inject` case I mentioned in https://bugs.ruby-lang.org/issues/20968#note-6.
I think this is strong enough to revert that change.

ruby-master:
```
$ ruby -e '[1,2].inject(:tap)'   
-e:in '<main>': wrong number of arguments (given 1, expected 0) (ArgumentError)
	from -e:1:in 'Enumerable#inject'
	from -e:1:in '<main>'
```

This backtrace does not show `tap` is called, that's a bug, since the ArgumentError is from `Kernel#tap`.
Instead, this backtrace pretends the ArgumentError comes from `-e:in '<main>'`, that is wrong and incorrect, `-e:in '<main>'` does not raise an exception itself, there is no `raise` in `<main>`.
BTW, that location is missing a line number (`-e` instead of `-e:1`), that's another problem & inconsistency.
I think no one wants this backtrace, it's wrong in many ways.

With `ruby -e '[1,2].inject(:class)'` ruby-master gives the exact same backtrace, even though the exception originates from a different method (Kernel#class) but the backtrace completely hides this crucial information.

3.4.2:
```
$ ruby -e '[1,2].inject(:tap)'
<internal:kernel>:89:in 'tap': wrong number of arguments (given 1, expected 0) (ArgumentError)
	from -e:1:in 'Enumerable#inject'
	from -e:1:in '<main>'
```

This is correct, it is clear that it is `tap` that raises the `ArgumentError`, and that `tap` is defined in `<internal:kernel>:89` and that `tap` is called by `inject`.
I think most people would expect this backtrace.
(nitpick: it would be nice if it would show `in 'Kernel#tap'` instead of `in 'tap'` but that is probably a separate improvement)

This bug happens whenever a core method (whether defined in C or Ruby) calls another core method defined in Ruby, because the change here hides crucial information.
See [this list](https://gist.github.com/eregon/912e6359e83781c5fa1c638d3768c526) of core methods defined in Ruby if you want to experiment more.

---

FWIW, this is what it looks on TruffleRuby:
```
$ ruby -ve '[1,2].inject(:tap)'
truffleruby 24.2.1, like ruby 3.3.7, Oracle GraalVM Native [x86_64-linux]
<internal:core> core/kernel.rb:519:in `tap': wrong number of arguments (given 1, expected 0) (ArgumentError)
	from <internal:core> core/enumerable.rb:528:in `inject'
	from -e:1:in `<main>'
```
It's correct and similar to CRuby 3.4, except `Enumerable#inject` is also defined in Ruby.

----------------------------------------
Misc #20968: `Array#fetch_values` unexpected method name in stack trace
https://bugs.ruby-lang.org/issues/20968#change-113811

* Author: koic (Koichi ITO)
* Status: Closed
----------------------------------------

It seems that the current Ruby implementation is displaying unexpected method name in stack trace.

## Expected

Similar to `Hash#fetch_values`, the method name `Array#fetch_values` is expected to be displayed in the stack trace.

```console
$ ruby -e '{k: 42}.fetch_values(:unknown)'
-e:1:in 'Hash#fetch_values': key not found: :unknown (KeyError)
        from -e:1:in '<main>'

$ ruby -e '[1].fetch_values(42)'
-e:1:in 'Array#fetch_values': index 42 outside of array bounds: -1...1 (IndexError)
        from -e:1:in '<main>'
```


## Actual

The stack trace displays the `Array#fetch` method, which user is not aware of, along with the `<internal.array>` stack trace.

```console
$ ruby -e '[1].fetch_values(42)'
<internal:array>:211:in 'Array#fetch': index 42 outside of array bounds: -1...1 (IndexError)
        from <internal:array>:211:in 'block in Array#fetch_values'
        from <internal:array>:211:in 'Array#map!'
        from <internal:array>:211:in 'Array#fetch_values'
        from -e:1:in '<main>'
```


It likely requires an approach such as implementing it in C, as suggested in https://github.com/ruby/ruby/pull/11555.



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