From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@...>
Date: 2025-06-24T02:45:54+00:00
Subject: [ruby-core:122587] [Ruby Misc#20968] `Array#fetch_values` unexpected method name in stack trace

Issue #20968 has been updated by mame (Yusuke Endoh).


Thanks, I fixed the issue by commit:3546cedde3f6f46f00fd67b73081cbfbb83144de.

```
$ ./miniruby -ve '[1,2].inject(:tap)'
ruby 3.5.0dev (2025-06-24T02:39:58Z master 3546cedde3) +PRISM [x86_64-linux]
-e:1:in 'Kernel#tap': wrong number of arguments (given 1, expected 0) (ArgumentError)
        from -e:1:in 'Enumerable#inject'
        from -e:1:in '<main>'
```

There was another problem that the class to which a method belonged was not displayed when an ArgumentError is raised at the time of argument passing. The commit fixes that problem as well:

* ruby 3.4.2: `<internal:kernel>:89:in 'tap': ...`
* master: `-e:1:in 'Kernel#tap': ...`.

----------------------------------------
Misc #20968: `Array#fetch_values` unexpected method name in stack trace
https://bugs.ruby-lang.org/issues/20968#change-113822

* 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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