Issue #20968 has been updated by koic (Koichi ITO). Thank you for your prompt response. I hadn’t realized that the same issue occurs with `1.ceildiv(0)` as well. This is not a bug, but my concern arises from the asymmetry in how exceptions are displayed for `Array#fetch_values`. Even though `Array#fetch_values` was used incorrectly, the backtrace displays `Array#fetch` at the top, which was not explicitly called, and this caused some confusion. This is just a personal opinion, but it seems more natural for exception related to `Array#fetch_values` to show `Array#fetch_values` itself instead of the internal implementation of `Array#fetch`. This is not specific to `Array#fetch_values`, as the same can be said for cases like `1.ceildiv(0)`. ---------------------------------------- Bug #20968: `Array#fetch_values` unexpected method name in stack trace https://bugs.ruby-lang.org/issues/20968#change-111095 * Author: koic (Koichi ITO) * Status: Open * ruby -v: ruby 3.4.0dev (2024-12-19T04:44:56Z master 2783868de2) +PRISM [x86_64-darwin23] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- 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. -- https://bugs.ruby-lang.org/