From: "marcper (Marcelo Pereira) via ruby-core" <ruby-core@...>
Date: 2023-10-29T11:38:00+00:00
Subject: [ruby-core:115195] [Ruby master Bug#18743] Enumerator#next / peek re-use each others stacktraces

Issue #18743 has been updated by marcper (Marcelo Pereira).





Hi @nobu, and @ko1. The change was merged in July. Shouldn't this issue be closed?



----------------------------------------

Bug #18743: Enumerator#next / peek re-use each others stacktraces

https://bugs.ruby-lang.org/issues/18743#change-105109



* Author: sos4nt (Stefan Sch��ler)

* Status: Open

* Priority: Normal

* Assignee: ko1 (Koichi Sasada)

* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN

----------------------------------------

I encountered an odd behavior.



If I rescue the `StopIteration` exception from `peek` and call `next` afterwards: (or vice-versa)



```ruby

# enum.rb             # 1

                      # 2

enum = [].each        # 3

enum.peek rescue nil  # 4

enum.next             # 5

```



it will show the stacktrace from the rescued `peek` call:



```

$ ruby enum.rb

enum.rb:4:in `peek': iteration reached an end (StopIteration)

	from enum.rb:4:in `<main>'

```



Whereas the error should refer to `next` on line number 5.



The same happens when calling `peek` after `next` or when having muliple `peek` / `next` calls:



```ruby

# enum.rb                # 1

                         # 2

enum = [].each           # 3

enum.peek rescue nil     # 4

enum.next rescue nil     # 5

enum.peek rescue nil     # 6

puts "line #{__LINE__}"  # 7

enum.next                # 8

```



The stacktrace from the first (rescued) `peek` or `next` call will be shown which doesn't reflect the actual error location:



```

$ ruby enum.rb

line 7

enum.rb:4:in `peek': iteration reached an end (StopIteration)

	from enum.rb:4:in `<main>'

```



This is very confusing when debugging code.



---Files--------------------------------

01-Recreate-stacktrace-enumerator.patch (1.29 KB)





-- 

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