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Make rb_debug_inspector_backtrace_locations return a raw backtrace #13510

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Merged
merged 3 commits into from
Jun 4, 2025

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@mame mame commented Jun 4, 2025

Previously, a user of the debug inspector API was supposed to use rb_debug_inspector_backtrace_locations to get an array of Thread::Backtrace::Location, and then used its index to get more information from rb_debug_inspector _frame_binding_get(index), etc.

However, rb_debug_inspector_backtrace_locations returned an array of backtraces excluding rescue/ensure frames. On the other hand, rb_debug_inspector_frame_binding_get(index) interprets index with rescue/ensure frames. This led to inconsistency of the index, and it was very difficult to correctly use the debug inspector API.

This is a minimal fix for the issue by making
rb_debug_inspector_backtrace_locations return a raw backtrace including rescue/ensure frames.

Previously, a user of the debug inspector API was supposed to use
`rb_debug_inspector_backtrace_locations` to get an array of
`Thread::Backtrace::Location`, and then used its index to get more
information from `rb_debug_inspector _frame_binding_get(index)`, etc.

However, `rb_debug_inspector_backtrace_locations` returned an array of
backtraces excluding rescue/ensure frames. On the other hand,
`rb_debug_inspector_frame_binding_get(index)` interprets index with
rescue/ensure frames. This led to inconsistency of the index, and it was
very difficult to correctly use the debug inspector API.

This is a minimal fix for the issue by making
`rb_debug_inspector_backtrace_locations` return a raw backtrace
including rescue/ensure frames.
mame added a commit to mame/debug that referenced this pull request Jun 4, 2025
```
$ ruby -Ilib exe/rdbg rescue-test.rb
[1, 7] in rescue-test.rb
=>   1| 1.times do
     2|   begin
     3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    <main> at rescue-test.rb:1
(rdbg) s    # step command
[1, 7] in rescue-test.rb
     1| 1.times do
     2|   begin
=>   3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    block in <main> at rescue-test.rb:3
  ruby#1    Integer#times at <internal:numeric>:257
  # and 1 frames (use `bt' command for all frames)
(rdbg) s    # step command
/home/mame/work/debug/lib/debug/thread_client.rb:85:in 'DEBUGGER__::ThreadClient#default_frame_formatter': undefined method '+' for nil (NoMethodError)

          "#{colorize_blue("block")}#{args_str} in #{colorize_blue(block_loc + level)}"
                                                                             ^
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'Method#call'
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'DEBUGGER__::ThreadClient#frame_str'
        from /home/mame/work/debug/lib/debug/thread_client.rb:742:in 'block in DEBUGGER__::ThreadClient#show_frames'
        from <internal:numeric>:257:in 'Integer#times'
        from /home/mame/work/debug/lib/debug/thread_client.rb:739:in 'DEBUGGER__::ThreadClient#show_frames'
        from /home/mame/work/debug/lib/debug/thread_client.rb:304:in 'DEBUGGER__::ThreadClient#suspend'
        from /home/mame/work/debug/lib/debug/thread_client.rb:358:in 'block in DEBUGGER__::ThreadClient#step_tp'
        from rescue-test.rb:5:in 'block in <main>'
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
rescue-test.rb:3:in 'block in <main>': unhandled exception
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
```

This is because `rb_debug_inspector_backtrace_locations` returned a
modified backtrace, which skips rescue/ensure frames, but
`rb_debug_inspector_frame_XXX_get`'s index is considered for a raw
backtrace, which includes rescue/ensure frames.

The problem wil be fixed by ruby/ruby#13510.
However, now the backtrace includes rescue/ensure frames, so some tests
in debug gem fails. This fixes the test failures.
mame added a commit to ruby/debug that referenced this pull request Jun 4, 2025
```
$ ruby -Ilib exe/rdbg rescue-test.rb
[1, 7] in rescue-test.rb
=>   1| 1.times do
     2|   begin
     3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    <main> at rescue-test.rb:1
(rdbg) s    # step command
[1, 7] in rescue-test.rb
     1| 1.times do
     2|   begin
=>   3|     raise
     4|   rescue
     5|     p 1
     6|   end
     7| end
=>#0    block in <main> at rescue-test.rb:3
  #1    Integer#times at <internal:numeric>:257
  # and 1 frames (use `bt' command for all frames)
(rdbg) s    # step command
/home/mame/work/debug/lib/debug/thread_client.rb:85:in 'DEBUGGER__::ThreadClient#default_frame_formatter': undefined method '+' for nil (NoMethodError)

          "#{colorize_blue("block")}#{args_str} in #{colorize_blue(block_loc + level)}"
                                                                             ^
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'Method#call'
        from /home/mame/work/debug/lib/debug/thread_client.rb:755:in 'DEBUGGER__::ThreadClient#frame_str'
        from /home/mame/work/debug/lib/debug/thread_client.rb:742:in 'block in DEBUGGER__::ThreadClient#show_frames'
        from <internal:numeric>:257:in 'Integer#times'
        from /home/mame/work/debug/lib/debug/thread_client.rb:739:in 'DEBUGGER__::ThreadClient#show_frames'
        from /home/mame/work/debug/lib/debug/thread_client.rb:304:in 'DEBUGGER__::ThreadClient#suspend'
        from /home/mame/work/debug/lib/debug/thread_client.rb:358:in 'block in DEBUGGER__::ThreadClient#step_tp'
        from rescue-test.rb:5:in 'block in <main>'
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
rescue-test.rb:3:in 'block in <main>': unhandled exception
        from <internal:numeric>:257:in 'Integer#times'
        from rescue-test.rb:1:in '<main>'
```

This is because `rb_debug_inspector_backtrace_locations` returned a
modified backtrace, which skips rescue/ensure frames, but
`rb_debug_inspector_frame_XXX_get`'s index is considered for a raw
backtrace, which includes rescue/ensure frames.

The problem wil be fixed by ruby/ruby#13510.
However, now the backtrace includes rescue/ensure frames, so some tests
in debug gem fails. This fixes the test failures.
@mame mame marked this pull request as ready for review June 4, 2025 08:26
@mame
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mame commented Jun 4, 2025

Approved by @ko1

@mame mame merged commit 8d49c05 into ruby:master Jun 4, 2025
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