From: mame@... Date: 2020-09-07T15:08:34+00:00 Subject: [ruby-core:99964] [Ruby master Bug#17160] Wrong exception backtrace Issue #17160 has been updated by mame (Yusuke Endoh). Status changed from Open to Rejected It is confusing, but I think there is nothing wrong. There are two points. The first point is that the location for a method written in C is represented by its caller's location. This is an example: `Integer#times` is implemented in C, so its location is represented as `t.rb:2`. ``` 1: def foo 2: 1.times do 3: raise 4: end 5: end 6: 7: foo ``` ``` $ ./miniruby t.rb t.rb:3:in `block in foo': unhandled exception from t.rb:2:in `times' # <== See this line from t.rb:2:in `foo' from t.rb:7:in `
' ``` Note that there is no `t.rb:1` location in the backtrace. A backtrace location represents where the interpreter is executing, so usually, the first line of a method body tend not to be included in a backtrace (unless an exception occurs during evaluation of optional arguments, for example). The second point is that a rescue clause for a method body is considered as if the clause is called from the first line of the method body. This is exceptional, and may be confusing; it reflects the implementation detail. But currently it is at least intentional, I think. This is an example: `t.rb:4` is virtually called from `t.rb:1` which is the first line of the method body. ``` def foo raise rescue raise "foo", cause: nil end foo ``` ``` $ ./miniruby t.rb t.rb:4:in `rescue in foo': foo (RuntimeError) from t.rb:1:in `foo' # <== See this line from t.rb:7:in `
' ``` So, now your example can be understood as: ``` # exc.backtrace -e:1:in `
' /builddir/t/evaluator.rb:22:in `eval' # This line is for `Binding#eval`; the method is written in C, so it shows its caller's location /builddir/t/evaluator.rb:22:in `eval' # This line is for `WebConsole::Evaluator#eval`; the interpreter now executes Line 22, so it is correct -e:1:in `
' # caller /builddir/t/evaluator.rb:24:in `rescue in eval' /builddir/t/evaluator.rb:21:in `eval' # This is included for the exception of a method rescue clause -e:1:in `
' ``` ---------------------------------------- Bug #17160: Wrong exception backtrace https://bugs.ruby-lang.org/issues/17160#change-87503 * Author: vo.x (Vit Ondruch) * Status: Rejected * Priority: Normal * ruby -v: ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-linux] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- Looking at web-console test results [1], there is following error reported: ~~~ WebConsole::EvaluatorTest#test_Evaluator_callers_are_cleaned_up_of_unneeded_backtraces [/home/travis/build/rails/web-console/test/web_console/evaluator_test.rb:63]: --- expected +++ actual @@ -1,3 +1,3 @@ "RuntimeError: oops -\tfrom /home/travis/build/rails/web-console/test/web_console/evaluator_test.rb:61:in `block in ' +\tfrom (eval):1:in `block in ' " ~~~ Trying to reproduce the issue, it seems that the exception backtrace is not correct. I have used slightly modified version of [2] included in attachment and the output is: ~~~ $ ruby -ractive_support -r./evaluator -e 'e = WebConsole::Evaluator.new(binding); puts e.eval("raise %{oops}")' # exc.backtrace # -e:1:in `
' /builddir/t/evaluator.rb:22:in `eval' /builddir/t/evaluator.rb:22:in `eval' -e:1:in `
' # caller # /builddir/t/evaluator.rb:24:in `rescue in eval' /builddir/t/evaluator.rb:21:in `eval' -e:1:in `
' RuntimeError: oops ~~~ I believe, that the `exc.backtrace` is wrong and the second line should actually be ```/builddir/t/evaluator.rb:21:in `eval'``` similarly to the output of the `caller`. [1]: https://travis-ci.org/github/rails/web-console/jobs/719200769 [2]: https://raw.githubusercontent.com/rails/web-console/master/lib/web_console/evaluator.rb ---Files-------------------------------- evaluator.rb (1.12 KB) -- https://bugs.ruby-lang.org/ Unsubscribe: