From: "mame (Yusuke Endoh)" <noreply@...>
Date: 2022-09-27T08:10:50+00:00
Subject: [ruby-core:110103] [Ruby master Bug#19016] syntax_suggest is not working with Ruby 3.2.0-preview2

Issue #19016 has been updated by mame (Yusuke Endoh).


There are two different sub-issues in this issue.

### 1. syntax_suggest does not work for `ruby foo.rb`.

This is because a SyntaxError exception is not thrown even if there is a syntax error in foo.rb of `ruby foo.rb`. Instead, the interpreter prints the syntax error directly. So `Exception#detailed_message` is not called, which means syntax_suggest cannot intercept the exception handling.

This could be fixed by throwing a SyntaxError exception even if there is a parse error in foo.rb, but I don't know how hard this fix will be implemented.

### 2. syntax_suggest does not work for `ruby -e 'load "foo.rb"'`.

In this case, a SyntaxError exception is thrown, so `Exception#detailed_message` of syntax_suggest is actually called.
However, `Exception#detailed_message` is called after the interpreter termination process has started.
It is prohibited to create a new thread in this state, but syntax_suggest uses Timeout.timeout, which tries to create a new thread.
This causes the failure `#<ThreadError: can't alloc thread>` which @hsbt mentioned.

[My PR](https://github.com/ruby/ruby/pull/6452) changes the order so that `Exception#detailed_message` is called *before* the interpreter termination process.
However, I am a little afraid that this change has unforeseen side effects because it will print an error message when other threads are still running.

@ko1 pointed that the following script prints `sub thread (RuntimeError)` and then `main thread (RuntimeError)` in Ruby 3.1, and that `main thread (RuntimeError)` and then `sub thread (RuntimeError)` with my PR applied.

```ruby
Thread.new { begin sleep; ensure; raise "sub thread"; end }
raise "main thread"
```

```
$ ruby -v tt.rb
ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux]
#<Thread:0x00007ffff3f0b2e8 tt.rb:1 aborting> terminated with exception (report_on_exception is true):
tt.rb:1:in `ensure in block in <main>': sub thread (RuntimeError)
        from tt.rb:1:in `block in <main>'
tt.rb:2:in `<main>': main thread (RuntimeError)
```

```
$ ./miniruby -v tt.rb
ruby 3.2.0dev (2022-09-27T06:08:48Z error_print-before.. 4e8618306b) [x86_64-linux]
tt.rb:2:in `<main>': main thread (RuntimeError)
#<Thread:0x00007ffff7408fb8 tt.rb:1 aborting> terminated with exception (report_on_exception is true):
tt.rb:1:in `ensure in block in <main>': sub thread (RuntimeError)
        from tt.rb:1:in `block in <main>'
```

----------------------------------------
Bug #19016: syntax_suggest is not working with Ruby 3.2.0-preview2
https://bugs.ruby-lang.org/issues/19016#change-99361

* Author: hsbt (Hiroshi SHIBATA)
* Status: Assigned
* Priority: Normal
* Assignee: hsbt (Hiroshi SHIBATA)
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
----------------------------------------
`syntax_suggest` is merged as default gems in Ruby 3.2.0-preview2. But it's not working yet.

```
$ cat bar.rb
def foo
  def bar
end

$ ruby -v bar.rb
ruby 3.2.0dev (2022-09-22T05:37:56Z master f07e651a90) +YJIT [arm64-darwin22]
bar.rb:3: warning: mismatched indentations at 'end' with 'def' at 2
bar.rb:3: syntax error, unexpected end-of-input, expecting `end'
```

and gem version is also not working now.

```
$ cat foo.rb
require "bundler/inline"

gemfile do
  source "https://rubygems.org"
  gem "syntax_suggest"
end

require_relative "bar"
```

```
$ ruby -v foo.rb
ruby 3.2.0dev (2022-09-22T05:37:56Z master f07e651a90) +YJIT [arm64-darwin22]
/path/to/bar.rb:3: warning: mismatched indentations at 'end' with 'def' at 2
foo.rb:8:in `require_relative': /path/to/bar.rb:3: syntax error, unexpected end-of-input, expecting `end' (SyntaxError)
        from foo.rb:8:in `<main>'
```

But Ruby 3.1 is works.

```
$ ruby -v foo.rb
ruby 3.1.3p51 (2022-09-10 revision 9581248c4a) [arm64-darwin22]
/path/to/bar.rb:3: warning: mismatched indentations at 'end' with 'def' at 2
--> /path/to/bar.rb

Unmatched keyword, missing `end' ?

  1  def foo
��� 2    def bar
  3  end

/Users/hsbt/.local/share/gem/gems/syntax_suggest-0.0.1/lib/syntax_suggest/core_ext.rb:93:in `require': /path/to/bar.rb:3: syntax error, unexpected end-of-input, expecting `end' (SyntaxError)
        from /Users/hsbt/.local/share/gem/gems/syntax_suggest-0.0.1/lib/syntax_suggest/core_ext.rb:93:in `require_relative'
        from foo.rb:8:in `<main>'
```




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