[ruby-core:86555] [Ruby trunk Bug#14690] Invalid CMDARG state after command_args followed by tLBRACE_ARG

Issue #14690 has been updated by ibylich (Ilya Bylich).


Thank you!

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Bug #14690: Invalid CMDARG state after command_args followed by tLBRACE_ARG
https://bugs.ruby-lang.org/issues/14690#change-71496

* Author: ibylich (Ilya Bylich)
* Status: Closed
* Priority: Normal
* Assignee: 
* Target version: 
* ruby -v: ruby 2.6.0dev (2018-04-15 trunk 63161) [x86_64-darwin17]
* Backport: 2.3: UNKNOWN, 2.4: UNKNOWN, 2.5: UNKNOWN
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~~~ ruby
assert_valid_syntax('let () { m(a) do; end }')
~~~

The patch that fixes it is attached.

tLBRACE_ARG does "CMDARG_PUSH(0)" in the lexer and then the parser leaves the "command_args" rule. The parser does "CMDARG_POP" to remove 1 from the top of the "CMDARG", but the thing here is that there's a 0 on top (the one pushed by tLBRACE_ARG) and the parser pops a wrong value. If the next token is tLBRACE_ARG the parser should pop 2nd top value (like "tmp = pop; pop; push(tmp)").

From what I understand that's the only token that can mutate "CMDARG" in the lexer and that can be emitted after command args.

I've found it during stress-testing a parser gem and that's the only issue that I was able to find so far.

---Files--------------------------------
cmdarg_in_command_args_followed_by_tlbrace_arg.patch (1.18 KB)


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