RFR: 8301580: Error recovery does not clear returnResult [v2]

[Jan Lahoda]

> Considering code like:
> 
> class C {
>     void m
>     {
>         return;
>     }
> }
> 
> 
> `void m` is wrapped in an erroneous tree (which is good), and if/when `Attr` is processing it in `visitErroneous`, it will create a new `Env` to attribute the erroneous part.
> 
> But, `Attr` will set a `returnResult` into the `Env`'s info - and that info is shared with the outter `Env`, so there will be a `returnResult` set after `visitErroneous`. `{ return ; }` is interpreted as an initializer, and there should be an error for the `return` there, but this error is missing, due to the set `returnResult`. This will then fail later in `Flow` with an exception:
> 
> 
> $ javac -XDshould-stop.at=FLOW -XDdev /tmp/C.java

Jan Lahoda has updated the pull request incrementally with one additional commit since the last revision:

  Using info.dup(), as suggested.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12361/files
  - new: https://git.openjdk.org/jdk/pull/12361/files/4acb0d43..06a70c81

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12361&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12361&range=00-01

  Stats: 9 lines in 1 file changed: 0 ins; 5 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12361.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12361/head:pull/12361

PR: https://git.openjdk.org/jdk/pull/12361