RFR: 8253584: Redunant errors for partial member selects

[Vicente Romero]

On Thu, 24 Sep 2020 10:33:55 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> For code like:
> package t;
> 
> class Test {
> 
>     void t() {
>         if (true) {
>             s().
>         } else {
>         }
>     }
> 
>     String s() {
>         return null;
>     }
> }
> 
> (note the missing member name after `s().`), javac will produce a number of compile-time errors:
> $ javac /tmp/Test.java
> 
>             s().
>                 ^
> 
>             s().
>                ^
> 
>         } else {
>          ^
> 
>         } else {
>           ^
> 
>     String s() {
>             ^
> 
> }
>  ^
> 6 errors
> 
> The reason is that after not seeing an identifier after the `.` javac will skip the token that follows the dot. This
> was done to improve errors in https://bugs.openjdk.java.net/browse/JDK-8081769 . But here, reading the next token will
> skip the closing `}`, and the parser will de-synchronize with the braces, leading to the follow-up errors.  The
> proposal here is to handle incorrect `.class` specially, and avoid reading the next token when an identifier is no
> specified in a member select, except when the next token is `class`.  The errors with this patch are:
> $ javac /tmp/Test.java
> 
>             s().
>                 ^
> 
>             s().
>                ^
> 2 errors
> 
> This seems much better.

looks good to me

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

Marked as reviewed by vromero (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/333