8253584: Redunant errors for partial member selects

[lahodaj]

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
/tmp/Test.java:7: error: <identifier> expected
            s().
                ^
/tmp/Test.java:7: error: not a statement
            s().
               ^
/tmp/Test.java:8: error: ';' expected
        } else {
         ^
/tmp/Test.java:8: error: 'else' without 'if'
        } else {
          ^
/tmp/Test.java:12: error: ';' expected
    String s() {
            ^
/tmp/Test.java:15: error: reached end of file while parsing
}
 ^
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 
/tmp/Test.java:7: error: <identifier> expected
            s().
                ^
/tmp/Test.java:7: error: not a statement
            s().
               ^
2 errors

This seems much better.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8253584: Redunant errors for partial member selects

Reviewers

• Vicente Romero (@vicente-romero-oracle - Reviewer) ⚠️ Review applies to 914c9fd

Download

$ git fetch https://git.openjdk.java.net/jdk pull/333/head:pull/333
$ git checkout pull/333

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[mlbridge]

Webrevs

• 01: Full - Incremental (9bc235a)
• 00: Full (914c9fd)

[vicente-romero-oracle]

looks good to me

[openjdk]

@lahodaj This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for more details.

After integration, the commit message for the final commit will be:

8253584: Redunant errors for partial member selects

Reviewed-by: vromero

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[lahodaj]

/integrate

[openjdk]

@lahodaj Since your change was applied there have been 7 commits pushed to the master branch:

• ebf443a: 8253590: java/foreign tests are still failing on x86_32 after foreign-memaccess integration
• 431338b: 8212107: VMThread issues and cleanup
• 6bddeb7: 8238761: Asynchronous handshakes
• 6d19fe6: 8253763: ParallelObjectIterator should have virtual destructor
• 55c90a1: 6514600: AbstractAction can throw NullPointerException when clone()d
• b659132: 8252888: Collapse G1MMUTracker class hierarchy
• e63b90c: 8251358: Clean up Access configuration after Shenandoah barrier change

Your commit was automatically rebased without conflicts.

Pushed as commit 86491a5.

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