RFR: 8286895: InternalError: Exception during analyze

[Vicente Romero]

On Tue, 24 May 2022 11:25:10 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> Consider code like:
> 
> Number n = 0;
> if (!n instanceof Integer i) {}
> 
> javac parses this like:
> 
> Number n = 0;
> if ((!n) instanceof Integer i) {}
> 
> 
> This is obviously erroneous, and will report an error in `Attr`, but if this code gets to `Flow`, like in JShell, then it will split the `inits`/`uninits` of variables to the `true`/`false` inits while processing the unary negation. But, then, the `instanceof` operator will try to declare a variable, which will fail with on an assertion, as that shouldn't be done when the inits are split to `true`/`false`:
> 
> Caused by: java.lang.AssertionError
>         at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
>         at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
>         at jdk.compiler/com.sun.tools.javac.util.Bits.excl(Bits.java:220)
>         at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.newVar(Flow.java:1883)
>         at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitVarDef(Flow.java:2261)
>         at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:1027)
>         at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
>         at jdk.compiler/com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:444)
>         at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.scan(Flow.java:1743)
>         at jdk.compiler/com.sun.tools.javac.tree.TreeScanner.visitBindingPattern(TreeScanner.java:307)
>         at jdk.compiler/com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitBindingPattern(Flow.java:2848)
> ...
> 
> 
> The proposed solution is to use `scanExpr` when handling the `instanceof`'s expression, which will merge the `true`/`false` inits, and let the variable be declared.

looks good to me

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

Marked as reviewed by vromero (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/8866