RFR: JDK-8191981: javac crash when detecting lambda candidates

[Maurizio Cimadamore]

Your fix looks fine - unfortunately the 
'ArguymentAttr.withLocalCacheContext' was created for this very reason, 
but I think that approach is not sufficient to fully disable the cache. 
It will simply avoid cache changes to propagate out - while here you 
want something which basically disables the cache entirely.

Maurizio


On 28/11/17 11:46, Jan Lahoda wrote:
> Hi,
>
> Consider this code:
> ---
> public class LambdaWithMethod {
>     public static void run(Runnable r) {
>         run(new Runnable() {
>             public void run() {
>                 put(get());
>             }
>         });
>     }
>     private static String get() { return null; }
>     private static void put(String i) {}
> }
> ---
>
> When detecting lambda candidates, this crashes javac (please see the 
> bug for full exception):
> ---
> $ javac -XDfind=lambda /tmp/LambdaWithMethod.java
> [snip]
> java.lang.AssertionError: Analyzer error when processing: [snip]
> at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:162)
> at 
> jdk.compiler/com.sun.tools.javac.comp.Analyzer.doAnalysis(Analyzer.java:562)
> [snip]
> ---
>
> The underlying exception is:
> ---
> java.lang.ClassCastException: 
> jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation cannot 
> be cast to jdk.compiler/com.sun.tools.javac.tree.JCTree$JCLambda
>         at 
> jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr$ExplicitLambdaType.dup(ArgumentAttr.java:456)
>         at 
> jdk.compiler/com.sun.tools.javac.comp.ArgumentAttr.processArg(ArgumentAttr.java:237)
> [snip]
> ---
>
> (Full exception in the bug.)
>
> The problem appears to be that when the trial lambda node (that 
> replaces the anonymous class) is created, there is no explicit 
> position set, and so the last position set is used. And the 
> ArgumentAttr.argumentTypeCache uses the position as key, and so the 
> value for "get()" is (appears to be) used for the lambda, which leads 
> to the crash.
>
> Bug; https://bugs.openjdk.java.net/browse/JDK-8191981
> Proposed patch: http://cr.openjdk.java.net/~jlahoda/8191981/webrev.00
>
> How does this look?
>
> Thanks,
>    Jan
>
>