javac throws a NPE when compiling a lambda expression
Arul Dhesiaseelan
aruld at acm.org
Mon Jun 13 05:19:20 PDT 2011
Hmm, my bad, I did not notice that missing import, was using a text editor
to develop lambdas, which proved to be a disaster in this case.
Thanks Maurizio and Ali.
On Mon, Jun 13, 2011 at 4:41 AM, Maurizio Cimadamore <
maurizio.cimadamore at oracle.com> wrote:
> On 13/06/11 11:37, Ali Ebrahimi wrote:
> > Hi Maurizio,
> > similar crash for this code:
> > call(#{ -> System.out.println(
> > undefinedVar ); });
> Yeah, all these problems have gone now (fixed in the latest push).
> Thanks for the headsup.
>
> Maurizio
> > Ali Ebrahimi
> >
> > On Mon, Jun 13, 2011 at 12:07 PM, Maurizio Cimadamore
> > <maurizio.cimadamore at oracle.com
> > <mailto:maurizio.cimadamore at oracle.com>> wrote:
> >
> > I confirm that the following simplified example actually fails
> > with the latest compiler:
> >
> > class TestLambda {
> >
> >
> > interface SAM {
> > void m();
> > }
> >
> > {
> > call(#{ -> log(new Date() + ""); });
> > }
> >
> > void call(SAM s) { }
> >
> >
> > void log(String msg) {
> > System.out.println(msg);
> > }
> > }
> >
> > The problem is caused by a bad error recovery - in the above
> > example java.util.Date cannot be found, because the corresponding
> > import is missing. Which means that the compiler should emit an
> > error, but in this case the error is swallen when attributing the
> > lambda body - which means that the compiler tries to emit code for
> > an incorrect source program - hence the NPE.
> >
> > Maurizio
> >
> >
> >
> > On 13/06/11 07:46, Ali Ebrahimi wrote:
> >
> > Hi,
> > This sample code compiles with current lambda repository build.
> >
> > Ali Ebrahimi
> >
> > On Sat, Jun 11, 2011 at 9:00 AM, Arul
> > Dhesiaseelan<aruld at acm.org <mailto:aruld at acm.org>> wrote:
> >
> > public class TestLambda {
> >
> > class Payment {
> > private int amount;
> >
> > Payment(int amount) {
> > this.amount = amount;
> > }
> >
> > public int getAmount() {
> > return amount;
> > }
> > }
> >
> > interface PaymentProcessor {
> > void process(Payment pmt);
> > }
> >
> > {
> > invokeProcessor(# { pmt -> log("Processed # " +
> > pmt.getAmount() + " at
> > " + new Date()) });
> > }
> >
> > void invokeProcessor(PaymentProcessor processor) {
> > processor.process(new Payment(42));
> > }
> >
> > void log(String msg) {
> > System.out.println(msg);
> > }
> > }
> >
> > I am trying to rebuild my old Lambda example (which used
> > to work with
> > earlier prototype using build 115), but failed to compile
> > with the latest
> > prototype using build 145:
> >
> > An exception has occurred in the compiler
> > (1.7.0-internal). Please file a
> > bug at the Java Developer Connection (
> > http://java.sun.com/webapps/bugreport)
> > after checking the Bug Parade for duplicates. Include your
> > program and the
> > following diagnostic in your report. Thank you.
> > java.lang.NullPointerException
> > at
> > com.sun.tools.javac.comp.Flow.visitNewClass(Flow.java:1308)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1391)
> > at
> >
> com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
> > at
> > com.sun.tools.javac.comp.Flow.scanExpr(Flow.java:572)
> > at
> > com.sun.tools.javac.comp.Flow.visitBinary(Flow.java:1504)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCBinary.accept(JCTree.java:1654)
> > at
> >
> com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
> > at
> > com.sun.tools.javac.comp.Flow.scanExpr(Flow.java:572)
> > at
> > com.sun.tools.javac.comp.Flow.scanExprs(Flow.java:582)
> > at
> > com.sun.tools.javac.comp.Flow.visitApply(Flow.java:1299)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1337)
> > at
> >
> com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
> > at
> > com.sun.tools.javac.comp.Flow.scanStat(Flow.java:556)
> > at
> > com.sun.tools.javac.comp.Flow.analyzeLambda(Flow.java:1370)
> > at
> > com.sun.tools.javac.comp.Attr.attribLambda(Attr.java:2314)
> > at
> > com.sun.tools.javac.comp.Attr$1.deferredAttr(Attr.java:2194)
> > at
> > com.sun.tools.javac.comp.Attr$1.deferredAttr(Attr.java:2185)
> > at
> >
> >
> com.sun.tools.javac.comp.Attr$SAMDeferredAttribution.complete(Attr.java:2793)
> > at
> >
> com.sun.tools.javac.comp.Infer$InferPolyCompleter.complete(Infer.java:737)
> > at
> >
> com.sun.tools.javac.comp.Infer.instantiatePoly(Infer.java:748)
> > at
> >
> >
> com.sun.tools.javac.comp.Resolve.checkRawArgumentsAcceptable(Resolve.java:553)
> > at
> >
> com.sun.tools.javac.comp.Infer.instantiateMethod(Infer.java:419)
> > at
> >
> com.sun.tools.javac.comp.Resolve.rawInstantiate(Resolve.java:396)
> > at
> > com.sun.tools.javac.comp.Resolve.selectBest(Resolve.java:820)
> > at
> >
> com.sun.tools.javac.comp.Resolve.findMethod(Resolve.java:1064)
> > at
> >
> com.sun.tools.javac.comp.Resolve.findMethod(Resolve.java:1025)
> > at
> > com.sun.tools.javac.comp.Resolve.findFun(Resolve.java:1158)
> > at
> >
> com.sun.tools.javac.comp.Resolve.resolveMethod(Resolve.java:1582)
> > at
> > com.sun.tools.javac.comp.Attr.visitIdent(Attr.java:2546)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCIdent.accept(JCTree.java:1826)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:466)
> > at
> > com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1578)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1337)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:466)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:484)
> > at
> > com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:499)
> > at
> > com.sun.tools.javac.comp.Attr.visitExec(Attr.java:1334)
> > at
> >
> >
> com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1180)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:466)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:484)
> > at
> > com.sun.tools.javac.comp.Attr.attribStat(Attr.java:519)
> > at
> > com.sun.tools.javac.comp.Attr.attribStats(Attr.java:535)
> > at
> > com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:952)
> > at
> >
> com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:794)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:466)
> > at
> > com.sun.tools.javac.comp.Attr.attribTree(Attr.java:484)
> > at
> > com.sun.tools.javac.comp.Attr.attribStat(Attr.java:519)
> > at
> > com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:3793)
> > at
> > com.sun.tools.javac.comp.Attr.attribClass(Attr.java:3715)
> > at
> > com.sun.tools.javac.comp.Attr.attribClass(Attr.java:3651)
> > at
> com.sun.tools.javac.comp.Attr.attrib(Attr.java:3625)
> > at
> >
> com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1189)
> > at
> >
> com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:877)
> > at
> >
> com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:836)
> > at
> com.sun.tools.javac.main.Main.compile(Main.java:417)
> > at
> com.sun.tools.javac.main.Main.compile(Main.java:331)
> > at
> com.sun.tools.javac.main.Main.compile(Main.java:322)
> > at com.sun.tools.javac.Main.compile(Main.java:76)
> > at com.sun.tools.javac.Main.main(Main.java:61)
> >
> >
> > java version "1.7.0-ea"
> > Java(TM) SE Runtime Environment (build 1.7.0-ea-b145)
> > Java HotSpot(TM) 64-Bit Server VM (build 21.0-b15, mixed
> mode)
> >
> > I am not sure what has changed since then. Any clues?
> >
> > -Arul
> >
> >
> >
> >
>
>
>
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