NPE in ProceedOnErrorGen.visitAssign

[akurtakov]

Didn't manage to narrow the case but it happens multiple times with eclipse.platform.ui workspace:

!ENTRY org.eclipse.jdt.core 4 0 2025-01-09 22:21:40.876
!MESSAGE Cannot read field "type" because "tree" is null
!STACK 0
java.lang.NullPointerException: Cannot read field "type" because "tree" is null
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:847)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitAssign(Gen.java:2097)
	at org.eclipse.jdt.internal.javac.ProceedOnErrorGen.visitAssign(ProceedOnErrorGen.java:124)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:2101)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:859)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitExec(Gen.java:1802)
	at org.eclipse.jdt.internal.javac.ProceedOnErrorGen.visitExec(ProceedOnErrorGen.java:115)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1644)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:588)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:623)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:609)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:660)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.internalVisitBlock(Gen.java:1121)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1085)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1133)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:588)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:623)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:949)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:912)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:957)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:588)
	at jdk.compiler/com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2494)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:770)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1700)
	at org.eclipse.jdt.internal.javac.JavacCompiler$2.generate(JavacCompiler.java:161)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1668)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:977)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:897)
	at org.eclipse.jdt.internal.javac.JavacCompiler.compile(JavacCompiler.java:193)
	at org.eclipse.jdt.internal.core.builder.AbstractImageBuilder.compile(AbstractImageBuilder.java:441)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder.compile(BatchImageBuilder.java:250)
	at org.eclipse.jdt.internal.core.builder.AbstractImageBuilder.compile(AbstractImageBuilder.java:372)
	at org.eclipse.jdt.internal.core.builder.BatchImageBuilder.build(BatchImageBuilder.java:118)
	at org.eclipse.jdt.internal.core.builder.JavaBuilder.buildAll(JavaBuilder.java:317)
	at org.eclipse.jdt.internal.core.builder.JavaBuilder.build(JavaBuilder.java:220)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:1077)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:296)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:352)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:441)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:444)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:555)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:503)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:585)
	at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:207)
	at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:300)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

[mickaelistria]

We could just add some extra checks but I'm not sure it'd be suitable. I suggest we leave it open for a few days to capture some potential examples to reproduce.

[mickaelistria]

This one was probably fixed with #1152