[GROOVY-9079] STC: NPE in StaticTypeCheckingVisitor.inferSAMTypeGenericsInAssignment

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0-beta-1, 2.5.7
• Assignee: Paul King
• Reporter: Eric Milles
• Created: 11/Apr/19 21:17
• Updated: 20/May/19 07:31
• Resolved: 14/Apr/19 23:10

Description

Consider the following:

@groovy.transform.CompileStatic
void meth() {
  java.util.concurrent.Callable<String> call = { -> '' }
}

This code produces:

BUG! exception in phase 'instruction selection' in source unit 'Blah.groovy' unexpected NullpointerException
	at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:1148)
	at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:654)
	at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:632)
	at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:609)
	...
Caused by: java.lang.NullPointerException
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.inferSAMTypeGenericsInAssignment(StaticTypeCheckingVisitor.java:4282)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.getResultType(StaticTypeCheckingVisitor.java:4133)
	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.visitBinaryExpression(StaticTypeCheckingVisitor.java:831)
	...

The method in StaticTypeCheckingVisitor calls ClosureExpression.getParameters(), which returns null for a closure expression like "

{ -> '' }

".