Verifier crashes on a field or enum constant whose declaring class cannot be resolved

The crash is in Utils.qualifyFieldName (Utils.java, around line 56), reached from RefinementTypeChecker.visitCtFieldRead (line 325) when a CtFieldReference has a null declaring type. Start by running the four-line Repro class from the issue against the verifier and checking how the null case is handled for other field reads. Done means the reproducer prints the 'Passed Verification' result with the compilation warning instead of throwing, and the unresolved-type case is covered by a test.

Impact: verification stops with an internal error: 5 of the 53 real-world files below.

Description

Reading a field whose declaring type is unknown (an enum constant in a case label, a field generated by Lombok such as log, an array's .length on a value of an unresolved type): CtFieldReference.getDeclaringType() is null and Utils.qualifyFieldName calls getQualifiedName() on it.

Minimal reproducer (org.example.missing is not on the classpath)

import org.example.missing.Mode;

public class Repro {
    static int weight(Mode mode) {
        switch (mode) {
            case STATEFUL:
                return 2;
            default:
                return 1;
        }
    }
}

Expected

Correct! Passed Verification. (with the "Java compilation encountered issues" warning).

Actual

Exception in thread "main" java.lang.RuntimeException: 
Error while checking CtMethodImpl
  on weight(Mode mode) { 
  at Repro.java:4
  with 
Error while checking CtBlockImpl
  on { 
  at Repro.java:4
  with 
Error while checking CtSwitchImpl
  on switch (mode) { 
  at Repro.java:5
  with 
Error while checking CtCaseImpl
  on case STATEFUL: 
  at Repro.java:6
  with 
Error while checking CtFieldReadImpl
  on STATEFUL: 
  at Repro.java:6
  with Cannot invoke "spoon.reflect.reference.CtTypeReference.getQualifiedName()" because the return value of "spoon.reflect.reference.CtFieldReference.getDeclaringType()" is null
	at liquidjava.processor.refinement_checker.TypeChecker.scan(TypeChecker.java:80)
	at spoon.reflect.visitor.CtScanner.scan(CtScanner.java:189)
	at spoon.reflect.visitor.CtScanner.scan(CtScanner.java:154)
	at spoon.reflect.visitor.CtScanner.visitCtClass(CtScanner.java:363)
	at liquidjava.processor.refinement_checker.RefinementTypeChecker.visitCtClass(RefinementTypeChecker.java:97)
	at spoon.support.reflect.declaration.CtClassImpl.accept(CtClassImpl.java:63)
	at liquidjava.processor.RefinementProcessor.lambda$processPackage$3(RefinementProcessor.java:51)
	at java.base/java.lang.Iterable.forEach(Iterable.java:75)
	at liquidjava.processor.RefinementProcessor.processPackage(RefinementProcessor.java:50)
	at liquidjava.processor.RefinementProcessor.process(RefinementProcessor.java:35)
	at liquidjava.processor.RefinementProcessor.process(RefinementProcessor.java:15)
	at spoon.support.visitor.ProcessingVisitor.scan(ProcessingVisitor.java:72)
	at spoon.support.QueueProcessingManager.process(QueueProcessingManager.java:118)
	at spoon.support.QueueProcessingManager.process(QueueProcessingManager.java:132)
	at liquidjava.api.CommandLineLauncher.launch(CommandLineLauncher.java:92)
	at liquidjava.api.CommandLineLauncher.main(CommandLineLauncher.java:41)
...
Caused by: java.lang.NullPointerException: Cannot invoke "spoon.reflect.reference.CtTypeReference.getQualifiedName()" because the return value of "spoon.reflect.reference.CtFieldReference.getDeclaringType()" is null
	at liquidjava.utils.Utils.qualifyFieldName(Utils.java:56)
	at liquidjava.processor.refinement_checker.RefinementTypeChecker.visitCtFieldRead(RefinementTypeChecker.java:325)
	at liquidjava.processor.refinement_checker.TypeChecker.scan(TypeChecker.java:69)

Reproduced on main at dcfc4eb2 (liquidjava-verifier 0.0.35).

Real-world files that hit it

• log.error("get host name error:{}", e.getMessage()); — apache/ozhera (file)
• UNKNOWN_CASING; — apache/derby (file)
• (p.define().length > 0 || p.include().length > 0 || p.cinclude().length > 0 || — larael/javacpp (file)
• STATEFUL: — stratwine/openejb (file)
• (config.httpAdminPassword.length() < MIN_ADMIN_PASSWORD_LENGTH) { — spazio17/muralis (file)

Context

Found while running LiquidJava on the original repository files of 53 real-world typestate and refinement bugs (the same files as our study exercises, before simplification). Each file is verified on its own, as a user would on one file of a project, so the project's other classes and its dependencies are not on the classpath. On main this crash and the two related ones (#388 binary operator, #389 unary operator, #390 field read) stop verification in 33 of the 53 files.