[BUG] UtilityClass with generics produces NullPointerException in Javac

[juriad]

Describe the bug

@UtilityClass together with a generic method and two methods of the same name causes Javac to crash with NPE in Java 11, 17, 18 and 19 but not 8 (not tested others).

There are a lot of small changes that make the code compile:

• static is added to the inner class DTO;
• one of the convert methods is renamed;
• convertValue(DTO.class) is replaced with just null;
• the parameter of convertValue method is removed.
• changing Class<T> to Class.

I have seen a few NPE reports but all were connected with val, while this is not.

To Reproduce

import lombok.experimental.UtilityClass;

@UtilityClass
class Converter {
    <T> T convertValue(Class<T> toValueType) {
        return null;
    }

    DTO convert(Object json) {
        return convertValue(DTO.class);
    }

    Object convert(DTO dto) {
        return null;
    }

    class DTO {
    }
}

The full stack trace is:

An exception has occurred in the compiler (11.0.16.1). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
	at jdk.compiler/com.sun.tools.javac.code.Types.asSuper(Types.java:2111)
	at jdk.compiler/com.sun.tools.javac.code.Types$4.visitClassType(Types.java:1179)
	at jdk.compiler/com.sun.tools.javac.code.Types$4.visitClassType(Types.java:1100)
	at jdk.compiler/com.sun.tools.javac.code.Type$ClassType.accept(Type.java:993)
	at jdk.compiler/com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:4857)
	at jdk.compiler/com.sun.tools.javac.code.Types.isSubtype(Types.java:1096)
	at jdk.compiler/com.sun.tools.javac.code.Types.isSubtypeNoCapture(Types.java:1070)
	at jdk.compiler/com.sun.tools.javac.code.Types$4.visitClassType(Types.java:1186)
	at jdk.compiler/com.sun.tools.javac.code.Types$4.visitClassType(Types.java:1100)
	at jdk.compiler/com.sun.tools.javac.code.Type$ClassType.accept(Type.java:993)
	at jdk.compiler/com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:4857)
	at jdk.compiler/com.sun.tools.javac.code.Types.isSubtype(Types.java:1096)
	at jdk.compiler/com.sun.tools.javac.code.Types.isSubtypeUncheckedInternal(Types.java:1022)
	at jdk.compiler/com.sun.tools.javac.code.Types.isSubtypeUnchecked(Types.java:1008)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$IncorporationBinaryOpKind$1.apply(Infer.java:1183)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$IncorporationBinaryOp.apply(Infer.java:1238)
	at jdk.compiler/com.sun.tools.javac.comp.Infer.doIncorporationOp(Infer.java:1169)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$IncorporationAction.isSubtype(Infer.java:721)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$CheckBounds.checkBound(Infer.java:796)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$CheckBounds.apply(Infer.java:772)
	at jdk.compiler/com.sun.tools.javac.comp.Infer.doIncorporation(Infer.java:1115)
	at jdk.compiler/com.sun.tools.javac.comp.Infer$GraphSolver.solve(Infer.java:1655)
	at jdk.compiler/com.sun.tools.javac.comp.InferenceContext.solve(InferenceContext.java:475)
	at jdk.compiler/com.sun.tools.javac.comp.InferenceContext.solve(InferenceContext.java:482)
	at jdk.compiler/com.sun.tools.javac.comp.Infer.instantiateMethod(Infer.java:218)
	at jdk.compiler/com.sun.tools.javac.comp.Resolve.rawInstantiate(Resolve.java:605)
	at jdk.compiler/com.sun.tools.javac.comp.Resolve.checkMethod(Resolve.java:644)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.checkMethod(Attr.java:4122)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.checkIdInternal(Attr.java:3915)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.checkMethodIdInternal(Attr.java:3820)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.checkId(Attr.java:3805)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.visitIdent(Attr.java:3555)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCIdent.accept(JCTree.java:2264)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.visitApply(Attr.java:2006)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1650)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.visitReturn(Attr.java:1866)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1562)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStats(Attr.java:743)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1294)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1036)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1098)
	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:866)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribTree(Attr.java:655)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribStat(Attr.java:724)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4685)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4576)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4505)
	at jdk.compiler/com.sun.tools.javac.comp.Attr.attrib(Attr.java:4450)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1337)
	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
	at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:311)
	at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:170)
	at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
	at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)

Stacktrace in Java 17 looks very similar (frames are a few lines off) but we get more information:

An exception has occurred in the compiler (17.0.4.1). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
java.lang.NullPointerException: Cannot read field "type" because "sym" is null

Version info:

• Lombok version org.projectlombok:lombok:1.18.24 (used in Gradle)
• Platform: Javas were installed using SDKMAN!

works:
openjdk version "1.8.0_345"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_345-b01)
OpenJDK 64-Bit Server VM (Temurin)(build 25.345-b01, mixed mode)

fails:
openjdk version "11.0.12" 2021-07-20
OpenJDK Runtime Environment 18.9 (build 11.0.12+7)
OpenJDK 64-Bit Server VM 18.9 (build 11.0.12+7, mixed mode)

also fails:
openjdk version "17.0.4.1" 2022-08-12
OpenJDK Runtime Environment Temurin-17.0.4.1+1 (build 17.0.4.1+1)
OpenJDK 64-Bit Server VM Temurin-17.0.4.1+1 (build 17.0.4.1+1, mixed mode, sharing)

[Rawi01]

Thanks for this excellent bug report. It is similar to #3097 but it seems like I missed to also reset a second field that only gets used sometimes.