GROOVY-11907: trait field reference transform restructure

[eric-milles]

Restructure the trait receiver transformer to funnel all the field reference transformation through a single method. I replaced the instanceof checking with a simpler set of choices.

1. When the self parameter is "$static$self" use directly
2. When the field is static use "$self.getClass()"
3. Otherwise, cast "$self" to the field helper type

    private Expression transformFieldReference(final Expression exp, final FieldNode fn, final Expression value) {
        Expression receiver;
        if (ClassHelper.isClassType(weaved.getOriginType())) {
            receiver = varX(weaved); // $static$self
        } else if (fn.isStatic()) {
            var call = callX(varX(weaved), "getClass"); // $self.getClass()
            call.setImplicitThis(false);
            call.setMethodTarget(ClassHelper.OBJECT_TYPE.getGetterMethod("getClass", false));
            receiver = call;
        } else {
            receiver = castX(fieldHelper, varX(weaved)); // (<trait class>$Trait$FieldHelper) $self
        }

        MethodCallExpression mce;
        if (value == null) {
            mce = callX(receiver, Traits.helperGetterName(fn));
        } else {
            mce = callX(receiver, Traits.helperSetterName(fn), transform(value));
        }
        mce.setImplicitThis(false);
        mce.setSourcePosition(exp);

        // GROOVY-7255: static fields are available via the implementing class, which is not checkable
        if (fn.isStatic()) mce.putNodeMetaData(TraitASTTransformation.DO_DYNAMIC, fn.getOriginType());

        return mce;
    }

see #2443

This was the grails error before the change:

java.lang.AssertionError
        at groovyjarjarasm.asm.Frame.putAbstractType(Frame.java:1482)
        at groovyjarjarasm.asm.MethodWriter.putAbstractTypes(MethodWriter.java:1961)
        at groovyjarjarasm.asm.MethodWriter.putFrame(MethodWriter.java:1920)
        at groovyjarjarasm.asm.MethodWriter.visitFrameEnd(MethodWriter.java:1852)
        at groovyjarjarasm.asm.Frame.accept(Frame.java:1405)
        at groovyjarjarasm.asm.MethodWriter.computeAllFrames(MethodWriter.java:1630)
        at groovyjarjarasm.asm.MethodWriter.visitMaxs(MethodWriter.java:1548)
        at org.codehaus.groovy.classgen.AsmClassGenerator.visitConstructorOrMethod(AsmClassGenerator.java:626)
        at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitMethod(ClassCodeVisitorSupport.java:110)
        at org.codehaus.groovy.classgen.AsmClassGenerator.visitMethod(AsmClassGenerator.java:771)
        at org.codehaus.groovy.ast.ClassNode.visitMethods(ClassNode.java:1335)
        at org.codehaus.groovy.ast.ClassNode.visitContents(ClassNode.java:1328)
        at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitClass(ClassCodeVisitorSupport.java:52)
        at org.codehaus.groovy.classgen.AsmClassGenerator.visitClass(AsmClassGenerator.java:379)
        at org.codehaus.groovy.control.CompilationUnit$3.call(CompilationUnit.java:780)
        at org.codehaus.groovy.control.CompilationUnit$IPrimaryClassNodeOperation.doPhaseOperation(CompilationUnit.java:922)
        at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:668)
        at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:642)
        at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:623)
        at org.gradle.api.internal.tasks.compile.ApiGroovyCompiler.execute(ApiGroovyCompiler.java:285)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.4934%. Comparing base (bc8bc7a) to head (19f3899).

Files with missing lines	Patch %	Lines
...oovy/transform/trait/TraitReceiverTransformer.java	92.5926%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@                Coverage Diff                 @@
##               master      #2451        +/-   ##
==================================================
- Coverage     66.4994%   66.4934%   -0.0060%     
+ Complexity      30215      30211         -4     
==================================================
  Files            1408       1408                
  Lines          117744     117732        -12     
  Branches        20907      20906         -1     
==================================================
- Hits            78299      78284        -15     
- Misses          33020      33022         +2     
- Partials         6425       6426         +1     

Files with missing lines	Coverage Δ
...oovy/transform/trait/TraitReceiverTransformer.java	88.6228% <92.5926%> (-0.7627%)	⬇️

... and 3 files with indirect coverage changes

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