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jonpryorjonpryor
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[Xamarin.Android.Tools.Bytecode] Support @jvmoverloads (#651)
@moljac ran into an interesting warning from `class-parse` when binding [OfficeUIFrabric][0]: warning : class-parse: warning: method com/microsoft/officeuifabric/widget/BottomNavigationView.<init>(Landroid/content/Context;)V: Local variables array has 0 entries ('LocalVariableTableAttribute(LocalVariableTableEntry(Name='context', Descriptor='Landroid/content/Context;'))'); descriptor has 1 entries! For starters, this shouldn't be a warning; it's not actionable. There is nothing a user can do to fix this warning; it's only meaningful to the Java.Interop team. Update `Xamarin.Android.Tools.Bytecode.MethodInfo.GetParameters()` so that these messages are *debug* messages, not warnings. `class-parse` knows how many parameters are present based on the JNI method descriptor, in this case `(Landroid/content/Context;)V`, which specifies one parameter type. The JNI descriptor *doesn't* contain parameter name information; where do parameter names come from? If the `.class` file was built via `javac -parameters`, then the `MethodParametersAttribute` blob can be used; see 4273e5c. However, before checking for `MethodParametersAttribute`, `class-parse` will attempt to use the `LocalVariableTableAttribute` and `LocalVariableTableEntry` values to infer parameter names. As part of this inference, method parameters are assumed to be variables with `LocalVariableTableEntry.StartPC` is 0; from `class-parse --dump BottomNavigationView.class`: LocalVariableTableAttribute( LocalVariableTableEntry(Name='context', Descriptor='Landroid/content/Context;', StartPC=0, Index=1)) Next, `class-parse` will "skip" the first variable for instance methods. This results in "skipping" the `context` variable, resulting in the message: Local variables array has 0 entries …; descriptor has 1 entries! To fix this, `class-parse` needs a stricter "skip the `this` parameter" check: the first parameter should *only* be skipped when: 1. The method is an instance method, not a `static` method, *and* 2. The JNI descriptor of the first parameter is the same as the descriptor of the declaring type. Additionally, update the code style to use `enumValue.HasFlag(V)` instead of `(enumValue & V) == V` for readability. Finally, why was this failing in the first place? In some circumstances, when the Kotlin [`@JvmOverloads`][2] annotation is used on a `constructor`, Kotlin will emit all possible overloads for the constructor, and in many of those overloads the `this` parameter *won't* be present in the `LocalVariableTableAttribute` data, as seen above with `BottomNavigationView`. [0]: https://jcenter.bintray.com/com/microsoft/uifabric/OfficeUIFabric/ [1]: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.jvm/-jvm-overloads/
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8 files changed

Lines changed: 284 additions & 7 deletions

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‎src/Xamarin.Android.Tools.Bytecode/AttributeInfo.cs‎

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@@ -429,7 +429,7 @@ public string Descriptor {
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public override string ToString ()
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{
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return string.Format ("LocalVariableTableEntry(Name='{0}', Descriptor='{1}')", Name, Descriptor);
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return $"LocalVariableTableEntry(Name='{Name}', Descriptor='{Descriptor}', StartPC={StartPC}, Index={Index})";
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}
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}
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‎src/Xamarin.Android.Tools.Bytecode/ClassFile.cs‎

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@@ -98,6 +98,8 @@ public string PackageName {
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}
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}
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public string FullJniName => "L" + ThisClass.Name.Value + ";";
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public string SourceFileName {
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get {
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var sourceFile = Attributes.Get<SourceFileAttribute> ();

‎src/Xamarin.Android.Tools.Bytecode/Methods.cs‎

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@@ -90,17 +90,21 @@ public ParameterInfo[] GetParameters ()
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if (locals != null) {
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var names = locals.LocalVariables.Where (p => p.StartPC == 0).ToList ();
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int start = 0;
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if ((AccessFlags & MethodAccessFlags.Static) == 0)
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if (names.Count != parameters.Length &&
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!AccessFlags.HasFlag (MethodAccessFlags.Static) &&
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names.Count > start &&
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names [start].Descriptor == DeclaringType.FullJniName) {
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start++; // skip `this` parameter
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}
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if (!DeclaringType.IsStatic &&
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names.Count > start &&
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(parameters.Length == 0 || parameters [0].Type.BinaryName != names [start].Descriptor)) {
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start++; // JDK 8?
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}
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if (((AccessFlags & MethodAccessFlags.Synthetic) != MethodAccessFlags.Synthetic) &&
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if (!AccessFlags.HasFlag (MethodAccessFlags.Synthetic) &&
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((names.Count - start) != parameters.Length) &&
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!enumCtor) {
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Log.Warning (1,"class-parse: warning: method {0}.{1}{2}: " +
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Log.Debug ("class-parse: method {0}.{1}{2}: " +
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"Local variables array has {3} entries ('{4}'); descriptor has {5} entries!",
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DeclaringType.ThisClass.Name.Value, Name, Descriptor,
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names.Count - start,
@@ -111,7 +115,7 @@ public ParameterInfo[] GetParameters ()
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for (int i = 0; i < max; ++i) {
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parameters [i].Name = names [start+i].Name;
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if (parameters [i].Type.BinaryName != names [start + i].Descriptor) {
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Log.Warning (1, "class-parse: warning: method {0}.{1}{2}: " +
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Log.Debug ("class-parse: method {0}.{1}{2}: " +
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"Local variable type descriptor mismatch! Got '{3}'; expected '{4}'.",
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DeclaringType.ThisClass.Name.Value, Name, Descriptor,
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parameters [i].Type.BinaryName,
@@ -122,7 +126,7 @@ public ParameterInfo[] GetParameters ()
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var sig = GetSignature ();
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if (sig != null) {
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if ((sig.Parameters.Count != parameters.Length) && !enumCtor) {
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Log.Warning (1,"class-parse: warning: method {0}.{1}{2}: " +
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Log.Debug ("class-parse: method {0}.{1}{2}: " +
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"Signature ('{3}') has {4} entries; Descriptor '{5}' has {6} entries!",
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DeclaringType.ThisClass.Name.Value, Name, Descriptor,
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Attributes.Get<SignatureAttribute>(),

‎src/Xamarin.Android.Tools.Bytecode/XmlClassDeclarationBuilder.cs‎

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@@ -39,7 +39,7 @@ public XElement ToXElement ()
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GetExtendsGenericAware (),
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new XAttribute ("final", (classFile.AccessFlags & ClassAccessFlags.Final) != 0),
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new XAttribute ("name", GetThisClassName ()),
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new XAttribute ("jni-signature", "L" + classFile.ThisClass.Name.Value + ";"),
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new XAttribute ("jni-signature", classFile.FullJniName),
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GetSourceFile (),
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new XAttribute ("static", classFile.IsStatic),
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new XAttribute ("visibility", GetVisibility (classFile.Visibility)),

‎tests/Xamarin.Android.Tools.Bytecode-Tests/JvmOverloadsConstructorTests.cs‎

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using Xamarin.Android.Tools.Bytecode;
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using NUnit.Framework;
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using Assembly = System.Reflection.Assembly;
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namespace Xamarin.Android.Tools.BytecodeTests {
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[TestFixture]
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public class JvmOverloadsConstructorTests : ClassFileFixture {
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const string ClassFile = "JvmOverloadsConstructor.class";
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const string XmlFile = "JvmOverloadsConstructor.xml";
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[Test]
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public void ClassFile_WithJavaType_class ()
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{
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var c = LoadClassFile (ClassFile);
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new ExpectedTypeDeclaration {
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MajorVersion = 0x32,
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MinorVersion = 0,
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ConstantPoolCount = 59,
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AccessFlags = ClassAccessFlags.Public | ClassAccessFlags.Final | ClassAccessFlags.Super,
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FullName = "JvmOverloadsConstructor",
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Superclass = new TypeInfo ("java/lang/Object", "Ljava/lang/Object;"),
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Methods = {
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new ExpectedMethodDeclaration {
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Name = "<init>",
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AccessFlags = MethodAccessFlags.Public,
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ReturnDescriptor = "V",
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Parameters = {
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new ParameterInfo ("something", "LJvmOverloadsConstructor;", "LJvmOverloadsConstructor;"),
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new ParameterInfo ("id", "I", "I"),
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new ParameterInfo ("imageId", "I", "I"),
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new ParameterInfo ("title", "Ljava/lang/String;", "Ljava/lang/String;"),
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new ParameterInfo ("useDivider", "Z", "Z"),
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},
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},
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new ExpectedMethodDeclaration {
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Name = "<init>",
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AccessFlags = MethodAccessFlags.Public | MethodAccessFlags.Synthetic,
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ReturnDescriptor = "V",
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Parameters = {
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new ParameterInfo ("p0", "LJvmOverloadsConstructor;", "LJvmOverloadsConstructor;"),
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new ParameterInfo ("p1", "I", "I"),
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new ParameterInfo ("p2", "I", "I"),
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new ParameterInfo ("p3", "Ljava/lang/String;", "Ljava/lang/String;"),
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new ParameterInfo ("p4", "Z", "Z"),
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new ParameterInfo ("p5", "I", "I"),
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new ParameterInfo ("p6", "Lkotlin/jvm/internal/DefaultConstructorMarker;", "Lkotlin/jvm/internal/DefaultConstructorMarker;"),
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},
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},
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new ExpectedMethodDeclaration {
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Name = "<init>",
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AccessFlags = MethodAccessFlags.Public,
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ReturnDescriptor = "V",
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Parameters = {
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new ParameterInfo ("something", "LJvmOverloadsConstructor;", "LJvmOverloadsConstructor;"),
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new ParameterInfo ("id", "I", "I"),
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new ParameterInfo ("imageId", "I", "I"),
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new ParameterInfo ("title", "Ljava/lang/String;", "Ljava/lang/String;"),
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},
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},
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new ExpectedMethodDeclaration {
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Name = "<init>",
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AccessFlags = MethodAccessFlags.Public,
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ReturnDescriptor = "V",
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Parameters = {
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new ParameterInfo ("something", "LJvmOverloadsConstructor;", "LJvmOverloadsConstructor;"),
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new ParameterInfo ("id", "I", "I"),
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new ParameterInfo ("title", "Ljava/lang/String;", "Ljava/lang/String;"),
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},
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},
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new ExpectedMethodDeclaration {
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Name = "<init>",
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AccessFlags = MethodAccessFlags.Public,
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ReturnDescriptor = "V",
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Parameters = {
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new ParameterInfo ("something", "LJvmOverloadsConstructor;", "LJvmOverloadsConstructor;"),
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new ParameterInfo ("title", "Ljava/lang/String;", "Ljava/lang/String;"),
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},
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},
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},
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}.Assert (c);
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}
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[Test]
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public void XmlDeclaration_WithJavaType_class ()
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{
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AssertXmlDeclaration (ClassFile, XmlFile);
95+
}
96+
}
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}
98+

‎tests/Xamarin.Android.Tools.Bytecode-Tests/Resources/JvmOverloadsConstructor.xml‎

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<api
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api-source="class-parse">
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<package
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name=""
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jni-name="">
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<class
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abstract="false"
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deprecated="not deprecated"
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jni-extends="Ljava/lang/Object;"
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extends="java.lang.Object"
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extends-generic-aware="java.lang.Object"
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final="true"
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name="JvmOverloadsConstructor"
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jni-signature="LJvmOverloadsConstructor;"
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source-file-name="JvmOverloadsConstructor.kt"
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static="false"
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visibility="public">
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<constructor
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deprecated="not deprecated"
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final="false"
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name="JvmOverloadsConstructor"
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static="false"
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visibility="public"
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bridge="false"
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synthetic="false"
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jni-signature="(LJvmOverloadsConstructor;IILjava/lang/String;)V">
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<parameter
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name="something"
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type="JvmOverloadsConstructor"
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jni-type="LJvmOverloadsConstructor;"
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not-null="true" />
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<parameter
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name="id"
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type="int"
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jni-type="I" />
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<parameter
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name="imageId"
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type="int"
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jni-type="I" />
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<parameter
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name="title"
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type="java.lang.String"
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jni-type="Ljava/lang/String;"
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not-null="true" />
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</constructor>
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<constructor
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deprecated="not deprecated"
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final="false"
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name="JvmOverloadsConstructor"
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static="false"
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visibility="public"
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bridge="false"
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synthetic="false"
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jni-signature="(LJvmOverloadsConstructor;IILjava/lang/String;Z)V">
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<parameter
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name="something"
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type="JvmOverloadsConstructor"
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jni-type="LJvmOverloadsConstructor;"
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not-null="true" />
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<parameter
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name="id"
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type="int"
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jni-type="I" />
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<parameter
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name="imageId"
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type="int"
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jni-type="I" />
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<parameter
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name="title"
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type="java.lang.String"
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jni-type="Ljava/lang/String;"
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not-null="true" />
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<parameter
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name="useDivider"
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type="boolean"
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jni-type="Z" />
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</constructor>
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<constructor
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deprecated="not deprecated"
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final="false"
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name="JvmOverloadsConstructor"
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static="false"
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visibility="public"
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bridge="false"
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synthetic="true"
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jni-signature="(LJvmOverloadsConstructor;IILjava/lang/String;ZILkotlin/jvm/internal/DefaultConstructorMarker;)V">
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<parameter
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name="p0"
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type="JvmOverloadsConstructor"
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jni-type="LJvmOverloadsConstructor;" />
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<parameter
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name="p1"
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type="int"
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jni-type="I" />
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<parameter
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name="p2"
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type="int"
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jni-type="I" />
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<parameter
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name="p3"
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type="java.lang.String"
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jni-type="Ljava/lang/String;" />
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<parameter
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name="p4"
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type="boolean"
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jni-type="Z" />
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<parameter
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name="p5"
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type="int"
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jni-type="I" />
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<parameter
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name="p6"
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type="kotlin.jvm.internal.DefaultConstructorMarker"
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jni-type="Lkotlin/jvm/internal/DefaultConstructorMarker;" />
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</constructor>
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<constructor
117+
deprecated="not deprecated"
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final="false"
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name="JvmOverloadsConstructor"
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static="false"
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visibility="public"
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bridge="false"
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synthetic="false"
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jni-signature="(LJvmOverloadsConstructor;ILjava/lang/String;)V">
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<parameter
126+
name="something"
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type="JvmOverloadsConstructor"
128+
jni-type="LJvmOverloadsConstructor;"
129+
not-null="true" />
130+
<parameter
131+
name="id"
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type="int"
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jni-type="I" />
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<parameter
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name="title"
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type="java.lang.String"
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jni-type="Ljava/lang/String;"
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not-null="true" />
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</constructor>
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<constructor
141+
deprecated="not deprecated"
142+
final="false"
143+
name="JvmOverloadsConstructor"
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static="false"
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visibility="public"
146+
bridge="false"
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synthetic="false"
148+
jni-signature="(LJvmOverloadsConstructor;Ljava/lang/String;)V">
149+
<parameter
150+
name="something"
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type="JvmOverloadsConstructor"
152+
jni-type="LJvmOverloadsConstructor;"
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not-null="true" />
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<parameter
155+
name="title"
156+
type="java.lang.String"
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jni-type="Ljava/lang/String;"
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not-null="true" />
159+
</constructor>
160+
</class>
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</package>
162+
</api>

‎tests/Xamarin.Android.Tools.Bytecode-Tests/kotlin/JvmOverloadsConstructor.class‎

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‎tests/Xamarin.Android.Tools.Bytecode-Tests/kotlin/JvmOverloadsConstructor.kt‎

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1+
class JvmOverloadsConstructor {
2+
@JvmOverloads
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constructor(
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something : JvmOverloadsConstructor,
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id: Int = 1,
6+
imageId: Int = 2,
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title: String,
8+
useDivider: Boolean = false
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) {
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}
11+
}

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