[wasm] Fix JSExport on structs, records and expression bodied methos (#74763)

- Fix generating qualified name for JSExport on structs, record classes and record structs.
- Fix using expression bodied methods for JSExport.
- Add unit test using all these variants with and without namespace and nested types.
- Rewrite concatenating method name.

Author: maraf

src/libraries/System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSExportGenerator.cs

@@ -319,7 +319,7 @@ private static bool ShouldVisitNode(SyntaxNode syntaxNode)
             // Verify the method has no generic types or defined implementation
             // and is marked static and partial.
             if (methodSyntax.TypeParameterList is not null
-                || methodSyntax.Body is null
+                || (methodSyntax.Body is null && methodSyntax.ExpressionBody is null)
                 || !methodSyntax.Modifiers.Any(SyntaxKind.StaticKeyword)
                 || methodSyntax.Modifiers.Any(SyntaxKind.PartialKeyword))
             {

src/libraries/System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSImportStubContext.cs

@@ -4,7 +4,9 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.Linq;
+using System.Text;
 using System.Threading;
 
 using Microsoft.CodeAnalysis;
@@ -16,6 +18,11 @@ namespace Microsoft.Interop.JavaScript
 {
     internal sealed class JSSignatureContext : IEquatable<JSSignatureContext>
     {
+        private static SymbolDisplayFormat s_typeNameFormat { get; } = new SymbolDisplayFormat(
+            globalNamespaceStyle: SymbolDisplayGlobalNamespaceStyle.Omitted,
+            typeQualificationStyle: SymbolDisplayTypeQualificationStyle.NameAndContainingTypes
+        );
+
         internal static readonly string GeneratorName = typeof(JSImportGenerator).Assembly.GetName().Name;
 
         internal static readonly string GeneratorVersion = typeof(JSImportGenerator).Assembly.GetName().Version.ToString();
@@ -118,14 +125,8 @@ public static JSSignatureContext Create(
             };
             int typesHash = Math.Abs((int)hash);
 
-
-
             var fullName = $"{method.ContainingType.ToDisplayString()}.{method.Name}";
-            string qualifiedName;
-            var ns = string.Join(".", method.ContainingType.ToDisplayParts().Where(p => p.Kind == SymbolDisplayPartKind.NamespaceName).Select(x => x.ToString()).ToArray());
-            var cn = string.Join("/", method.ContainingType.ToDisplayParts().Where(p => p.Kind == SymbolDisplayPartKind.ClassName).Select(x => x.ToString()).ToArray());
-            var qclasses = method.ContainingType.ContainingNamespace == null ? ns : ns + "." + cn;
-            qualifiedName = $"[{env.Compilation.AssemblyName}]{qclasses}:{method.Name}";
+            string qualifiedName = GetFullyQualifiedMethodName(env, method);
 
             return new JSSignatureContext()
             {
@@ -143,6 +144,17 @@ public static JSSignatureContext Create(
             };
         }
 
+        private static string GetFullyQualifiedMethodName(StubEnvironment env, IMethodSymbol method)
+        {
+            // Mono style nested class name format.
+            string typeName = method.ContainingType.ToDisplayString(s_typeNameFormat).Replace(".", "/");
+
+            if (!method.ContainingType.ContainingNamespace.IsGlobalNamespace)
+                typeName = $"{method.ContainingType.ContainingNamespace.ToDisplayString()}.{typeName}";
+
+            return $"[{env.Compilation.AssemblyName}]{typeName}:{method.Name}";
+        }
+
         private static (ImmutableArray<TypePositionInfo>, IMarshallingGeneratorFactory) GenerateTypeInformation(IMethodSymbol method, GeneratorDiagnostics diagnostics, StubEnvironment env)
         {
             ImmutableArray<IUseSiteAttributeParser> useSiteAttributeParsers = ImmutableArray.Create<IUseSiteAttributeParser>(new JSMarshalAsAttributeParser(env.Compilation));

src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportExportTest.cs

@@ -1199,7 +1199,62 @@ public void JsExportString(string value)
         public void JsExportStringNoNs()
         {
             var actual = JavaScriptTestHelper.invoke2_String("test", nameof(JavaScriptTestHelperNoNamespace.EchoString));
-            Assert.Equal("test!", actual);
+            Assert.Equal("test51", actual);
+        }
+
+        [Fact]
+        public void JsExportStructClassRecords()
+        {
+            var actual = JavaScriptTestHelper.invokeStructClassRecords("test");
+            Assert.Equal(48, actual.Length);
+            Assert.Equal("test11", actual[0]);
+            Assert.Equal("test12", actual[1]);
+            Assert.Equal("test13", actual[2]);
+            Assert.Equal("test14", actual[3]);
+            Assert.Equal("test15", actual[4]);
+            Assert.Equal("test16", actual[5]);
+            Assert.Equal("test17", actual[6]);
+            Assert.Equal("test18", actual[7]);
+            Assert.Equal("test19", actual[8]);
+            Assert.Equal("test21", actual[9]);
+            Assert.Equal("test22", actual[10]);
+            Assert.Equal("test23", actual[11]);
+            Assert.Equal("test24", actual[12]);
+            Assert.Equal("test25", actual[13]);
+            Assert.Equal("test31", actual[14]);
+            Assert.Equal("test32", actual[15]);
+            Assert.Equal("test33", actual[16]);
+            Assert.Equal("test34", actual[17]);
+            Assert.Equal("test35", actual[18]);
+            Assert.Equal("test41", actual[19]);
+            Assert.Equal("test42", actual[20]);
+            Assert.Equal("test43", actual[21]);
+            Assert.Equal("test44", actual[22]);
+            Assert.Equal("test45", actual[23]);
+            Assert.Equal("test51", actual[24]);
+            Assert.Equal("test52", actual[25]);
+            Assert.Equal("test53", actual[26]);
+            Assert.Equal("test54", actual[27]);
+            Assert.Equal("test55", actual[28]);
+            Assert.Equal("test56", actual[29]);
+            Assert.Equal("test57", actual[30]);
+            Assert.Equal("test58", actual[31]);
+            Assert.Equal("test59", actual[32]);
+            Assert.Equal("test61", actual[33]);
+            Assert.Equal("test62", actual[34]);
+            Assert.Equal("test63", actual[35]);
+            Assert.Equal("test64", actual[36]);
+            Assert.Equal("test65", actual[37]);
+            Assert.Equal("test71", actual[38]);
+            Assert.Equal("test72", actual[39]);
+            Assert.Equal("test73", actual[40]);
+            Assert.Equal("test74", actual[41]);
+            Assert.Equal("test75", actual[42]);
+            Assert.Equal("test81", actual[43]);
+            Assert.Equal("test82", actual[44]);
+            Assert.Equal("test83", actual[45]);
+            Assert.Equal("test84", actual[46]);
+            Assert.Equal("test85", actual[47]);
         }
 
         [Fact]