Add new ConversionKind to IsImplicitConversion test (#35095)

src/Compilers/CSharp/Portable/Binder/Semantics/Conversions/ConversionKindExtensions.cs

@@ -21,6 +21,7 @@ public static bool IsImplicitConversion(this ConversionKind conversionKind)
             switch (conversionKind)
             {
                 case ConversionKind.NoConversion:
+                case ConversionKind.UnsetConversionKind:
                     return false;
 
                 case ConversionKind.Identity:

src/Compilers/CSharp/Test/Symbol/Compilation/GetSemanticInfoTests.cs

@@ -5916,5 +5916,36 @@ public void GetSpecialType_ThrowsOnGreaterThanCount()
 
             Assert.True(exceptionThrown, $"{nameof(comp.GetSpecialType)} did not throw when it should have.");
         }
+
+        [Fact]
+        [WorkItem(34984, "https://github.com/dotnet/roslyn/issues/34984")]
+        public void ConversionIsExplicit_UnsetConversionKind()
+        {
+            var source =
+@"class C1
+{
+}
+
+class C2
+{
+    public void M() 
+    {
+        var c = new C1();
+        foreach (string item in c.Items)
+        {
+        }
+}";
+            var comp = CreateCompilation(source);
+            var tree = comp.SyntaxTrees.Single();
+            var model = comp.GetSemanticModel(tree);
+
+            var root = tree.GetRoot();
+            var foreachSyntaxNode = root.DescendantNodes().OfType<ForEachStatementSyntax>().Single();
+            var foreachSymbolInfo = model.GetForEachStatementInfo(foreachSyntaxNode);
+
+            Assert.Equal(Conversion.UnsetConversion, foreachSymbolInfo.CurrentConversion);
+            Assert.True(foreachSymbolInfo.CurrentConversion.Exists);
+            Assert.False(foreachSymbolInfo.CurrentConversion.IsImplicit);
+        }
     }
 }