Parenthesize interpolations containing global::

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -137,6 +137,7 @@
     <Compile Include="TestCases\ILPretty\Issue3442.cs" />
     <Compile Include="TestCases\ILPretty\MonoFixed.cs" />
     <Compile Include="TestCases\Pretty\Comparisons.cs" />
+    <Compile Include="TestCases\Pretty\GloballyQualifiedTypeInStringInterpolation.cs" />
     <Compile Include="TestCases\Pretty\Issue3406.cs" />
     <Compile Include="TestCases\Pretty\PointerArithmetic.cs" />
     <Compile Include="TestCases\Pretty\Issue3439.cs" />

ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs

@@ -308,6 +308,19 @@ namespace ICSharpCode.Decompiler.Tests
 			await RunForLibrary(cscOptions: cscOptions);
 		}
 
+		[Test]
+		public async Task GloballyQualifiedTypeInStringInterpolation([ValueSource(nameof(roslynOnlyWithNet40Options))] CompilerOptions cscOptions)
+		{
+			// https://github.com/icsharpcode/ILSpy/issues/3447
+			await RunForLibrary(
+				cscOptions: cscOptions,
+				configureDecompiler: settings => {
+					settings.UsingDeclarations = false;
+					settings.AlwaysUseGlobal = true;
+				}
+			);
+		}
+
 		[Test]
 		public async Task LiftedOperators([ValueSource(nameof(defaultOptions))] CompilerOptions cscOptions)
 		{

ICSharpCode.Decompiler.Tests/TestCases/Pretty/GloballyQualifiedTypeInStringInterpolation.cs

@@ -0,0 +1,7 @@
+namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
+{
+	public static class GloballyQualifiedTypeInStringInterpolation
+	{
+		public static string CurrentDateTime => $"Time: {(global::System.DateTime.Now)}";
+	}
+}

ICSharpCode.Decompiler/CSharp/OutputVisitor/InsertParenthesesVisitor.cs

@@ -389,6 +389,26 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 			base.VisitAsExpression(asExpression);
 		}
 
+		public override void VisitInterpolation(Interpolation interpolation)
+		{
+			// If an interpolation contains global::, we need to parenthesize the expression.
+			if (IsThisOrChildMemberTypeWithDoubleColon(interpolation))
+				Parenthesize(interpolation.Expression);
+			base.VisitInterpolation(interpolation);
+
+			static bool IsThisOrChildMemberTypeWithDoubleColon(AstNode node)
+			{
+				if (node is MemberType { IsDoubleColon: true })
+					return true;
+				foreach (var child in node.Children)
+				{
+					if (IsThisOrChildMemberTypeWithDoubleColon(child))
+						return true;
+				}
+				return false;
+			}
+		}
+
 		// Conditional operator
 		public override void VisitConditionalExpression(ConditionalExpression conditionalExpression)
 		{