From b6e55eafc3b0d63bd2148464b900f6c863f291e7 Mon Sep 17 00:00:00 2001
From: ds5678 <49847914+ds5678@users.noreply.github.com>
Date: Sat, 26 Apr 2025 20:58:58 -0700
Subject: [PATCH] Parenthesize interpolations containing global::

---
 .../ICSharpCode.Decompiler.Tests.csproj       |  1 +
 .../PrettyTestRunner.cs                       | 13 ++++++++++++
 ...ballyQualifiedTypeInStringInterpolation.cs |  7 +++++++
 .../OutputVisitor/InsertParenthesesVisitor.cs | 20 +++++++++++++++++++
 4 files changed, 41 insertions(+)
 create mode 100644 ICSharpCode.Decompiler.Tests/TestCases/Pretty/GloballyQualifiedTypeInStringInterpolation.cs

diff --git a/ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj b/ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj
index e6053e558..5a89e7178 100644
--- a/ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj
+++ b/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" />
diff --git a/ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs b/ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs
index 9b4184aa7..b528cd65b 100644
--- a/ICSharpCode.Decompiler.Tests/PrettyTestRunner.cs
+++ b/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)
 		{
diff --git a/ICSharpCode.Decompiler.Tests/TestCases/Pretty/GloballyQualifiedTypeInStringInterpolation.cs b/ICSharpCode.Decompiler.Tests/TestCases/Pretty/GloballyQualifiedTypeInStringInterpolation.cs
new file mode 100644
index 000000000..d15031502
--- /dev/null
+++ b/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)}";
+	}
+}
diff --git a/ICSharpCode.Decompiler/CSharp/OutputVisitor/InsertParenthesesVisitor.cs b/ICSharpCode.Decompiler/CSharp/OutputVisitor/InsertParenthesesVisitor.cs
index 2fb3a4546..2c67b55a5 100644
--- a/ICSharpCode.Decompiler/CSharp/OutputVisitor/InsertParenthesesVisitor.cs
+++ b/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)
 		{