Fix bug in StringInterpolation transform: do not transform if arguments use string literals, nested string literals are not allowed.

ICSharpCode.Decompiler.Tests/CorrectnessTestRunner.cs

@@ -16,6 +16,7 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.CodeDom.Compiler;
 using System.IO;
 using System.Linq;
@@ -254,7 +255,7 @@ namespace ICSharpCode.Decompiler.Tests
 			try {
 				outputFile = Tester.CompileCSharp(Path.Combine(TestCasePath, testFileName), options,
 					outputFileName: Path.Combine(TestCasePath, testOutputFileName));
-				string decompiledCodeFile = Tester.DecompileCSharp(outputFile.PathToAssembly);
+				string decompiledCodeFile = Tester.DecompileCSharp(outputFile.PathToAssembly, GetSettings(options));
 				decompiledOutputFile = Tester.CompileCSharp(decompiledCodeFile, options);
 				
 				Tester.RunAndCompareOutput(testFileName, outputFile.PathToAssembly, decompiledOutputFile.PathToAssembly, decompiledCodeFile);
@@ -268,7 +269,7 @@ namespace ICSharpCode.Decompiler.Tests
 					decompiledOutputFile.TempFiles.Delete();
 			}
 		}
-		
+
 		void RunIL(string testFileName, CompilerOptions options = CompilerOptions.UseDebug, AssemblerOptions asmOptions = AssemblerOptions.None)
 		{
 			string outputFile = null;
@@ -276,7 +277,7 @@ namespace ICSharpCode.Decompiler.Tests
 
 			try {
 				outputFile = Tester.AssembleIL(Path.Combine(TestCasePath, testFileName), asmOptions);
-				string decompiledCodeFile = Tester.DecompileCSharp(outputFile);
+				string decompiledCodeFile = Tester.DecompileCSharp(outputFile, GetSettings(options));
 				decompiledOutputFile = Tester.CompileCSharp(decompiledCodeFile, options);
 				
 				Tester.RunAndCompareOutput(testFileName, outputFile, decompiledOutputFile.PathToAssembly, decompiledCodeFile);
@@ -288,5 +289,15 @@ namespace ICSharpCode.Decompiler.Tests
 					decompiledOutputFile.TempFiles.Delete();
 			}
 		}
+
+		DecompilerSettings GetSettings(CompilerOptions options)
+		{
+			if (!options.HasFlag(CompilerOptions.UseRoslyn)) {
+				return new DecompilerSettings {
+					StringInterpolation = false
+				};
+			}
+			return new DecompilerSettings();
+		}
 	}
 }

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CS6_StringInterpolation.cs

@@ -38,6 +38,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			Console.WriteLine(string.Format("{}", args.Length));
 			Console.WriteLine(string.Format("{0:}", args.Length));
 			Console.WriteLine(string.Format("{0{a}0}", args.Length));
+			Console.WriteLine(string.Format("test: {0}", string.Join(",", args)));
 		}
 	}
 }

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CS6_StringInterpolation.opt.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CS6_StringInterpolation.dll
-// MVID: {12BAF781-868E-4161-A197-F81DC457D96B}
+// MVID: {F5FD4CCF-66AB-4E03-8E45-96F42947A65D}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x03620000
+// Image base: 0x03070000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -115,8 +115,8 @@
 
   .method public hidebysig static void  Invalid(string[] args) cil managed
   {
-    // Code size       530 (0x212)
-    .maxstack  2
+    // Code size       556 (0x22c)
+    .maxstack  3
     IL_0000:  ldstr      ""
     IL_0005:  ldarg.0
     IL_0006:  ldlen
@@ -301,7 +301,15 @@
     IL_0207:  call       string [mscorlib]System.String::Format(string,
                                                                 object)
     IL_020c:  call       void [mscorlib]System.Console::WriteLine(string)
-    IL_0211:  ret
+    IL_0211:  ldstr      "test: {0}"
+    IL_0216:  ldstr      ","
+    IL_021b:  ldarg.0
+    IL_021c:  call       string [mscorlib]System.String::Join(string,
+                                                              string[])
+    IL_0221:  call       string [mscorlib]System.String::Format(string,
+                                                                object)
+    IL_0226:  call       void [mscorlib]System.Console::WriteLine(string)
+    IL_022b:  ret
   } // end of method CS6_StringInterpolation::Invalid
 
   .method public hidebysig specialname rtspecialname 

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CS6_StringInterpolation.roslyn.il

@@ -25,14 +25,14 @@
   .ver 0:0:0:0
 }
 .module CS6_StringInterpolation.dll
-// MVID: {97DDF3A3-A5BD-433E-B982-F6DD427CE8FF}
+// MVID: {FE9286DD-8C20-4FC8-8786-543E572641EA}
 .custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
 .imagebase 0x10000000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x03970000
+// Image base: 0x03840000
 
 
 // =============== CLASS MEMBERS DECLARATION ===================
@@ -121,8 +121,8 @@
 
   .method public hidebysig static void  Invalid(string[] args) cil managed
   {
-    // Code size       554 (0x22a)
-    .maxstack  2
+    // Code size       581 (0x245)
+    .maxstack  3
     IL_0000:  nop
     IL_0001:  ldstr      ""
     IL_0006:  ldarg.0
@@ -331,7 +331,16 @@
                                                                 object)
     IL_0223:  call       void [mscorlib]System.Console::WriteLine(string)
     IL_0228:  nop
-    IL_0229:  ret
+    IL_0229:  ldstr      "test: {0}"
+    IL_022e:  ldstr      ","
+    IL_0233:  ldarg.0
+    IL_0234:  call       string [mscorlib]System.String::Join(string,
+                                                              string[])
+    IL_0239:  call       string [mscorlib]System.String::Format(string,
+                                                                object)
+    IL_023e:  call       void [mscorlib]System.Console::WriteLine(string)
+    IL_0243:  nop
+    IL_0244:  ret
   } // end of method CS6_StringInterpolation::Invalid
 
   .method public hidebysig specialname rtspecialname 

ICSharpCode.Decompiler/CSharp/Transforms/ReplaceMethodCallsWithOperators.cs

@@ -110,7 +110,8 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 					break;
 				case "System.String.Format":
 					if (context.Settings.StringInterpolation && arguments.Length > 1
-						&& arguments[0] is PrimitiveExpression stringExpression && stringExpression.Value is string)
+						&& arguments[0] is PrimitiveExpression stringExpression && stringExpression.Value is string
+						&& arguments.Skip(1).All(a => !a.DescendantsAndSelf.OfType<PrimitiveExpression>().Any(p => p.Value is string)))
 					{
 						var tokens = new List<(TokenKind, int, string)>();
 						int i = 0;