Fix #1319: Property name collides with variable name

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

@@ -29,5 +29,14 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			get;
 			set;
 		}
+
+		public int issue1319 {
+			get;
+		}
+
+		public AutoProperties(int issue1319)
+		{
+			this.issue1319 = issue1319;
+		}
 	}
 }

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

@@ -47,6 +47,8 @@
   .field private int32 '<PropertyWithAttributeOnBackingField>k__BackingField'
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
   .custom instance void [mscorlib]System.ObsoleteAttribute::.ctor(string) = ( 01 00 05 46 69 65 6C 64 00 00 )                   // ...Field..
+  .field private initonly int32 '<issue1319>k__BackingField'
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
   .method public hidebysig specialname instance int32 
           get_A() cil managed
   {
@@ -135,10 +137,21 @@
     IL_0007:  ret
   } // end of method AutoProperties::set_PropertyWithAttributeOnBackingField
 
+  .method public hidebysig specialname instance int32 
+          get_issue1319() cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld      int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::'<issue1319>k__BackingField'
+    IL_0006:  ret
+  } // end of method AutoProperties::get_issue1319
+
   .method public hidebysig specialname rtspecialname 
-          instance void  .ctor() cil managed
+          instance void  .ctor(int32 issue1319) cil managed
   {
-    // Code size       21 (0x15)
+    // Code size       28 (0x1c)
     .maxstack  8
     IL_0000:  ldarg.0
     IL_0001:  ldc.i4.1
@@ -148,7 +161,10 @@
     IL_0009:  stfld      int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::'<B>k__BackingField'
     IL_000e:  ldarg.0
     IL_000f:  call       instance void [mscorlib]System.Object::.ctor()
-    IL_0014:  ret
+    IL_0014:  ldarg.0
+    IL_0015:  ldarg.1
+    IL_0016:  stfld      int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::'<issue1319>k__BackingField'
+    IL_001b:  ret
   } // end of method AutoProperties::.ctor
 
   .method private hidebysig specialname rtspecialname static 
@@ -187,6 +203,10 @@
     .get instance int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::get_PropertyWithAttributeOnBackingField()
     .set instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::set_PropertyWithAttributeOnBackingField(int32)
   } // end of property AutoProperties::PropertyWithAttributeOnBackingField
+  .property instance int32 issue1319()
+  {
+    .get instance int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::get_issue1319()
+  } // end of property AutoProperties::issue1319
 } // end of class ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties
 
 

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

@@ -52,6 +52,9 @@
   .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
   .custom instance void [mscorlib]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggerBrowsableState) = ( 01 00 00 00 00 00 00 00 ) 
   .custom instance void [mscorlib]System.ObsoleteAttribute::.ctor(string) = ( 01 00 05 46 69 65 6C 64 00 00 )                   // ...Field..
+  .field private initonly int32 '<issue1319>k__BackingField'
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
+  .custom instance void [mscorlib]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggerBrowsableState) = ( 01 00 00 00 00 00 00 00 ) 
   .method public hidebysig specialname instance int32 
           get_A() cil managed
   {
@@ -140,10 +143,21 @@
     IL_0007:  ret
   } // end of method AutoProperties::set_PropertyWithAttributeOnBackingField
 
+  .method public hidebysig specialname instance int32 
+          get_issue1319() cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       7 (0x7)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld      int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::'<issue1319>k__BackingField'
+    IL_0006:  ret
+  } // end of method AutoProperties::get_issue1319
+
   .method public hidebysig specialname rtspecialname 
-          instance void  .ctor() cil managed
+          instance void  .ctor(int32 issue1319) cil managed
   {
-    // Code size       22 (0x16)
+    // Code size       30 (0x1e)
     .maxstack  8
     IL_0000:  ldarg.0
     IL_0001:  ldc.i4.1
@@ -154,7 +168,11 @@
     IL_000e:  ldarg.0
     IL_000f:  call       instance void [mscorlib]System.Object::.ctor()
     IL_0014:  nop
-    IL_0015:  ret
+    IL_0015:  nop
+    IL_0016:  ldarg.0
+    IL_0017:  ldarg.1
+    IL_0018:  stfld      int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::'<issue1319>k__BackingField'
+    IL_001d:  ret
   } // end of method AutoProperties::.ctor
 
   .method private hidebysig specialname rtspecialname static 
@@ -193,6 +211,10 @@
     .get instance int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::get_PropertyWithAttributeOnBackingField()
     .set instance void ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::set_PropertyWithAttributeOnBackingField(int32)
   } // end of property AutoProperties::PropertyWithAttributeOnBackingField
+  .property instance int32 issue1319()
+  {
+    .get instance int32 ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties::get_issue1319()
+  } // end of property AutoProperties::issue1319
 } // end of class ICSharpCode.Decompiler.Tests.TestCases.Pretty.AutoProperties
 
 

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -192,14 +192,31 @@ namespace ICSharpCode.Decompiler.CSharp
 			return currentFunction.Ancestors.OfType<ILFunction>().SelectMany(f => f.Variables).Any(v => v.Name == name);
 		}
 
+		bool RequiresQualifier(IMember member, TranslatedExpression target)
+		{
+			if (HidesVariableWithName(member.Name))
+				return true;
+			if (member.IsStatic)
+				return !IsCurrentOrContainingType(member.DeclaringTypeDefinition);
+			return !(target.Expression is ThisReferenceExpression || target.Expression is BaseReferenceExpression);
+		}
+
 		ExpressionWithResolveResult ConvertField(IField field, ILInstruction targetInstruction = null)
 		{
 			var target = TranslateTarget(targetInstruction,
 				nonVirtualInvocation: true,
 				memberStatic: field.IsStatic,
 				memberDeclaringType: field.DeclaringType);
-			bool requireTarget = HidesVariableWithName(field.Name)
+			bool requireTarget;
-				|| (field.IsStatic ? !IsCurrentOrContainingType(field.DeclaringTypeDefinition) : !(target.Expression is ThisReferenceExpression || target.Expression is BaseReferenceExpression));
+			// If this is a reference to the backing field of an automatic property and we're going to transform automatic properties
+			// in PatternStatementTransform, then we have to do the "requires qualifier"-check based on the property instead of the field.
+			// It is easier to solve this special case here than in PatternStatementTransform, because here we perform all resolver checks.
+			// It feels a bit hacky, though.
+			if (settings.AutomaticProperties && PatternStatementTransform.IsBackingFieldOfAutomaticProperty(field, out var property)) {
+				requireTarget = RequiresQualifier(property, target);
+			} else {
+				requireTarget = RequiresQualifier(field, target);
+			}
 			bool targetCasted = false;
 			var targetResolveResult = requireTarget ? target.ResolveResult : null;
 

ICSharpCode.Decompiler/CSharp/Transforms/PatternStatementTransform.cs

@@ -565,6 +565,19 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			return base.VisitIdentifier(identifier);
 		}
 
+		internal static bool IsBackingFieldOfAutomaticProperty(IField field, out IProperty property)
+		{
+			property = null;
+			if (!(field.Name.StartsWith("<") && field.Name.EndsWith(">k__BackingField")))
+				return false;
+			if (!field.IsCompilerGenerated())
+				return false;
+			var propertyName = field.Name.Substring(1, field.Name.Length - 1 - ">k__BackingField".Length);
+			property = field.DeclaringTypeDefinition
+				.GetProperties(p => p.Name == propertyName, GetMemberOptions.IgnoreInheritedMembers).FirstOrDefault();
+			return property != null;
+		}
+
 		Identifier ReplaceBackingFieldUsage(Identifier identifier)
 		{
 			if (identifier.Name.StartsWith("<") && identifier.Name.EndsWith(">k__BackingField")) {