add fix

Author: daveMueller

src/coverlet.core/Abstractions/ICecilSymbolHelper.cs

@@ -12,5 +12,6 @@ internal interface ICecilSymbolHelper
   {
     IReadOnlyList<BranchPoint> GetBranchPoints(MethodDefinition methodDefinition);
     bool SkipNotCoverableInstruction(MethodDefinition methodDefinition, Instruction instruction);
+    bool SkipInlineAssignedAutoProperty(bool skipAutoProps, MethodDefinition methodDefinition, Instruction instruction);
   }
 }

src/coverlet.core/Instrumentation/Instrumenter.cs

@@ -592,7 +592,8 @@ private void InstrumentIL(MethodDefinition method)
 
         if (sequencePoint != null && !sequencePoint.IsHidden)
         {
-          if (IsInsideExcludedMethodSection(sequencePoint))
+          if (_cecilSymbolHelper.SkipInlineAssignedAutoProperty(_parameters.SkipAutoProps, method,
+                currentInstruction) || IsInsideExcludedMethodSection(sequencePoint))
           {
             index++;
             continue;

src/coverlet.core/Symbols/CecilSymbolHelper.cs

@@ -1362,6 +1362,44 @@ private bool SkipExpressionBreakpointsSequences(MethodDefinition methodDefinitio
       return false;
     }
 
+    public bool SkipInlineAssignedAutoProperty(bool skipAutoProps, MethodDefinition methodDefinition, Instruction instruction)
+    {
+      if (!skipAutoProps) return false;
+
+      return SkipGeneratedBackingFieldAssignment(methodDefinition, instruction);
+    }
+
+    private static bool SkipGeneratedBackingFieldAssignment(MethodDefinition methodDefinition, Instruction instruction)
+    {
+      /*
+          For inline initialization of properties the compiler generates a field that is set in the constructor of the class. 
+          To skip this we search for compiler generated fields that are set in the constructor.
+
+          .field private string '<SurName>k__BackingField'
+          .custom instance void [System.Runtime]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() = (
+              01 00 00 00
+          )
+
+          .method public hidebysig specialname rtspecialname 
+          instance void .ctor () cil managed 
+          {
+              IL_0000: ldarg.0
+              IL_0001: ldsfld    string[System.Runtime] System.String::Empty
+              IL_0006: stfld     string TestRepro.ClassWithPropertyInit::'<SurName>k__BackingField'
+              ...
+          }
+          ...
+      */
+      IEnumerable<FieldDefinition> autogeneratedBackingFields = methodDefinition.DeclaringType.Fields.Where(x =>
+          x.CustomAttributes.Any(ca => ca.AttributeType.FullName.Equals(typeof(CompilerGeneratedAttribute).FullName)) &&
+          x.FullName.EndsWith("k__BackingField"));
+
+      return instruction.OpCode == OpCodes.Ldarg &&
+             instruction.Next?.Next?.OpCode == OpCodes.Stfld &&
+             instruction.Next?.Next?.Operand is FieldReference fr &&
+             autogeneratedBackingFields.Select(x => x.FullName).Contains(fr.FullName);
+    }
+
     private static bool SkipBranchGeneratedExceptionFilter(Instruction branchInstruction, MethodDefinition methodDefinition)
     {
       if (!methodDefinition.Body.HasExceptionHandlers)