Bug1058058: AccessViolationException during EnC

During EnC, we serialize local variable signatures and keep them in LocalMap for the next time. However, we store the wrong value, so the next EnC would go wrong by using the invalid value from the previous EnC. (changeset 1358334)

Src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/EditAndContinueTests.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Linq;
+using System.IO;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
 using Microsoft.CodeAnalysis.CodeGen;
@@ -3366,9 +3367,9 @@ static void M()
 @"{
   // Code size       10 (0xa)
   .maxstack  1
-  .locals init ([unchanged] V_0,
-  string V_1, //b
-  int V_2) //a
+  .locals init ([object] V_0,
+                string V_1, //b
+                int V_2) //a
   IL_0000:  nop
   IL_0001:  ldc.i4.1
   IL_0002:  stloc.2
@@ -4108,9 +4109,9 @@ .maxstack  2
 {
   // Code size       33 (0x21)
   .maxstack  1
-  .locals init ([unchanged] V_0,
+  .locals init ([int] V_0,
            [object] V_1,
-           [unchanged] V_2,
+           [object] V_2,
            <>f__AnonymousType0<A> V_3, //x
            <>f__AnonymousType1<int> V_4, //y
            object V_5)
@@ -4141,9 +4142,9 @@ .maxstack  1
     @"{
   // Code size       39 (0x27)
   .maxstack  1
-  .locals init ([unchanged] V_0,
+  .locals init ([int] V_0,
            [object] V_1,
-           [unchanged] V_2,
+           [object] V_2,
            <>f__AnonymousType0<A> V_3, //x
            <>f__AnonymousType1<int> V_4, //y
            object V_5)
@@ -5590,5 +5591,73 @@ public void SymWriterErrors()
                 Assert.False(diff1.EmitResult.Success);
             }
         }
+
+        [WorkItem(1058058)]
+        [Fact]
+        public void BlobContainsInvalidValues()
+        {
+            var source0 =
+@"class C
+{
+    static void F()
+    {
+        string foo = ""abc"";
+    }
+}";
+            var source1 =
+@"class C
+{
+    static void F()
+    {
+        float foo = 10;
+    }
+}";
+            var source2 =
+@"class C
+{
+    static void F()
+    {
+        bool foo = true;
+    }
+}";
+            var compilation0 = CreateCompilationWithMscorlib(source0, options: TestOptions.DebugDll);
+            var compilation1 = CreateCompilationWithMscorlib(source1, options: TestOptions.DebugDll);
+            var compilation2 = CreateCompilationWithMscorlib(source2, options: TestOptions.DebugDll);
+            var bytes0 = compilation0.EmitToArray();
+            using (var md0 = ModuleMetadata.CreateFromImage(bytes0))
+            {
+                var reader0 = md0.MetadataReader;
+                CheckNames(reader0, reader0.GetAssemblyRefNames(), "mscorlib");
+                var method0F = compilation0.GetMember<MethodSymbol>("C.F");
+                var generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider);
+                var method1F = compilation1.GetMember<MethodSymbol>("C.F");
+                var diff1 = compilation1.EmitDifference(
+                    generation0,
+                    ImmutableArray.Create(new SemanticEdit(SemanticEditKind.Update, method0F, method1F, syntaxMap: s => null, preserveLocalVariables: true)));
+
+                var handle = MetadataTokens.BlobHandle(1);
+                byte[] value0 = reader0.GetBlobBytes(handle);
+                Assert.Equal("20-01-01-08", BitConverter.ToString(value0));
+
+                using (var md1 = diff1.GetMetadata())
+                {
+                    var reader1 = md1.Reader;
+                    var method2F = compilation2.GetMember<MethodSymbol>("C.F");
+                    var diff2F = compilation2.EmitDifference(
+                        diff1.NextGeneration,
+                        ImmutableArray.Create(new SemanticEdit(SemanticEditKind.Update, method1F, method2F, syntaxMap: s => null, preserveLocalVariables: true)));
+
+                    byte[] value1 = reader1.GetBlobBytes(handle);
+                    Assert.Equal("07-02-0E-0C", BitConverter.ToString(value1));
+
+                    using (var md2 = diff2F.GetMetadata())
+                    {
+                        var reader2 = md2.Reader;
+                        byte[] value2 = reader2.GetBlobBytes(handle);
+                        Assert.Equal("07-03-0E-0C-02", BitConverter.ToString(value2));
+                    }
+                }
+            }
+        }
     }
 }

Src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaPeWriter.cs

@@ -624,7 +624,7 @@ protected override uint SerializeLocalVariablesSignature(IMethodBody body)
                     {
                         uint start = stream.Position;
                         this.SerializeLocalVariableSignature(writer, local);
-                        uint length = stream.Position - start + 1;
+                        uint length = stream.Position - start;
                         signature = new byte[length];
                         for (int i = 0; i < length; i++)
                         {

Src/Compilers/VisualBasic/Test/Emit/Emit/EditAndContinueTests.vb

@@ -1610,9 +1610,9 @@ End Class
 {
   // Code size       10 (0xa)
   .maxstack  1
-  .locals init ([unchanged] V_0,
-  String V_1, //b
-  Integer V_2) //a
+  .locals init ([object] V_0,
+                String V_1, //b
+                Integer V_2) //a
   IL_0000:  nop
   IL_0001:  ldc.i4.1
   IL_0002:  stloc.2
@@ -3601,7 +3601,7 @@ End Class
   // Code size       30 (0x1e)
   .maxstack  1
   .locals init (Object V_0, //G
-                [unchanged] V_1,
+                [int] V_1,
                 VB$AnonymousType_0(Of A) V_2, //x
                 VB$AnonymousType_1(Of Integer) V_3) //y
   IL_0000:  nop
@@ -3632,7 +3632,7 @@ End Class
   // Code size       35 (0x23)
   .maxstack  1
   .locals init (Object V_0, //G
-                [unchanged] V_1,
+                [int] V_1,
                 VB$AnonymousType_0(Of A) V_2, //x
                 VB$AnonymousType_1(Of Integer) V_3) //y
   IL_0000:  nop