Allow parameter renames in Edit and Continue (#54856)

src/Compilers/CSharp/Portable/Emitter/EditAndContinue/CSharpSymbolMatcher.cs

@@ -760,8 +760,7 @@ private bool AreNamespacesEqual(NamespaceSymbol @namespace, NamespaceSymbol othe
             private bool AreParametersEqual(ParameterSymbol parameter, ParameterSymbol other)
             {
                 Debug.Assert(parameter.Ordinal == other.Ordinal);
-                return StringOrdinalComparer.Equals(parameter.MetadataName, other.MetadataName) &&
-                    (parameter.RefKind == other.RefKind) &&
+                return (parameter.RefKind == other.RefKind) &&
                     _comparer.Equals(parameter.Type, other.Type);
             }
 

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

@@ -294,6 +294,97 @@ static void Main() { }
                 Handle(2, TableIndex.AssemblyRef));
         }
 
+        [Fact]
+        public void ModifyMethod_RenameParameter()
+        {
+            var source0 =
+@"class C
+{
+    static string F(int a) { return a.ToString(); }
+}";
+            var source1 =
+@"class C
+{
+    static string F(int x) { return x.ToString(); }
+}";
+            var source2 =
+@"class C
+{
+    static string F(int b) { return b.ToString(); }
+}";
+
+            var compilation0 = CreateCompilation(source0, options: TestOptions.DebugDll);
+            var compilation1 = compilation0.WithSource(source1);
+            var compilation2 = compilation1.WithSource(source2);
+
+            var method0 = compilation0.GetMember<MethodSymbol>("C.F");
+
+            // Verify full metadata contains expected rows.
+            var bytes0 = compilation0.EmitToArray(EmitOptions.Default.WithDebugInformationFormat(DebugInformationFormat.PortablePdb));
+            using var md0 = ModuleMetadata.CreateFromImage(bytes0);
+            var reader0 = md0.MetadataReader;
+
+            CheckNames(reader0, reader0.GetTypeDefNames(), "<Module>", "C");
+            CheckNames(reader0, reader0.GetMethodDefNames(), "F", ".ctor");
+            CheckNames(reader0, reader0.GetParameterDefNames(), "a");
+
+            var generation0 = EmitBaseline.CreateInitialBaseline(
+                md0,
+                EmptyLocalsProvider);
+            var method1 = compilation1.GetMember<MethodSymbol>("C.F");
+
+            var diff1 = compilation1.EmitDifference(
+                generation0,
+                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method0, method1)));
+
+            // Verify delta metadata contains expected rows.
+            using var md1 = diff1.GetMetadata();
+            var reader1 = md1.Reader;
+            var readers = new[] { reader0, reader1 };
+
+            EncValidation.VerifyModuleMvid(1, reader0, reader1);
+
+            CheckNames(readers, reader1.GetTypeDefNames());
+            CheckNames(readers, reader1.GetMethodDefNames(), "F");
+            CheckNames(readers, reader1.GetParameterDefNames(), "x");
+
+            CheckEncLogDefinitions(reader1,
+                Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                Row(1, TableIndex.Param, EditAndContinueOperation.Default));
+
+            CheckEncMapDefinitions(reader1,
+                Handle(1, TableIndex.MethodDef),
+                Handle(1, TableIndex.Param),
+                Handle(2, TableIndex.StandAloneSig));
+
+            var method2 = compilation2.GetMember<MethodSymbol>("C.F");
+
+            var diff2 = compilation2.EmitDifference(
+                diff1.NextGeneration,
+                ImmutableArray.Create(SemanticEdit.Create(SemanticEditKind.Update, method1, method2)));
+
+            // Verify delta metadata contains expected rows.
+            using var md2 = diff2.GetMetadata();
+            var reader2 = md2.Reader;
+            readers = new[] { reader0, reader1, reader2 };
+
+            CheckNames(readers, reader2.GetTypeDefNames());
+            CheckNames(readers, reader2.GetMethodDefNames(), "F");
+            CheckNames(readers, reader2.GetMemberRefNames(), "ToString");
+            CheckNames(readers, reader2.GetParameterDefNames(), "b");
+
+            CheckEncLogDefinitions(reader2,
+                Row(3, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                Row(1, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                Row(1, TableIndex.Param, EditAndContinueOperation.Default));
+
+            CheckEncMapDefinitions(reader2,
+                Handle(1, TableIndex.MethodDef),
+                Handle(1, TableIndex.Param),
+                Handle(3, TableIndex.StandAloneSig));
+        }
+
         [CompilerTrait(CompilerFeature.Tuples)]
         [Fact]
         public void ModifyMethod_WithTuples()
@@ -1404,6 +1495,10 @@ class C
             EncValidation.VerifyModuleMvid(2, reader1, reader2);
 
             CheckNames(readers, reader2.GetTypeDefNames());
+            CheckNames(readers, reader2.GetMethodDefNames(), "F");
+            CheckNames(readers, reader2.GetParameterDefNames(), "", "arg");
+            CheckNames(readers, diff2.EmitResult.ChangedTypes, "C");
+            CheckNames(readers, diff2.EmitResult.UpdatedMethods, "F");
 
             CheckEncLogDefinitions(reader2,
                 Row(3, TableIndex.MethodDef, EditAndContinueOperation.Default), // C.F2
@@ -12043,5 +12138,89 @@ public void TopLevelStatement_Update()
                 Handle(8, TableIndex.MemberRef),
                 Handle(2, TableIndex.AssemblyRef));
         }
+
+        [Fact]
+        public void LambdaParameterToDiscard()
+        {
+            var source0 = MarkedSource(@"
+using System;
+class C
+{
+    void M()
+    {
+        var x = new Func<int, int, int>(<N:0>(a, b) => a + b + 1</N:0>);
+        Console.WriteLine(x(1, 2));
+    }
+}");
+            var source1 = MarkedSource(@"
+using System;
+class C
+{
+    void M()
+    {
+        var x = new Func<int, int, int>(<N:0>(_, _) => 10</N:0>);
+        Console.WriteLine(x(1, 2));
+    }
+}");
+
+            var compilation0 = CreateCompilation(source0.Tree, options: ComSafeDebugDll);
+            var compilation1 = compilation0.WithSource(source1.Tree);
+
+            var method0 = compilation0.GetMember<MethodSymbol>("C.M");
+            var method1 = compilation1.GetMember<MethodSymbol>("C.M");
+
+            var v0 = CompileAndVerify(compilation0, verify: Verification.Skipped);
+
+            using var md0 = ModuleMetadata.CreateFromImage(v0.EmittedAssemblyData);
+
+            var generation0 = EmitBaseline.CreateInitialBaseline(md0, v0.CreateSymReader().GetEncMethodDebugInfo);
+
+            var diff = compilation1.EmitDifference(
+                generation0,
+                ImmutableArray.Create(
+                    SemanticEdit.Create(SemanticEditKind.Update, method0, method1, GetSyntaxMapFromMarkers(source0, source1), preserveLocalVariables: true)));
+
+            // There should be no diagnostics from rude edits
+            diff.EmitResult.Diagnostics.Verify();
+
+            diff.VerifySynthesizedMembers(
+                "C: {<>c}",
+                "C.<>c: {<>9__0_0, <M>b__0_0}");
+
+            diff.VerifyIL("C.M",
+                @"
+ {
+      // Code size       48 (0x30)
+      .maxstack  3
+      .locals init ([unchanged] V_0,
+                    System.Func<int, int, int> V_1) //x
+      IL_0000:  nop
+      IL_0001:  ldsfld     ""System.Func<int, int, int> C.<>c.<>9__0_0""
+      IL_0006:  dup
+      IL_0007:  brtrue.s   IL_0020
+      IL_0009:  pop
+      IL_000a:  ldsfld     ""C.<>c C.<>c.<>9""
+      IL_000f:  ldftn      ""int C.<>c.<M>b__0_0(int, int)""
+      IL_0015:  newobj     ""System.Func<int, int, int>..ctor(object, System.IntPtr)""
+      IL_001a:  dup
+      IL_001b:  stsfld     ""System.Func<int, int, int> C.<>c.<>9__0_0""
+      IL_0020:  stloc.1
+      IL_0021:  ldloc.1
+      IL_0022:  ldc.i4.1
+      IL_0023:  ldc.i4.2
+      IL_0024:  callvirt   ""int System.Func<int, int, int>.Invoke(int, int)""
+      IL_0029:  call       ""void System.Console.WriteLine(int)""
+      IL_002e:  nop
+      IL_002f:  ret
+}");
+
+            diff.VerifyIL("C.<>c.<M>b__0_0(int, int)", @"
+{
+    // Code size        3 (0x3)
+    .maxstack  1
+    IL_0000:  ldc.i4.s   10
+    IL_0002:  ret
+}");
+        }
     }
 }

src/Compilers/CSharp/Test/Emit/Emit/EditAndContinue/SymbolMatcherTests.cs

@@ -1112,6 +1112,68 @@ class C
             Assert.NotNull(other);
         }
 
+        [Fact]
+        public void Method_ParameterRename()
+        {
+            var source0 = @"
+using System.Collections.Generic;
+class C
+{
+    string M(string s) => s.ToString();
+}";
+            var source1 = @"
+using System.Collections.Generic;
+class C
+{
+     string M(string m) => m.ToString();
+}";
+            var compilation0 = CreateCompilation(source0, options: TestOptions.DebugDll);
+            var compilation1 = compilation0.WithSource(source1);
+
+            var matcher = new CSharpSymbolMatcher(
+                null,
+                compilation1.SourceAssembly,
+                default,
+                compilation0.SourceAssembly,
+                default,
+                null);
+
+            var member = compilation1.GetMember<MethodSymbol>("C.M");
+            var other = matcher.MapDefinition(member.GetCciAdapter());
+            Assert.NotNull(other);
+        }
+
+        [Fact]
+        public void Method_ParameterRenameToDiscard()
+        {
+            var source0 = @"
+using System.Collections.Generic;
+class C
+{
+    string M(string s) => s.ToString();
+}";
+            var source1 = @"
+using System.Collections.Generic;
+class C
+{
+     string M(string _) => ""Hello"";
+}";
+            var compilation0 = CreateCompilation(source0, options: TestOptions.DebugDll);
+            var compilation1 = compilation0.WithSource(source1);
+
+            var matcher = new CSharpSymbolMatcher(
+                null,
+                compilation1.SourceAssembly,
+                default,
+                compilation0.SourceAssembly,
+                default,
+                null);
+
+            var member = compilation1.GetMember<MethodSymbol>("C.M");
+            var other = matcher.MapDefinition(member.GetCciAdapter());
+            Assert.NotNull(other);
+        }
+
         [Fact]
         public void Field_NullableChange()
         {

src/Compilers/VisualBasic/Portable/Emit/EditAndContinue/VisualBasicSymbolMatcher.vb

@@ -597,7 +597,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Emit
 
             Private Function AreParametersEqual(parameter As ParameterSymbol, other As ParameterSymbol) As Boolean
                 Debug.Assert(parameter.Ordinal = other.Ordinal)
-                Return s_nameComparer.Equals(parameter.Name, other.Name) AndAlso parameter.IsByRef = other.IsByRef AndAlso Me._comparer.Equals(parameter.Type, other.Type)
+                Return parameter.IsByRef = other.IsByRef AndAlso Me._comparer.Equals(parameter.Type, other.Type)
             End Function
 
             Private Function ArePropertiesEqual([property] As PropertySymbol, other As PropertySymbol) As Boolean

src/Compilers/VisualBasic/Test/Emit/Emit/EditAndContinue/EditAndContinueTestBase.vb

@@ -186,12 +186,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
         End Sub
 
         Friend Shared Sub CheckEncLogDefinitions(reader As MetadataReader, ParamArray rows As EditAndContinueLogEntry())
-            AssertEx.Equal(rows, reader.GetEditAndContinueLogEntries().Where(Function(entry) IsDefinition(entry)), itemInspector:=AddressOf EncLogRowToString)
+            AssertEx.Equal(rows, reader.GetEditAndContinueLogEntries().Where(Function(entry) IsDefinition(entry.Handle.Kind)), itemInspector:=AddressOf EncLogRowToString)
         End Sub
 
-        Friend Shared Function IsDefinition(entry As EditAndContinueLogEntry) As Boolean
+        Friend Shared Function IsDefinition(kind As HandleKind) As Boolean
             Dim index As TableIndex
-            Assert.True(MetadataTokens.TryGetTableIndex(entry.Handle.Kind, index))
+            Assert.True(MetadataTokens.TryGetTableIndex(kind, index))
 
             Select Case index
                 Case TableIndex.MethodDef,
@@ -232,6 +232,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests
             AssertEx.Equal([handles], reader.GetEditAndContinueMapEntries(), itemInspector:=AddressOf EncMapRowToString)
         End Sub
 
+        Friend Shared Sub CheckEncMapDefinitions(reader As MetadataReader, ParamArray [handles] As EntityHandle())
+            AssertEx.Equal([handles], reader.GetEditAndContinueMapEntries().Where(Function(e) IsDefinition(e.Kind)), itemInspector:=AddressOf EncMapRowToString)
+        End Sub
+
         Friend Shared Sub CheckNames(reader As MetadataReader, [handles] As StringHandle(), ParamArray expectedNames As String())
             CheckNames({reader}, [handles], expectedNames)
         End Sub

src/Compilers/VisualBasic/Test/Emit/Emit/EditAndContinue/EditAndContinueTests.vb

@@ -185,6 +185,60 @@ End Class
             End Using
         End Sub
 
+        <Fact>
+        Public Sub ModifyMethod_RenameParameter()
+            Dim source0 =
+"
+Class C
+    Shared Function F(i As Integer) As Integer
+        Return i
+    End Function
+End Class
+"
+            Dim source1 =
+"
+Class C
+    Shared Function F(x As Integer) As Integer
+        Return x
+    End Function
+End Class
+"
+            Dim compilation0 = CreateCompilationWithMscorlib40({source0}, options:=TestOptions.DebugDll, references:={ValueTupleRef, SystemRuntimeFacadeRef})
+            Dim compilation1 = compilation0.WithSource(source1)
+
+            Dim bytes0 = compilation0.EmitToArray()
+            Using md0 = ModuleMetadata.CreateFromImage(bytes0)
+                Dim reader0 = md0.MetadataReader
+                Dim method0 = compilation0.GetMember(Of MethodSymbol)("C.F")
+                Dim generation0 = EmitBaseline.CreateInitialBaseline(md0, EmptyLocalsProvider)
+
+                CheckNames(reader0, reader0.GetParameterDefNames(), "i")
+
+                Dim method1 = compilation1.GetMember(Of MethodSymbol)("C.F")
+                Dim diff1 = compilation1.EmitDifference(generation0, ImmutableArray.Create(New SemanticEdit(SemanticEditKind.Update, method0, method1)))
+
+                ' Verify delta metadata contains expected rows.
+                Using md1 = diff1.GetMetadata()
+                    Dim reader1 = md1.Reader
+                    Dim readers = {reader0, reader1}
+                    EncValidation.VerifyModuleMvid(1, reader0, reader1)
+                    CheckNames(readers, reader1.GetTypeDefNames())
+                    CheckNames(readers, reader1.GetMethodDefNames(), "F")
+                    CheckNames(readers, reader1.GetParameterDefNames(), "x")
+
+                    CheckEncLogDefinitions(reader1,
+                        Row(2, TableIndex.StandAloneSig, EditAndContinueOperation.Default),
+                        Row(2, TableIndex.MethodDef, EditAndContinueOperation.Default),
+                        Row(1, TableIndex.Param, EditAndContinueOperation.Default))
+
+                    CheckEncMapDefinitions(reader1,
+                        Handle(2, TableIndex.MethodDef),
+                        Handle(1, TableIndex.Param),
+                        Handle(2, TableIndex.StandAloneSig))
+                End Using
+            End Using
+        End Sub
+
         <WorkItem(962219, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/962219")>
         <Fact>
         Public Sub PartialMethod()