Merge pull request #42411 from CyrusNajmabadi/pluralizeVarNames

Infer better variable names for a foreach expression.

src/CodeStyle/CSharp/Analyzers/Microsoft.CodeAnalysis.CSharp.CodeStyle.csproj

@@ -10,6 +10,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="$(MicrosoftCodeAnalysisCSharpFixedVersion)" />
+    <PackageReference Include="Humanizer.Core" Version="$(HumanizerCoreVersion)" PrivateAssets="compile" />
   </ItemGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\..\Core\Analyzers\Microsoft.CodeAnalysis.CodeStyle.csproj" />

src/CodeStyle/CSharp/CodeFixes/Microsoft.CodeAnalysis.CSharp.CodeStyle.Fixes.csproj

@@ -36,6 +36,7 @@
   </Target>
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="$(MicrosoftCodeAnalysisCSharpWorkspacesFixedVersion)" />
+    <PackageReference Include="Humanizer.Core" Version="$(HumanizerCoreVersion)" PrivateAssets="compile" />
   </ItemGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\..\Core\Analyzers\Microsoft.CodeAnalysis.CodeStyle.csproj" />

src/EditorFeatures/CSharpTest/CodeActions/ConvertLinq/ConvertLinqQueryToForEachTests.cs

@@ -170,13 +170,13 @@ static void Main(string[] args)
     {
         System.Collections.Generic.IEnumerable<int> enumerable()
         {
-            var v1 = new int[] { 1, 2 };
-            var v = new int[] { 3, 4 };
-            foreach (var num in v1)
+            var vs1 = new int[] { 1, 2 };
+            var vs = new int[] { 3, 4 };
+            foreach (var num in vs1)
             {
                 foreach (var a in new int[] { 5, 6 })
                 {
-                    foreach (var x1 in v)
+                    foreach (var x1 in vs)
                     {
                         if (object.Equals(num, x1))
                         {
@@ -219,18 +219,18 @@ static void Main(string[] args)
     {
         System.Collections.Generic.IEnumerable<int> enumerable()
         {
-            var v2 = new int[] { 1, 2 };
-            var v1 = new int[] { 3, 4 };
-            var v = new int[] { 7, 8 };
-            foreach (var num in v2)
+            var vs2 = new int[] { 1, 2 };
+            var vs1 = new int[] { 3, 4 };
+            var vs = new int[] { 7, 8 };
+            foreach (var num in vs2)
             {
                 foreach (var a in new int[] { 5, 6 })
                 {
-                    foreach (var x1 in v1)
+                    foreach (var x1 in vs1)
                     {
                         if (object.Equals(num, x1))
                         {
-                            foreach (var x2 in v)
+                            foreach (var x2 in vs)
                             {
                                 if (object.Equals(num, x2))
                                 {
@@ -2141,7 +2141,7 @@ class C
 {
     void M(IEnumerable<int> nums)
     {
-        IEnumerable<B> enumerable()
+        IEnumerable<B> @as()
         {
             foreach (B a in nums)
             {
@@ -2152,7 +2152,7 @@ IEnumerable<B> enumerable()
             }
         }
 
-        foreach (A a in enumerable())
+        foreach (A a in @as())
         {
             Console.Write(a.ToString());
         }
@@ -2238,7 +2238,7 @@ class C
 {
     void M(IEnumerable<int> nums)
     {
-        IEnumerable<int> enumerable()
+        IEnumerable<int> bs()
         {
             foreach (int n1 in nums)
             {
@@ -2249,7 +2249,7 @@ IEnumerable<int> enumerable()
             }
         }
 
-        foreach (var b in enumerable())
+        foreach (var b in bs())
         {
             int n1 = 5;
             Console.WriteLine(b);
@@ -2318,7 +2318,7 @@ class C
 
     void Test()
     {
-        IEnumerable<C> enumerable()
+        IEnumerable<C> xes()
         {
             foreach (var x in new[] { 1, 2, 3, })
             {
@@ -2326,7 +2326,7 @@ IEnumerable<C> enumerable()
             }
         }
 
-        foreach (int x in enumerable())
+        foreach (int x in xes())
         {
             Console.Write(x);
         }
@@ -2480,7 +2480,7 @@ class C
 {
     void M(IEnumerable<int> nums)
     {
-        IEnumerable<int> queryable()
+        IEnumerable<int> queryables()
         {
             foreach (int n1 in nums.AsQueryable())
             {
@@ -2488,7 +2488,7 @@ IEnumerable<int> queryable()
             }
         }
 
-        IEnumerable<int> q = queryable();
+        IEnumerable<int> q = queryables();
     }
 }";
 

src/EditorFeatures/CSharpTest/CodeActions/IntroduceVariable/IntroduceVariableTests.cs

@@ -1478,8 +1478,8 @@ static void Main(string[] args)
     static void Main(string[] args)
     {
         int[] a = null;
-        var {|Rename:v|} = a = new[] { 1, 2, 3 };
-        int[] temp = checked(v);
+        var {|Rename:vs|} = a = new[] { 1, 2, 3 };
+        int[] temp = checked(vs);
     }
 }",
 options: ImplicitTypingEverywhere());
@@ -5980,8 +5980,8 @@ class C
     byte[] getArray() => null;
     void test()
     {
-        byte[] {|Rename:v|} = getArray();
-        var goo = v[0];
+        byte[] {|Rename:vs|} = getArray();
+        var goo = vs[0];
     }
 }");
         }
@@ -7399,6 +7399,48 @@ private object Bar()
 }");
         }
 
+        [WorkItem(56, "https://github.com/dotnet/roslyn/issues/56")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsIntroduceVariable)]
+        public async Task TestGenerateNameForForeachExpression()
+        {
+            await TestInRegularAndScriptAsync(
+@"using System.Collections.Generic;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        foreach (var num in [|GetNumbers()|])
+        {
+
+        }
+    }
+
+    static IEnumerable<int> GetNumbers()
+    {
+        return new[] { 1, 2, 3 };
+    }
+}",
+@"using System.Collections.Generic;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        IEnumerable<int> {|Rename:nums|} = GetNumbers();
+        foreach (var num in nums)
+        {
+
+        }
+    }
+
+    static IEnumerable<int> GetNumbers()
+    {
+        return new[] { 1, 2, 3 };
+    }
+}");
+        }
+
         [WorkItem(15770, "https://github.com/dotnet/roslyn/issues/15770")]
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsIntroduceVariable)]
         public async Task TestKeepReplacementIndentation1()

src/EditorFeatures/CSharpTest/GenerateConstructor/GenerateConstructorTests.cs

@@ -2323,22 +2323,23 @@ enum A
 [AttributeUsage(AttributeTargets.Class)]
 class MyAttrAttribute : Attribute
 {
-    private int[] v1;
+    private int[] vs;
     private A a1;
-    private bool v2;
-    private byte v3;
-    private char v4;
-    private short v5;
-    private int v6;
-    private long v7;
-    private double v8;
-    private float v9;
-    private string v10;
-
-    public MyAttrAttribute(int[] v1, A a1, bool v2, byte v3, char v4, short v5, int v6, long v7, double v8, float v9, string v10)
-    {
-        this.v1 = v1;
+    private bool v1;
+    private byte v2;
+    private char v3;
+    private short v4;
+    private int v5;
+    private long v6;
+    private double v7;
+    private float v8;
+    private string v9;
+
+    public MyAttrAttribute(int[] vs, A a1, bool v1, byte v2, char v3, short v4, int v5, long v6, double v7, float v8, string v9)
+    {
+        this.vs = vs;
         this.a1 = a1;
+        this.v1 = v1;
         this.v2 = v2;
         this.v3 = v3;
         this.v4 = v4;
@@ -2347,7 +2348,6 @@ public MyAttrAttribute(int[] v1, A a1, bool v2, byte v3, char v4, short v5, int
         this.v7 = v7;
         this.v8 = v8;
         this.v9 = v9;
-        this.v10 = v10;
     }
 }
 

src/Workspaces/CSharp/Portable/Microsoft.CodeAnalysis.CSharp.Workspaces.csproj

@@ -19,6 +19,9 @@
     <ProjectReference Include="..\..\..\Compilers\CSharp\Portable\Microsoft.CodeAnalysis.CSharp.csproj" />
     <ProjectReference Include="..\..\Core\Portable\Microsoft.CodeAnalysis.Workspaces.csproj" />
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Humanizer.Core" Version="$(HumanizerCoreVersion)" PrivateAssets="compile" />
+  </ItemGroup>
   <ItemGroup>
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.EditorFeatures" />
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.CSharp.Features" />

src/Workspaces/SharedUtilitiesAndExtensions/Workspace/CSharp/Extensions/SemanticModelExtensions.cs

@@ -6,11 +6,10 @@
 using System.Collections.Immutable;
 using System.Linq;
 using System.Threading;
+using Humanizer;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.Diagnostics.Analyzers.NamingStyles;
-using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.Shared.Extensions;
-using Microsoft.CodeAnalysis.Shared.Utilities;
 using Microsoft.CodeAnalysis.Utilities;
 using Roslyn.Utilities;
 
@@ -205,9 +204,9 @@ private static bool CanBindToken(SyntaxToken token)
             {
                 current = current.WalkDownParentheses();
 
-                if (current.Kind() == SyntaxKind.IdentifierName)
+                if (current is IdentifierNameSyntax identifierName)
                 {
-                    return ((IdentifierNameSyntax)current).Identifier.ValueText.ToCamelCase();
+                    return identifierName.Identifier.ValueText.ToCamelCase();
                 }
                 else if (current is MemberAccessExpressionSyntax memberAccess)
                 {
@@ -234,6 +233,11 @@ private static bool CanBindToken(SyntaxToken token)
 
                     return name.Identifier.ValueText.ToCamelCase();
                 }
+                else if (current.Parent is ForEachStatementSyntax foreachStatement &&
+                         foreachStatement.Expression == expression)
+                {
+                    return foreachStatement.Identifier.ValueText.ToCamelCase().Pluralize();
+                }
                 else
                 {
                     break;
@@ -255,7 +259,22 @@ private static bool CanBindToken(SyntaxToken token)
 
             // If we can't determine the type, then fallback to some placeholders.
             var type = info.Type;
-            return type.CreateParameterName(capitalize);
+            var pluralize = Pluralize(semanticModel, type);
+
+            var parameterName = type.CreateParameterName(capitalize);
+            return pluralize ? parameterName.Pluralize() : parameterName;
+        }
+
+        private static bool Pluralize(SemanticModel semanticModel, ITypeSymbol type)
+        {
+            if (type == null)
+                return false;
+
+            if (type.SpecialType == SpecialType.System_String)
+                return false;
+
+            var enumerableType = semanticModel.Compilation.IEnumerableOfTType();
+            return type.AllInterfaces.Any(i => i.OriginalDefinition.Equals(enumerableType));
         }
 
         private static string TryGenerateNameForArgumentExpression(