Minor tweaks to avoid some allocations

src/Compilers/CSharp/Portable/Binder/Binder_AnonymousTypes.cs

@@ -80,7 +80,7 @@ private BoundExpression BindAnonymousObjectCreation(AnonymousObjectCreationExpre
 
                 // build anonymous type field descriptor
                 fieldSyntaxNodes[i] = (nameToken.Kind() == SyntaxKind.IdentifierToken) ? (CSharpSyntaxNode)nameToken.Parent : fieldInitializer;
-                fields[i] = new AnonymousTypeField(fieldName == null ? '$' + i.ToString() : fieldName, fieldSyntaxNodes[i].Location, fieldType);
+                fields[i] = new AnonymousTypeField(fieldName == null ? "$" + i.ToString() : fieldName, fieldSyntaxNodes[i].Location, fieldType);
 
                 //  NOTE: ERR_InvalidAnonymousTypeMemberDeclarator (CS0746) would be generated by parser if needed
             }

src/Features/CSharp/EncapsulateField/CSharpEncapsulateFieldService.cs

@@ -171,7 +171,7 @@ private bool IsNew(IFieldSymbol field)
 
         private string GenerateFieldName(IFieldSymbol field, string correspondingPropertyName)
         {
-            return char.ToLower(correspondingPropertyName[0]) + correspondingPropertyName.Substring(1);
+            return char.ToLower(correspondingPropertyName[0]).ToString() + correspondingPropertyName.Substring(1);
         }
 
         protected string MakeUnique(string baseName, INamedTypeSymbol containingType, bool considerBaseMembers = true)

src/Features/Core/Completion/CommonCompletionUtilities.cs

@@ -18,7 +18,7 @@ namespace Microsoft.CodeAnalysis.Completion
 {
     internal static class CommonCompletionUtilities
     {
-        private const char NonBreakingSpace = (char)0x00A0;
+        private const string NonBreakingSpaceString = "\x00A0";
 
         public static TextSpan GetTextChangeSpan(SourceText text, int position,
             Func<char, bool> isWordStartCharacter, Func<char, bool> isWordCharacter)
@@ -123,7 +123,7 @@ private static async Task<ImmutableArray<SymbolDisplayPart>> CreateDescriptionAs
                         textContentBuilder.AddSpace();
                         textContentBuilder.AddPunctuation("(");
                         textContentBuilder.AddPunctuation("+");
-                        textContentBuilder.AddText(NonBreakingSpace + overloadCount.ToString());
+                        textContentBuilder.AddText(NonBreakingSpaceString + overloadCount.ToString());
 
                         AddOverloadPart(textContentBuilder, overloadCount, isGeneric);
 
@@ -170,7 +170,7 @@ private static void AddOverloadPart(List<SymbolDisplayPart> textContentBuilder,
                     ? FeaturesResources.Overload
                     : FeaturesResources.Overloads;
 
-            textContentBuilder.AddText(NonBreakingSpace + text);
+            textContentBuilder.AddText(NonBreakingSpaceString + text);
         }
 
         private static void AddDocumentationPart(List<SymbolDisplayPart> textContentBuilder, ISymbol symbol, SemanticModel semanticModel, int position, IDocumentationCommentFormattingService formatter, CancellationToken cancellationToken)

src/Features/Core/Diagnostics/EngineV1/DiagnosticIncrementalAnalyzer.DiagnosticAnalyzersAndStates.cs

@@ -175,7 +175,7 @@ private static ValueTuple<string, VersionStamp> GetUniqueDiagnosticStateNameAndV
                 var providerType = provider.GetType();
                 var location = providerType.Assembly.Location;
 
-                return ValueTuple.Create(UserDiagnosticsPrefixTableName + "_" + type + "_" + providerType.AssemblyQualifiedName, GetProviderVersion(location));
+                return ValueTuple.Create(UserDiagnosticsPrefixTableName + "_" + type.ToString() + "_" + providerType.AssemblyQualifiedName, GetProviderVersion(location));
             }
 
             private static VersionStamp GetProviderVersion(string path)

src/Features/Core/EditAndContinue/LineChange.cs

@@ -39,7 +39,7 @@ public override int GetHashCode()
 
         public override string ToString()
         {
-            return OldLine + " -> " + NewLine;
+            return OldLine.ToString() + " -> " + NewLine.ToString();
         }
     }
 }

src/Features/Core/EncapsulateField/AbstractEncapsulateFieldService.cs

@@ -348,10 +348,12 @@ protected IMethodSymbol CreateGet(string originalFieldName, IFieldSymbol field,
                 new[] { body }.ToList());
         }
 
+        private static readonly char[] s_underscoreCharArray = new[] { '_' };
+
         protected string GeneratePropertyName(string fieldName)
         {
             // Trim leading underscores
-            var baseName = fieldName.TrimStart('_');
+            var baseName = fieldName.TrimStart(s_underscoreCharArray);
 
             // Trim leading "m_"
             if (baseName.Length >= 2 && baseName[0] == 'm' && baseName[1] == '_')
@@ -366,7 +368,7 @@ protected string GeneratePropertyName(string fieldName)
             }
 
             // Make uppercase the first letter
-            return char.ToUpper(baseName[0]) + baseName.Substring(1);
+            return char.ToUpper(baseName[0]).ToString() + baseName.Substring(1);
         }
 
         protected abstract Task<SyntaxNode> RewriteFieldNameAndAccessibility(string originalFieldName, bool makePrivate, Document document, SyntaxAnnotation declarationAnnotation, CancellationToken cancellationToken);

src/Features/Core/ExtractMethod/MethodExtractor.cs

@@ -162,8 +162,9 @@ internal static string MakeMethodName(string prefix, string originalName)
             var startingWithLetter = originalName.SkipWhile(c => !char.IsLetter(c)).ToArray();
             var name = startingWithLetter.Length == 0 ? originalName : new string(startingWithLetter);
 
-            var methodName = char.IsUpper(name[0]) ? name : char.ToUpper(name[0]) + name.Substring(1);
-            return prefix + methodName;
+            return char.IsUpper(name[0]) ? 
+                prefix + name : 
+                prefix + char.ToUpper(name[0]).ToString() + name.Substring(1);
         }
     }
 }

src/Features/Core/LanguageServices/AnonymousTypeDisplayService/AbstractAnonymousTypeDisplayService.cs

@@ -80,10 +80,10 @@ private string GenerateAnonymousTypeName(int current)
             char c = (char)('a' + current);
             if (c >= 'a' && c <= 'z')
             {
-                return "'" + c;
+                return "'" + c.ToString();
             }
 
-            return "'" + current;
+            return "'" + current.ToString();
         }
 
         private IList<INamedTypeSymbol> OrderAnonymousTypes(

src/Samples/CSharp/ImplementNotifyPropertyChanged/Impl/ExpansionChecker.cs

@@ -86,7 +86,7 @@ internal static bool TryGetAccessors(
         private static string GenerateFieldName(PropertyDeclarationSyntax property, SemanticModel semanticModel)
         {
             var baseName = property.Identifier.ValueText;
-            baseName = char.ToLower(baseName[0]) + baseName.Substring(1);
+            baseName = char.ToLower(baseName[0]).ToString() + baseName.Substring(1);
 
             var propertySymbol = semanticModel.GetDeclaredSymbol(property);
             if (propertySymbol == null ||
@@ -99,7 +99,7 @@ private static string GenerateFieldName(PropertyDeclarationSyntax property, Sema
             var name = baseName;
             while (propertySymbol.ContainingType.MemberNames.Contains(name))
             {
-                name = baseName + ++index;
+                name = baseName + (++index).ToString();
             }
 
             return name;

src/Scripting/Core/ObjectFormatter.Formatter.cs

@@ -299,7 +299,7 @@ public int MinimalLength
 
                 public string GetDisplayName()
                 {
-                    return Name ?? "[" + Index + "]";
+                    return Name ?? "[" + Index.ToString() + "]";
                 }
 
                 public bool HasKeyName()

src/Scripting/Core/ScriptBuilder.cs

@@ -88,7 +88,7 @@ public ScriptBuilder(AssemblyLoader assemblyLoader = null)
                 assemblyLoader = new InteractiveAssemblyLoader();
             }
 
-            _assemblyNamePrefix = s_globalAssemblyNamePrefix + "#" + Interlocked.Increment(ref s_engineIdDispenser);
+            _assemblyNamePrefix = s_globalAssemblyNamePrefix + "#" + Interlocked.Increment(ref s_engineIdDispenser).ToString();
             _collectibleCodeManager = new CollectibleCodeManager(assemblyLoader, _assemblyNamePrefix);
             _uncollectibleCodeManager = new UncollectibleCodeManager(assemblyLoader, _assemblyNamePrefix);
         }
@@ -111,8 +111,9 @@ internal static bool IsReservedAssemblyName(AssemblyIdentity identity)
         public int GenerateSubmissionId(out string assemblyName, out string typeName)
         {
             int id = Interlocked.Increment(ref _submissionIdDispenser);
-            assemblyName = _assemblyNamePrefix + id;
-            typeName = "Submission#" + id;
+            string idAsString = id.ToString();
+            assemblyName = _assemblyNamePrefix + idAsString;
+            typeName = "Submission#" + idAsString;
             return id;
         }
 

src/VisualStudio/Core/Def/Implementation/GenerateType/GenerateTypeDialogViewModel.cs

@@ -280,7 +280,7 @@ internal bool TrySubmit()
                 trimmedFileName = trimmedFileName.StartsWith("\\") ? trimmedFileName.Substring(1) : trimmedFileName;
 
                 // Construct the full path of the file to be created
-                this.FullFilePath = implicitFilePath + '\\' + trimmedFileName;
+                this.FullFilePath = implicitFilePath + "\\" + trimmedFileName;
 
                 try
                 {

src/VisualStudio/Core/Def/Implementation/PreviewPane/PreviewPane.xaml.cs

@@ -14,7 +14,7 @@ namespace Microsoft.VisualStudio.LanguageServices.Implementation.PreviewPane
 {
     internal partial class PreviewPane : UserControl, IDisposable
     {
-        private static readonly string s_dummyThreeLineTitle = 'A' + Environment.NewLine + 'A' + Environment.NewLine + 'A';
+        private static readonly string s_dummyThreeLineTitle = "A" + Environment.NewLine + "A" + Environment.NewLine + "A";
         private static readonly Size s_infiniteSize = new Size(double.PositiveInfinity, double.PositiveInfinity);
 
         private readonly string _errorId;

src/Workspaces/CSharp/Desktop/MSBuild/CSharpProjectFileLoader.CSharpProjectFile.cs

@@ -84,9 +84,10 @@ private IEnumerable<ProjectFileReference> GetProjectReferencesCore(ProjectInstan
             private ProjectFileInfo CreateProjectFileInfo(CSharpCompilerInputs compilerInputs, MSB.Execution.ProjectInstance executedProject)
             {
                 string projectDirectory = executedProject.Directory;
-                if (!projectDirectory.EndsWith(Path.DirectorySeparatorChar.ToString(), StringComparison.OrdinalIgnoreCase))
+                string directorySeparator = Path.DirectorySeparatorChar.ToString();
+                if (!projectDirectory.EndsWith(directorySeparator, StringComparison.OrdinalIgnoreCase))
                 {
-                    projectDirectory += Path.DirectorySeparatorChar;
+                    projectDirectory += directorySeparator;
                 }
 
                 var docs = compilerInputs.Sources

src/Workspaces/CSharp/Portable/Extensions/StringExtensions.cs

@@ -25,7 +25,7 @@ public static string EscapeIdentifier(
             // Check if we need to escape this contextual keyword
             needsEscaping = needsEscaping || (isQueryContext && SyntaxFacts.IsQueryContextualKeyword(SyntaxFacts.GetContextualKeywordKind(identifier)));
 
-            return needsEscaping ? '@' + identifier : identifier;
+            return needsEscaping ? "@" + identifier : identifier;
         }
 
         public static SyntaxToken ToIdentifierToken(
@@ -44,7 +44,7 @@ public static SyntaxToken ToIdentifierToken(
                 : identifier;
 
             var token = SyntaxFactory.Identifier(
-                default(SyntaxTriviaList), SyntaxKind.None, '@' + unescaped, unescaped, default(SyntaxTriviaList));
+                default(SyntaxTriviaList), SyntaxKind.None, "@" + unescaped, unescaped, default(SyntaxTriviaList));
 
             if (!identifier.StartsWith("@"))
             {

src/Workspaces/Core/Desktop/InternalUtilities/FilePathUtilities.cs

@@ -68,9 +68,13 @@ public static string GetRelativePath(string baseDirectory, string fullPath)
 
             // add backup notation for remaining base path levels beyond the index
             var remainingParts = basePathParts.Length - index;
-            for (int i = 0; i < remainingParts; i++)
+            if (remainingParts > 0)
             {
-                relativePath += relativePath + ".." + Path.DirectorySeparatorChar;
+                string directorySeparator = Path.DirectorySeparatorChar.ToString();
+                for (int i = 0; i < remainingParts; i++)
+                {
+                    relativePath += relativePath + ".." + directorySeparator;
+                }
             }
 
             // add the rest of the full path parts