Enforce braces on all control-flow bodies in the C# emitter (cop)

packages/http-client-csharp/cop-checks/braces.cop

@@ -1,49 +1,51 @@
-# Rule: enforce braces on control-flow statements in the C# emitter.
+# Rule: enforce braces on every control-flow body in the C# emitter.
 #
-# Flags `if` / `else` / `else if` / `for` / `foreach` / `while` whose body is
-# written inline on the same line without a `{ ... }` block, e.g.:
+# Flags `if` / `else` / `else if` / `for` / `foreach` / `while` whose body is not
+# wrapped in a `{ ... }` block, whether the body is written inline or on its own
+# line, e.g.:
 #
-#     if (a) DoX();              -> violation
-#     if (x is null) throw ...;  -> violation (guard clause without braces)
+#     if (a) DoX();              -> violation (inline body)
+#     if (x is null) throw ...;  -> violation (inline guard clause)
+#     if (x is null)             -> violation (Allman guard clause)
+#         return;
 #     for (...) Step();          -> violation
 #     while (a) Tick();          -> violation
 #     else Two();                -> violation
+#     else if (a) DoY();         -> violation (inner `if` body is unbraced)
 #
-# These are allowed (body is a brace-delimited block, Allman or K&R):
+# These are allowed (body is a brace-delimited block):
 #
 #     if (a) { ... }
-#     if (a)                     # Allman: brace on the next line
+#     if (a)
 #     {
 #         ...
 #     }
+#     else if (a) { ... }        # `else if` chains are idiomatic when braced
 #
-# A line is reported when it is a control-flow header that also contains an
-# inline body terminated by `;` and introduces no `{` block. Keying on a
-# trailing `;` avoids false positives on multi-line conditions whose first
-# line ends in an operator (e.g. `if (a &&`), which are not complete headers.
+# The rule is driven by the code provider's structural parse rather than line
+# text: a control-flow statement exposes `Braced` (true only when its body is a
+# `{ ... }` block) and `Children` (its body statements). A violation is any
+# unbraced control-flow statement. Keying on the structural model removes the
+# false positives on multi-line conditions and recognizes `else if` chains
+# correctly.
 #
-# Known limitation: an unbraced body written on a *separate* line (Allman
-# header followed by a single unbraced statement) is not detected, because the
-# header line is indistinguishable from a valid Allman braced header.
+# An `else if` is modeled as an `else` whose body is the inner (braced or
+# unbraced) `if`, so the `else` itself reports `Braced == false`. That is
+# idiomatic C#, so the `else` is excluded; the inner `if` is still checked on its
+# own, so `else if (a) DoY();` is reported via that inner `if`.
 #
 # Predicates only; the runnable command/test live in main.cop.
 
 import code
 
-# A control-flow header whose condition closes on this line.
-predicate isControlHeader(Line) => Line.Text:matches('^\s*(else\s+)?(if|for|foreach|while)\s*\(.*\)')
+# True when the statement has a direct child `if` -- i.e. it is the `else` of an
+# `else if` chain. `where` is used instead of `any` so a child that carries no
+# statement kind does not poison the result with a null.
+predicate hasChildIf(Statement) => Statement.Children:where((c) => c.Kind == 'if').Count > 0
 
-# An `else` that is not `else if`.
-predicate isElseHeader(Line) => Line.Text:matches('^\s*else\b') && !Line.Text:matches('^\s*else\s+if\b')
-
-# The line introduces a `{ ... }` block.
-predicate hasBrace(Line) => Line.Text:matches('\{')
-
-# The line ends with a `;`-terminated statement (the inline body), optionally
-# followed by a trailing line comment.
-predicate hasInlineBody(Line) => Line.Text:matches(';\s*(//.*)?$')
-
-predicate missingBraces(Line) =>
-    !Line:hasBrace
-    && Line:hasInlineBody
-    && (Line:isControlHeader || Line:isElseHeader)
+# A control-flow statement (if / else / for / foreach / while) whose body is not a
+# brace-delimited block, excluding the idiomatic `else if` chain header.
+predicate missingBraces(Statement) =>
+    Statement:isControlFlow
+    && !Statement.Braced
+    && !(Statement.Kind == 'else' && Statement:hasChildIf)

packages/http-client-csharp/cop-checks/main.cop

@@ -18,9 +18,9 @@ import csharp
 let cb : Codebase = provider('csharp')
 
 # Rule: braces.cop
-command CHECK-BRACES = foreach cb.Lines:missingBraces => '{error:@red} {item.File.Path}:{item.Number}: missing braces -> {item.Text}'
+command CHECK-BRACES = foreach cb.Statements:missingBraces => '{error:@red} {item.File.Path}:{item.Line}: missing braces on {item.Kind} statement'
 
-test no-missing-braces = assert(cb.Lines:missingBraces.Count == 0, 'control-flow statements must use braces')
+test no-missing-braces = assert(cb.Statements:missingBraces.Count == 0, 'control-flow statements must use braces')
 
 # Rule: snippet-factory.cop
 command CHECK-SNIPPETS = foreach cb.Lines:usesCtorOverSnippet => '{error:@red} {item.File.Path}:{item.Number}: use the Snippet factory instead of constructing the expression directly -> {item.Text}'

packages/http-client-csharp/eng/scripts/Invoke-Cop.ps1

@@ -38,7 +38,7 @@ param(
     # Pinned cop release. Bump deliberately after verifying the cop-checks/ rules
     # still run against the new release (cop can make breaking API changes
     # between releases). Pass "latest" to test against the newest release.
-    [string] $Version = "v2026.6.10.1"
+    [string] $Version = "v2026.6.23.2"
 )
 
 $ErrorActionPreference = 'Stop'

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel.StubLibrary/src/StubLibraryVisitor.cs

@@ -21,7 +21,9 @@ internal class StubLibraryVisitor : ScmLibraryVisitor
             if (!type.DeclarationModifiers.HasFlag(TypeSignatureModifiers.Public) &&
                 !type.Name.StartsWith("Unknown", StringComparison.Ordinal) &&
                 !type.Name.Equals("MultiPartFormDataBinaryContent", StringComparison.Ordinal))
+            {
                 return null;
+            }
 
             type.Update(xmlDocs: XmlDocProvider.Empty);
             return type;
@@ -48,7 +50,9 @@ internal class StubLibraryVisitor : ScmLibraryVisitor
                 !IsParameterlessInternalCtorOnMrwSerializationType(constructor) &&
                 !IsInternalClientConstructor(constructor) &&
                 (constructor.EnclosingType is not ModelProvider model || model.DerivedModels.Count == 0))
+            {
                 return null;
+            }
 
             constructor.Update(
                 bodyStatements: null,
@@ -61,18 +65,24 @@ internal class StubLibraryVisitor : ScmLibraryVisitor
         private static bool IsInternalClientConstructor(ConstructorProvider constructor)
         {
             if (!constructor.Signature.Modifiers.HasFlag(MethodSignatureModifiers.Internal))
+            {
                 return false;
+            }
 
             return constructor.EnclosingType is ClientProvider;
         }
 
         private static bool IsParameterlessInternalCtorOnMrwSerializationType(ConstructorProvider constructor)
         {
             if (constructor.Signature.Parameters.Count != 0)
+            {
                 return false;
+            }
 
             if (!constructor.Signature.Modifiers.HasFlag(MethodSignatureModifiers.Internal))
+            {
                 return false;
+            }
 
             return constructor.EnclosingType is MrwSerializationTypeDefinition;
         }
@@ -101,7 +111,9 @@ private static bool IsCallingBaseCtor(ConstructorProvider constructor)
         protected override MethodProvider? VisitMethod(MethodProvider method)
         {
             if (method.Signature.ExplicitInterface is null && !IsEffectivelyPublic(method.Signature.Modifiers))
+            {
                 return null;
+            }
 
             method.Signature.Update(modifiers: method.Signature.Modifiers & ~MethodSignatureModifiers.Async);
 
@@ -116,7 +128,9 @@ private static bool IsCallingBaseCtor(ConstructorProvider constructor)
         protected override PropertyProvider? VisitProperty(PropertyProvider property)
         {
             if (!property.IsDiscriminator && !IsEffectivelyPublic(property.Modifiers))
+            {
                 return null;
+            }
 
             var propertyBody = new ExpressionPropertyBody(_throwNull, property.Body.HasSetter ? _throwNull : null);
 
@@ -130,10 +144,14 @@ private static bool IsCallingBaseCtor(ConstructorProvider constructor)
         private bool IsEffectivelyPublic(MethodSignatureModifiers modifiers)
         {
             if (modifiers.HasFlag(MethodSignatureModifiers.Public))
+            {
                 return true;
+            }
 
             if (modifiers.HasFlag(MethodSignatureModifiers.Protected) && !modifiers.HasFlag(MethodSignatureModifiers.Private))
+            {
                 return true;
+            }
 
             return false;
         }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/FixedEnumSerializationProvider.cs

@@ -49,7 +49,9 @@ private bool NeedsSerializationMethod()
             // fixed enum with int based types, we do not write a method for serialization because it was embedded in the definition
             bool isIntValueType = _enumProvider.EnumUnderlyingType.Equals(typeof(int)) || _enumProvider.EnumUnderlyingType.Equals(typeof(long));
             if (!_enumType.IsExtensible && isIntValueType)
+            {
                 return false;
+            }
 
             // otherwise we need a serialization method with the name of `ToSerial{UnderlyingTypeName}`
             return true;

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ModelReaderWriterContextDefinition.cs

@@ -327,7 +327,9 @@ private static bool ImplementsIPersistableModel(CSharpType? type, TypeProvider?
             }
 
             if (!type.IsFrameworkType || type.IsEnum || type.IsLiteral)
+            {
                 return false;
+            }
 
             return type.FrameworkType.GetInterfaces().Any(i => i.Name == "IPersistableModel`1" || i.Name == "IJsonModel`1");
         }
@@ -346,15 +348,19 @@ protected override XmlDocProvider BuildXmlDocs()
         private static string RemovePeriods(string input)
         {
             if (string.IsNullOrEmpty(input))
+            {
                 return input;
+            }
 
             Span<char> buffer = stackalloc char[input.Length];
             int index = 0;
 
             foreach (char c in input)
             {
                 if (c != '.')
+                {
                     buffer[index++] = c;
+                }
             }
 
             return buffer.Slice(0, index).ToString();
@@ -363,7 +369,9 @@ private static string RemovePeriods(string input)
         private static bool ImplementsModelReaderWriter(Type type)
         {
             if (type.IsEnum || type.IsValueType)
+            {
                 return false;
+            }
 
             return type.GetInterfaces().Any(i => i.Name == "IPersistableModel`1" || i.Name == "IJsonModel`1");
         }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.Dynamic.cs

@@ -505,7 +505,10 @@ [new VariableExpression(valueVar.Type, valueVar.Declaration, IsOut: true)]))
         private static bool IsDirectDynamicListProperty(PropertyProvider property)
         {
             if (!property.Type.IsList && !property.Type.IsArray)
+            {
                 return false;
+            }
+
             return ScmCodeModelGenerator.Instance.TypeFactory.CSharpTypeMap.TryGetValue(
                 property.Type.ElementType,
                 out var provider) &&

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.cs

@@ -1881,7 +1881,9 @@ private MethodBodyStatement WrapInIsDefined(
                 (IsNonNullableValueType(propertyType) || (propertyIsRequired && !propertyIsNullable)))
             {
                 if (patchCheck == null)
+                {
                     return writePropertySerializationStatement;
+                }
 
                 return (propertyType.IsList || propertyType.IsArray)
                     ? CreateConditionalPatchSerializationStatement(jsonSerializedName, null, writePropertySerializationStatement, writePropertySerializationStatement)
@@ -2208,26 +2210,34 @@ internal static MethodBodyStatement SerializeJsonValueCore(
                 if (valueType.IsStruct) // extensible enum
                 {
                     if (valueType.UnderlyingEnumType.Equals(typeof(string)))
+                    {
                         return utf8JsonWriter.WriteStringValue(value.Invoke(nameof(ToString)));
+                    }
 
                     return utf8JsonWriter.WriteNumberValue(value.Invoke($"ToSerial{valueType.UnderlyingEnumType.Name}"));
                 }
                 else // fixed enum
                 {
                     if (valueType.UnderlyingEnumType.Equals(typeof(int)))
+                    {
                         // when the fixed enum is implemented as int, we cast to the value
                         return utf8JsonWriter.WriteNumberValue(value.CastTo(valueType.UnderlyingEnumType));
+                    }
 
                     if (valueType.UnderlyingEnumType.Equals(typeof(string)))
+                    {
                         return utf8JsonWriter.WriteStringValue(value.Invoke($"ToSerial{valueType.UnderlyingEnumType.Name}"));
+                    }
 
                     return utf8JsonWriter.WriteNumberValue(value.Invoke($"ToSerial{valueType.UnderlyingEnumType.Name}"));
                 }
             }
 
             // Handle non-enum types
             if (!valueType.IsFrameworkType)
+            {
                 return utf8JsonWriter.WriteObjectValue(value.As(valueType), options: mrwOptionsParameter);
+            }
 
             // Handle framework types
             var frameworkType = valueType.FrameworkType;

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/RestClientProvider.cs

@@ -469,7 +469,9 @@ private List<MethodBodyStatement> AppendQueryParameters(ScopedApi uri, InputOper
             foreach (var inputParameter in operation.Parameters)
             {
                 if (inputParameter is not InputQueryParameter inputQueryParameter)
+                {
                     continue;
+                }
 
                 var queryStatement = BuildQueryParameterStatement(uri, inputQueryParameter, paramMap, operation, isNextLinkRequest);
                 if (queryStatement != null)
@@ -993,7 +995,9 @@ private static List<int> GetSuccessStatusCodes(InputOperation operation)
             foreach (var response in operation.Responses)
             {
                 if (response.IsErrorResponse)
+                {
                     continue;
+                }
 
                 foreach (var statusCode in response.StatusCodes)
                 {

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ScmMethodProviderCollection.cs

@@ -278,7 +278,9 @@ private IEnumerable<MethodBodyStatement> GetStackVariablesForProtocolParamConver
             foreach (var parameter in convenienceMethodParameters)
             {
                 if (parameter.SpreadSource != null)
+                {
                     continue;
+                }
 
                 if (parameter.Location == ParameterLocation.Body)
                 {

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/Definitions/ModelReaderWriterContextDefinitionTests.cs

@@ -408,7 +408,10 @@ public void ValidateFrameworkTypesWithMRWInterfacesAreIncluded()
                 {
                     // Map string property to a framework type that implements MRW
                     if (input == InputPrimitiveType.String)
+                    {
                         return new CSharpType(typeof(FrameworkModelWithMRW));
+                    }
+
                     return ScmCodeModelGenerator.Instance.TypeFactory.CreateCSharpType(input)!;
                 },
                 createCSharpTypeCoreFallback: input => input == InputPrimitiveType.String);
@@ -448,7 +451,10 @@ public void ValidateTypesWithoutMRWButWithMRWPropertiesAreTraversed()
                 createModelCore: input =>
                 {
                     if (input.Name == "NonMRWModel")
+                    {
                         return new NonMRWModelProvider(input);
+                    }
+
                     return new ModelProvider(input);
                 });
 
@@ -562,7 +568,10 @@ public void ValidateFrameworkTypePropertiesAreTraversedUsingReflection()
                 createCSharpTypeCore: input =>
                 {
                     if (input == InputPrimitiveType.String)
+                    {
                         return new CSharpType(typeof(ComplexFrameworkType));
+                    }
+
                     return ScmCodeModelGenerator.Instance.TypeFactory.CreateCSharpType(input)!;
                 },
                 createCSharpTypeCoreFallback: input => input == InputPrimitiveType.String);
@@ -684,7 +693,10 @@ public void ValidateNestedFrameworkTypeHierarchy()
                 createCSharpTypeCore: input =>
                 {
                     if (input == InputPrimitiveType.String)
+                    {
                         return new CSharpType(typeof(NestedFrameworkType));
+                    }
+
                     return ScmCodeModelGenerator.Instance.TypeFactory.CreateCSharpType(input)!;
                 });
 

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/SystemObjectModelSerializationTests.cs

@@ -40,7 +40,10 @@ private static (ModelProvider Model, MrwSerializationTypeDefinition Serializatio
                 createModelCore: (model) =>
                 {
                     if (model.Name == "Resource")
+                    {
                         return systemBase;
+                    }
+
                     return new ModelProvider(model);
                 },
                 createSerializationsCore: (inputType, typeProvider) =>

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/RestClientProviders/RestClientProviderTests.cs

@@ -636,7 +636,10 @@ public void ValidateClientResponseClassifiers(InputClient inputClient)
                 foreach (var response in inputOperation.Responses)
                 {
                     if (response.IsErrorResponse)
+                    {
                         continue;
+                    }
+
                     expectedStatusCodes.AddRange(response.StatusCodes);
                 }