[clang-tidy] Add scoped enum constants to identifier naming check

Added option `ScopedEnumConstant(Prefix|Case|Suffix)` to readability-identitied-naming.
This controls the style for constants in scoped enums, declared as enum (class|struct).
If this option is unspecified the EnumConstant style will be used instead.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D89407

clang-tools-extra/clang-tidy/readability/IdentifierNamingCheck.cpp

@@ -55,6 +55,7 @@ namespace readability {
     m(Namespace) \
     m(InlineNamespace) \
     m(EnumConstant) \
+    m(ScopedEnumConstant) \
     m(ConstexprVariable) \
     m(ConstantMember) \
     m(PrivateMember) \
@@ -405,7 +406,11 @@ static StyleKind findStyleKind(
   if (isa<EnumDecl>(D) && NamingStyles[SK_Enum])
     return SK_Enum;
 
-  if (isa<EnumConstantDecl>(D)) {
+  if (const auto *EnumConst = dyn_cast<EnumConstantDecl>(D)) {
+    if (cast<EnumDecl>(EnumConst->getDeclContext())->isScoped() &&
+        NamingStyles[SK_ScopedEnumConstant])
+      return SK_ScopedEnumConstant;
+
     if (NamingStyles[SK_EnumConstant])
       return SK_EnumConstant;
 

clang-tools-extra/docs/ReleaseNotes.rst

@@ -127,6 +127,9 @@ Changes in existing checks
 
   Now renames overridden virtual methods if the method they override has a
   style violation.
+
+  Added support for specifying the style of scoped ``enum`` constants. If 
+  unspecified, will fall back to the style for regular ``enum`` constants.
 
 - Removed `google-runtime-references` check because the rule it checks does
   not exist in the Google Style Guide anymore.

clang-tools-extra/docs/clang-tidy/checks/readability-identifier-naming.rst

@@ -76,6 +76,7 @@ The following options are describe below:
  - :option:`ProtectedMethodCase`, :option:`ProtectedMethodPrefix`, :option:`ProtectedMethodSuffix`
  - :option:`PublicMemberCase`, :option:`PublicMemberPrefix`, :option:`PublicMemberSuffix`
  - :option:`PublicMethodCase`, :option:`PublicMethodPrefix`, :option:`PublicMethodSuffix`
+ - :option:`ScopedEnumConstantCase`, :option:`ScopedEnumConstantPrefix`, :option:`ScopedEnumConstantSuffix`
  - :option:`StaticConstantCase`, :option:`StaticConstantPrefix`, :option:`StaticConstantSuffix`
  - :option:`StaticVariableCase`, :option:`StaticVariablePrefix`, :option:`StaticVariableSuffix`
  - :option:`StructCase`, :option:`StructPrefix`, :option:`StructSuffix`
@@ -1595,6 +1596,41 @@ After:
       int pre_member_method_post();
     }
 
+.. option:: ScopedEnumConstantCase
+
+    When defined, the check will ensure scoped enum constant names conform to 
+    the selected casing.
+
+.. option:: ScopedEnumConstantPrefix
+
+    When defined, the check will ensure scoped enum constant names will add the
+    prefixed with the given value (regardless of casing).
+
+.. option:: ScopedEnumConstantSuffix
+
+    When defined, the check will ensure scoped enum constant names will add the
+    suffix with the given value (regardless of casing).
+
+For example using values of:
+
+   - ScopedEnumConstantCase of ``lower_case``
+   - ScopedEnumConstantPrefix of ``pre_``
+   - ScopedEnumConstantSuffix of ``_post``
+
+Identifies and/or transforms enumeration constant names as follows:
+
+Before:
+
+.. code-block:: c++
+
+    enum class FOO { One, Two, Three };
+
+After:
+
+.. code-block:: c++
+
+    enum class FOO { pre_One_post, pre_Two_post, pre_Three_post };
+
 .. option:: StaticConstantCase
 
     When defined, the check will ensure static constant names conform to the

clang-tools-extra/test/clang-tidy/checkers/readability-identifier-naming.cpp

@@ -18,6 +18,7 @@
 // RUN:     {key: readability-identifier-naming.ConstexprVariableCase, value: lower_case}, \
 // RUN:     {key: readability-identifier-naming.EnumCase, value: CamelCase}, \
 // RUN:     {key: readability-identifier-naming.EnumPrefix, value: 'E'}, \
+// RUN:     {key: readability-identifier-naming.ScopedEnumConstantCase, value: CamelCase}, \
 // RUN:     {key: readability-identifier-naming.EnumConstantCase, value: UPPER_CASE}, \
 // RUN:     {key: readability-identifier-naming.FunctionCase, value: camelBack}, \
 // RUN:     {key: readability-identifier-naming.GlobalConstantCase, value: UPPER_CASE}, \
@@ -160,6 +161,18 @@ enum my_enumeration {
 // CHECK-FIXES: {{^}}    THIS_CONST_VALUE = 1,{{$}}
 };
 
+enum class EMyEnumeration {
+    myConstant = 1,
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: invalid case style for scoped enum constant 'myConstant'
+// CHECK-FIXES: {{^}}    MyConstant = 1,{{$}}
+    your_CONST = 1,
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: invalid case style for scoped enum constant 'your_CONST'
+// CHECK-FIXES: {{^}}    YourConst = 1,{{$}}
+    THIS_ConstValue = 1,
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: invalid case style for scoped enum constant 'THIS_ConstValue'
+// CHECK-FIXES: {{^}}    ThisConstValue = 1,{{$}}
+};
+
 constexpr int ConstExpr_variable = MyConstant;
 // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: invalid case style for constexpr variable 'ConstExpr_variable'
 // CHECK-FIXES: {{^}}constexpr int const_expr_variable = MY_CONSTANT;{{$}}