[clang-tidy] Fix Hungarian Prefix in readability-identifier-naming (#…

…84236)

Fix handling of Hungarian Prefix when configured to LowerCase.
Warnings no longer will be emited for names that already match
this style.

Fixes: #80268

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

@@ -888,8 +888,14 @@ bool IdentifierNamingCheck::matchesStyle(
     return false;
   if (IdentifierNamingCheck::HungarianPrefixType::HPT_Off != Style.HPType) {
     std::string HNPrefix = HungarianNotation.getPrefix(Decl, HNOption);
-    if (!Name.consume_front(HNPrefix))
-      return false;
+    if (!HNPrefix.empty()) {
+      if (!Name.consume_front(HNPrefix))
+        return false;
+      if (Style.HPType ==
+              IdentifierNamingCheck::HungarianPrefixType::HPT_LowerCase &&
+          !Name.consume_front("_"))
+        return false;
+    }
   }
 
   // Ensure the name doesn't have any extra underscores beyond those specified

clang-tools-extra/docs/ReleaseNotes.rst

@@ -235,7 +235,8 @@ Changes in existing checks
 
 - Improved :doc:`readability-identifier-naming
   <clang-tidy/checks/readability/identifier-naming>` check in `GetConfigPerFile`
-  mode by resolving symbolic links to header files.
+  mode by resolving symbolic links to header files. Fixed handling of Hungarian
+  Prefix when configured to `LowerCase`.
 
 Removed checks
 ^^^^^^^^^^^^^^

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

@@ -11,14 +11,14 @@ another if a mismatch is detected
 
 Casing types include:
 
- - ``lower_case``,
- - ``UPPER_CASE``,
- - ``camelBack``,
- - ``CamelCase``,
- - ``camel_Snake_Back``,
- - ``Camel_Snake_Case``,
- - ``aNy_CasE``,
- - ``Leading_upper_snake_case``.
+ - ``lower_case``
+ - ``UPPER_CASE``
+ - ``camelBack``
+ - ``CamelCase``
+ - ``camel_Snake_Back``
+ - ``Camel_Snake_Case``
+ - ``aNy_CasE``
+ - ``Leading_upper_snake_case``
 
 It also supports a fixed prefix and suffix that will be prepended or appended
 to the identifiers, regardless of the casing.
@@ -32,8 +32,16 @@ but not where they are overridden, as it can't be fixed locally there.
 This also applies for pseudo-override patterns like CRTP.
 
 ``Leading_upper_snake_case`` is a naming convention where the first word is capitalized
-followed by lower case word(s) seperated by underscore(s) '_'. Examples include:
-Cap_snake_case, Cobra_case, Foo_bar_baz, and Master_copy_8gb.
+followed by lower case word(s) separated by underscore(s) '_'. Examples include:
+`Cap_snake_case`, `Cobra_case`, `Foo_bar_baz`, and `Master_copy_8gb`.
+
+Hungarian notation can be customized using different *HungarianPrefix* settings.
+The options and their corresponding values are:
+
+ - ``Off`` - the default setting
+ - ``On`` - example: ``int iVariable``
+ - ``LowerCase`` - example: ``int i_Variable``
+ - ``CamelCase`` - example: ``int IVariable``
 
 Options
 -------

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/identifier-naming/hungarian-notation3/.clang-tidy

@@ -0,0 +1,60 @@
+Checks: readability-identifier-naming
+CheckOptions:
+  readability-identifier-naming.AbstractClassCase: CamelCase
+  readability-identifier-naming.StructCase: CamelCase
+  readability-identifier-naming.UnionCase: camelBack
+  readability-identifier-naming.ClassCase: CamelCase
+  readability-identifier-naming.ClassConstantCase: CamelCase
+  readability-identifier-naming.ClassMemberCase: CamelCase
+  readability-identifier-naming.ConstantCase: CamelCase
+  readability-identifier-naming.ConstantMemberCase: CamelCase
+  readability-identifier-naming.ConstantParameterCase: CamelCase
+  readability-identifier-naming.ConstantPointerParameterCase: CamelCase
+  readability-identifier-naming.ConstexprVariableCase: CamelCase
+  readability-identifier-naming.EnumConstantCase: CamelCase
+  readability-identifier-naming.GlobalConstantCase: CamelCase
+  readability-identifier-naming.GlobalConstantPointerCase: CamelCase
+  readability-identifier-naming.GlobalPointerCase: CamelCase
+  readability-identifier-naming.GlobalVariableCase: CamelCase
+  readability-identifier-naming.LocalConstantCase: CamelCase
+  readability-identifier-naming.LocalConstantPointerCase: CamelCase
+  readability-identifier-naming.LocalPointerCase: CamelCase
+  readability-identifier-naming.LocalVariableCase: CamelCase
+  readability-identifier-naming.MemberCase: CamelCase
+  readability-identifier-naming.ParameterCase: CamelCase
+  readability-identifier-naming.PointerParameterCase: CamelCase
+  readability-identifier-naming.PrivateMemberCase: CamelCase
+  readability-identifier-naming.ProtectedMemberCase: CamelCase
+  readability-identifier-naming.PublicMemberCase: CamelCase
+  readability-identifier-naming.ScopedEnumConstantCase: CamelCase
+  readability-identifier-naming.StaticConstantCase: CamelCase
+  readability-identifier-naming.StaticVariableCase: CamelCase
+  readability-identifier-naming.VariableCase: CamelCase
+  readability-identifier-naming.AbstractClassHungarianPrefix: LowerCase
+  readability-identifier-naming.ClassHungarianPrefix: LowerCase
+  readability-identifier-naming.ClassConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.ClassMemberHungarianPrefix: LowerCase
+  readability-identifier-naming.ConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.ConstantMemberHungarianPrefix: LowerCase
+  readability-identifier-naming.ConstantParameterHungarianPrefix: LowerCase
+  readability-identifier-naming.ConstantPointerParameterHungarianPrefix: LowerCase
+  readability-identifier-naming.ConstexprVariableHungarianPrefix: LowerCase
+  readability-identifier-naming.EnumConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.GlobalConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.GlobalConstantPointerHungarianPrefix: LowerCase
+  readability-identifier-naming.GlobalPointerHungarianPrefix: LowerCase
+  readability-identifier-naming.GlobalVariableHungarianPrefix: LowerCase
+  readability-identifier-naming.LocalConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.LocalConstantPointerHungarianPrefix: LowerCase
+  readability-identifier-naming.LocalPointerHungarianPrefix: LowerCase
+  readability-identifier-naming.LocalVariableHungarianPrefix: LowerCase
+  readability-identifier-naming.MemberHungarianPrefix: LowerCase
+  readability-identifier-naming.ParameterHungarianPrefix: LowerCase
+  readability-identifier-naming.PointerParameterHungarianPrefix: LowerCase
+  readability-identifier-naming.PrivateMemberHungarianPrefix: LowerCase
+  readability-identifier-naming.ProtectedMemberHungarianPrefix: LowerCase
+  readability-identifier-naming.PublicMemberHungarianPrefix: LowerCase
+  readability-identifier-naming.ScopedEnumConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.StaticConstantHungarianPrefix: LowerCase
+  readability-identifier-naming.StaticVariableHungarianPrefix: LowerCase
+  readability-identifier-naming.VariableHungarianPrefix: LowerCase