[clang-tidy] Fixed an issue in readability-identifier-naming not using options specified.

[njames93]

Summary

Fixed an issue where specifying empty strings for prefix or suffix would be ignored preventing using those to override a different style.

Fixes https://github.com/llvm/llvm-project/issues/56358.

[njames93]

Small tweak.

[PiotrZSL]

Rebase on top of main + Change llvm::Optional into std::optional

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

struct HungarianNotationOption {
     llvm::StringMap<std::string> PrimitiveType;
     llvm::StringMap<std::string> UserDefinedType;
     llvm::StringMap<std::string> DerivedType;
   };
 
   struct NamingStyle {
     NamingStyle() = default;
 
-    NamingStyle(std::optional<CaseType> Case, const std::string &Prefix,
-                const std::string &Suffix, const std::string &IgnoredRegexpStr,
+    NamingStyle(std::optional<CaseType> Case, StringRef Prefix,
+                StringRef Suffix, StringRef IgnoredRegexpStr,
                 HungarianPrefixType HPType);
     NamingStyle(const NamingStyle &O) = delete;
     NamingStyle &operator=(NamingStyle &&O) = default;
     NamingStyle(NamingStyle &&O) = default;
 
     std::optional<CaseType> Case;
     std::string Prefix;
     std::string Suffix;

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

 #undef STRINGIZE
 };
 
 
 #undef NAMING_KEYS
 // clang-format on
 
 IdentifierNamingCheck::NamingStyle::NamingStyle(
-    std::optional<IdentifierNamingCheck::CaseType> Case,
-    const std::string &Prefix, const std::string &Suffix,
-    const std::string &IgnoredRegexpStr, HungarianPrefixType HPType)
+    std::optional<IdentifierNamingCheck::CaseType> Case, StringRef Prefix,
+    StringRef Suffix, StringRef IgnoredRegexpStr, HungarianPrefixType HPType)
     : Case(Case), Prefix(Prefix), Suffix(Suffix),
       IgnoredRegexpStr(IgnoredRegexpStr), HPType(HPType) {
   if (!IgnoredRegexpStr.empty()) {
     IgnoredRegexp =
         llvm::Regex(llvm::SmallString<128>({"^", IgnoredRegexpStr, "$"}));
     if (!IgnoredRegexp.isValid())
       llvm::errs() << "Invalid IgnoredRegexp regular expression: "
                    << IgnoredRegexpStr;
for (unsigned I = 0; I < SK_Count; ++I) {
 
     auto HPTOpt =
         Options.get<IdentifierNamingCheck::HungarianPrefixType>(StyleString);
     if (HPTOpt && !HungarianNotation.checkOptionValid(I))
       configurationDiag("invalid identifier naming option '%0'") << StyleString;
 
     memcpy(&StyleString[StyleSize], "IgnoredRegexp", 13);
     StyleString.truncate(StyleSize + 13);
-    StringRef IgnoredRegexpStr = Options.get(StyleString, "");
+    std::optional<StringRef> IgnoredRegexpStr = Options.get(StyleString);
     memcpy(&StyleString[StyleSize], "Prefix", 6);
     StyleString.truncate(StyleSize + 6);
-    std::string Prefix(Options.get(StyleString, ""));
+    std::optional<StringRef> Prefix(Options.get(StyleString));
     // Fast replacement of [Pre]fix -> [Suf]fix.
     memcpy(&StyleString[StyleSize], "Suf", 3);
-    std::string Postfix(Options.get(StyleString, ""));
+    std::optional<StringRef> Postfix(Options.get(StyleString));
     memcpy(&StyleString[StyleSize], "Case", 4);
     StyleString.pop_back_n(2);
-    auto CaseOptional =
+    std::optional<CaseType> CaseOptional =
         Options.get<IdentifierNamingCheck::CaseType>(StyleString);
 
-    if (CaseOptional || !Prefix.empty() || !Postfix.empty() ||
-        !IgnoredRegexpStr.empty() || HPTOpt)
-      Styles[I].emplace(std::move(CaseOptional), std::move(Prefix),
-                        std::move(Postfix), IgnoredRegexpStr.str(),
+    if (CaseOptional || Prefix || Postfix || IgnoredRegexpStr || HPTOpt)
+      Styles[I].emplace(std::move(CaseOptional), Prefix.value_or(""),
+                        Postfix.value_or(""), IgnoredRegexpStr.value_or(""),
                         HPTOpt.value_or(IdentifierNamingCheck::HPT_Off));
   }
   bool IgnoreMainLike = Options.get("IgnoreMainLikeFunctions", false);
   return {std::move(Styles), std::move(HNOption), IgnoreMainLike};
 }
 
 std::string IdentifierNamingCheck::HungarianNotation::getDeclTypeName(
     const NamedDecl *ND) const {

clang-tools-extra/docs/ReleaseNotes.rst

 - Fixed a false positive in :doc:`cppcoreguidelines-slicing
   <clang-tidy/checks/cppcoreguidelines/slicing>` check when warning would be
   emitted in constructor for virtual base class initialization.
 
 - Improved :doc:`bugprone-use-after-move
   <clang-tidy/checks/bugprone/use-after-move>` to understand that there is a
   sequence point between designated initializers.
 
+- Fixed an issue in :doc:`readability-identifier-naming
+  <clang-tidy/checks/readability/identifier-naming>` when specifying an empty
+  string for ``Prefix`` or ``Suffix`` options could result in the style not
+  being used.
+
 Removed checks
 ^^^^^^^^^^^^^^
 
 Improvements to include-fixer
 -----------------------------
 
 The improvements are...
 

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

+// RUN: %check_clang_tidy %s readability-identifier-naming %t -- \
+// RUN:   -config='{CheckOptions: { \
+// RUN:     readability-identifier-naming.GlobalConstantPrefix: "", \
+// RUN:     readability-identifier-naming.GlobalVariablePrefix: g_ }}'
+
+int BadGlobalVariable;
+// CHECK-MESSAGES: :[[@LINE-1]]:5: warning: invalid case style for global variable 'BadGlobalVariable' [readability-identifier-naming]
+// CHECK-FIXES: int g_BadGlobalVariable;
+int g_GoodGlobalVariable;
+
+const int GoodGlobalConstant = 0;
+const int g_IgnoreGlobalConstant = 0;