fix: formatted the check code, added tests and documentation

Author: lakshsidhu04

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

@@ -7,14 +7,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "DuplicateIncludeCheck.h"
+#include "../utils/OptionsUtils.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Preprocessor.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/Support/Regex.h"
-#include "llvm/Support/Path.h"
-#include "../utils/OptionsUtils.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Regex.h"
 #include <memory>
 #include <vector>
 
@@ -38,9 +38,9 @@ using FileList = SmallVector<StringRef>;
 class DuplicateIncludeCallbacks : public PPCallbacks {
 public:
   DuplicateIncludeCallbacks(DuplicateIncludeCheck &Check,
-                            const SourceManager &SM, 
+                            const SourceManager &SM,
                             const std::vector<std::string> &AllowedStrings);
-  
+
   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
                    SrcMgr::CharacteristicKind FileType,
                    FileID PrevFID) override;
@@ -74,7 +74,8 @@ class DuplicateIncludeCallbacks : public PPCallbacks {
 
 DuplicateIncludeCallbacks::DuplicateIncludeCallbacks(
     DuplicateIncludeCheck &Check, const SourceManager &SM,
-    const std::vector<std::string> &AllowedStrings) : Check(Check), SM(SM) {
+    const std::vector<std::string> &AllowedStrings)
+    : Check(Check), SM(SM) {
   // The main file doesn't participate in the FileChanged notification.
   Files.emplace_back();
   AllowedDuplicateRegex.reserve(AllowedStrings.size());
@@ -83,9 +84,10 @@ DuplicateIncludeCallbacks::DuplicateIncludeCallbacks(
   }
 }
 
-void DuplicateIncludeCallbacks::FileChanged(
-        SourceLocation Loc, FileChangeReason Reason,
-        SrcMgr::CharacteristicKind FileType, FileID PrevFID) {
+void DuplicateIncludeCallbacks::FileChanged(SourceLocation Loc,
+                                            FileChangeReason Reason,
+                                            SrcMgr::CharacteristicKind FileType,
+                                            FileID PrevFID) {
   if (Reason == EnterFile)
     Files.emplace_back();
   else if (Reason == ExitFile)
@@ -101,12 +103,11 @@ void DuplicateIncludeCallbacks::InclusionDirective(
   if (FilenameRange.getBegin().isMacroID() ||
       FilenameRange.getEnd().isMacroID())
     return;
-  
+
   // if duplicate allowed, record and return
-  if(IsAllowedDuplicateInclude(FileName, File, RelativePath))
-  {
-      Files.back().push_back(FileName);
-      return;
+  if (IsAllowedDuplicateInclude(FileName, File, RelativePath)) {
+    Files.back().push_back(FileName);
+    return;
   }
 
   if (llvm::is_contained(Files.back(), FileName)) {
@@ -133,21 +134,20 @@ void DuplicateIncludeCallbacks::MacroUndefined(const Token &MacroNameTok,
   Files.back().clear();
 }
 
-bool DuplicateIncludeCallbacks::IsAllowedDuplicateInclude(StringRef TokenName,
-                                                OptionalFileEntryRef File,
-                                                StringRef RelativePath) {
+bool DuplicateIncludeCallbacks::IsAllowedDuplicateInclude(
+    StringRef TokenName, OptionalFileEntryRef File, StringRef RelativePath) {
   SmallVector<StringRef, 3> matchArguments;
   matchArguments.push_back(TokenName);
-  
+
   if (!RelativePath.empty())
     matchArguments.push_back(llvm::sys::path::filename(RelativePath));
-  
+
   if (File) {
     StringRef RealPath = File->getFileEntry().tryGetRealPathName();
     if (!RealPath.empty())
       matchArguments.push_back(llvm::sys::path::filename(RealPath));
   }
-  
+
   // try to match with each regex
   for (const llvm::Regex &reg : AllowedDuplicateRegex) {
     for (StringRef arg : matchArguments) {
@@ -165,9 +165,9 @@ DuplicateIncludeCheck::DuplicateIncludeCheck(StringRef Name,
   if (!Raw.empty()) {
     SmallVector<StringRef, 4> StringParts;
     StringRef(Raw).split(StringParts, ',', -1, false);
-    
+
     for (StringRef Part : StringParts) {
-      Part = Part.trim(); 
+      Part = Part.trim();
       if (!Part.empty())
         AllowedDuplicateIncludes.push_back(Part.str());
     }
@@ -176,7 +176,8 @@ DuplicateIncludeCheck::DuplicateIncludeCheck(StringRef Name,
 
 void DuplicateIncludeCheck::registerPPCallbacks(
     const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
-  PP->addPPCallbacks(std::make_unique<DuplicateIncludeCallbacks>(*this, SM, AllowedDuplicateIncludes));
+  PP->addPPCallbacks(std::make_unique<DuplicateIncludeCallbacks>(
+      *this, SM, AllowedDuplicateIncludes));
 }
 
 void DuplicateIncludeCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {

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

@@ -10,8 +10,8 @@
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_DUPLICATE_INCLUDE_CHECK_H
 
 #include "../ClangTidyCheck.h"
-#include <vector>
 #include <string>
+#include <vector>
 namespace clang::tidy::readability {
 
 /// \brief Find and remove duplicate #include directives.
@@ -24,8 +24,9 @@ class DuplicateIncludeCheck : public ClangTidyCheck {
 
   void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
                            Preprocessor *ModuleExpanderPP) override;
-  
+
   void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
 private:
   std::vector<std::string> AllowedDuplicateIncludes;
 };

clang-tools-extra/docs/ReleaseNotes.rst

@@ -480,6 +480,11 @@ Changes in existing checks
   <clang-tidy/checks/readability/uppercase-literal-suffix>` check to recognize
   literal suffixes added in C++23 and C23.
 
+- Improved :doc:`readability-duplicate-include
+  <clang-tidy/checks/readability/duplicate-include>` check by introducing the
+  ``AllowedDuplicateIncludes`` option, which exempts specified headers from
+  duplicate include warnings.
+
 Removed checks
 ^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/readability/duplicate-include.rst

@@ -10,7 +10,7 @@ then the list of included files is cleared.
 Examples:
 
 .. code-block:: c++
-
+  
   #include <memory>
   #include <vector>
   #include <memory>
@@ -33,3 +33,21 @@ Because of the intervening macro definitions, this code remains unchanged:
   #define NDEBUG
   #include "assertion.h"
   // ...code with assertions disabled
+
+Option: ``AllowedDuplicateIncludes``
+------------------------------------
+
+Headers listed in this option are exempt from warnings. For example:
+
+.. code-block:: c++
+
+  -config='{CheckOptions: [{key: readability-duplicate-include.AllowedDuplicateIncludes, value: "pack_begin.h,pack_end.h"}]}'
+
+This allows regex matches with ``pack_begin.h`` and ``pack_end.h`` to be included multiple times
+without triggering diagnostics.
+
+Notes
+-----
+
+- Only direct includes in the current translation unit are checked.
+- Useful for removing redundant includes and improving compile times in large codebases.

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/duplicate-include-allowed/other.h

@@ -0,0 +1,2 @@
+// dummy other.h (should warn on duplicate includes)
+#pragma once

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/duplicate-include-allowed/pack_begin.h

@@ -0,0 +1,2 @@
+// dummy pack_begin.h (allowed duplicate)
+#pragma once

clang-tools-extra/test/clang-tidy/checkers/readability/Inputs/duplicate-include-allowed/pack_end.h

@@ -0,0 +1,2 @@
+// dummy pack_end.h (allowed duplicate)
+#pragma once

clang-tools-extra/test/clang-tidy/checkers/readability/duplicate-include-allowed.cpp

@@ -0,0 +1,19 @@
+// RUN: %check_clang_tidy %s readability-duplicate-include %t -- \
+// RUN:   -header-filter='' \
+// RUN:   -config='{CheckOptions: [{key: readability-duplicate-include.AllowedDuplicateIncludes, value: "pack_begin.h,pack_end.h"}]}' \
+// RUN:   -- -I %S/Inputs/duplicate-include-allowed
+//
+// This test lives in test/clang-tidy/checkers/
+// Inputs for allowed duplicate includes are in test/clang-tidy/checkers/Inputs/duplicate-include-allowed
+
+#include "pack_begin.h"
+#include "pack_begin.h" 
+// No warning expected
+
+#include "other.h"
+#include "other.h" 
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: duplicate include [readability-duplicate-include]
+
+#include "pack_end.h"
+#include "pack_end.h" 
+// No warning expected