[clang-tidy] White List Option for performance-unnecessary-value-param, performance-unnecessary-copy-initialization and performance-for-range-copy

New option added to these three checks to be able to silence false positives on
types that are intentionally passed by value or copied. Such types are e.g.
intrusive reference counting pointer types like llvm::IntrusiveRefCntPtr. The
new option is named WhiteListTypes and can contain a semicolon-separated list of
names of these types. Regular expressions are allowed. Default is empty.

Differential Revision: https://reviews.llvm.org/D52727

llvm-svn: 344340

clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.cpp

@@ -10,6 +10,8 @@
 #include "ForRangeCopyCheck.h"
 #include "../utils/DeclRefExprUtils.h"
 #include "../utils/FixItHintUtils.h"
+#include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
 #include "../utils/TypeTraits.h"
 #include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
 
@@ -21,10 +23,14 @@ namespace performance {
 
 ForRangeCopyCheck::ForRangeCopyCheck(StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
-      WarnOnAllAutoCopies(Options.get("WarnOnAllAutoCopies", 0)) {}
+      WarnOnAllAutoCopies(Options.get("WarnOnAllAutoCopies", 0)),
+      AllowedTypes(
+          utils::options::parseStringList(Options.get("AllowedTypes", ""))) {}
 
 void ForRangeCopyCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "WarnOnAllAutoCopies", WarnOnAllAutoCopies);
+  Options.store(Opts, "AllowedTypes",
+                utils::options::serializeStringList(AllowedTypes));
 }
 
 void ForRangeCopyCheck::registerMatchers(MatchFinder *Finder) {
@@ -32,7 +38,10 @@ void ForRangeCopyCheck::registerMatchers(MatchFinder *Finder) {
   // initialized through MaterializeTemporaryExpr which indicates a type
   // conversion.
   auto LoopVar = varDecl(
-      hasType(hasCanonicalType(unless(anyOf(referenceType(), pointerType())))),
+      hasType(qualType(
+          unless(anyOf(hasCanonicalType(anyOf(referenceType(), pointerType())),
+                       hasDeclaration(namedDecl(
+                           matchers::matchesAnyListedName(AllowedTypes))))))),
       unless(hasInitializer(expr(hasDescendant(materializeTemporaryExpr())))));
   Finder->addMatcher(cxxForRangeStmt(hasLoopVariable(LoopVar.bind("loopVar")))
                          .bind("forRange"),
@@ -41,6 +50,7 @@ void ForRangeCopyCheck::registerMatchers(MatchFinder *Finder) {
 
 void ForRangeCopyCheck::check(const MatchFinder::MatchResult &Result) {
   const auto *Var = Result.Nodes.getNodeAs<VarDecl>("loopVar");
+
   // Ignore code in macros since we can't place the fixes correctly.
   if (Var->getBeginLoc().isMacroID())
     return;

clang-tools-extra/clang-tidy/performance/ForRangeCopyCheck.h

@@ -40,6 +40,7 @@ private:
                                        ASTContext &Context);
 
   const bool WarnOnAllAutoCopies;
+  const std::vector<std::string> AllowedTypes;
 };
 
 } // namespace performance

clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp

@@ -12,6 +12,7 @@
 #include "../utils/DeclRefExprUtils.h"
 #include "../utils/FixItHintUtils.h"
 #include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
 
 namespace clang {
 namespace tidy {
@@ -30,6 +31,12 @@ void recordFixes(const VarDecl &Var, ASTContext &Context,
 using namespace ::clang::ast_matchers;
 using utils::decl_ref_expr::isOnlyUsedAsConst;
 
+UnnecessaryCopyInitialization::UnnecessaryCopyInitialization(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      AllowedTypes(
+          utils::options::parseStringList(Options.get("AllowedTypes", ""))) {}
+
 void UnnecessaryCopyInitialization::registerMatchers(MatchFinder *Finder) {
   auto ConstReference = referenceType(pointee(qualType(isConstQualified())));
   auto ConstOrConstReference =
@@ -50,12 +57,17 @@ void UnnecessaryCopyInitialization::registerMatchers(MatchFinder *Finder) {
       callExpr(callee(functionDecl(returns(ConstReference))),
                unless(callee(cxxMethodDecl())));
 
-  auto localVarCopiedFrom = [](const internal::Matcher<Expr> &CopyCtorArg) {
+  auto localVarCopiedFrom = [this](const internal::Matcher<Expr> &CopyCtorArg) {
     return compoundStmt(
                forEachDescendant(
                    declStmt(
                        has(varDecl(hasLocalStorage(),
-                                   hasType(matchers::isExpensiveToCopy()),
+                                   hasType(qualType(
+                                       allOf(hasCanonicalType(
+                                                 matchers::isExpensiveToCopy()),
+                                             unless(hasDeclaration(namedDecl(
+                                                 matchers::matchesAnyListedName(
+                                                     AllowedTypes))))))),
                                    unless(isImplicit()),
                                    hasInitializer(
                                        cxxConstructExpr(
@@ -84,6 +96,7 @@ void UnnecessaryCopyInitialization::check(
   const auto *ObjectArg = Result.Nodes.getNodeAs<VarDecl>("objectArg");
   const auto *BlockStmt = Result.Nodes.getNodeAs<Stmt>("blockStmt");
   const auto *CtorCall = Result.Nodes.getNodeAs<CXXConstructExpr>("ctorCall");
+
   // Do not propose fixes if the DeclStmt has multiple VarDecls or in macros
   // since we cannot place them correctly.
   bool IssueFix =
@@ -144,6 +157,12 @@ void UnnecessaryCopyInitialization::handleCopyFromLocalVar(
     recordFixes(NewVar, Context, Diagnostic);
 }
 
+void UnnecessaryCopyInitialization::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "AllowedTypes",
+                utils::options::serializeStringList(AllowedTypes));
+}
+
 } // namespace performance
 } // namespace tidy
 } // namespace clang

clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.h

@@ -26,10 +26,10 @@ namespace performance {
 // const references, and const pointers to const.
 class UnnecessaryCopyInitialization : public ClangTidyCheck {
 public:
-  UnnecessaryCopyInitialization(StringRef Name, ClangTidyContext *Context)
+  UnnecessaryCopyInitialization(StringRef Name, ClangTidyContext *Context);
-      : ClangTidyCheck(Name, Context) {}
   void registerMatchers(ast_matchers::MatchFinder *Finder) override;
   void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
 
 private:
   void handleCopyFromMethodReturn(const VarDecl &Var, const Stmt &BlockStmt,
@@ -38,6 +38,7 @@ private:
   void handleCopyFromLocalVar(const VarDecl &NewVar, const VarDecl &OldVar,
                               const Stmt &BlockStmt, bool IssueFix,
                               ASTContext &Context);
+  const std::vector<std::string> AllowedTypes;
 };
 
 } // namespace performance

clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.cpp

@@ -12,6 +12,7 @@
 #include "../utils/DeclRefExprUtils.h"
 #include "../utils/FixItHintUtils.h"
 #include "../utils/Matchers.h"
+#include "../utils/OptionsUtils.h"
 #include "../utils/TypeTraits.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/Lexer.h"
@@ -68,17 +69,22 @@ UnnecessaryValueParamCheck::UnnecessaryValueParamCheck(
     StringRef Name, ClangTidyContext *Context)
     : ClangTidyCheck(Name, Context),
       IncludeStyle(utils::IncludeSorter::parseIncludeStyle(
-          Options.getLocalOrGlobal("IncludeStyle", "llvm"))) {}
+          Options.getLocalOrGlobal("IncludeStyle", "llvm"))),
+      AllowedTypes(
+          utils::options::parseStringList(Options.get("AllowedTypes", ""))) {}
 
 void UnnecessaryValueParamCheck::registerMatchers(MatchFinder *Finder) {
   // This check is specific to C++ and doesn't apply to languages like
   // Objective-C.
   if (!getLangOpts().CPlusPlus)
     return;
-  const auto ExpensiveValueParamDecl =
+  const auto ExpensiveValueParamDecl = parmVarDecl(
-      parmVarDecl(hasType(hasCanonicalType(allOf(
+      hasType(qualType(allOf(
-                      unless(referenceType()), matchers::isExpensiveToCopy()))),
+          hasCanonicalType(matchers::isExpensiveToCopy()),
-                  decl().bind("param"));
+          unless(anyOf(hasCanonicalType(referenceType()),
+                       hasDeclaration(namedDecl(
+                           matchers::matchesAnyListedName(AllowedTypes)))))))),
+      decl().bind("param"));
   Finder->addMatcher(
       functionDecl(hasBody(stmt()), isDefinition(), unless(isImplicit()),
                    unless(cxxMethodDecl(anyOf(isOverride(), isFinal()))),
@@ -173,6 +179,8 @@ void UnnecessaryValueParamCheck::storeOptions(
     ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "IncludeStyle",
                 utils::IncludeSorter::toString(IncludeStyle));
+  Options.store(Opts, "AllowedTypes",
+                utils::options::serializeStringList(AllowedTypes));
 }
 
 void UnnecessaryValueParamCheck::onEndOfTranslationUnit() {

clang-tools-extra/clang-tidy/performance/UnnecessaryValueParamCheck.h

@@ -40,6 +40,7 @@ private:
       MutationAnalyzers;
   std::unique_ptr<utils::IncludeInserter> Inserter;
   const utils::IncludeSorter::IncludeStyle IncludeStyle;
+  const std::vector<std::string> AllowedTypes;
 };
 
 } // namespace performance

clang-tools-extra/clang-tidy/utils/Matchers.h

@@ -48,6 +48,13 @@ AST_MATCHER_FUNCTION(ast_matchers::TypeMatcher, isReferenceToConst) {
   return referenceType(pointee(qualType(isConstQualified())));
 }
 
+AST_MATCHER_P(NamedDecl, matchesAnyListedName, std::vector<std::string>,
+              NameList) {
+  return llvm::any_of(NameList, [&Node](const std::string &Name) {
+      return llvm::Regex(Name).match(Node.getName());
+    });
+}
+
 } // namespace matchers
 } // namespace tidy
 } // namespace clang

clang-tools-extra/docs/clang-tidy/checks/performance-for-range-copy.rst

@@ -25,3 +25,10 @@ Options
 
    When non-zero, warns on any use of `auto` as the type of the range-based for
    loop variable. Default is `0`.
+
+.. option:: AllowedTypes
+
+   A semicolon-separated list of names of types allowed to be copied in each
+   iteration. Regular expressions are accepted, e.g. `[Rr]ef(erence)?$` matches
+   every type with suffix `Ref`, `ref`, `Reference` and `reference`. The default
+   is empty.

clang-tools-extra/docs/clang-tidy/checks/performance-unnecessary-copy-initialization.rst

@@ -35,3 +35,13 @@ Example:
     string UnnecessaryCopy2 = UnnecessaryCopy1;
     UnnecessaryCopy2.find("bar");
   }
+
+Options
+-------
+
+.. option:: AllowedTypes
+
+   A semicolon-separated list of names of types allowed to be initialized by
+   copying. Regular expressions are accepted, e.g. `[Rr]ef(erence)?$` matches
+   every type with suffix `Ref`, `ref`, `Reference` and `reference`. The
+   default is empty.

clang-tools-extra/docs/clang-tidy/checks/performance-unnecessary-value-param.rst

@@ -61,3 +61,9 @@ Options
 
    A string specifying which include-style is used, `llvm` or `google`. Default
    is `llvm`.
+
+.. option:: AllowedTypes
+
+   A semicolon-separated list of names of types allowed to be passed by value.
+   Regular expressions are accepted, e.g. `[Rr]ef(erence)?$` matches every type
+   with suffix `Ref`, `ref`, `Reference` and `reference`. The default is empty.

clang-tools-extra/test/clang-tidy/performance-for-range-copy-allowed-types.cpp

@@ -0,0 +1,124 @@
+// RUN: %check_clang_tidy %s performance-for-range-copy %t -- -config="{CheckOptions: [{key: performance-for-range-copy.AllowedTypes, value: '[Pp]ointer$;[Pp]tr$;[Rr]ef(erence)?$'}]}" -- -std=c++11 -fno-delayed-template-parsing
+
+template <typename T>
+struct Iterator {
+  void operator++() {}
+  const T& operator*() {
+    static T* TT = new T();
+    return *TT;
+  }
+  bool operator!=(const Iterator &) { return false; }
+  typedef const T& const_reference;
+};
+template <typename T>
+struct View {
+  T begin() { return T(); }
+  T begin() const { return T(); }
+  T end() { return T(); }
+  T end() const { return T(); }
+  typedef typename T::const_reference const_reference;
+};
+
+struct SmartPointer {
+  ~SmartPointer();
+};
+
+struct smart_pointer {
+  ~smart_pointer();
+};
+
+struct SmartPtr {
+  ~SmartPtr();
+};
+
+struct smart_ptr {
+  ~smart_ptr();
+};
+
+struct SmartReference {
+  ~SmartReference();
+};
+
+struct smart_reference {
+  ~smart_reference();
+};
+
+struct SmartRef {
+  ~SmartRef();
+};
+
+struct smart_ref {
+  ~smart_ref();
+};
+
+struct OtherType {
+  ~OtherType();
+};
+
+template <typename T> struct SomeComplexTemplate {
+  ~SomeComplexTemplate();
+};
+
+typedef SomeComplexTemplate<int> NotTooComplexRef;
+
+void negativeSmartPointer() {
+  for (auto P : View<Iterator<SmartPointer>>()) {
+    auto P2 = P;
+  }
+}
+
+void negative_smart_pointer() {
+  for (auto p : View<Iterator<smart_pointer>>()) {
+    auto p2 = p;
+  }
+}
+
+void negativeSmartPtr() {
+  for (auto P : View<Iterator<SmartPtr>>()) {
+    auto P2 = P;
+  }
+}
+
+void negative_smart_ptr() {
+  for (auto p : View<Iterator<smart_ptr>>()) {
+    auto p2 = p;
+  }
+}
+
+void negativeSmartReference() {
+  for (auto R : View<Iterator<SmartReference>>()) {
+    auto R2 = R;
+  }
+}
+
+void negative_smart_reference() {
+  for (auto r : View<Iterator<smart_reference>>()) {
+    auto r2 = r;
+  }
+}
+
+void negativeSmartRef() {
+  for (auto R : View<Iterator<SmartRef>>()) {
+    auto R2 = R;
+  }
+}
+
+void negative_smart_ref() {
+  for (auto r : View<Iterator<smart_ref>>()) {
+    auto r2 = r;
+  }
+}
+
+void positiveOtherType() {
+  for (auto O : View<Iterator<OtherType>>()) {
+  // CHECK-MESSAGES: [[@LINE-1]]:13: warning: loop variable is copied but only used as const reference; consider making it a const reference [performance-for-range-copy]
+  // CHECK-FIXES: for (const auto& O : View<Iterator<OtherType>>()) {
+    auto O2 = O;
+  }
+}
+
+void negativeNotTooComplexRef() {
+  for (NotTooComplexRef R : View<Iterator<NotTooComplexRef>>()) {
+    auto R2 = R;
+  }
+}

clang-tools-extra/test/clang-tidy/performance-unnecessary-copy-initialization-allowed-types.cpp

@@ -0,0 +1,98 @@
+// RUN: %check_clang_tidy %s performance-unnecessary-copy-initialization %t -- -config="{CheckOptions: [{key: performance-unnecessary-copy-initialization.AllowedTypes, value: '[Pp]ointer$;[Pp]tr$;[Rr]ef(erence)?$'}]}" --
+
+struct SmartPointer {
+  ~SmartPointer();
+};
+
+struct smart_pointer {
+  ~smart_pointer();
+};
+
+struct SmartPtr {
+  ~SmartPtr();
+};
+
+struct smart_ptr {
+  ~smart_ptr();
+};
+
+struct SmartReference {
+  ~SmartReference();
+};
+
+struct smart_reference {
+  ~smart_reference();
+};
+
+struct SmartRef {
+  ~SmartRef();
+};
+
+struct smart_ref {
+  ~smart_ref();
+};
+
+struct OtherType {
+  ~OtherType();
+};
+
+template <typename T> struct SomeComplexTemplate {
+  ~SomeComplexTemplate();
+};
+
+typedef SomeComplexTemplate<int> NotTooComplexRef;
+
+const SmartPointer &getSmartPointer();
+const smart_pointer &get_smart_pointer();
+const SmartPtr &getSmartPtr();
+const smart_ptr &get_smart_ptr();
+const SmartReference &getSmartReference();
+const smart_reference &get_smart_reference();
+const SmartRef &getSmartRef();
+const smart_ref &get_smart_ref();
+const OtherType &getOtherType();
+const NotTooComplexRef &getNotTooComplexRef();
+
+void negativeSmartPointer() {
+  const auto P = getSmartPointer();
+}
+
+void negative_smart_pointer() {
+  const auto p = get_smart_pointer();
+}
+
+void negativeSmartPtr() {
+  const auto P = getSmartPtr();
+}
+
+void negative_smart_ptr() {
+  const auto p = get_smart_ptr();
+}
+
+void negativeSmartReference() {
+  const auto R = getSmartReference();
+}
+
+void negative_smart_reference() {
+  const auto r = get_smart_reference();
+}
+
+void negativeSmartRef() {
+  const auto R = getSmartRef();
+}
+
+void negative_smart_ref() {
+  const auto r = get_smart_ref();
+}
+
+void positiveOtherType() {
+  const auto O = getOtherType();
+  // CHECK-MESSAGES: [[@LINE-1]]:14: warning: the const qualified variable 'O' is copy-constructed from a const reference; consider making it a const reference [performance-unnecessary-copy-initialization]
+  // CHECK-FIXES: const auto& O = getOtherType();
+}
+
+void negativeNotTooComplexRef() {
+  const NotTooComplexRef R = getNotTooComplexRef();
+  // Using `auto` here would result in the "canonical" type which does not match
+  // the pattern.
+}

clang-tools-extra/test/clang-tidy/performance-unnecessary-value-param-allowed-types.cpp

@@ -0,0 +1,75 @@
+// RUN: %check_clang_tidy %s performance-unnecessary-value-param %t -- -config="{CheckOptions: [{key: performance-unnecessary-value-param.AllowedTypes, value: '[Pp]ointer$;[Pp]tr$;[Rr]ef(erence)?$'}]}" --
+
+struct SmartPointer {
+  ~SmartPointer();
+};
+
+struct smart_pointer {
+  ~smart_pointer();
+};
+
+struct SmartPtr {
+  ~SmartPtr();
+};
+
+struct smart_ptr {
+  ~smart_ptr();
+};
+
+struct SmartReference {
+  ~SmartReference();
+};
+
+struct smart_reference {
+  ~smart_reference();
+};
+
+struct SmartRef {
+  ~SmartRef();
+};
+
+struct smart_ref {
+  ~smart_ref();
+};
+
+struct OtherType {
+  ~OtherType();
+};
+
+template <typename T> struct SomeComplexTemplate {
+  ~SomeComplexTemplate();
+};
+
+typedef SomeComplexTemplate<int> NotTooComplexRef;
+
+void negativeSmartPointer(SmartPointer P) {
+}
+
+void negative_smart_pointer(smart_pointer p) {
+}
+
+void negativeSmartPtr(SmartPtr P) {
+}
+
+void negative_smart_ptr(smart_ptr p) {
+}
+
+void negativeSmartReference(SmartReference R) {
+}
+
+void negative_smart_reference(smart_reference r) {
+}
+
+void negativeSmartRef(SmartRef R) {
+}
+
+void negative_smart_ref(smart_ref r) {
+}
+
+void positiveOtherType(OtherType O) {
+  // CHECK-MESSAGES: [[@LINE-1]]:34: warning: the parameter 'O' is copied for each invocation but only used as a const reference; consider making it a const reference [performance-unnecessary-value-param]
+  // CHECK-FIXES: void positiveOtherType(const OtherType& O) {
+}
+
+void negativeNotTooComplexRef(NotTooComplexRef R) {
+}