[clang-tidy] Add bugprone-smartptr-reset-ambiguous-call check (#121291)

Add new clang-tidy check that finds potentially erroneous calls to
``reset()`` method on smart pointers when
the pointee type also has a ``reset()`` method.

It's easy to make typo and delete object because the difference between
``.`` and ``->`` is really small.

Sometimes IDE's autocomplete will change ``->`` to ``.`` automatically.
For example, developer wrote ``ptr->res`` but after pressing _Tab_ it
became ``ptr.reset()``.

Fixes #120908

Author: vbvictor

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

@@ -0,0 +1,126 @@
+//===--- AmbiguousSmartptrResetCallCheck.cpp - clang-tidy -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "AmbiguousSmartptrResetCallCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang::tidy::readability {
+
+namespace {
+
+AST_MATCHER(CXXMethodDecl, hasOnlyDefaultParameters) {
+  for (const auto *Param : Node.parameters()) {
+    if (!Param->hasDefaultArg())
+      return false;
+  }
+
+  return true;
+}
+
+const auto DefaultSmartPointers = "::std::shared_ptr;::std::unique_ptr;"
+                                  "::boost::shared_ptr";
+} // namespace
+
+AmbiguousSmartptrResetCallCheck::AmbiguousSmartptrResetCallCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      SmartPointers(utils::options::parseStringList(
+          Options.get("SmartPointers", DefaultSmartPointers))) {}
+
+void AmbiguousSmartptrResetCallCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "SmartPointers",
+                utils::options::serializeStringList(SmartPointers));
+}
+
+void AmbiguousSmartptrResetCallCheck::registerMatchers(MatchFinder *Finder) {
+  const auto IsSmartptr = hasAnyName(SmartPointers);
+
+  const auto ResetMethod =
+      cxxMethodDecl(hasName("reset"), hasOnlyDefaultParameters());
+
+  const auto TypeWithReset =
+      anyOf(cxxRecordDecl(
+                anyOf(hasMethod(ResetMethod),
+                      isDerivedFrom(cxxRecordDecl(hasMethod(ResetMethod))))),
+            classTemplateSpecializationDecl(
+                hasSpecializedTemplate(classTemplateDecl(has(ResetMethod)))));
+
+  const auto SmartptrWithReset = expr(hasType(hasUnqualifiedDesugaredType(
+      recordType(hasDeclaration(classTemplateSpecializationDecl(
+          IsSmartptr,
+          hasTemplateArgument(
+              0, templateArgument(refersToType(hasUnqualifiedDesugaredType(
+                     recordType(hasDeclaration(TypeWithReset))))))))))));
+
+  Finder->addMatcher(
+      cxxMemberCallExpr(
+          callee(ResetMethod),
+          unless(hasAnyArgument(expr(unless(cxxDefaultArgExpr())))),
+          anyOf(on(cxxOperatorCallExpr(hasOverloadedOperatorName("->"),
+                                       hasArgument(0, SmartptrWithReset))
+                       .bind("ArrowOp")),
+                on(SmartptrWithReset)))
+          .bind("MemberCall"),
+      this);
+}
+
+void AmbiguousSmartptrResetCallCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *MemberCall =
+      Result.Nodes.getNodeAs<CXXMemberCallExpr>("MemberCall");
+  assert(MemberCall);
+
+  if (const auto *Arrow =
+          Result.Nodes.getNodeAs<CXXOperatorCallExpr>("ArrowOp")) {
+    const CharSourceRange SmartptrSourceRange =
+        Lexer::getAsCharRange(Arrow->getArg(0)->getSourceRange(),
+                              *Result.SourceManager, getLangOpts());
+
+    diag(MemberCall->getBeginLoc(),
+         "ambiguous call to 'reset()' on a pointee of a smart pointer, prefer "
+         "more explicit approach");
+
+    diag(MemberCall->getBeginLoc(),
+         "consider dereferencing smart pointer to call 'reset' method "
+         "of the pointee here",
+         DiagnosticIDs::Note)
+        << FixItHint::CreateInsertion(SmartptrSourceRange.getBegin(), "(*")
+        << FixItHint::CreateInsertion(SmartptrSourceRange.getEnd(), ")")
+        << FixItHint::CreateReplacement(
+               CharSourceRange::getCharRange(
+                   Arrow->getOperatorLoc(),
+                   Arrow->getOperatorLoc().getLocWithOffset(2)),
+               ".");
+  } else {
+    const auto *Member = cast<MemberExpr>(MemberCall->getCallee());
+    assert(Member);
+
+    diag(MemberCall->getBeginLoc(),
+         "ambiguous call to 'reset()' on a smart pointer with pointee that "
+         "also has a 'reset()' method, prefer more explicit approach");
+
+    diag(MemberCall->getBeginLoc(),
+         "consider assigning the pointer to 'nullptr' here",
+         DiagnosticIDs::Note)
+        << FixItHint::CreateReplacement(
+               SourceRange(Member->getOperatorLoc(), Member->getOperatorLoc()),
+               " =")
+        << FixItHint::CreateReplacement(
+               SourceRange(Member->getMemberLoc(), MemberCall->getEndLoc()),
+               " nullptr");
+  }
+}
+
+} // namespace clang::tidy::readability

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

@@ -0,0 +1,37 @@
+//===--- AmbiguousSmartptrResetCallCheck.h - clang-tidy ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AMBIGUOUSSMARTPTRRESETCALLCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AMBIGUOUSSMARTPTRRESETCALLCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang::tidy::readability {
+
+/// Finds potentially erroneous calls to 'reset' method on smart pointers when
+/// the pointee type also has a 'reset' method
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability/ambiguous-smartptr-reset-call.html
+class AmbiguousSmartptrResetCallCheck : public ClangTidyCheck {
+public:
+  AmbiguousSmartptrResetCallCheck(StringRef Name, ClangTidyContext *Context);
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus;
+  }
+
+private:
+  const std::vector<StringRef> SmartPointers;
+};
+
+} // namespace clang::tidy::readability
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_AMBIGUOUSSMARTPTRRESETCALLCHECK_H

clang-tools-extra/clang-tidy/readability/CMakeLists.txt

@@ -4,6 +4,7 @@ set(LLVM_LINK_COMPONENTS
   )
 
 add_clang_library(clangTidyReadabilityModule STATIC
+  AmbiguousSmartptrResetCallCheck.cpp
   AvoidConstParamsInDecls.cpp
   AvoidNestedConditionalOperatorCheck.cpp
   AvoidReturnWithVoidValueCheck.cpp

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

@@ -9,6 +9,7 @@
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
+#include "AmbiguousSmartptrResetCallCheck.h"
 #include "AvoidConstParamsInDecls.h"
 #include "AvoidNestedConditionalOperatorCheck.h"
 #include "AvoidReturnWithVoidValueCheck.h"
@@ -68,6 +69,8 @@ namespace readability {
 class ReadabilityModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
+    CheckFactories.registerCheck<AmbiguousSmartptrResetCallCheck>(
+        "readability-ambiguous-smartptr-reset-call");
     CheckFactories.registerCheck<AvoidConstParamsInDecls>(
         "readability-avoid-const-params-in-decls");
     CheckFactories.registerCheck<AvoidNestedConditionalOperatorCheck>(

clang-tools-extra/docs/ReleaseNotes.rst

@@ -100,6 +100,12 @@ New checks
   Finds unintended character output from ``unsigned char`` and ``signed char`` to an
   ``ostream``.
 
+- New :doc:`readability-ambiguous-smartptr-reset-call
+  <clang-tidy/checks/readability/ambiguous-smartptr-reset-call>` check.
+
+  Finds potentially erroneous calls to ``reset`` method on smart pointers when
+  the pointee type also has a ``reset`` method.
+
 New check aliases
 ^^^^^^^^^^^^^^^^^
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -353,6 +353,7 @@ Clang-Tidy Checks
    :doc:`portability-simd-intrinsics <portability/simd-intrinsics>`,
    :doc:`portability-std-allocator-const <portability/std-allocator-const>`,
    :doc:`portability-template-virtual-member-function <portability/template-virtual-member-function>`,
+   :doc:`readability-ambiguous-smartptr-reset-call <readability/ambiguous-smartptr-reset-call>`, "Yes"
    :doc:`readability-avoid-const-params-in-decls <readability/avoid-const-params-in-decls>`, "Yes"
    :doc:`readability-avoid-nested-conditional-operator <readability/avoid-nested-conditional-operator>`,
    :doc:`readability-avoid-return-with-void-value <readability/avoid-return-with-void-value>`, "Yes"

clang-tools-extra/docs/clang-tidy/checks/readability/ambiguous-smartptr-reset-call.rst

@@ -0,0 +1,62 @@
+.. title:: clang-tidy - readability-ambiguous-smartptr-reset-call
+
+readability-ambiguous-smartptr-reset-call
+=========================================
+
+Finds potentially erroneous calls to ``reset`` method on smart pointers when
+the pointee type also has a ``reset`` method. Having a ``reset`` method in
+both classes makes it easy to accidentally make the pointer null when
+intending to reset the underlying object.
+
+.. code-block:: c++
+
+  struct Resettable {
+    void reset() { /* Own reset logic */ }
+  };
+
+  auto ptr = std::make_unique<Resettable>();
+
+  ptr->reset();  // Calls underlying reset method
+  ptr.reset();   // Makes the pointer null
+
+Both calls are valid C++ code, but the second one might not be what the
+developer intended, as it destroys the pointed-to object rather than resetting
+its state. It's easy to make such a typo because the difference between
+``.`` and ``->`` is really small.
+
+The recommended approach is to make the intent explicit by using either member
+access or direct assignment:
+
+.. code-block:: c++
+
+  std::unique_ptr<Resettable> ptr = std::make_unique<Resettable>();
+
+  (*ptr).reset();  // Clearly calls underlying reset method
+  ptr = nullptr;   // Clearly makes the pointer null
+
+The default smart pointers and classes that are considered are
+``std::unique_ptr``, ``std::shared_ptr``, ``boost::shared_ptr``. To specify
+other smart pointers or other classes use the :option:`SmartPointers` option.
+
+
+.. note::
+    
+  The check may emit invalid fix-its and misleading warning messages when
+  specifying custom smart pointers or other classes in the
+  :option:`SmartPointers` option. For example, ``boost::scoped_ptr`` does not
+  have an ``operator=`` which makes fix-its invalid.
+
+.. note::
+    
+  Automatic fix-its are enabled only if :program:`clang-tidy` is invoked with
+  the `--fix-notes` option.
+
+
+Options
+-------
+
+.. option:: SmartPointers
+
+    Semicolon-separated list of fully qualified class names of custom smart
+    pointers. Default value is `::std::unique_ptr;::std::shared_ptr;
+    ::boost::shared_ptr`.

clang-tools-extra/test/clang-tidy/checkers/readability/ambiguous-smartptr-reset-call-custom-pointers.cpp

@@ -0,0 +1,52 @@
+// RUN: %check_clang_tidy %s readability-ambiguous-smartptr-reset-call %t -- \
+// RUN: -config='{CheckOptions: \
+// RUN:  {readability-ambiguous-smartptr-reset-call.SmartPointers: "::std::unique_ptr;::other_ptr"}}' \
+// RUN: --fix-notes -- -I %S/../modernize/Inputs/smart-ptr
+
+#include "unique_ptr.h"
+#include "shared_ptr.h"
+
+template <typename T>
+struct other_ptr {
+  T& operator*() const;
+  T* operator->() const;
+  void reset();
+};
+
+struct Resettable {
+  void reset();
+  void doSomething();
+};
+
+void Positive() {
+  std::unique_ptr<Resettable> u;
+  u.reset();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: ambiguous call to 'reset()' on a smart pointer with pointee that also has a 'reset()' method, prefer more explicit approach
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: note: consider assigning the pointer to 'nullptr' here
+  // CHECK-FIXES: u = nullptr;
+  u->reset();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: ambiguous call to 'reset()' on a pointee of a smart pointer, prefer more explicit approach
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: note: consider dereferencing smart pointer to call 'reset' method of the pointee here
+  // CHECK-FIXES: (*u).reset();
+
+  other_ptr<Resettable> s;
+  s.reset();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: ambiguous call to 'reset()' on a smart pointer with pointee that also has a 'reset()' method, prefer more explicit approach
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: note: consider assigning the pointer to 'nullptr' here
+  // CHECK-FIXES: s = nullptr;
+  s->reset();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: ambiguous call to 'reset()' on a pointee of a smart pointer, prefer more explicit approach
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: note: consider dereferencing smart pointer to call 'reset' method of the pointee here
+  // CHECK-FIXES: (*s).reset();
+}
+
+void Negative() {
+  std::shared_ptr<Resettable> s_ptr;
+  s_ptr.reset();
+  s_ptr->reset();
+  s_ptr->doSomething();
+
+  std::unique_ptr<Resettable> u_ptr;
+  u_ptr.reset(nullptr);
+  u_ptr->doSomething();
+}