[clang-tidy] Add support for lambdas in cppcoreguidelines-owning-memory

[PiotrZSL]

Summary

Implement proper support for lambdas and sub-functions/classes.

Fixes: #59389

clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp

 #include <string>
 #include <vector>
 
 using namespace clang::ast_matchers;
 using namespace clang::ast_matchers::internal;
 
 namespace clang::tidy::cppcoreguidelines {
 
+namespace {
+AST_MATCHER_P(LambdaExpr, hasCallOperator,
+              ast_matchers::internal::Matcher<CXXMethodDecl>, InnerMatcher) {
+  return InnerMatcher.matches(*Node.getCallOperator(), Finder, Builder);
+}
+
+AST_MATCHER_P(LambdaExpr, hasLambdaBody, ast_matchers::internal::Matcher<Stmt>,
+              InnerMatcher) {
+  return InnerMatcher.matches(*Node.getBody(), Finder, Builder);
+}
+} // namespace
+
 void OwningMemoryCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
   Options.store(Opts, "LegacyResourceProducers", LegacyResourceProducers);
   Options.store(Opts, "LegacyResourceConsumers", LegacyResourceConsumers);
 }
 
 /// Match common cases, where the owner semantic is relevant, like function
 /// calls, delete expressions and others.
 void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
 
   const auto CreatesOwner =
       anyOf(cxxNewExpr(),
             callExpr(callee(
                 functionDecl(returns(qualType(hasDeclaration(OwnerDecl)))))),
             CreatesLegacyOwner, LegacyOwnerCast);
 
   const auto ConsideredOwner = eachOf(IsOwnerType, CreatesOwner);
+  const auto ScopeDeclaration = anyOf(translationUnitDecl(), namespaceDecl(),
+                                      recordDecl(), functionDecl());
 
   // Find delete expressions that delete non-owners.
   Finder->addMatcher(
       traverse(TK_AsIs,
                cxxDeleteExpr(hasDescendant(declRefExpr(unless(ConsideredOwner))
                                                .bind("deleted_variable")))
                    .bind("delete_expr")),
       this);
Finder->addMatcher(callExpr(forEachArgumentWithParam(
                          expr(CreatesOwner).bind("bad_owner_creation_argument"),
                          parmVarDecl(unless(IsOwnerType))
                              .bind("bad_owner_creation_parameter"))),
                      this);
 
   // Matching on functions, that return an owner/resource, but don't declare
   // their return type as owner.
   Finder->addMatcher(
-      functionDecl(hasDescendant(returnStmt(hasReturnValue(ConsideredOwner))
-                                     .bind("bad_owner_return")),
-                   unless(returns(qualType(hasDeclaration(OwnerDecl)))))
-          .bind("function_decl"),
+      functionDecl(
+          decl().bind("function_decl"),
+          hasBody(stmt(
+              stmt().bind("body"),
+              hasDescendant(
+                  returnStmt(hasReturnValue(ConsideredOwner),
+                             // Ignore sub-lambda expressions
+                             hasAncestor(stmt(anyOf(equalsBoundNode("body"),
+                                                    lambdaExpr()))
+                                             .bind("scope")),
+                             hasAncestor(stmt(equalsBoundNode("scope"),
+                                              equalsBoundNode("body"))),
+                             // Ignore sub-functions
+                             hasAncestor(functionDecl().bind("context")),
+                             hasAncestor(functionDecl(
+                                 equalsBoundNode("context"),
+                                 equalsBoundNode("function_decl"))))
+                      .bind("bad_owner_return")))),
+          returns(qualType(qualType().bind("result"),
+                           unless(hasDeclaration(OwnerDecl))))),
+      this);
+
+  // Matching on lambdas, that return an owner/resource, but don't declare
+  // their return type as owner.
+  Finder->addMatcher(
+      lambdaExpr(
+          hasAncestor(decl(ScopeDeclaration).bind("scope-decl")),
+          hasLambdaBody(stmt(
+              stmt().bind("body"),
+              hasDescendant(
+                  returnStmt(
+                      hasReturnValue(ConsideredOwner),
+                      // Ignore sub-lambdas
+                      hasAncestor(
+                          stmt(anyOf(equalsBoundNode("body"), lambdaExpr()))
+                              .bind("scope")),
+                      hasAncestor(stmt(equalsBoundNode("scope"),
+                                       equalsBoundNode("body"))),
+                      // Ignore sub-functions
+                      hasAncestor(decl(ScopeDeclaration).bind("context")),
+                      hasAncestor(decl(equalsBoundNode("context"),
+                                       equalsBoundNode("scope-decl"))))
+                      .bind("bad_owner_return")))),
+          hasCallOperator(returns(qualType(qualType().bind("result"),
+                                           unless(hasDeclaration(OwnerDecl))))))
+          .bind("lambda"),
       this);
 
   // Match on classes that have an owner as member, but don't declare a
   // destructor to properly release the owner.
   Finder->addMatcher(
       cxxRecordDecl(
           has(fieldDecl(IsOwnerType).bind("undestructed_owner_member")),
           anyOf(unless(has(cxxDestructorDecl())),
bool OwningMemoryCheck::handleAssignmentFromNewOwner(const BoundNodes &Nodes) {
   }
   return false;
 }
 
 bool OwningMemoryCheck::handleReturnValues(const BoundNodes &Nodes) {
   // Function return statements, that are owners/resources, but the function
   // declaration does not declare its return value as owner.
   const auto *BadReturnType = Nodes.getNodeAs<ReturnStmt>("bad_owner_return");
-  const auto *Function = Nodes.getNodeAs<FunctionDecl>("function_decl");
+  const auto *ResultType = Nodes.getNodeAs<QualType>("result");
 
   // Function return values, that should be owners but aren't.
   if (BadReturnType) {
     // The returned value is a resource or variable that was not annotated with
     // owner<> and the function return type is not owner<>.
     diag(BadReturnType->getBeginLoc(),
          "returning a newly created resource of "
          "type %0 or 'gsl::owner<>' from a "
-         "function whose return type is not 'gsl::owner<>'")
-        << Function->getReturnType() << BadReturnType->getSourceRange();
+         "%select{function|lambda}1 whose return type is not 'gsl::owner<>'")
+        << *ResultType << (Nodes.getNodeAs<Expr>("lambda") != nullptr)
+        << BadReturnType->getSourceRange();
 
     // FIXME: Rewrite the return type as 'gsl::owner<OriginalType>'
     return true;
   }
   return false;
 }
 
 bool OwningMemoryCheck::handleOwnerMembers(const BoundNodes &Nodes) {

clang-tools-extra/docs/ReleaseNotes.rst

- Fixed bug in :doc:`bugprone-reserved-identifier
   <clang-tidy/checks/bugprone/reserved-identifier>`, so that it does not warn
   on macros starting with underscore and lowercase letter.
 
 - Improved :doc:`cppcoreguidelines-avoid-non-const-global-variables
   <clang-tidy/checks/cppcoreguidelines/avoid-non-const-global-variables>` check
   to ignore ``static`` variables declared within the scope of
   ``class``/``struct``.
 
+- Improved :doc:`cppcoreguidelines-owning-memory
+  <clang-tidy/checks/cppcoreguidelines/owning-memory>` check to properly handle
+  return type in lambdas and in nested functions.
+
 - Improved :doc:`cppcoreguidelines-prefer-member-initializer
   <clang-tidy/checks/cppcoreguidelines/prefer-member-initializer>` check to
   ignore delegate constructors.
 
 - Improved :doc:`llvm-namespace-comment
   <clang-tidy/checks/llvm/namespace-comment>` check to provide fixes for
   ``inline`` namespaces in the same format as :program:`clang-format`.
 

clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp

namespace PR63994 {
 
   struct B : public A {};
 
   A* foo(int x) {
     return new B;
     // CHECK-NOTES: [[@LINE-1]]:5: warning: returning a newly created resource of type 'A *' or 'gsl::owner<>' from a function whose return type is not 'gsl::owner<>'
   }
 }
+
+namespace PR59389 {
+  struct S {
+    S();
+    S(int);
+
+    int value = 1;
+  };
+
+  void testLambdaInFunctionNegative() {
+    const auto MakeS = []() -> ::gsl::owner<S*> {
+      return ::gsl::owner<S*>{new S{}};
+    };
+  }
+
+  void testLambdaInFunctionPositive() {
+    const auto MakeS = []() -> S* {
+      return ::gsl::owner<S*>{new S{}};
+      // CHECK-NOTES: [[@LINE-1]]:7: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a lambda whose return type is not 'gsl::owner<>'
+    };
+  }
+
+  void testFunctionInFunctionNegative() {
+    struct C {
+      ::gsl::owner<S*> test() {
+        return ::gsl::owner<S*>{new S{}};
+      }
+    };
+  }
+
+  void testFunctionInFunctionPositive() {
+    struct C {
+      S* test() {
+        return ::gsl::owner<S*>{new S{}};
+        // CHECK-NOTES: [[@LINE-1]]:9: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a function whose return type is not 'gsl::owner<>'
+      }
+    };
+  }
+
+  ::gsl::owner<S*> testReverseLambdaNegative() {
+    const auto MakeI = [] -> int { return 5; };
+    return ::gsl::owner<S*>{new S(MakeI())};
+  }
+
+  S* testReverseLambdaPositive() {
+    const auto MakeI = [] -> int { return 5; };
+    return ::gsl::owner<S*>{new S(MakeI())};
+    // CHECK-NOTES: [[@LINE-1]]:5: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a function whose return type is not 'gsl::owner<>'
+  }
+
+  ::gsl::owner<S*> testReverseFunctionNegative() {
+    struct C {
+      int test() { return 5; }
+    };
+    return ::gsl::owner<S*>{new S(C().test())};
+  }
+
+  S* testReverseFunctionPositive() {
+    struct C {
+      int test() { return 5; }
+    };
+    return ::gsl::owner<S*>{new S(C().test())};
+    // CHECK-NOTES: [[@LINE-1]]:5: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a function whose return type is not 'gsl::owner<>'
+  }
+
+  void testLambdaInLambdaNegative() {
+    const auto MakeS = []() -> ::gsl::owner<S*> {
+      const auto MakeI = []() -> int { return 5; };
+      return ::gsl::owner<S*>{new S(MakeI())};
+    };
+  }
+
+  void testLambdaInLambdaPositive() {
+    const auto MakeS = []() -> S* {
+      const auto MakeI = []() -> int { return 5; };
+      return ::gsl::owner<S*>{new S(MakeI())};
+      // CHECK-NOTES: [[@LINE-1]]:7: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a lambda whose return type is not 'gsl::owner<>'
+    };
+  }
+
+  void testReverseLambdaInLambdaNegative() {
+    const auto MakeI = []() -> int {
+      const auto MakeS = []() -> ::gsl::owner<S*> { return new S(); };
+      return 5;
+    };
+  }
+
+  void testReverseLambdaInLambdaPositive() {
+    const auto MakeI = []() -> int {
+      const auto MakeS = []() -> S* { return new S(); };
+      // CHECK-NOTES: [[@LINE-1]]:39: warning: returning a newly created resource of type 'S *' or 'gsl::owner<>' from a lambda whose return type is not 'gsl::owner<>'
+      return 5;
+    };
+  }
+}