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

[PiotrZSL]

Implement proper support for lambdas and sub-functions/classes.
Moved from https://reviews.llvm.org/D157285

Fixes: #59389

[llvmbot]

@llvm/pr-subscribers-clang-tools-extra

@llvm/pr-subscribers-clang-tidy

Author: Piotr Zegar (PiotrZSL)

Changes

Implement proper support for lambdas and sub-functions/classes.
Moved from https://reviews.llvm.org/D157285

Fixes: #59389

---

Full diff: https://github.com/llvm/llvm-project/pull/77246.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp (+64-7)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5-1)
• (modified) clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp (+95)

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
index 9215b833573afd..89450149820f30 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/OwningMemoryCheck.cpp
@@ -19,6 +19,18 @@ 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);
@@ -55,6 +67,8 @@ void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
             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(
@@ -147,10 +161,52 @@ void OwningMemoryCheck::registerMatchers(MatchFinder *Finder) {
   // 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
@@ -329,7 +385,7 @@ 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) {
@@ -338,8 +394,9 @@ bool OwningMemoryCheck::handleReturnValues(const BoundNodes &Nodes) {
     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;
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 1bd5a72126c10b..e9abcae8902c5c 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -119,7 +119,7 @@ Improvements to clang-tidy
 
 - Improved `--dump-config` to print check options in alphabetical order.
 
-- Improved :program:`clang-tidy-diff.py` script. 
+- Improved :program:`clang-tidy-diff.py` script.
     * Return exit code `1` if any :program:`clang-tidy` subprocess exits with
       a non-zero code or if exporting fixes fails.
 
@@ -310,6 +310,10 @@ Changes in existing checks
   extending the `IgnoreConversionFromTypes` option to include types without a
   declaration, such as built-in types.
 
+- 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 and ignore re-assignment for reference or when
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
index eb8ad1b8b87925..d308f1dcc4f0e2 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/owning-memory.cpp
@@ -395,3 +395,98 @@ namespace PR63994 {
     // 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;
+    };
+  }
+}

[5chmidti]

I only have two nits

[5chmidti]

I had an idea for the added matchers that improves their readability.

[5chmidti]

LGTM

[5chmidti]

But wait for @HerrCai0907, you commented earlier as well.

[HerrCai0907]

LGTM