Add a new clang-tidy check (misc-move-constructor-init) that diagnoses move constructor initializations that call copy constructors instead of move constructors.

llvm-svn: 245571

1 files changed, 77 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/misc/MoveConstructorInitCheck.cpp b/clang-tools-extra/clang-tidy/misc/MoveConstructorInitCheck.cpp
new file mode 100644
index 00000000000..b1ec6da74a7
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/MoveConstructorInitCheck.cpp
@@ -0,0 +1,77 @@
+//===--- MoveConstructorInitCheck.cpp - clang-tidy-------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MoveConstructorInitCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+void MoveConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+    constructorDecl(unless(isImplicit()), allOf(
+      isMoveConstructor(),
+      hasAnyConstructorInitializer(
+        ctorInitializer(withInitializer(constructExpr(hasDeclaration(
+          constructorDecl(isCopyConstructor()).bind("ctor")
+        )))).bind("init")
+      )
+    )), this);
+}
+
+void MoveConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *CopyCtor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
+  const auto *Initializer = Result.Nodes.getNodeAs<CXXCtorInitializer>("init");
+
+  // Do not diagnose if the expression used to perform the initialization is a
+  // trivially-copyable type.
+  QualType QT = Initializer->getInit()->getType();
+  if (QT.isTriviallyCopyableType(*Result.Context))
+    return;
+  
+  const auto *RD = QT->getAsCXXRecordDecl();
+  if (RD && RD->isTriviallyCopyable())
+    return;
+
+  // Diagnose when the class type has a move constructor available, but the
+  // ctor-initializer uses the copy constructor instead.
+  const CXXConstructorDecl *Candidate = nullptr;
+  for (const auto *Ctor : CopyCtor->getParent()->ctors()) {
+    if (Ctor->isMoveConstructor() && Ctor->getAccess() <= AS_protected &&
+        !Ctor->isDeleted()) {
+      // The type has a move constructor that is at least accessible to the
+      // initializer.
+      //
+      // FIXME: Determine whether the move constructor is a viable candidate
+      // for the ctor-initializer, perhaps provide a fixit that suggests
+      // using std::move().
+      Candidate = Ctor;
+      break;
+    }
+  }
+
+  if (Candidate) {
+    // There's a move constructor candidate that the caller probably intended
+    // to call instead.
+    diag(Initializer->getSourceLocation(),
+         "move constructor initializes %0 by calling a copy constructor")
+        << (Initializer->isBaseInitializer() ? "base class" : "class member");
+    diag(CopyCtor->getLocation(), "copy constructor being called",
+         DiagnosticIDs::Note);
+    diag(Candidate->getLocation(), "candidate move constructor here",
+         DiagnosticIDs::Note);
+  }
+}
+
+} // namespace tidy
+} // namespace clang
+