1 files changed, 74 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp b/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
new file mode 100644
index 00000000000..48eee8e6949
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/cert/DefaultOperatorNewAlignmentCheck.cpp
@@ -0,0 +1,74 @@
+//===--- DefaultOperatorNewCheck.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 "DefaultOperatorNewAlignmentCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace cert {
+
+AST_MATCHER(CXXNewExpr, isPlacementNew) {
+  return Node.getNumPlacementArgs() > 0;
+}
+
+void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) {
+  // Check not applicable in C++17 (or newer).
+  if (getLangOpts().CPlusPlus17)
+    return;
+
+  Finder->addMatcher(cxxNewExpr(unless(isPlacementNew())).bind("new"), this);
+}
+
+void DefaultOperatorNewAlignmentCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  // Get the found 'new' expression.
+  const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>("new");
+
+  QualType T = NewExpr->getAllocatedType();
+  // Dependent types do not have fixed alignment.
+  if (T->isDependentType())
+    return;
+  const TagDecl *D = T->getAsTagDecl();
+  // Alignment can not be obtained for undefined type.
+  if (!D || !D->getDefinition() || !D->isCompleteDefinition())
+    return;
+
+  ASTContext &Context = D->getASTContext();
+
+  // Check if no alignment was specified for the type.
+  if (!Context.isAlignmentRequired(T))
+    return;
+
+  // The user-specified alignment (in bits).
+  unsigned SpecifiedAlignment = D->getMaxAlignment();
+  // Double-check if no alignment was specified.
+  if (!SpecifiedAlignment)
+    return;
+  // The alignment used by default 'operator new' (in bits).
+  unsigned DefaultNewAlignment = Context.getTargetInfo().getNewAlign();
+
+  bool OverAligned = SpecifiedAlignment > DefaultNewAlignment;
+  bool HasDefaultOperatorNew =
+      !NewExpr->getOperatorNew() || NewExpr->getOperatorNew()->isImplicit();
+
+  unsigned CharWidth = Context.getTargetInfo().getCharWidth();
+  if (HasDefaultOperatorNew && OverAligned)
+    diag(NewExpr->getBeginLoc(),
+         "allocation function returns a pointer with alignment %0 but the "
+         "over-aligned type being allocated requires alignment %1")
+        << (DefaultNewAlignment / CharWidth)
+        << (SpecifiedAlignment / CharWidth);
+}
+
+} // namespace cert
+} // namespace tidy
+} // namespace clang