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//===--- 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"
#include "clang/Basic/TargetInfo.h"
using namespace clang::ast_matchers;
namespace clang::tidy::cert {
void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(
cxxNewExpr(unless(hasAnyPlacementArg(anything()))).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 clang::tidy::cert
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