clang-tools 10.0.0

DefaultOperatorNewAlignmentCheck.cpp
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1 //===--- DefaultOperatorNewCheck.cpp - clang-tidy --------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "DefaultOperatorNewAlignmentCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12
13 using namespace clang::ast_matchers;
14
15 namespace clang {
16 namespace tidy {
17 namespace cert {
18
19 AST_MATCHER(CXXNewExpr, isPlacementNew) {
20 return Node.getNumPlacementArgs() > 0;
21 }
22
23 void DefaultOperatorNewAlignmentCheck::registerMatchers(MatchFinder *Finder) {
24 // Check not applicable in C++17 (or newer).
25 if (getLangOpts().CPlusPlus17)
26 return;
27
28 Finder->addMatcher(cxxNewExpr(unless(isPlacementNew())).bind("new"), this);
29 }
30
31 void DefaultOperatorNewAlignmentCheck::check(
32 const MatchFinder::MatchResult &Result) {
33 // Get the found 'new' expression.
34 const auto *NewExpr = Result.Nodes.getNodeAs<CXXNewExpr>("new");
35
36 QualType T = NewExpr->getAllocatedType();
37 // Dependent types do not have fixed alignment.
38 if (T->isDependentType())
39 return;
40 const TagDecl *D = T->getAsTagDecl();
41 // Alignment can not be obtained for undefined type.
42 if (!D || !D->getDefinition() || !D->isCompleteDefinition())
43 return;
44
45 ASTContext &Context = D->getASTContext();
46
47 // Check if no alignment was specified for the type.
48 if (!Context.isAlignmentRequired(T))
49 return;
50
51 // The user-specified alignment (in bits).
52 unsigned SpecifiedAlignment = D->getMaxAlignment();
53 // Double-check if no alignment was specified.
54 if (!SpecifiedAlignment)
55 return;
56 // The alignment used by default 'operator new' (in bits).
57 unsigned DefaultNewAlignment = Context.getTargetInfo().getNewAlign();
58
59 bool OverAligned = SpecifiedAlignment > DefaultNewAlignment;
60 bool HasDefaultOperatorNew =
61 !NewExpr->getOperatorNew() || NewExpr->getOperatorNew()->isImplicit();
62
63 unsigned CharWidth = Context.getTargetInfo().getCharWidth();
64 if (HasDefaultOperatorNew && OverAligned)
65 diag(NewExpr->getBeginLoc(),
66 "allocation function returns a pointer with alignment %0 but the "
67 "over-aligned type being allocated requires alignment %1")
68 << (DefaultNewAlignment / CharWidth)
69 << (SpecifiedAlignment / CharWidth);
70 }
71
72 } // namespace cert
73 } // namespace tidy
74 } // namespace clang
clang::ast_matchers
Definition: AbseilMatcher.h:14
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:18
DefaultOperatorNewAlignmentCheck.h
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27