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//===--- ProBoundsArrayToPointerDecayCheck.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 "ProBoundsArrayToPointerDecayCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ParentMapContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
namespace clang {
namespace tidy {
namespace cppcoreguidelines {
namespace {
AST_MATCHER_P(CXXForRangeStmt, hasRangeBeginEndStmt,
ast_matchers::internal::Matcher<DeclStmt>, InnerMatcher) {
for (const DeclStmt *Stmt : {Node.getBeginStmt(), Node.getEndStmt()})
if (Stmt != nullptr && InnerMatcher.matches(*Stmt, Finder, Builder))
return true;
return false;
}
AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt) {
return stmt(hasAncestor(cxxForRangeStmt(
hasRangeBeginEndStmt(hasDescendant(equalsNode(&Node))))))
.matches(Node, Finder, Builder);
}
AST_MATCHER_P(Expr, hasParentIgnoringImpCasts,
ast_matchers::internal::Matcher<Expr>, InnerMatcher) {
const Expr *E = &Node;
do {
DynTypedNodeList Parents = Finder->getASTContext().getParents(*E);
if (Parents.size() != 1)
return false;
E = Parents[0].get<Expr>();
if (!E)
return false;
} while (isa<ImplicitCastExpr>(E));
return InnerMatcher.matches(*E, Finder, Builder);
}
} // namespace
void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
// The only allowed array to pointer decay
// 1) just before array subscription
// 2) inside a range-for over an array
// 3) if it converts a string literal to a pointer
Finder->addMatcher(
traverse(
TK_AsIs,
implicitCastExpr(
unless(hasParent(arraySubscriptExpr())),
unless(hasParentIgnoringImpCasts(explicitCastExpr())),
unless(isInsideOfRangeBeginEndStmt()),
unless(hasSourceExpression(ignoringParens(stringLiteral()))),
unless(hasSourceExpression(ignoringParens(conditionalOperator(
allOf(hasTrueExpression(stringLiteral()),
hasFalseExpression(stringLiteral())))))))
.bind("cast")),
this);
}
void ProBoundsArrayToPointerDecayCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
return;
diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into a "
"pointer; consider using gsl::array_view or "
"an explicit cast instead");
}
} // namespace cppcoreguidelines
} // namespace tidy
} // namespace clang
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