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//===--- ProBoundsConstantArrayIndexCheck.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 "ProBoundsConstantArrayIndexCheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Lex/Preprocessor.h"
#include <optional>
using namespace clang::ast_matchers;
namespace clang::tidy::cppcoreguidelines {
ProBoundsConstantArrayIndexCheck::ProBoundsConstantArrayIndexCheck(
StringRef Name, ClangTidyContext *Context)
: ClangTidyCheck(Name, Context), GslHeader(Options.get("GslHeader", "")),
Inserter(Options.getLocalOrGlobal("IncludeStyle",
utils::IncludeSorter::IS_LLVM),
areDiagsSelfContained()) {}
void ProBoundsConstantArrayIndexCheck::storeOptions(
ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "GslHeader", GslHeader);
Options.store(Opts, "IncludeStyle", Inserter.getStyle());
}
void ProBoundsConstantArrayIndexCheck::registerPPCallbacks(
const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
Inserter.registerPreprocessor(PP);
}
void ProBoundsConstantArrayIndexCheck::registerMatchers(MatchFinder *Finder) {
// Note: if a struct contains an array member, the compiler-generated
// constructor has an arraySubscriptExpr.
Finder->addMatcher(arraySubscriptExpr(hasBase(ignoringImpCasts(hasType(
constantArrayType().bind("type")))),
hasIndex(expr().bind("index")),
unless(hasAncestor(decl(isImplicit()))))
.bind("expr"),
this);
Finder->addMatcher(
cxxOperatorCallExpr(
hasOverloadedOperatorName("[]"),
hasArgument(
0, hasType(hasUnqualifiedDesugaredType(recordType(hasDeclaration(
cxxRecordDecl(hasName("::std::array")).bind("type")))))),
hasArgument(1, expr().bind("index")))
.bind("expr"),
this);
}
void ProBoundsConstantArrayIndexCheck::check(
const MatchFinder::MatchResult &Result) {
const auto *Matched = Result.Nodes.getNodeAs<Expr>("expr");
const auto *IndexExpr = Result.Nodes.getNodeAs<Expr>("index");
// This expression can only appear inside ArrayInitLoopExpr, which
// is always implicitly generated. ArrayInitIndexExpr is not a
// constant, but we shouldn't report a warning for it.
if (isa<ArrayInitIndexExpr>(IndexExpr))
return;
if (IndexExpr->isValueDependent())
return; // We check in the specialization.
std::optional<llvm::APSInt> Index =
IndexExpr->getIntegerConstantExpr(*Result.Context);
if (!Index) {
SourceRange BaseRange;
if (const auto *ArraySubscriptE = dyn_cast<ArraySubscriptExpr>(Matched))
BaseRange = ArraySubscriptE->getBase()->getSourceRange();
else
BaseRange =
cast<CXXOperatorCallExpr>(Matched)->getArg(0)->getSourceRange();
SourceRange IndexRange = IndexExpr->getSourceRange();
auto Diag = diag(Matched->getExprLoc(),
"do not use array subscript when the index is "
"not an integer constant expression");
if (!GslHeader.empty()) {
Diag << FixItHint::CreateInsertion(BaseRange.getBegin(), "gsl::at(")
<< FixItHint::CreateReplacement(
SourceRange(BaseRange.getEnd().getLocWithOffset(1),
IndexRange.getBegin().getLocWithOffset(-1)),
", ")
<< FixItHint::CreateReplacement(Matched->getEndLoc(), ")")
<< Inserter.createMainFileIncludeInsertion(GslHeader);
}
return;
}
const auto *StdArrayDecl =
Result.Nodes.getNodeAs<ClassTemplateSpecializationDecl>("type");
// For static arrays, this is handled in clang-diagnostic-array-bounds.
if (!StdArrayDecl)
return;
if (Index->isSigned() && Index->isNegative()) {
diag(Matched->getExprLoc(), "std::array<> index %0 is negative")
<< toString(*Index, 10);
return;
}
const TemplateArgumentList &TemplateArgs = StdArrayDecl->getTemplateArgs();
if (TemplateArgs.size() < 2)
return;
// First template arg of std::array is the type, second arg is the size.
const auto &SizeArg = TemplateArgs[1];
if (SizeArg.getKind() != TemplateArgument::Integral)
return;
llvm::APInt ArraySize = SizeArg.getAsIntegral();
// Get uint64_t values, because different bitwidths would lead to an assertion
// in APInt::uge.
if (Index->getZExtValue() >= ArraySize.getZExtValue()) {
diag(Matched->getExprLoc(),
"std::array<> index %0 is past the end of the array "
"(which contains %1 elements)")
<< toString(*Index, 10) << toString(ArraySize, 10, false);
}
}
} // namespace clang::tidy::cppcoreguidelines
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