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//===--- DanglingHandleCheck.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 "DanglingHandleCheck.h"
#include "../utils/Matchers.h"
#include "../utils/OptionsUtils.h"
#include "clang/AST/ASTContext.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
using namespace clang::ast_matchers;
using namespace clang::tidy::matchers;
namespace clang::tidy::bugprone {
namespace {
ast_matchers::internal::BindableMatcher<Stmt>
handleFrom(const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle,
const ast_matchers::internal::Matcher<Expr> &Arg) {
return expr(
anyOf(cxxConstructExpr(hasDeclaration(cxxMethodDecl(ofClass(IsAHandle))),
hasArgument(0, Arg)),
cxxMemberCallExpr(hasType(cxxRecordDecl(IsAHandle)),
callee(memberExpr(member(cxxConversionDecl()))),
on(Arg))));
}
ast_matchers::internal::Matcher<Stmt> handleFromTemporaryValue(
const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle) {
// If a ternary operator returns a temporary value, then both branches hold a
// temporary value. If one of them is not a temporary then it must be copied
// into one to satisfy the type of the operator.
const auto TemporaryTernary =
conditionalOperator(hasTrueExpression(cxxBindTemporaryExpr()),
hasFalseExpression(cxxBindTemporaryExpr()));
return handleFrom(IsAHandle, anyOf(cxxBindTemporaryExpr(), TemporaryTernary));
}
ast_matchers::internal::Matcher<RecordDecl> isASequence() {
return hasAnyName("::std::deque", "::std::forward_list", "::std::list",
"::std::vector");
}
ast_matchers::internal::Matcher<RecordDecl> isASet() {
return hasAnyName("::std::set", "::std::multiset", "::std::unordered_set",
"::std::unordered_multiset");
}
ast_matchers::internal::Matcher<RecordDecl> isAMap() {
return hasAnyName("::std::map", "::std::multimap", "::std::unordered_map",
"::std::unordered_multimap");
}
ast_matchers::internal::BindableMatcher<Stmt> makeContainerMatcher(
const ast_matchers::internal::Matcher<RecordDecl> &IsAHandle) {
// This matcher could be expanded to detect:
// - Constructors: eg. vector<string_view>(3, string("A"));
// - emplace*(): This requires a different logic to determine that
// the conversion will happen inside the container.
// - map's insert: This requires detecting that the pair conversion triggers
// the bug. A little more complicated than what we have now.
return callExpr(
hasAnyArgument(
ignoringParenImpCasts(handleFromTemporaryValue(IsAHandle))),
anyOf(
// For sequences: assign, push_back, resize.
cxxMemberCallExpr(
callee(functionDecl(hasAnyName("assign", "push_back", "resize"))),
on(expr(hasType(hasUnqualifiedDesugaredType(
recordType(hasDeclaration(recordDecl(isASequence())))))))),
// For sequences and sets: insert.
cxxMemberCallExpr(callee(functionDecl(hasName("insert"))),
on(expr(hasType(hasUnqualifiedDesugaredType(
recordType(hasDeclaration(recordDecl(
anyOf(isASequence(), isASet()))))))))),
// For maps: operator[].
cxxOperatorCallExpr(callee(cxxMethodDecl(ofClass(isAMap()))),
hasOverloadedOperatorName("[]"))));
}
} // anonymous namespace
DanglingHandleCheck::DanglingHandleCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
HandleClasses(utils::options::parseStringList(Options.get(
"HandleClasses",
"std::basic_string_view;std::experimental::basic_string_view"))),
IsAHandle(cxxRecordDecl(hasAnyName(HandleClasses)).bind("handle")) {}
void DanglingHandleCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "HandleClasses",
utils::options::serializeStringList(HandleClasses));
}
void DanglingHandleCheck::registerMatchersForVariables(MatchFinder *Finder) {
const auto ConvertedHandle = handleFromTemporaryValue(IsAHandle);
// Find 'Handle foo(ReturnsAValue());'
Finder->addMatcher(
varDecl(hasType(hasUnqualifiedDesugaredType(
recordType(hasDeclaration(cxxRecordDecl(IsAHandle))))),
hasInitializer(
exprWithCleanups(has(ignoringParenImpCasts(ConvertedHandle)))
.bind("bad_stmt"))),
this);
// Find 'Handle foo = ReturnsAValue();'
Finder->addMatcher(
traverse(TK_AsIs,
varDecl(hasType(hasUnqualifiedDesugaredType(recordType(
hasDeclaration(cxxRecordDecl(IsAHandle))))),
unless(parmVarDecl()),
hasInitializer(exprWithCleanups(
has(ignoringParenImpCasts(handleFrom(
IsAHandle, ConvertedHandle))))
.bind("bad_stmt")))),
this);
// Find 'foo = ReturnsAValue(); // foo is Handle'
Finder->addMatcher(
traverse(TK_AsIs,
cxxOperatorCallExpr(callee(cxxMethodDecl(ofClass(IsAHandle))),
hasOverloadedOperatorName("="),
hasArgument(1, ConvertedHandle))
.bind("bad_stmt")),
this);
// Container insertions that will dangle.
Finder->addMatcher(
traverse(TK_AsIs, makeContainerMatcher(IsAHandle).bind("bad_stmt")),
this);
}
void DanglingHandleCheck::registerMatchersForReturn(MatchFinder *Finder) {
// Return a local.
Finder->addMatcher(
traverse(
TK_AsIs,
returnStmt(
// The AST contains two constructor calls:
// 1. Value to Handle conversion.
// 2. Handle copy construction.
// We have to match both.
has(ignoringImplicit(handleFrom(
IsAHandle,
handleFrom(IsAHandle,
declRefExpr(to(varDecl(
// Is function scope ...
hasAutomaticStorageDuration(),
// ... and it is a local array or Value.
anyOf(hasType(arrayType()),
hasType(hasUnqualifiedDesugaredType(
recordType(hasDeclaration(recordDecl(
unless(IsAHandle)))))))))))))),
// Temporary fix for false positives inside lambdas.
unless(hasAncestor(lambdaExpr())))
.bind("bad_stmt")),
this);
// Return a temporary.
Finder->addMatcher(
traverse(
TK_AsIs,
returnStmt(has(exprWithCleanups(has(ignoringParenImpCasts(handleFrom(
IsAHandle, handleFromTemporaryValue(IsAHandle)))))))
.bind("bad_stmt")),
this);
}
void DanglingHandleCheck::registerMatchers(MatchFinder *Finder) {
registerMatchersForVariables(Finder);
registerMatchersForReturn(Finder);
}
void DanglingHandleCheck::check(const MatchFinder::MatchResult &Result) {
auto *Handle = Result.Nodes.getNodeAs<CXXRecordDecl>("handle");
diag(Result.Nodes.getNodeAs<Stmt>("bad_stmt")->getBeginLoc(),
"%0 outlives its value")
<< Handle->getQualifiedNameAsString();
}
} // namespace clang::tidy::bugprone
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