llvm-project/clang-tools-extra/clang-tidy/misc/UnusedRAIICheck.cpp

86 lines
3.1 KiB
C++

//===--- UnusedRAIICheck.cpp - clang-tidy ---------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "UnusedRAIICheck.h"
#include "clang/AST/ASTContext.h"
#include "clang/Lex/Lexer.h"
using namespace clang::ast_matchers;
namespace clang {
namespace {
AST_MATCHER(CXXRecordDecl, hasNonTrivialDestructor) {
// TODO: If the dtor is there but empty we don't want to warn either.
return Node.hasDefinition() && Node.hasNonTrivialDestructor();
}
} // namespace
namespace tidy {
namespace misc {
void UnusedRAIICheck::registerMatchers(MatchFinder *Finder) {
// Look for temporaries that are constructed in-place and immediately
// destroyed. Look for temporaries created by a functional cast but not for
// those returned from a call.
auto BindTemp = bindTemporaryExpr(unless(has(callExpr()))).bind("temp");
Finder->addMatcher(
exprWithCleanups(unless(isInTemplateInstantiation()),
hasParent(compoundStmt().bind("compound")),
hasType(recordDecl(hasNonTrivialDestructor())),
anyOf(has(BindTemp), has(functionalCastExpr(
has(BindTemp))))).bind("expr"),
this);
}
void UnusedRAIICheck::check(const MatchFinder::MatchResult &Result) {
const auto *E = Result.Nodes.getStmtAs<Expr>("expr");
// We ignore code expanded from macros to reduce the number of false
// positives.
if (E->getLocStart().isMacroID())
return;
// Don't emit a warning for the last statement in the surrounding compund
// statement.
const auto *CS = Result.Nodes.getStmtAs<CompoundStmt>("compound");
if (E == CS->body_back())
return;
// Emit a warning.
auto D = diag(E->getLocStart(), "object destroyed immediately after "
"creation; did you mean to name the object?");
const char *Replacement = " give_me_a_name";
// If this is a default ctor we have to remove the parens or we'll introduce a
// most vexing parse.
const auto *BTE = Result.Nodes.getStmtAs<CXXBindTemporaryExpr>("temp");
if (const auto *TOE = dyn_cast<CXXTemporaryObjectExpr>(BTE->getSubExpr()))
if (TOE->getNumArgs() == 0) {
D << FixItHint::CreateReplacement(
CharSourceRange::getTokenRange(TOE->getParenOrBraceRange()),
Replacement);
return;
}
// Otherwise just suggest adding a name. To find the place to insert the name
// find the first TypeLoc in the children of E, which always points to the
// written type.
auto Matches =
match(expr(hasDescendant(typeLoc().bind("t"))), *E, *Result.Context);
const auto *TL = selectFirst<TypeLoc>("t", Matches);
D << FixItHint::CreateInsertion(
Lexer::getLocForEndOfToken(TL->getLocEnd(), 0, *Result.SourceManager,
Result.Context->getLangOpts()),
Replacement);
}
} // namespace misc
} // namespace tidy
} // namespace clang