/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#ifndef LO_CLANG_SHARED_PLUGINS
#include <algorithm>
#include <cassert>
#include <map>
#include <stack>
#include "check.hxx"
#include "compat.hxx"
#include "plugin.hxx"
// Find cases where a variable of a OString/OUString type is initialized
// with a literal value (incl. as an empty string) and used only once. Conservatively this only
// covers local non-static variables that are not defined outside of the loop (if any) in which they
// are used, as other cases may deliberately use the variable for performance (or even correctness,
// if addresses are taken and compared) reasons.
//
// For one, the historically heavy syntax for such uses of string literals
// (RTL_CONSTASCII_USTRINGPARAM etc.) probably explains many of these redundant variables, which can
// now be considered cargo-cult baggage. For another, some of those variables are used as arguments
// to functions which also have more efficient overloads directly taking string literals. And for
// yet another, some cases with default-initialized variables turned out to be effectively unused
// code that could be removed completely (d073cca5f7c04de3e1bcedda334d864e98ac7835 "Clean up dead
// code", 91345e7dde6100496a7c9e815b72b2821ae82bc2 "Clean up dead code",
// 868b0763ac47f765cb48c277897274a595b831d0 "Upcoming loplugin:elidestringvar: dbaccess" in
// dbaccess/source/ui/app/AppController.cxx, bde0aac4ccf7b830b5ef21d5b9e75e62aee6aaf9 "Clean up dead
// code", 354aefec42de856b4ab6201ada54a3a3c630b4bd "Upcoming loplugin:elidestringvar: cui" in
// cui/source/dialogs/SpellDialog.cxx).
namespace
{
bool isStringType(QualType type)
{
loplugin::TypeCheck
const c(type);
return c.
Class(
"OString").
Namespace(
"rtl").GlobalNamespace()
|| c.
Class(
"OUString").
Namespace(
"rtl").GlobalNamespace();
}
class ElideStringVar :
public loplugin::FilteringPlugin<ElideStringVar>
{
public:
explicit ElideStringVar(loplugin::InstantiationData
const& data)
: FilteringPlugin(data)
{
}
bool preRun() override {
return compiler.getLangOpts().CPlusPlus; }
void postRun() override
{
for (
auto const& var : vars_)
{
if (!var.second.singleUse || *var.second.singleUse == nullptr)
{
continue;
}
if (containsPreprocessingConditionalInclusion(
SourceRange(var.first->getBeginLoc(), (*var.second.singleUse)->getEndLoc())))
{
// This is not perfect, as additional uses can be hidden in conditional blocks that
// only start after the (would-be) single use (as was the case in
// 3bc5057f9689e024957cfa898a221ee2c4c4afe7 "Upcoming loplugin:elidestringvar:
// testtools" when built with --enable-debug, but where also fixing the hidden
// additional use was trivial). If this ever becomes a real problem, we can extend
// the above check to cover more of the current function body's remainder.
continue;
}
report(DiagnosticsEngine::Warning,
"replace single use of literal %0 variable with a literal",
(*var.second.singleUse)->getExprLoc())
<< var.first->getType() << (*var.second.singleUse)->getSourceRange();
report(DiagnosticsEngine::Note,
"literal %0 variable defined here",
var.first->getLocation())
<< var.first->getType() << var.first->getSourceRange();
}
}
bool VisitVarDecl(VarDecl
const* decl)
{
if (ignoreLocation(decl))
{
return true;
}
if (!decl->isThisDeclarationADefinition())
{
return true;
}
if (isa<ParmVarDecl>(decl))
{
return true;
}
if (decl->getStorageDuration() != SD_Automatic)
{
return true;
}
if (!isStringType(decl->getType()))
{
return true;
}
if (!decl->hasInit())
{
return true;
}
auto const e1 = dyn_cast<CXXConstructExpr>(decl->getInit()->IgnoreParenImpCasts());
if (e1 == nullptr)
{
return true;
}
if (!isStringType(e1->getType()))
{
return true;
}
switch (e1->getNumArgs())
{
case 0:
break;
case 1:
{
auto const e2 = e1->getArg(0);
loplugin::TypeCheck
const c(e2->getType());
if (c.
Class(
"OStringLiteral").
Namespace(
"rtl").GlobalNamespace()
|| c.
Class(
"OUStringLiteral").
Namespace(
"rtl").GlobalNamespace())
{
break;
}
if (!e2->isValueDependent() && e2->isIntegerConstantExpr(compiler.getASTContext()))
{
break;
}
return true;
}
case 2:
{
auto const e2 = e1->getArg(0);
auto const t = e2->getType();
if (!(t.isConstQualified() && t->isConstantArrayType()))
{
return true;
}
if (isa<AbstractConditionalOperator>(e2->IgnoreParenImpCasts()))
{
return true;
}
auto const e3 = e1->getArg(1);
if (!(isa<CXXDefaultArgExpr>(e3)
&& loplugin::TypeCheck(e3->getType())
.
Struct(
"Dummy")
.
Namespace(
"libreoffice_internal")
.
Namespace(
"rtl")
.GlobalNamespace()))
{
return true;
}
break;
}
default:
return true;
}
auto const ok = vars_.emplace(decl, Data(getInnermostLoop()));
assert(ok.second);
(
void)ok;
return true;
}
bool VisitDeclRefExpr(DeclRefExpr
const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
auto const var = dyn_cast<VarDecl>(expr->getDecl());
if (var == nullptr)
{
return true;
}
auto const i = vars_.find(var);
if (i == vars_.end())
{
return true;
}
i->second.singleUse
= i->second.singleUse || i->second.innermostLoop != getInnermostLoop() ? nullptr : expr;
return true;
}
bool VisitMemberExpr(MemberExpr
const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
auto const e = dyn_cast<DeclRefExpr>(expr->getBase()->IgnoreParenImpCasts());
if (e == nullptr)
{
return true;
}
auto const var = dyn_cast<VarDecl>(e->getDecl());
if (var == nullptr)
{
return true;
}
auto const i = vars_.find(var);
if (i == vars_.end())
{
return true;
}
i->second.singleUse = nullptr;
return true;
}
bool VisitUnaryOperator(UnaryOperator
const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
if (expr->getOpcode() != UO_AddrOf)
{
return true;
}
auto const e = dyn_cast<DeclRefExpr>(expr->getSubExpr()->IgnoreParenImpCasts());
if (e == nullptr)
{
return true;
}
auto const var = dyn_cast<VarDecl>(e->getDecl());
if (var == nullptr)
{
return true;
}
auto const i = vars_.find(var);
if (i == vars_.end())
{
return true;
}
i->second.singleUse = nullptr;
return true;
}
bool VisitCallExpr(CallExpr
const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
auto const fun = expr->getDirectCallee();
if (fun == nullptr)
{
return true;
}
unsigned const n = std::min(fun->getNumParams(), expr->getNumArgs());
for (
unsigned i = 0; i != n; ++i)
{
if (!loplugin::TypeCheck(fun->getParamDecl(i)->getType())
.LvalueReference()
.NonConstVolatile())
{
continue;
}
auto const e = dyn_cast<DeclRefExpr>(expr->getArg(i)->IgnoreParenImpCasts());
if (e == nullptr)
{
continue;
}
auto const var = dyn_cast<VarDecl>(e->getDecl());
if (var == nullptr)
{
continue;
}
auto const j = vars_.find(var);
if (j == vars_.end())
{
continue;
}
j->second.singleUse = nullptr;
}
return true;
}
bool VisitCXXConstructExpr(CXXConstructExpr
const* expr)
{
if (ignoreLocation(expr))
{
return true;
}
auto const ctor = expr->getConstructor();
unsigned const n = std::min(ctor->getNumParams(), expr->getNumArgs());
for (
unsigned i = 0; i != n; ++i)
{
if (!loplugin::TypeCheck(ctor->getParamDecl(i)->getType())
.LvalueReference()
.NonConstVolatile())
{
continue;
}
auto const e = dyn_cast<DeclRefExpr>(expr->getArg(i)->IgnoreParenImpCasts());
if (e == nullptr)
{
continue;
}
auto const var = dyn_cast<VarDecl>(e->getDecl());
if (var == nullptr)
{
continue;
}
auto const j = vars_.find(var);
if (j == vars_.end())
{
continue;
}
j->second.singleUse = nullptr;
}
return true;
}
bool TraverseWhileStmt(WhileStmt* stmt)
{
bool ret =
true;
if (PreTraverseWhileStmt(stmt))
{
ret = FilteringPlugin::TraverseWhileStmt(stmt);
PostTraverseWhileStmt(stmt, ret);
}
return ret;
}
bool PreTraverseWhileStmt(WhileStmt* stmt)
{
innermostLoop_.push(stmt);
return true;
}
bool PostTraverseWhileStmt(WhileStmt* stmt,
bool)
{
assert(!innermostLoop_.empty());
assert(innermostLoop_.top() == stmt);
(
void)stmt;
innermostLoop_.pop();
return true;
}
bool TraverseDoStmt(DoStmt* stmt)
{
bool ret =
true;
if (PreTraverseDoStmt(stmt))
{
ret = FilteringPlugin::TraverseDoStmt(stmt);
PostTraverseDoStmt(stmt, ret);
}
return ret;
}
bool PreTraverseDoStmt(DoStmt* stmt)
{
innermostLoop_.push(stmt);
return true;
}
bool PostTraverseDoStmt(DoStmt* stmt,
bool)
{
assert(!innermostLoop_.empty());
assert(innermostLoop_.top() == stmt);
(
void)stmt;
innermostLoop_.pop();
return true;
}
bool TraverseForStmt(ForStmt* stmt)
{
bool ret =
true;
if (PreTraverseForStmt(stmt))
{
ret = FilteringPlugin::TraverseForStmt(stmt);
PostTraverseForStmt(stmt, ret);
}
return ret;
}
bool PreTraverseForStmt(ForStmt* stmt)
{
innermostLoop_.push(stmt);
return true;
}
bool PostTraverseForStmt(ForStmt* stmt,
bool)
{
assert(!innermostLoop_.empty());
assert(innermostLoop_.top() == stmt);
(
void)stmt;
innermostLoop_.pop();
return true;
}
bool TraverseCXXForRangeStmt(CXXForRangeStmt* stmt)
{
bool ret =
true;
if (PreTraverseCXXForRangeStmt(stmt))
{
ret = FilteringPlugin::TraverseCXXForRangeStmt(stmt);
PostTraverseCXXForRangeStmt(stmt, ret);
}
return ret;
}
bool PreTraverseCXXForRangeStmt(CXXForRangeStmt* stmt)
{
innermostLoop_.push(stmt);
return true;
}
bool PostTraverseCXXForRangeStmt(CXXForRangeStmt* stmt,
bool)
{
assert(!innermostLoop_.empty());
assert(innermostLoop_.top() == stmt);
(
void)stmt;
innermostLoop_.pop();
return true;
}
private:
void run() override
{
if (preRun() && TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()))
{
postRun();
}
}
Stmt
const* getInnermostLoop()
const
{
return innermostLoop_.empty() ? nullptr : innermostLoop_.top();
}
struct Data
{
Data(Stmt
const* theInnermostLoop)
: innermostLoop(theInnermostLoop)
{
}
Stmt
const* innermostLoop;
compat::optional<Expr
const*> singleUse;
};
std::stack<Stmt
const*> innermostLoop_;
std::map<VarDecl
const*, Data> vars_;
};
loplugin::Plugin::Registration<ElideStringVar> elidestringvar(
"elidestringvar");
}
#endif
/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
