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/*
* This file is part of the LibreOffice project.
*
* Based on LLVM/Clang.
*
* This file is distributed under the University of Illinois Open Source
* License. See LICENSE.TXT for details.
*
*/
#include "plugin.hxx"
#include <clang/AST/ASTContext.h>
#include <clang/Basic/SourceManager.h>
#include <clang/Lex/Lexer.h>
namespace loplugin
{
/*
This is a compile check.
Check for pointer-to-bool conversions (that are sadly implicit) which are unwanted
and potentially mistakes.
So far the only places that are checked are passing arguments to functions, as those
could easily choose a different overload.
The original idea was that to follow the explicit bool feature from C++11, where
the only conversions that would be considered safe are in conditions (which
in turn means also in ||, && and ! operators) and places where it's considered
unlikely for it to be a problem (or rather, less of a problem
than explicitly avoiding the warning in the code). The code for this is currently
commented out (there are a couple of places such as 'bool foo = returns_pointer();'
that would need modification), possibly enable those later.
*/
class PointerToBool
: public RecursiveASTVisitor< PointerToBool >
, public Plugin
{
public:
explicit PointerToBool( CompilerInstance& compiler );
void run();
bool VisitImplicitCastExpr( const ImplicitCastExpr* expr );
private:
bool ignoreConversion( const Stmt* stmt );
};
PointerToBool::PointerToBool( CompilerInstance& compiler )
: Plugin( compiler )
{
}
void PointerToBool::run()
{
TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
}
bool PointerToBool::VisitImplicitCastExpr( const ImplicitCastExpr* expr )
{
if( ignoreLocation( expr ))
return true;
// Warning about CK_MemberPointerToBoolean would mean warning about
// cases there the 'safe bool' idiom is used, so give that such
// a conversion is otherwise unlikely anyway, it's probably better
// not to warn here at all (at least as long as the 'explicit bool'
// from C++11 is not in use).
if( expr->getCastKind() == CK_PointerToBoolean )
{
if( ignoreConversion( expr ))
return true;
report( DiagnosticsEngine::Warning,
"pointer %0 implicitly converted to bool", expr->getLocStart())
<< expr->getSubExpr()->getType() << expr->getSourceRange();
SourceLocation endOfExpression = locationAfterToken( expr->getLocEnd());
report( DiagnosticsEngine::Note,
"explicitly compare to null pointer to silence this warning", endOfExpression )
<< FixItHint::CreateInsertion( endOfExpression, " != NULL" );
}
return true;
}
bool PointerToBool::ignoreConversion( const Stmt* stmt )
{
#if 1 // less strict version
const Stmt* parent = parentStmt( stmt );
if( parent == NULL )
return true;
switch( parent->getStmtClass())
{
case Stmt::ConditionalOperatorClass:
if( stmt == cast< ConditionalOperator >( parent )->getCond())
return true;
break;
case Stmt::BinaryOperatorClass:
{
const BinaryOperator* binary = cast< BinaryOperator >( parent );
if(( binary->getOpcode() == BO_LAnd || binary->getOpcode() == BO_LOr )
&& ( stmt == binary->getLHS() || stmt == binary->getRHS()))
{
return true;
}
break;
}
case Stmt::UnaryOperatorClass:
{
const UnaryOperator* unary = cast< UnaryOperator >( parent );
if( unary->getOpcode() == UO_LNot && stmt == unary->getSubExpr())
return true;
break;
}
default:
if( const ExplicitCastExpr* castexpr = dyn_cast< ExplicitCastExpr >( parent ))
if( castexpr->getTypeAsWritten()->isBooleanType() && stmt == castexpr->getSubExpr())
return true;
if( dyn_cast< CallExpr >( parent ))
return false; // The only place where it's not ignored.
break;
}
return ignoreConversion( parent );
#else // more strict version
// Warn only if the expression is not used in a conditional context.
const Stmt* parent = parentStmt( stmt );
if( parent == NULL ) // Should not happen inside a function, but can happen inside
return false; // ctor initializer list.
switch( parent->getStmtClass())
{
case Stmt::IfStmtClass:
return ( stmt == cast< IfStmt >( parent )->getCond());
case Stmt::WhileStmtClass:
return ( stmt == cast< WhileStmt >( parent )->getCond());
case Stmt::DoStmtClass:
return ( stmt == cast< DoStmt >( parent )->getCond());
case Stmt::ForStmtClass:
return ( stmt == cast< ForStmt >( parent )->getCond());
case Stmt::ConditionalOperatorClass:
return ( stmt == cast< ConditionalOperator >( parent )->getCond());
case Stmt::BinaryOperatorClass:
{
const BinaryOperator* binary = cast< BinaryOperator >( parent );
return (( binary->getOpcode() == BO_LAnd || binary->getOpcode() == BO_LOr )
&& ( stmt == binary->getLHS() || stmt == binary->getRHS()));
}
case Stmt::UnaryOperatorClass:
{
const UnaryOperator* unary = cast< UnaryOperator >( parent );
return ( unary->getOpcode() == UO_LNot && stmt == unary->getSubExpr());
}
case Stmt::ExprWithCleanupsClass: // Often happens inside if() condition.
return isInConditionalContext( parent );
default:
if( const ExplicitCastExpr* castexpr = dyn_cast< ExplicitCastExpr >( parent ))
if( castexpr->getTypeAsWritten()->isBooleanType() && stmt == castexpr->getSubExpr())
return true;
break;
}
return false;
#endif
}
static Plugin::Registration< PointerToBool > X( "pointertobool" );
} // namespace