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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* 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 "tutorial2.hxx"
/*
This is a compile check.
Warns about if statements with a comparison followed by literal return false:
if( a == 1 )
return false;
*/
namespace loplugin
{
Tutorial2::Tutorial2( CompilerInstance& compiler )
: Plugin( compiler )
{
}
void Tutorial2::run()
{
// The Clang AST helper class will call VisitIfStmt for every if statement.
TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
}
// This function is called for every if statement.
bool Tutorial2::VisitIfStmt( const IfStmt* ifstmt )
{
if( ignoreLocation( ifstmt ))
return true;
// Check if the condition of the if statement is a binary operator.
if( const BinaryOperator* oper = dyn_cast< BinaryOperator >( ifstmt->getCond()))
{
// And if it's operator==.
if( oper->getOpcode() == BO_EQ )
{
// Now check if the sub-statement is 'return false'.
const Stmt* warn = NULL; // The return statement (for the warning message).
// Check if the sub-statement is directly 'return false;'.
if( isReturnFalse( ifstmt->getThen()))
warn = ifstmt->getThen();
// Check if the sub-statement is '{ return false; }'
else if( const CompoundStmt* compound = dyn_cast< CompoundStmt >( ifstmt->getThen()))
{
if( compound->size() == 1 ) // one statement
if( isReturnFalse( *compound->body_begin())) // check the one sub-statement
warn = *compound->body_begin();
}
if( warn != NULL ) // there is a return statement to warn about.
{
report( DiagnosticsEngine::Warning,
"returning false after if with equality comparison",
cast< ReturnStmt >( warn )->getRetValue()->getLocStart()) // the 'false' in the return
<< warn->getSourceRange();
// Also add a note showing the if statement.
report( DiagnosticsEngine::Note,
"the if statement is here",
ifstmt->getLocStart());
}
}
}
return true;
}
bool Tutorial2::isReturnFalse( const Stmt* stmt )
{
// Is it return statement?
if( const ReturnStmt* returnstmt = dyn_cast< ReturnStmt >( stmt ))
{
// dyn_cast_or_null<> can also be passed NULL, unlike dyn_cast<>
if( const CXXBoolLiteralExpr* boolliteral = dyn_cast_or_null< CXXBoolLiteralExpr >( returnstmt->getRetValue()))
{
if( boolliteral->getValue() == false )
return true;
}
}
return false;
}
// Register the plugin action with the LO plugin handling.
static Plugin::Registration< Tutorial2 > X( "tutorial2" );
} // namespace
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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