compiler plugin for RTL_CONSTASCII_USTRINGPARAM removal

Change-Id: Ibc487aa78d9eba3f936b4f4cc0298adfaef60d5c

compilerplugins/clang/rtlconstasciimacro.cxx

+/*
+ * 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.
+ *
+ */
+
+/*
+This is a rewriter.
+
+Remove uses of the macro RTL_CONSTASCII_USTRINGPARAM. One run is for one
+specific use (see below), modify source to remove other uses.
+*/
+
+#include "plugin.hxx"
+
+#include <clang/Lex/Preprocessor.h>
+
+namespace loplugin
+{
+
+class RtlConstAsciiMacro
+    : public RecursiveASTVisitor< RtlConstAsciiMacro >
+    , public PPCallbacks
+    , public RewritePlugin
+    {
+    public:
+        explicit RtlConstAsciiMacro( CompilerInstance& compiler, Rewriter& rewriter );
+        virtual void run();
+        bool VisitCXXConstructExpr( CXXConstructExpr* expr );
+        bool VisitCXXTemporaryObjectExpr( CXXTemporaryObjectExpr* expr );
+        bool VisitStringLiteral( const StringLiteral* literal );
+        virtual void MacroExpands( const Token& macro, const MacroInfo* info, SourceRange range );
+    private:
+        map< SourceLocation, SourceLocation > expansions; // start location -> end location
+        bool searchingForString;
+        bool suitableString;
+    };
+
+RtlConstAsciiMacro::RtlConstAsciiMacro( CompilerInstance& compiler, Rewriter& rewriter )
+    : RewritePlugin( compiler, rewriter )
+    , searchingForString( false )
+    {
+    compiler.getPreprocessor().addPPCallbacks( this );
+    }
+
+void RtlConstAsciiMacro::run()
+    {
+    TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+
+void RtlConstAsciiMacro::MacroExpands( const Token& macro, const MacroInfo*, SourceRange range )
+    {
+    if( macro.getIdentifierInfo()->getName() != "RTL_CONSTASCII_USTRINGPARAM" )
+        return;
+    expansions[ range.getBegin() ] = range.getEnd();
+    }
+
+/* Remove use with the following ctor:
+    OUString( const sal_Char * value, sal_Int32 length,
+              rtl_TextEncoding encoding,
+              sal_uInt32 convertFlags = OSTRING_TO_OUSTRING_CVTFLAGS )
+   This means searching for CXXConstructExpr.
+   For removal when used with functions it should check e.g. for CallExpr.
+*/
+bool RtlConstAsciiMacro::VisitCXXConstructExpr( CXXConstructExpr* expr )
+    {
+    if( ignoreLocation( expr ))
+        return true;
+    if( expr->getNumArgs() != 4 )
+        return true;
+    // The last argument should be the default one when the macro is used.
+    if( dyn_cast< CXXDefaultArgExpr >( expr->getArg( 3 )) == NULL )
+        return true;
+    if( expr->getConstructor()->getQualifiedNameAsString() != "rtl::OUString::OUString" )
+        return true;
+    const SourceManager& src = compiler.getSourceManager();
+    SourceLocation start = src.getExpansionLoc( expr->getArg( 0 )->getLocStart());
+    // Macro fills in the first 3 arguments, so they must all come from the same expansion.
+    if( start != src.getExpansionLoc( expr->getArg( 2 )->getLocEnd()))
+        return true;
+    if( expansions.find( start ) == expansions.end())
+        return true;
+    SourceLocation end = expansions[ start ];
+    // Remove the location, since sometimes the same code may be processed more than once
+    // (e.g. non-trivial default arguments).
+    expansions.erase( start );
+    // Check if the string argument to the macro is suitable.
+    searchingForString = true;
+    suitableString = false;
+    TraverseStmt( expr->getArg( 0 ));
+    searchingForString = false;
+    if( !suitableString )
+        return true;
+    // Seach for '(' (don't just remove a given length to handle possible whitespace).
+    const char* text = compiler.getSourceManager().getCharacterData( start );
+    const char* pos = text;
+    while( *pos != '(' )
+        ++pos;
+    ++pos;
+    if( text[ -1 ] == ' ' && *pos == ' ' )
+        ++pos; // do not leave two spaces
+    removeText( start, pos - text, RemoveLineIfEmpty );
+    const char* textend = compiler.getSourceManager().getCharacterData( end );
+    if( textend[ -1 ] == ' ' && textend[ 1 ] == ' ' )
+        removeText( end, 2, RemoveLineIfEmpty ); // Remove ') '.
+    else
+        removeText( end, 1, RemoveLineIfEmpty ); // Remove ')'.
+    return true;
+    }
+
+bool RtlConstAsciiMacro::VisitCXXTemporaryObjectExpr( CXXTemporaryObjectExpr* expr )
+    {
+    return VisitCXXConstructExpr( expr );
+    }
+
+bool RtlConstAsciiMacro::VisitStringLiteral( const StringLiteral* literal )
+    {
+    if( !searchingForString )
+        return true;
+    if( suitableString ) // two string literals?
+        {
+        report( DiagnosticsEngine::Warning, "cannot analyze RTL_CONSTASCII_USTRINGPARAM (plugin needs fixing)" )
+            << literal->getSourceRange();
+        return true;
+        }
+    if( !literal->isAscii()) // ignore
+        return true;
+    if( !literal->containsNonAsciiOrNull())
+        suitableString = true;
+    return true;
+    }
+
+static Plugin::Registration< RtlConstAsciiMacro > X( "rtlconstasciimacro" );
+
+} // namespace