compiler plugin to check incorrect #ifdef for config_XXX.h macros

http://lists.freedesktop.org/archives/libreoffice/2013-March/047769.html

Change-Id: Ibba9d3dcc87d6d6eee58ab3690a8f87339d00956

compilerplugins/clang/checkconfigmacros.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.
+ *
+ */
+
+#include "plugin.hxx"
+
+#include <clang/Lex/Preprocessor.h>
+
+namespace loplugin
+{
+
+/*
+This is a compile check.
+
+Feature macros from config_XXX.h headers are always #defined (to 1 or 0 in case of yes/no
+settings). It is a mistake to use #ifdef/#ifndef/defined to check them.
+
+Using 1/0 instead of defined/undefined avoids undetected problems when e.g. the necessary
+#include of the config_XXX.h file is missing.
+*/
+
+class CheckConfigMacros
+    : public PPCallbacks
+    , public Plugin
+    {
+    public:
+        explicit CheckConfigMacros( CompilerInstance& compiler );
+        virtual void run();
+        virtual void MacroDefined( const Token& macroToken, const MacroInfo* info );
+        virtual void MacroUndefined( const Token& macroToken , const MacroInfo* info );
+        virtual void Ifdef( SourceLocation location, const Token& macroToken );
+        virtual void Ifndef( SourceLocation location, const Token& macroToken );
+        virtual void Defined( const Token& macroToken );
+    private:
+        void checkMacro( const Token& macroToken, SourceLocation location );
+        std::set< string > configMacros;
+    };
+
+CheckConfigMacros::CheckConfigMacros( CompilerInstance& compiler )
+    : Plugin( compiler )
+    {
+    compiler.getPreprocessor().addPPCallbacks( this );
+    }
+
+void CheckConfigMacros::run()
+    {
+    // nothing, only check preprocessor usage
+    }
+
+void CheckConfigMacros::MacroDefined( const Token& macroToken, const MacroInfo* info )
+    {
+    const char* filename = compiler.getSourceManager().getPresumedLoc( info->getDefinitionLoc()).getFilename();
+    if( filename != NULL
+        && ( strncmp( filename, BUILDDIR "/config_host/", strlen( BUILDDIR "/config_host/" )) == 0
+            || strncmp( filename, BUILDDIR "/config_build/", strlen( BUILDDIR "/config_build/" )) == 0 ))
+        {
+//        fprintf(stderr,"DEF: %s %s\n", macroToken.getIdentifierInfo()->getName().data(), filename );
+        configMacros.insert( macroToken.getIdentifierInfo()->getName());
+        }
+    }
+
+void CheckConfigMacros::MacroUndefined( const Token& macroToken, const MacroInfo* )
+    {
+    configMacros.erase( macroToken.getIdentifierInfo()->getName());
+    }
+
+void CheckConfigMacros::Ifdef( SourceLocation location, const Token& macroToken )
+    {
+    checkMacro( macroToken, location );
+    }
+
+void CheckConfigMacros::Ifndef( SourceLocation location, const Token& macroToken )
+    {
+    checkMacro( macroToken, location );
+    }
+
+void CheckConfigMacros::Defined( const Token& macroToken )
+    {
+    checkMacro( macroToken, macroToken.getLocation());
+    }
+
+void CheckConfigMacros::checkMacro( const Token& macroToken, SourceLocation location )
+    {
+    if( configMacros.find( macroToken.getIdentifierInfo()->getName()) != configMacros.end())
+        {
+        report( DiagnosticsEngine::Error, "checking whether a config macro %0 is defined",
+            location ) << macroToken.getIdentifierInfo()->getName();
+        report( DiagnosticsEngine::Note, "use #if instead of #ifdef/#ifndef/defined", location );
+        }
+    }
+
+static Plugin::Registration< CheckConfigMacros > X( "bodynotinblock" );
+
+} // namespace