base for unusedcode compiler plugin

Needs work to actually do something useful, but the basics are there.

Change-Id: I193922f2f5572760c8c20def0f9b830138f47fef

1 files changed, 75 insertions, 0 deletions

diff --git a/compilerplugins/clang/store/unusedcode.cxx b/compilerplugins/clang/store/unusedcode.cxx
new file mode 100644
index 000000000000..d42cb6020ccd
--- /dev/null
+++ b/compilerplugins/clang/store/unusedcode.cxx
@@ -0,0 +1,75 @@
+/*
+ * 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 technically a rewriter, but it actually only generates data about code.
+
+This is incomplete.
+
+Checks for all function declarations for whether they are used or not. This information
+should be output to files and in a second pass it should be checked (by another tool)
+which functions are never used.
+*/
+
+#include "plugin.hxx"
+
+namespace loplugin
+{
+
+class UnusedCode
+    : public RecursiveASTVisitor< UnusedCode >
+    , public RewritePlugin
+    {
+    public:
+        explicit UnusedCode( CompilerInstance& compiler, Rewriter& rewriter );
+        virtual void run();
+        bool VisitFunctionDecl( FunctionDecl* declaration );
+    };
+
+UnusedCode::UnusedCode( CompilerInstance& compiler, Rewriter& rewriter )
+    : RewritePlugin( compiler, rewriter )
+    {
+    }
+
+void UnusedCode::run()
+    {
+    TraverseDecl( compiler.getASTContext().getTranslationUnitDecl());
+    }
+
+bool UnusedCode::VisitFunctionDecl( FunctionDecl* declaration )
+    {
+    if( ignoreLocation( declaration ))
+        return true;
+    bool isUsed = declaration->isUsed();
+    if( CXXMethodDecl* cxxmethod = dyn_cast< CXXMethodDecl >( declaration ))
+        {
+        if( !isUsed && cxxmethod->isVirtual())
+            { // Virtual methods are used also if a method they override is used.
+            for( CXXMethodDecl::method_iterator it = cxxmethod->begin_overridden_methods();
+                 it != cxxmethod->end_overridden_methods();
+                 ++it )
+                {
+                if( (*it)->isUsed())
+                    {
+                    isUsed = true;
+                    break;
+                    }
+                }
+            }
+        }
+    // Fully qualified name: declaration->getQualifiedNameAsString()
+    // Is used: isUsed
+    // The main source file compiled: compiler.getSourceManager().getFileEntryForID( compiler.getSourceManager().getMainFileID())->getName()
+    return true;
+    }
+
+static Plugin::Registration< UnusedCode > X( "unusedcode" );
+
+} // namespace