WIP, first attempt at emitting compiler warning

Author: Nixoncole

clang/include/clang/Basic/DiagnosticASTKinds.td

@@ -343,4 +343,10 @@ def warn_padded_struct_size : Warning<
   InGroup<Padded>, DefaultIgnore;
 def warn_unnecessary_packed : Warning<
   "packed attribute is unnecessary for %0">, InGroup<Packed>, DefaultIgnore;
+
+// RandStruct implementation
+def warn_randomize_attr_conflict : Warning<
+  "struct declared with 'randomize_layout' and 'no_randomize_layout' attributes. "
+  "attribute 'no_randomize_layout' takes precedence ">;
+
 }

clang/lib/AST/RecordLayoutBuilder.cpp

@@ -2986,11 +2986,27 @@ ASTContext::getASTRecordLayout(const RecordDecl *D) const {
   if (Entry) return *Entry;
 
   const ASTRecordLayout *NewEntry = nullptr;
-
+  
   bool ShouldBeRandomized = D->getAttr<RandomizeLayoutAttr>() != nullptr;
   if (ShouldBeRandomized) {
 	  Randstruct randstruct;
 	  randstruct.reorganizeFields(*this, D);
+  bool NotToBeRandomized = D->getAttr<NoRandomizeLayoutAttr>() != nullptr;
+  
+  if (ShouldBeRandomized && NotToBeRandomized) {
+    Diag(D->getLocation(), diag::warn_randomize_attr_conflict);  
+  }
+  else if (ShouldBeRandomized) {
+    // A staging area to easily reorder the fields
+    SmallVector<Decl *, 64> fields;
+    for (auto f : D->fields()) {
+      fields.push_back(f);
+    }
+
+    fields = rearrange(*this, fields);
+
+    // This will rebuild the Decl chain of fields
+    D->reorderFields(fields);
   }
 
   if (isMsLayout(*this)) {