Use derives to determine if record is copyable

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -664,6 +664,12 @@ bool Converter::RecordDerivesDefault(const clang::RecordDecl *decl) {
 }
 
 bool Converter::RecordDerivesCopy(const clang::RecordDecl *decl) {
+  auto *derives = Mapper::MappedDerives(ctx_.getCanonicalTagType(decl));
+  return derives &&
+         std::find(derives->begin(), derives->end(), "Copy") != derives->end();
+}
+
+bool Converter::RecordFieldsCopyable(const clang::RecordDecl *decl) {
   for (auto f : decl->fields()) {
     // Records that contain std::vector, std::array, std::string or anything
     // that is translated to Vec<>, do not derive Copy
@@ -750,8 +756,11 @@ void Converter::EmitRustStructOrUnion(clang::RecordDecl *decl) {
   if (EmitsReprCForRecords()) {
     StrCat("#[repr(C)]");
   }
+  auto attrs = GetStructAttributes(decl);
+  Mapper::SetDerives(ctx_.getCanonicalTagType(decl),
+                     std::vector<std::string>(attrs.begin(), attrs.end()));
   StrCat("#[derive(");
-  for (auto *attr : GetStructAttributes(decl)) {
+  for (auto *attr : attrs) {
     StrCat(attr, ',');
   }
   StrCat(")]");
@@ -3101,6 +3110,8 @@ bool Converter::VisitEnumDecl(clang::EnumDecl *decl) {
     return false;
   }
   Mapper::AddRuleForUserDefinedType(decl);
+  Mapper::SetDerives(ctx_.getCanonicalTagType(decl),
+                     {"Clone", "Copy", "PartialEq", "Debug", "Default"});
   StrCat("#[derive(Clone, Copy, PartialEq, Debug, Default)]");
   StrCat(std::format("enum {}", GetRecordName(decl)));
   StrCat('{');
@@ -3480,7 +3491,7 @@ Converter::GetStructAttributes(const clang::RecordDecl *decl) {
 
   std::vector<const char *> struct_attrs;
 
-  if (RecordDerivesCopy(decl)) {
+  if (RecordFieldsCopyable(decl)) {
     struct_attrs.emplace_back("Copy");
   }
 

cpp2rust/converter/converter.h

@@ -587,6 +587,8 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   bool RecordDerivesCopy(const clang::RecordDecl *decl);
 
+  bool RecordFieldsCopyable(const clang::RecordDecl *decl);
+
   bool ShouldReplaceWithMappedBody(clang::DeclRefExpr *expr) const;
 
   std::string *rs_code_;

cpp2rust/converter/mapper.cpp

@@ -702,6 +702,16 @@ bool MapsToRefcountPointer(clang::QualType qual_type) {
   return rule && rule->type_info.is_refcount_pointer;
 }
 
+const std::vector<std::string> *MappedDerives(clang::QualType qual_type) {
+  auto rule = search(qual_type).first;
+  return rule ? &rule->type_info.derives : nullptr;
+}
+
+void SetDerives(clang::QualType qual_type, std::vector<std::string> derives) {
+  if (auto *rule = search(qual_type).first) {
+    rule->type_info.derives = std::move(derives);
+  }
+}
 bool ReturnsPointer(const clang::Expr *expr) {
   auto rule = search(expr);
   return rule && rule->return_type.is_pointer();

cpp2rust/converter/mapper.h

@@ -37,6 +37,8 @@ std::string GetParamType(const clang::Expr *expr, unsigned index);
 bool ParamIsPointer(const clang::Expr *expr, unsigned index);
 bool MapsToPointer(clang::QualType qual_type);
 bool MapsToRefcountPointer(clang::QualType qual_type);
+const std::vector<std::string> *MappedDerives(clang::QualType qual_type);
+void SetDerives(clang::QualType qual_type, std::vector<std::string> derives);
 
 enum class ScalarSugar {
   kDesugar,