Skip cast if rust type does not need it

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -1769,6 +1769,19 @@ void Converter::ConvertIntegralToBooleanCast(clang::ImplicitCastExpr *expr) {
   }
 }
 
+bool Converter::IsSameRustType(clang::Expr *a, clang::Expr *b) {
+  auto get_converted_type_or_mapped_type = [&](clang::Expr *expr) {
+    if (!llvm::isa<clang::ImplicitCastExpr>(expr)) {
+      if (const auto *rule = Mapper::GetExprRule(expr)) {
+        return rule->return_type.type;
+      }
+    }
+    return GetUnsafeTypeAsString(expr->getType());
+  };
+  return get_converted_type_or_mapped_type(a) ==
+         get_converted_type_or_mapped_type(b);
+}
+
 bool Converter::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
   auto *sub_expr = expr->getSubExpr();
   auto type = expr->getType();
@@ -1866,8 +1879,7 @@ bool Converter::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
       break;
     }
     // Skip cast if source and target map to the same Rust type.
-    if (GetUnsafeTypeAsString(sub_expr->getType()) ==
-        GetUnsafeTypeAsString(type)) {
+    if (IsSameRustType(sub_expr, expr)) {
       Convert(sub_expr);
       break;
     }

cpp2rust/converter/converter.h

@@ -685,6 +685,8 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   TempMaterializationCtx CollectPrvalueToLRefArgs(clang::CallExpr *expr);
 
+  bool IsSameRustType(clang::Expr *a, clang::Expr *b);
+
 private:
   void materializeTemplateSpecialization(clang::CXXRecordDecl *decl);