remove str copies

Author: nunoplopes

cpp2rust/converter/converter.h

@@ -478,7 +478,7 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
     Void,
   };
 
-  inline std::string expr_kind_to_string(ExprKind kind) {
+  static const char *expr_kind_to_string(ExprKind kind) {
     switch (kind) {
     case ExprKind::LValue:
       return "LValue";
@@ -512,9 +512,9 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
                  int line = __builtin_LINE())
         : c(c) {
       c.curr_expr_kind_.push_back(k);
-      llvm::errs() << "PushExprKind " << file << ":" << line << " ";
+      llvm::errs() << "PushExprKind " << file << ':' << line << ' ';
       c.dump_expr_kinds();
-      llvm::errs() << "[";
+      llvm::errs() << '[';
       for (const auto k : c.curr_expr_kind_) {
         llvm::errs() << c.expr_kind_to_string(k) << ", ";
       }

cpp2rust/converter/models/converter_refcount.cpp

@@ -1574,8 +1574,8 @@ void ConverterRefCount::ConvertAssignment(clang::Expr *lhs, clang::Expr *rhs,
       // *ptr += val => { let __ptr = ptr.clone(); let __tmp = __ptr.read() +
       // val;
       // __ptr.write(__tmp) }
-      auto op = std::string(assign_operator);
-      op.pop_back(); // remove '='
+      auto op = assign_operator;
+      op.remove_suffix(1); // remove '='
       StrCat("{ let __ptr = ", ptr, ".clone(); let __tmp = __ptr.read() ", op,
              " ", rhs_as_string, "; __ptr.write(__tmp) }");
     } else {