Fix variables named _

Author: lucic71

cpp2rust/converter/converter_lib.cpp

@@ -968,6 +968,10 @@ std::string GetNamedDeclAsString(const clang::NamedDecl *decl) {
   // keyword -> keyword_
   // keyword_ -> keyword__
   // etc
+  if (!name.empty() &&
+      std::ranges::all_of(name, [](char c) { return c == '_'; })) {
+    name += '_';
+  }
   for (auto &keyword : rust_keywords) {
     if (!name.starts_with(keyword))
       continue;

tests/unit/union_basic.cpp

@@ -8,6 +8,11 @@ union basic {
 
 union empty {};
 
+union underscores {
+  int _;
+  double __;
+};
+
 int main(void) {
   union basic u;
   union empty e;
@@ -33,5 +38,15 @@ int main(void) {
   assert(*pf == 1.0f);
   assert(buf[3] == 0x3F);
 
+  union underscores us;
+  us._ = 5;
+  assert(us._ == 5);
+  us.__ = 2.5;
+  assert(us.__ == 2.5);
+
+  int _ = 1;
+  int __ = 2;
+  assert(_ + __ == 3);
+
   return 0;
 }