Don't generate empty thread_locals

Co-authored-by: Francisco Gouveia <francisco.t.gouveia@tecnico.ulisboa.pt>

Author: nunoplopes

cpp2rust/converter/converter.cpp

@@ -499,13 +499,12 @@ bool Converter::NeedsMut(const clang::VarDecl *decl, clang::QualType type,
 
 bool Converter::ConvertVarDeclSkipInit(clang::VarDecl *decl) {
   auto qual_type = decl->getType();
-  auto name = GetNamedDeclAsString(decl);
-
   if (IsVaListType(qual_type) && decl->isLocalVarDecl()) {
     ConvertVaListVarDecl(decl);
     return true;
   }
 
+  auto name = GetNamedDeclAsString(decl);
   if (decl->isFileVarDecl()) {
     if ((decl->isThisDeclarationADefinition() ==
              clang::VarDecl::DeclarationOnly &&

cpp2rust/converter/converter.h

@@ -453,10 +453,19 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
 #define StrCat(...) _StrCat(__FUNCTION__, __LINE__, __VA_ARGS__)
 
+  inline bool is_empty(char c) { return false; }
+  inline bool is_empty(const char* s) { return s == nullptr || *s == '\0'; }
+  template <size_t N>
+  inline bool is_empty(const char (&s)[N]) { return s[0] == '\0'; }
+  template <typename T>
+  inline bool is_empty(const T &s) { return s.empty(); }
+
   template <typename... Ts>
   inline void _StrCat(const char *func, int line, const Ts &...vals) {
     log() << '[' << func << ':' << line << "] ";
-    ((log() << vals << '\n', *rs_code_ += vals, *rs_code_ += ' '), ...);
+    ((log() << vals << '\n',
+      *rs_code_ += vals,
+      (is_empty(vals) ? void() : void(*rs_code_ += ' '))), ...);
   }
 
   class Buffer {

cpp2rust/converter/models/converter_refcount.cpp

@@ -721,10 +721,19 @@ void ConverterRefCount::EmitHoistedInArmAssignment(clang::VarDecl *decl) {
 }
 
 void ConverterRefCount::ConvertGlobalVarDecl(clang::VarDecl *decl) {
+  std::string str;
+  {
+    Buffer buf(*this);
+    ConvertVarDecl(decl);
+    str = std::move(buf).str();
+    if (str.empty()) {
+      return;
+    }
+  }
   StrCat("thread_local!");
   {
     PushParen paren(*this);
-    ConvertVarDecl(decl);
+    StrCat(str);
   }
   StrCat(token::kSemiColon);
 }

tests/unit/out/refcount/operator_member_pointer_member.rs

@@ -32,7 +32,6 @@ impl ByteRepr for Inner {
         }
     }
 }
-thread_local!();
 #[derive(Default)]
 pub struct Table {}
 impl Table {