Use Maybe<Id<T>> for {Func,Type,Var}DefDefinitionData

sizeof(db->funcs[0].def) 224  (-24)
sizeof(db->types[0].def) 248  (-24)
sizeof(db->vars[0].def) 160   (-24)

src/indexer.h

@@ -40,12 +40,14 @@ template <typename T>
 struct Id {
   size_t id;
 
-  Id() : id(0) {}  // Needed for containers. Do not use directly.
+  Id() : id(-1) {}  // Needed for containers and Maybe<Id>. Do not use directly.
   explicit Id(size_t id) : id(id) {}
 
   // Needed for google::dense_hash_map.
   explicit operator size_t() const { return id; }
 
+  bool HasValue() const { return id != size_t(-1); }
+
   bool operator==(const Id<T>& other) const { return id == other.id; }
 
   bool operator<(const Id<T>& other) const { return id < other.id; }
@@ -171,7 +173,7 @@ struct TypeDefDefinitionData {
 
   // If set, then this is the same underlying type as the given value (ie, this
   // type comes from a using or typedef statement).
-  optional<TypeId> alias_of;
+  Maybe<TypeId> alias_of;
 
   // Immediate parent types.
   std::vector<TypeId> parents;
@@ -269,7 +271,7 @@ struct FuncDefDefinitionData {
   Maybe<Range> definition_extent;
 
   // Type which declares this one (ie, it is a method)
-  optional<TypeId> declaring_type;
+  Maybe<TypeId> declaring_type;
 
   // Method this method overrides.
   std::vector<FuncId> base;
@@ -395,7 +397,7 @@ struct VarDefDefinitionData {
   Maybe<Range> definition_extent;
 
   // Type of the variable.
-  optional<TypeId> variable_type;
+  Maybe<TypeId> variable_type;
 
   // Function/type which declares this one.
   size_t parent_id = size_t(-1);

src/maybe.h

@@ -25,7 +25,9 @@ public:
   const T& operator*() const { return storage; }
   T& operator*() { return storage; }
 
-  bool has_value() const;
+  bool has_value() const {
+    return storage.HasValue();
+  }
   explicit operator bool() const { return has_value(); }
   operator optional<T>() const {
     if (has_value())

src/position.cc

@@ -146,16 +146,6 @@ bool Range::operator<(const Range& that) const {
   return end < that.end;
 }
 
-template <>
-bool Maybe<Position>::has_value() const {
-  return storage.line >= 0;
-}
-
-template <>
-bool Maybe<Range>::has_value() const {
-  return storage.start.line >= 0;
-}
-
 // Position
 void Reflect(Reader& visitor, Position& value) {
   if (visitor.Format() == SerializeFormat::Json) {

src/position.h

@@ -15,6 +15,7 @@ struct Position {
   Position(int16_t line, int16_t column);
   explicit Position(const char* encoded);
 
+  bool HasValue() const { return line >= 0; }
   std::string ToString();
   std::string ToPrettyString(const std::string& filename);
 
@@ -38,6 +39,7 @@ struct Range {
   Range(Position start, Position end);
   explicit Range(const char* encoded);
 
+  bool HasValue() const { return start.HasValue(); }
   bool Contains(int line, int column) const;
   Range RemovePrefix(Position position) const;
 
@@ -49,11 +51,6 @@ struct Range {
 };
 MAKE_HASHABLE(Range, t.start, t.end);
 
-template <>
-bool Maybe<Position>::has_value() const;
-template <>
-bool Maybe<Range>::has_value() const;
-
 // Reflection
 void Reflect(Reader& visitor, Position& value);
 void Reflect(Writer& visitor, Position& value);

src/query.h

@@ -33,6 +33,8 @@ struct QueryLocation {
     return result;
   }
 
+  bool HasValue() const { return range.HasValue(); }
+
   bool operator==(const QueryLocation& other) const {
     return path == other.path && range == other.range;
   }
@@ -57,9 +59,6 @@ struct hash<::SymbolKind> {
 };
 }  // namespace std
 
-template <>
-bool Maybe<QueryLocation>::has_value() const;
-
 struct SymbolIdx {
   SymbolKind kind;
   size_t idx;