Add Type -- Runtime type for comparing types (similar to TypeInfo but simpler)

src/exact_value.cpp

@@ -5,6 +5,8 @@
 
 struct AstNode;
 struct HashKey;
+struct Type;
+bool are_types_identical(Type *x, Type *y);
 
 struct Complex128 {
 	f64 real, imag;
@@ -20,6 +22,7 @@ enum ExactValueKind {
 	ExactValue_Complex,
 	ExactValue_Pointer,
 	ExactValue_Compound, // TODO(bill): Is this good enough?
+	ExactValue_Type,
 
 	ExactValue_Count,
 };
@@ -34,6 +37,7 @@ struct ExactValue {
 		i64           value_pointer;
 		Complex128    value_complex;
 		AstNode *     value_compound;
+		Type *        value_type;
 	};
 };
 
@@ -99,6 +103,12 @@ ExactValue exact_value_pointer(i64 ptr) {
 	return result;
 }
 
+ExactValue exact_value_type(Type *type) {
+	ExactValue result = {ExactValue_Type};
+	result.value_type = type;
+	return result;
+}
+
 
 ExactValue exact_value_integer_from_string(String string) {
 	return exact_value_u128(u128_from_string(string));
@@ -639,6 +649,13 @@ bool compare_exact_values(TokenKind op, ExactValue x, ExactValue y) {
 		case Token_GtEq:  return a >= b;
 		}
 	} break;
+
+	case ExactValue_Type:
+		switch (op) {
+		case Token_CmpEq: return are_types_identical(x.value_type, y.value_type);
+		case Token_NotEq: return !are_types_identical(x.value_type, y.value_type);
+		}
+		break;
 	}
 
 	GB_PANIC("Invalid comparison");