fixed compilation

source/orm/query/column.cpp

@@ -26,11 +26,13 @@ column::column(const char *name, const std::string& as)
 {}
 
 column::column(std::string name, std::string as)
-: name_(std::move(name))
+: table_(default_table())
+, name_(std::move(name))
 , alias_(std::move(as)) {}
 
 column::column(const sql::sql_function_t func, std::string name)
-: name_(std::move(name))
+: table_(default_table())
+, name_(std::move(name))
 , function_(func) {}
 
 column::column(const class table* tab, std::string name, std::string as)
@@ -95,4 +97,9 @@ column::operator const std::string&() const {
   return name_;
 }
 
-}
+query::table* column::default_table() {
+  static query::table default_table;
+
+  return &default_table;
+}
+}

source/orm/query/generator.cpp

@@ -1,7 +1,7 @@
 #include "matador/query/generator.hpp"
 
 namespace matador::query::generator {
-column_generator::column_generator( const std::string& table_name, const column_generator_options options)
+column_generator::column_generator(const std::string& table_name, const column_generator_options options)
 : options_(options) {
   table_stack_.push(table_name.empty() ? std::make_shared<table>() : std::make_shared<table>(table_name));
 }
@@ -12,7 +12,7 @@ column_generator::column_generator(const object::repository& repo, const std::st
   table_stack_.push(table_name.empty() ? std::make_shared<table>() : std::make_shared<table>(table_name));
 }
 
-void column_generator::on_revision( const char* id, uint64_t& ) {
+void column_generator::on_revision(const char* id, uint64_t&) {
   push(id);
 }
 
@@ -20,9 +20,9 @@ void column_generator::push( const std::string& column_name ) {
   if (is_column_generator_option_set(options_, column_generator_options::GenerateAlias)) {
       char str[4];
       snprintf(str, 4, "c%02d", ++column_index);
-      result_.emplace_back(table_stack_.top(), column_name, str);
+      result_.emplace_back(table_stack_.top().get(), column_name, str);
   } else {
-      result_.emplace_back(table_stack_.top(), column_name);
+      result_.emplace_back(table_stack_.top().get(), column_name);
   }
 }
 

source/orm/query/query_compiler.cpp

@@ -449,7 +449,7 @@ std::string query_compiler::build_add_constraint_string(const class constraint &
 }
 
 std::string query_compiler::build_drop_constraint_string(const class constraint &c) {
-
+  return dialect_->drop_constraint() + " " + build_constraint_name(c);
 }
 
 std::string query_compiler::build_constraint_name(const class constraint &c) {