From 57ceefbd0c306c521726187ce554bcaba9937966 Mon Sep 17 00:00:00 2001
From: rbock <rbock@eudoxos.de>
Date: Tue, 24 Feb 2015 08:02:14 +0100
Subject: [PATCH] Added missing checks for aggregate functions

---
 include/sqlpp11/count.h         | 4 +++-
 include/sqlpp11/max.h           | 1 +
 include/sqlpp11/min.h           | 1 +
 test_constraints/CMakeLists.txt | 4 ++--
 4 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/sqlpp11/count.h b/include/sqlpp11/count.h
index f2801f98..7abda19f 100644
--- a/include/sqlpp11/count.h
+++ b/include/sqlpp11/count.h
@@ -40,7 +40,7 @@ namespace sqlpp
 	{
 		using _traits = make_traits<integral, tag::is_expression, tag::is_selectable>;
 
-		using _nodes = detail::type_vector<Expr>;
+		using _nodes = detail::type_vector<Expr, aggregate_function>;
 		using _can_be_null = std::false_type;
 
 		static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value, "count() used with flag other than 'distinct'");
@@ -98,6 +98,7 @@ namespace sqlpp
 	template<typename T>
 		auto count(T t) -> count_t<noop, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "count() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "count() requires an expression as argument");
 			return { t };
 		}
@@ -105,6 +106,7 @@ namespace sqlpp
 	template<typename T>
 		auto count(const distinct_t&, T t) -> count_t<distinct_t, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "count() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "count() requires an expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/max.h b/include/sqlpp11/max.h
index c497a56d..f2011988 100644
--- a/include/sqlpp11/max.h
+++ b/include/sqlpp11/max.h
@@ -84,6 +84,7 @@ namespace sqlpp
 	template<typename T>
 		auto max(T t) -> max_t<wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "max() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "max() requires an expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/min.h b/include/sqlpp11/min.h
index 95649823..7f885c07 100644
--- a/include/sqlpp11/min.h
+++ b/include/sqlpp11/min.h
@@ -84,6 +84,7 @@ namespace sqlpp
 	template<typename T>
 		auto min(T t) -> min_t<wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "min() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "min() requires an expression as argument");
 			return { t };
 		}
diff --git a/test_constraints/CMakeLists.txt b/test_constraints/CMakeLists.txt
index 2281b371..d36c597f 100644
--- a/test_constraints/CMakeLists.txt
+++ b/test_constraints/CMakeLists.txt
@@ -24,8 +24,8 @@ function(test_constraint name pattern)
 
 endfunction(test_constraint)
 
-test_constraint(count_of_count "requires an expression as argument")
-test_constraint(max_of_max "requires an expression as argument")
+test_constraint(count_of_count "count() cannot be used on an aggregate function")
+test_constraint(max_of_max "max() cannot be used on an aggregate function")
 test_constraint(no_conversion_operator_if_null_not_trivial "int i = row.alpha")
 test_constraint(require_insert "required column is missing")
 test_constraint(must_not_insert "one assignment is prohibited")