Fixed bug introduced by experiment around concepts

Makefile

@@ -1,8 +1,6 @@
-CXX= g++
+CXX= clang++-10
 CXXFLAGS= --std=c++20 -O0 -g -pthread -DGP_TESTS -DFUZZ_STRENGTH=500 -DNO_BENCH=0 -pedantic \
- -frtti \
- 
- #-g -fprofile-instr-generate -fcoverage-mapping -Wno-unknown-attributes  \
+ -frtti -fprofile-instr-generate -fcoverage-mapping -Wno-unknown-attributes  \
  -fsanitize=address -fno-omit-frame-pointer
 all: tests
 

include/gp/iterator.hpp

@@ -17,6 +17,10 @@ struct pointer_iterator final
 	typedef std::size_t difference_type;
 	static constexpr iterator_type_t iterator_type = iterator_type_t::contiguous_iterator;
 
+	constexpr pointer_iterator()
+	: data{nullptr}
+	{}
+
 	constexpr pointer_iterator(const pointer_iterator& oth)
 	: data{oth.data}
 	{}

include/gp/range.hpp

@@ -3,13 +3,13 @@
 #include "gp/algorithm/tmp_manip.hpp"
 
 namespace gp{
-	k">template<typename T>
+	cm">/*template<typename T>
 	concept IsSubstractible = requires(T a, T b) 
 	{
 		{a - b} -> std::integral;
-	};
+	};*/
 
-	template<typename it, bool Enable = IsSubstractible<it>>
+	template<typename it, bool Enable = std::is_integral_v<decltype(it{} - it{})>/* IsSubstractible<it> */>
 	class nameless_range;
 
 	template<typename it>