Adding data() to Vector.

[crtrott]

Addresses issue #3077

[masterleinad]

C:\projects\source\tpls\gtest\gtest/gtest.h(18865,1): error C2679: binary '==': no operator found which takes a right-hand operand of type 'const T2' (or there is no acceptable conversion) [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
          with
          [
              T2=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<int>>>
          ]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\exception(269,28): message : could be 'bool std::operator ==(const std::exception_ptr &,const std::exception_ptr &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\exception(273,28): message : or       'bool std::operator ==(std::nullptr_t,const std::exception_ptr &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\exception(277,28): message : or       'bool std::operator ==(const std::exception_ptr &,std::nullptr_t) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\system_error(161,28): message : or       'bool std::operator ==(const std::error_code &,const std::error_code &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\system_error(165,28): message : or       'bool std::operator ==(const std::error_code &,const std::error_condition &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\system_error(169,28): message : or       'bool std::operator ==(const std::error_condition &,const std::error_code &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.25.28610\include\system_error(243,28): message : or       'bool std::operator ==(const std::error_condition &,const std::error_condition &) noexcept' [found using argument-dependent lookup] [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
C:\projects\source\tpls\gtest\gtest/gtest.h(18865,1): message : or       'built-in C++ operator==(T1, T1)' [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
          with
          [
              T1=int *
          ]
C:\projects\source\tpls\gtest\gtest/gtest.h(18865,1): message : while trying to match the argument list '(const T1, const T2)' [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
          with
          [
              T1=int *
          ]
          and
          [
              T2=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<int>>>
          ]
C:\projects\source\tpls\gtest\gtest/gtest.h(18902): message : see reference to function template instantiation 'testing::AssertionResult testing::internal::CmpHelperEQ<T1,T2>(const char *,const char *,const T1 &,const T2 &)' being compiled [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
          with
          [
              T1=int *,
              T2=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<int>>>
          ]
C:\projects\source\containers\unit_tests\TestVector.hpp(66): message : see reference to function template instantiation 'testing::AssertionResult testing::internal::EqHelper<false>::Compare<_Ty*,std::_Vector_iterator<std::_Vector_val<std::_Simple_types<_Ty>>>>(const char *,const char *,const T1 &,const T2 &)' being compiled [C:\projects\source\build\containers\unit_tests\KokkosContainers_UnitTest_Serial.vcxproj]
          with
          [
              _Ty=int,
              T1=int *,
              T2=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<int>>>
          ]

[dalg24]

Make sure you update the Synopsys in the API reference accordingly

[nliber]

A couple of questions on this:

Shouldn't data() return pointer, not iterator? I know they are the same type in this implementation, but not in general.

Why aren't there pairs of functions for this, with the following signatures:

iterator begin()
const_iterator begin() const
iterator end()
const_iterator end() const
pointer data()
const_pointer data() const
reference operator[](int)
const_reference operator[](int) const
reference operator()(int)
const_reference operator()(int) const

It is already that way for front() and back(), but not for the above functions.