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#1119 Forced compiler error in nth_type.h breaks containers for C++03

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This commit is contained in:
John Wellbelove 2025-06-06 12:17:49 +01:00
parent 896a2e43b7
commit 2085295358
3 changed files with 42 additions and 6 deletions
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41
include/etl/nth_type.h
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@ -32,13 +32,9 @@ SOFTWARE.
#include "platform.h"
#include "static_assert.h"
#if ETL_NOT_USING_CPP11
#if !defined(ETL_IN_UNIT_TEST)
#error NOT SUPPORTED FOR C++03 OR BELOW
#endif
#else
namespace etl
{
#if ETL_USING_CPP11 && !defined(ETL_NTH_TYPE_FORCE_CPP03_IMPLEMENTATION)
namespace private_nth_type
{
//***********************************
@ -67,6 +63,39 @@ namespace etl
//***********************************
template <size_t N, typename... TTypes>
using nth_type_t = typename nth_type<N, TTypes...>::type;
#else
// Primary template: Not defined, will cause a compile error if used with N > 7 or not enough types.
template <int N, typename T0 = void, typename T1 = void, typename T2 = void, typename T3 = void,
typename T4 = void, typename T5 = void, typename T6 = void, typename T7 = void>
struct nth_type;
// Specialisations for N = 0..7
template <typename T0, typename T1, typename T2>
struct nth_type<0, T0, T1, T2, void, void, void, void, void> { typedef T0 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<0, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T0 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<1, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T1 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<2, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T2 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<3, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T3 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<4, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T4 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<5, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T5 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<6, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T6 type; };
template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7>
struct nth_type<7, T0, T1, T2, T3, T4, T5, T6, T7> { typedef T7 type; };
#endif
}
#endif
#endif

1
test/etl_profile.h
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@ -103,6 +103,7 @@ SOFTWARE.
#define ETL_FLAT_SET_FORCE_CPP03_IMPLEMENTATION
#define ETL_FLAT_MULTISET_FORCE_CPP03_IMPLEMENTATION
#define ETL_VARIANT_POOL_FORCE_CPP03_IMPLEMENTATION
#define ETL_NTH_TYPE_FORCE_CPP03_IMPLEMENTATION
#endif
#if defined(ETL_FORCE_TEST_CPP11)

6
test/test_nth_type.cpp
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@ -38,9 +38,15 @@ namespace
//*************************************************************************
TEST(test_nth_type)
{
#if defined(ETL_NTH_TYPE_FORCE_CPP03_IMPLEMENTATION)
CHECK((std::is_same<etl::nth_type<0, int, long, double>::type, int>::value));
CHECK((std::is_same<etl::nth_type<1, int, long, double>::type, long>::value));
CHECK((std::is_same<etl::nth_type<2, int, long, double>::type, double>::value));
#else
CHECK((std::is_same<etl::nth_type_t<0, int, long, double>, int>::value));
CHECK((std::is_same<etl::nth_type_t<1, int, long, double>, long>::value));
CHECK((std::is_same<etl::nth_type_t<2, int, long, double>, double>::value));
#endif
}
}
}