Added ETL_ASSERT for copy construction of dynamic span to fixed span

Asserts if the sizes are not equal

Author: John Wellbelove

include/etl/span.h

@@ -90,6 +90,20 @@ namespace etl
     }
   };
 
+  //***************************************************************************
+  ///\ingroup span
+  /// span size exception.
+  //***************************************************************************
+  class span_size_mismatch : public span_exception
+  {
+  public:
+
+    span_size_mismatch(string_type file_name_, numeric_type line_number_)
+      : span_exception(ETL_ERROR_TEXT("span:size", ETL_SPAN_FILE_ID"B"), file_name_, line_number_)
+    {
+    }
+  };
+
   //***************************************************************************
   /// Span - Fixed Extent
   //***************************************************************************
@@ -137,11 +151,22 @@ namespace etl
     //*************************************************************************
     /// Construct from C array
     //*************************************************************************
-    template<size_t Array_Size, typename = typename etl::enable_if<(Extent == etl::dynamic_extent) || (Array_Size == Extent), void>::type>
+#if ETL_USING_CPP11
+    template<size_t Array_Size, typename = typename etl::enable_if<(Array_Size == Extent), void>::type>
     ETL_CONSTEXPR span(element_type(&begin_)[Array_Size]) ETL_NOEXCEPT
       : pbegin(begin_)
     {
     }
+#else
+    //*************************************************************************
+    /// Construct from C array
+    //*************************************************************************
+    template<size_t Array_Size>
+    ETL_CONSTEXPR span(element_type(&begin_)[Array_Size], typename etl::enable_if<(Array_Size == Extent), void>::type* = 0) ETL_NOEXCEPT
+      : pbegin(begin_)
+    {
+    }
+#endif
 
 #if ETL_USING_CPP11
     //*************************************************************************
@@ -194,11 +219,23 @@ namespace etl
 
     //*************************************************************************
     /// Copy constructor
+    /// From fixed extent span.
+    //*************************************************************************
+    template <typename U, size_t N>
+    ETL_CONSTEXPR span(const etl::span<U, N>& other, typename etl::enable_if<N == Extent, void>::type* = 0) ETL_NOEXCEPT
+      : pbegin(other.data())
+    {
+    }
+
+    //*************************************************************************
+    /// Copy constructor
+    /// From dynamic extent span.
     //*************************************************************************
     template <typename U, size_t N>
-    ETL_CONSTEXPR span(const etl::span<U, N>& other, typename etl::enable_if<(Extent == etl::dynamic_extent) || (N == etl::dynamic_extent) || (N == Extent), void>::type* = 0) ETL_NOEXCEPT
+    ETL_CONSTEXPR span(const etl::span<U, N>& other, typename etl::enable_if<N == etl::dynamic_extent, void>::type* = 0)
       : pbegin(other.data())
     {
+      ETL_ASSERT(other.size() == Extent, ETL_ERROR(span_size_mismatch));
     }
 
     //*************************************************************************
@@ -505,7 +542,7 @@ namespace etl
   /// Span - Dynamic Extent
   //***************************************************************************
   template <typename T>
-  class  span<T, etl::dynamic_extent>
+  class  span<T, etl::dynamic_extent> : public span_tag
   {
   public:
 
@@ -586,7 +623,8 @@ namespace etl
     /// data() and size() member functions.
     //*************************************************************************
     template <typename TContainer>
-    ETL_CONSTEXPR span(TContainer& a, typename etl::enable_if<!etl::is_pointer<typename etl::remove_reference<TContainer>::type>::value &&
+    ETL_CONSTEXPR span(TContainer& a, typename etl::enable_if<!etl::is_base_of<span_tag, typename etl::remove_reference<TContainer>::type>::value &&
+                                                              !etl::is_pointer<typename etl::remove_reference<TContainer>::type>::value &&
                                                               !etl::is_array<TContainer>::value &&
                                                               etl::is_same<typename etl::remove_cv<T>::type, typename etl::remove_cv<typename etl::remove_reference<TContainer>::type::value_type>::type>::value, void>::type* = 0) ETL_NOEXCEPT
       : pbegin(a.data())
@@ -599,7 +637,8 @@ namespace etl
     /// data() and size() member functions.
     //*************************************************************************
     template <typename TContainer>
-    ETL_CONSTEXPR span(const TContainer& a, typename etl::enable_if<!etl::is_pointer<typename etl::remove_reference<TContainer>::type>::value &&
+    ETL_CONSTEXPR span(const TContainer& a, typename etl::enable_if<!etl::is_base_of<span_tag, typename etl::remove_reference<TContainer>::type>::value &&
+                                                                    !etl::is_pointer<typename etl::remove_reference<TContainer>::type>::value &&
                                                                     !etl::is_array<TContainer>::value &&
                                                                     etl::is_same<typename etl::remove_cv<T>::type, typename etl::remove_cv<typename etl::remove_reference<TContainer>::type::value_type>::type>::value, void>::type* = 0) ETL_NOEXCEPT
       : pbegin(a.data())

test/test_span_fixed_extent.cpp

@@ -1245,6 +1245,21 @@ namespace
       }
     }
 
+    //*************************************************************************
+    TEST(test_dynamic_span_to_larger_fixed_span)
+    {
+      int data[5] = { 0, 1, 2, 3, 4 };
+      etl::span<int> sp1(data);
+
+      using span_4 = etl::span<int, 4>;
+      using span_5 = etl::span<int, 5>;
+      using span_8 = etl::span<int, 8>;
+
+      CHECK_NO_THROW({ span_5 sp2(sp1); });
+      CHECK_THROW({ span_4 sp3(sp1); }, etl::span_size_mismatch);
+      CHECK_THROW({ span_8 sp4(sp1); }, etl::span_size_mismatch);
+    }
+
 #include "etl/private/diagnostic_pop.h"
   };
 }