[complex.special] Reorder defaulted complex copy constructor to

emphasize relationship between it and the converting constructors.

Author: zygoloid

source/numerics.tex

@@ -437,8 +437,8 @@
   public:
     using value_type = float;
 
-    constexpr complex(const complex&) = default;
     constexpr complex(float re = 0.0f, float im = 0.0f);
+    constexpr complex(const complex<float>&) = default;
     constexpr explicit complex(const complex<double>&);
     constexpr explicit complex(const complex<long double>&);
 
@@ -465,9 +465,9 @@
   public:
     using value_type = double;
 
-    constexpr complex(const complex&) = default;
     constexpr complex(double re = 0.0, double im = 0.0);
     constexpr complex(const complex<float>&);
+    constexpr complex(const complex<double>&) = default;
     constexpr explicit complex(const complex<long double>&);
 
     constexpr double real() const;
@@ -493,10 +493,10 @@
   public:
     using value_type = long double;
 
-    constexpr complex(const complex&) = default;
     constexpr complex(long double re = 0.0L, long double im = 0.0L);
     constexpr complex(const complex<float>&);
     constexpr complex(const complex<double>&);
+    constexpr complex(const complex<long double>&) = default;
 
     constexpr long double real() const;
     constexpr void real(long double);