From 0354d50278d725d52084601300eb955cee6756d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Tue, 4 Apr 2017 15:19:15 +0200
Subject: [PATCH] Added templated constructor to C++11 Approx

When using C++11, comparison operators are already templated to take
anything that can be explicitly converted to double, but constructor
took only doubles. This lead to warnings when an `Approx` was
constructed from floats, which was problematic for some users.

Since just adding float constructor would be a large breaking change, as
suddenly `Approx( 1 )` would become ambiguous, I added a templated
constructor that will take anything that is explicitly convertible to
double. This has the added benefit of allowing constructing `Approx`
instances from instances of strong typedefs, ie allowing
`calculated_temp == Approx( known_temp)`.

Closes #873
---
 include/internal/catch_approx.hpp | 46 +++++++++++++++----------------
 1 file changed, 22 insertions(+), 24 deletions(-)

diff --git a/include/internal/catch_approx.hpp b/include/internal/catch_approx.hpp
index 5d6df1d7..940b641a 100644
--- a/include/internal/catch_approx.hpp
+++ b/include/internal/catch_approx.hpp
@@ -49,6 +49,12 @@ namespace Detail {
         }
 
 #if defined(CATCH_CONFIG_CPP11_TYPE_TRAITS)
+
+        template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
+        explicit Approx( T value ): Approx(static_cast<double>(value))
+        {}
+
+
         template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
         friend bool operator == ( const T& lhs, Approx const& rhs ) {
             // Thanks to Richard Harris for his help refining this formula
@@ -76,27 +82,23 @@ namespace Detail {
         }
 
         template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
-        friend bool operator <= ( T lhs, Approx const& rhs )
-        {
-          return double(lhs) < rhs.m_value || lhs == rhs;
+        friend bool operator <= ( T lhs, Approx const& rhs ) {
+            return double(lhs) < rhs.m_value || lhs == rhs;
         }
 
         template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
-        friend bool operator <= ( Approx const& lhs, T rhs )
-        {
-          return lhs.m_value < double(rhs) || lhs == rhs;
+        friend bool operator <= ( Approx const& lhs, T rhs ) {
+            return lhs.m_value < double(rhs) || lhs == rhs;
         }
 
         template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
-        friend bool operator >= ( T lhs, Approx const& rhs )
-        {
-          return double(lhs) > rhs.m_value || lhs == rhs;
+        friend bool operator >= ( T lhs, Approx const& rhs ) {
+            return double(lhs) > rhs.m_value || lhs == rhs;
         }
 
         template <typename T, typename = typename std::enable_if<std::is_constructible<double, T>::value>::type>
-        friend bool operator >= ( Approx const& lhs, T rhs )
-        {
-          return lhs.m_value > double(rhs) || lhs == rhs;
+        friend bool operator >= ( Approx const& lhs, T rhs ) {
+            return lhs.m_value > double(rhs) || lhs == rhs;
         }
 #else
         friend bool operator == ( double lhs, Approx const& rhs ) {
@@ -120,24 +122,20 @@ namespace Detail {
             return !operator==( rhs, lhs );
         }
 
-        friend bool operator <= ( double lhs, Approx const& rhs )
-        {
-          return lhs < rhs.m_value || lhs == rhs;
+        friend bool operator <= ( double lhs, Approx const& rhs ) {
+            return lhs < rhs.m_value || lhs == rhs;
         }
 
-        friend bool operator <= ( Approx const& lhs, double rhs )
-        {
-          return lhs.m_value < rhs || lhs == rhs;
+        friend bool operator <= ( Approx const& lhs, double rhs ) {
+            return lhs.m_value < rhs || lhs == rhs;
         }
 
-        friend bool operator >= ( double lhs, Approx const& rhs )
-        {
-          return lhs > rhs.m_value || lhs == rhs;
+        friend bool operator >= ( double lhs, Approx const& rhs ) {
+            return lhs > rhs.m_value || lhs == rhs;
         }
 
-        friend bool operator >= ( Approx const& lhs, double rhs )
-        {
-          return lhs.m_value > rhs || lhs == rhs;
+        friend bool operator >= ( Approx const& lhs, double rhs ) {
+            return lhs.m_value > rhs || lhs == rhs;
         }
 #endif