Stop accepting non-const comparison operators

A) non-const comparison operators should not exist and should not be
encouraged

B) The logic breaks comparing function pointers certain way

C) It was inconsistent anyway, as it only applied to `==` and `!=`

Closes #925

include/internal/catch_decomposer.h

@@ -76,7 +76,7 @@ namespace Catch {
 
     // Specialised comparison functions to handle equality comparisons between ints and pointers (NULL deduces as an int)
     template<typename LhsT, typename RhsT>
-    auto compareEqual( LhsT const& lhs, RhsT&& rhs ) -> bool { return const_cast<LhsT&>( lhs ) == rhs; };
+    auto compareEqual( LhsT const& lhs, RhsT&& rhs ) -> bool { return lhs == rhs; };
     template<typename T>
     auto compareEqual( T* const& lhs, int rhs ) -> bool { return lhs == reinterpret_cast<void const*>( rhs ); };
     template<typename T>
@@ -87,7 +87,7 @@ namespace Catch {
     auto compareEqual( long lhs, T* const& rhs ) -> bool { return reinterpret_cast<void const*>( lhs ) == rhs; };
 
     template<typename LhsT, typename RhsT>
-    auto compareNotEqual( LhsT const& lhs, RhsT&& rhs ) -> bool { return const_cast<LhsT&>( lhs ) != rhs; };
+    auto compareNotEqual( LhsT const& lhs, RhsT&& rhs ) -> bool { return lhs != rhs; };
     template<typename T>
     auto compareNotEqual( T* const& lhs, int rhs ) -> bool { return lhs != reinterpret_cast<void const*>( rhs ); };
     template<typename T>
@@ -150,10 +150,6 @@ namespace Catch {
     }
 
     struct Decomposer {
-        template<typename T>
-        auto operator <= ( T& lhs ) -> ExprLhs<T&> {
-            return ExprLhs<T&>( lhs );
-        }
         template<typename T>
         auto operator <= ( T const& lhs ) -> ExprLhs<T const&> {
             return ExprLhs<T const&>( lhs );

projects/SelfTest/Baselines/console.sw.approved.txt

@@ -156,6 +156,18 @@ with expansion:
 with message:
   dummy := 0
 
+-------------------------------------------------------------------------------
+#925: comparing function pointer to function address failed to compile
+-------------------------------------------------------------------------------
+TrickyTests.cpp:<line number>
+...............................................................................
+
+TrickyTests.cpp:<line number>:
+PASSED:
+  REQUIRE( utility::synchronizing_callback != test.testMethod_uponComplete_arg )
+with expansion:
+  1 != 0
+
 -------------------------------------------------------------------------------
 #961 -- Dynamically created sections should all be reported
   Looped section 0
@@ -1215,18 +1227,6 @@ ExceptionTests.cpp:<line number>: FAILED:
 due to unexpected exception with message:
   custom std exception
 
--------------------------------------------------------------------------------
-Demonstrate that a non-const == is not used
--------------------------------------------------------------------------------
-TrickyTests.cpp:<line number>
-...............................................................................
-
-TrickyTests.cpp:<line number>:
-PASSED:
-  REQUIRE( t == 1u )
-with expansion:
-  {?} == 1
-
 -------------------------------------------------------------------------------
 EndsWith string matcher
 -------------------------------------------------------------------------------

projects/SelfTest/Baselines/console.swa4.approved.txt

@@ -156,6 +156,18 @@ with expansion:
 with message:
   dummy := 0
 
+-------------------------------------------------------------------------------
+#925: comparing function pointer to function address failed to compile
+-------------------------------------------------------------------------------
+TrickyTests.cpp:<line number>
+...............................................................................
+
+TrickyTests.cpp:<line number>:
+PASSED:
+  REQUIRE( utility::synchronizing_callback != test.testMethod_uponComplete_arg )
+with expansion:
+  1 != 0
+
 -------------------------------------------------------------------------------
 #961 -- Dynamically created sections should all be reported
   Looped section 0
@@ -237,6 +249,6 @@ ConditionTests.cpp:<line number>: FAILED:
   CHECK_FALSE( true )
 
 ===============================================================================
-test cases:  9 |  6 passed | 1 failed | 2 failed as expected
+test cases: 10 |  7 passed | 1 failed | 2 failed as expected
-assertions: 26 | 19 passed | 4 failed | 3 failed as expected
+assertions: 27 | 20 passed | 4 failed | 3 failed as expected
 

projects/SelfTest/Baselines/junit.sw.approved.txt

@@ -27,6 +27,7 @@ MiscTests.cpp:<line number>
       </failure>
     </testcase>
     <testcase classname="<exe-name>.global" name="#872" time="{duration}"/>
+    <testcase classname="<exe-name>.global" name="#925: comparing function pointer to function address failed to compile" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="#961 -- Dynamically created sections should all be reported/Looped section 0" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="#961 -- Dynamically created sections should all be reported/Looped section 1" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="#961 -- Dynamically created sections should all be reported/Looped section 2" time="{duration}"/>
@@ -143,7 +144,6 @@ custom std exception
 ExceptionTests.cpp:<line number>
       </error>
     </testcase>
-    <testcase classname="<exe-name>.global" name="Demonstrate that a non-const == is not used" time="{duration}"/>
     <testcase classname="<exe-name>.global" name="EndsWith string matcher" time="{duration}">
       <failure message="&quot;this string contains 'abc' as a substring&quot; ends with: &quot;this&quot;" type="CHECK_THAT">
 MatchersTests.cpp:<line number>

projects/SelfTest/Baselines/xml.sw.approved.txt

@@ -169,6 +169,17 @@
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
+    <TestCase name="#925: comparing function pointer to function address failed to compile" filename="projects/<exe-name>/TrickyTests.cpp" >
+      <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/TrickyTests.cpp" >
+        <Original>
+          utility::synchronizing_callback != test.testMethod_uponComplete_arg
+        </Original>
+        <Expanded>
+          1 != 0
+        </Expanded>
+      </Expression>
+      <OverallResult success="true"/>
+    </TestCase>
     <TestCase name="#961 -- Dynamically created sections should all be reported" tags="[.]" filename="projects/<exe-name>/MiscTests.cpp" >
       <Section name="Looped section 0" filename="projects/<exe-name>/MiscTests.cpp" >
         <OverallResults successes="1" failures="0" expectedFailures="0"/>
@@ -1336,17 +1347,6 @@
       </Exception>
       <OverallResult success="false"/>
     </TestCase>
-    <TestCase name="Demonstrate that a non-const == is not used" tags="[Tricky]" filename="projects/<exe-name>/TrickyTests.cpp" >
-      <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/TrickyTests.cpp" >
-        <Original>
-          t == 1u
-        </Original>
-        <Expanded>
-          {?} == 1
-        </Expanded>
-      </Expression>
-      <OverallResult success="true"/>
-    </TestCase>
     <TestCase name="EndsWith string matcher" tags="[.][failing][matchers]" filename="projects/<exe-name>/MatchersTests.cpp" >
       <Expression success="false" type="CHECK_THAT" filename="projects/<exe-name>/MatchersTests.cpp" >
         <Original>

projects/SelfTest/TrickyTests.cpp

@@ -183,32 +183,6 @@ namespace ObjectWithConversions
     }
 }
 
-namespace ObjectWithNonConstEqualityOperator
-{
-    struct Test
-    {
-        Test( unsigned int v )
-        : m_value(v)
-        {}
-
-        bool operator==( const Test&rhs )
-        {
-            return (m_value == rhs.m_value);
-        }
-        bool operator==( const Test&rhs ) const
-        {
-            return (m_value != rhs.m_value);
-        }
-        unsigned int m_value;
-    };
-
-    TEST_CASE("Demonstrate that a non-const == is not used", "[Tricky]" )
-    {
-        Test t( 1 );
-        REQUIRE( t == 1u );
-    }
-}
-
 namespace EnumBitFieldTests
 {
     enum Bits : uint32_t {
@@ -448,3 +422,19 @@ TEST_CASE( "non-copyable objects", "[.][failing]" ) {
     std::type_info const& ti = typeid(int);
     CHECK( ti == typeid(int) );
 }
+
+// #925
+using signal_t = void (*) (void*);
+
+struct TestClass {
+    signal_t testMethod_uponComplete_arg = nullptr;
+};
+
+namespace utility {
+    inline static void synchronizing_callback( void * ) { }
+}
+
+TEST_CASE("#925: comparing function pointer to function address failed to compile") {
+    TestClass test;
+    REQUIRE(utility::synchronizing_callback != test.testMethod_uponComplete_arg);
+}