From c57b5cdf432b1983c6f1b1fd9fb1f7ff11397391 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <martin.horenovsky@gmail.com>
Date: Sat, 6 May 2023 14:31:29 +0200
Subject: [PATCH] Move-enable Catch::optional

This avoids copies in couple places through Catch2, e.g. reporter
spec handling, and moving around `AssertionResult` in `RunContext`.
---
 src/catch2/internal/catch_optional.hpp        | 53 ++++++++++++-------
 .../IntrospectiveTests/Details.tests.cpp      | 41 ++++++++++++++
 2 files changed, 76 insertions(+), 18 deletions(-)

diff --git a/src/catch2/internal/catch_optional.hpp b/src/catch2/internal/catch_optional.hpp
index ac3714ee..d1e953ad 100644
--- a/src/catch2/internal/catch_optional.hpp
+++ b/src/catch2/internal/catch_optional.hpp
@@ -8,6 +8,8 @@
 #ifndef CATCH_OPTIONAL_HPP_INCLUDED
 #define CATCH_OPTIONAL_HPP_INCLUDED
 
+#include <catch2/internal/catch_move_and_forward.hpp>
+
 #include <cassert>
 
 namespace Catch {
@@ -16,35 +18,50 @@ namespace Catch {
     template<typename T>
     class Optional {
     public:
-        Optional() : nullableValue( nullptr ) {}
-        Optional( T const& _value )
-        : nullableValue( new( storage ) T( _value ) )
-        {}
-        Optional( Optional const& _other )
-        : nullableValue( _other ? new( storage ) T( *_other ) : nullptr )
-        {}
+        Optional(): nullableValue( nullptr ) {}
+        ~Optional() { reset(); }
 
-        ~Optional() {
+        Optional( T const& _value ):
+            nullableValue( new ( storage ) T( _value ) ) {}
+        Optional( T&& _value ):
+            nullableValue( new ( storage ) T( CATCH_MOVE( _value ) ) ) {}
+
+        Optional& operator=( T const& _value ) {
             reset();
+            nullableValue = new ( storage ) T( _value );
+            return *this;
+        }
+        Optional& operator=( T&& _value ) {
+            reset();
+            nullableValue = new ( storage ) T( CATCH_MOVE( _value ) );
+            return *this;
         }
 
-        Optional& operator= ( Optional const& _other ) {
-            if( &_other != this ) {
+        Optional( Optional const& _other ):
+            nullableValue( _other ? new ( storage ) T( *_other ) : nullptr ) {}
+        Optional( Optional&& _other ):
+            nullableValue( _other ? new ( storage ) T( CATCH_MOVE( *_other ) )
+                                  : nullptr ) {}
+
+        Optional& operator=( Optional const& _other ) {
+            if ( &_other != this ) {
                 reset();
-                if( _other )
-                    nullableValue = new( storage ) T( *_other );
+                if ( _other ) { nullableValue = new ( storage ) T( *_other ); }
             }
             return *this;
         }
-        Optional& operator = ( T const& _value ) {
-            reset();
-            nullableValue = new( storage ) T( _value );
+        Optional& operator=( Optional&& _other ) {
+            if ( &_other != this ) {
+                reset();
+                if ( _other ) {
+                    nullableValue = new ( storage ) T( CATCH_MOVE( *_other ) );
+                }
+            }
             return *this;
         }
 
         void reset() {
-            if( nullableValue )
-                nullableValue->~T();
+            if ( nullableValue ) { nullableValue->~T(); }
             nullableValue = nullptr;
         }
 
@@ -91,7 +108,7 @@ namespace Catch {
         }
 
     private:
-        T *nullableValue;
+        T* nullableValue;
         alignas(alignof(T)) char storage[sizeof(T)];
     };
 
diff --git a/tests/SelfTest/IntrospectiveTests/Details.tests.cpp b/tests/SelfTest/IntrospectiveTests/Details.tests.cpp
index a5a43926..80eb647b 100644
--- a/tests/SelfTest/IntrospectiveTests/Details.tests.cpp
+++ b/tests/SelfTest/IntrospectiveTests/Details.tests.cpp
@@ -89,6 +89,47 @@ TEST_CASE("Optional comparison ops", "[optional][approvals]") {
     }
 }
 
+namespace {
+    struct MoveChecker {
+        bool has_moved = false;
+        MoveChecker() = default;
+        MoveChecker( MoveChecker const& rhs ) = default;
+        MoveChecker& operator=( MoveChecker const& rhs ) = default;
+        MoveChecker( MoveChecker&& rhs ) { rhs.has_moved = true; }
+        MoveChecker& operator=( MoveChecker&& rhs ) {
+            rhs.has_moved = true;
+            return *this;
+        }
+    };
+}
+
+TEST_CASE( "Optional supports move ops", "[optional][approvals]" ) {
+    using Catch::Optional;
+    MoveChecker a;
+    Optional<MoveChecker> opt_A( a );
+    REQUIRE_FALSE( a.has_moved );
+    REQUIRE_FALSE( opt_A->has_moved );
+
+    SECTION( "Move construction from element" ) {
+        Optional<MoveChecker> opt_B( CATCH_MOVE( a ) );
+        REQUIRE( a.has_moved );
+    }
+    SECTION( "Move assignment from element" ) {
+        opt_A = CATCH_MOVE( a );
+        REQUIRE( a.has_moved );
+    }
+    SECTION( "Move construction from optional" ) {
+        Optional<MoveChecker> opt_B( CATCH_MOVE( opt_A ) );
+        REQUIRE( opt_A->has_moved );
+    }
+    SECTION( "Move assignment from optional" ) {
+        Optional<MoveChecker> opt_B( opt_A );
+        REQUIRE_FALSE( opt_A->has_moved );
+        opt_B = CATCH_MOVE( opt_A );
+        REQUIRE( opt_A->has_moved );
+    }
+}
+
 TEST_CASE( "Decomposer checks that the argument is 0 when handling "
            "only-0-comparable types",
            "[decomposition][approvals]" ) {