Math: add explicit boolean conversion to BoolVector.

src/Magnum/Math/BoolVector.h

@@ -134,13 +134,33 @@ template<std::size_t size> class BoolVector {
             return !operator==(other);
         }
 
-        /** @brief Whether all bits are set */
+        /**
+         * @brief Boolean conversion
+         *
+         * Equivalent to @ref all().
+         * @see @ref any(), @ref none()
+         */
+        explicit operator bool() const { return all(); }
+
+        /**
+         * @brief Whether all bits are set
+         *
+         * @see @ref none(), @ref any(), @ref operator bool()
+         */
         bool all() const;
 
-        /** @brief Whether no bits are set */
+        /**
+         * @brief Whether no bits are set
+         *
+         * @see @ref all(), @ref any(), @ref operator bool()
+         */
         bool none() const;
 
-        /** @brief Whether any bit is set */
+        /**
+         * @brief Whether any bit is set
+         *
+         * @see @ref all(), @ref none(), @ref operator bool()
+         */
         bool any() const { return !none(); }
 
         /** @brief Bitwise inversion */

src/Magnum/Math/Test/BoolVectorTest.cpp

@@ -43,6 +43,7 @@ struct BoolVectorTest: Corrade::TestSuite::Tester {
 
     void compare();
     void compareUndefined();
+    void convertBool();
     void all();
     void none();
     void any();
@@ -70,6 +71,7 @@ BoolVectorTest::BoolVectorTest() {
 
               &BoolVectorTest::compare,
               &BoolVectorTest::compareUndefined,
+              &BoolVectorTest::convertBool,
               &BoolVectorTest::all,
               &BoolVectorTest::none,
               &BoolVectorTest::any,
@@ -193,6 +195,15 @@ void BoolVectorTest::compareUndefined() {
     CORRADE_VERIFY(a != c);
 }
 
+void BoolVectorTest::convertBool() {
+    /* The ! operation should *just work* using the bool conversion operator */
+    CORRADE_VERIFY(BoolVector19(0xff, 0xff, 0x07));
+    CORRADE_VERIFY(!BoolVector19(0xff, 0xff, 0x04));
+
+    /* Implicit conversion is not allowed */
+    CORRADE_VERIFY(!(std::is_convertible<BoolVector19, bool>::value));
+}
+
 void BoolVectorTest::all() {
     CORRADE_VERIFY(BoolVector19(0xff, 0xff, 0x07).all());