Dev/annagrin/sloppy not null (#712)

* Added c++17 test configurations for clang5.0 and clang6.0

* added transition helper sloppy_not_null

* Moved gsl_transition to a samples folder

* Fixed build break and static analysis warnings

tests/sloppy_notnull_tests.cpp

@@ -0,0 +1,124 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifdef _MSC_VER
+// blanket turn off warnings from CppCoreCheck from catch
+// so people aren't annoyed by them when running the tool.
+#pragma warning(disable : 26440 26426) // from catch
+
+// Fix VS2015 build breaks in Release
+#pragma warning(disable : 4702) // unreachable code
+#endif
+
+#include <catch/catch.hpp>    // for AssertionHandler, StringRef, CHECK, TEST_...
+
+#include <gsl/pointers>           // for not_null, operator<, operator<=, operator>
+#include <samples/gsl_transition> // for sloppy_not_null
+
+namespace gsl
+{
+struct fail_fast;
+} // namespace gsl
+
+using namespace gsl;
+using namespace gsl_helpers;
+
+GSL_SUPPRESS(f.4)  // NO-FORMAT: attribute
+bool helper(not_null<int*> p) { return *p == 12; }
+GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+bool helper_const(not_null<const int*> p) { return *p == 12; }
+
+GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+bool sloppy_helper(sloppy_not_null<int*> p) { return *p == 12; }
+GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+bool sloppy_helper_const(sloppy_not_null<const int*> p) { return *p == 12; }
+
+TEST_CASE("TestSloppyNotNull")
+{
+    {
+        // raw ptr <-> sloppy_not_null
+        int x = 42;
+
+        const sloppy_not_null<int*> snn = &x;
+
+        sloppy_helper(&x);
+        sloppy_helper_const(&x);
+
+        CHECK(*snn == 42);
+    }
+
+    {
+        // sloppy_not_null -> sloppy_not_null
+        int x = 42;
+
+        sloppy_not_null<int*> snn1{&x};
+        const sloppy_not_null<int*> snn2{&x};
+
+        sloppy_helper(snn1);
+        sloppy_helper_const(snn1);
+
+        CHECK(snn1 == snn2);
+    }
+
+    {
+        // sloppy_not_null -> not_null
+        int x = 42;
+
+        sloppy_not_null<int*> snn{&x};
+
+        const not_null<int*> nn1 = snn;
+        const not_null<int*> nn2{snn};
+
+        helper(snn);
+        helper_const(snn);
+
+        CHECK(snn == nn1);
+        CHECK(snn == nn2);
+    }
+
+    {
+        // not_null -> sloppy_not_null
+        int x = 42;
+
+        not_null<int*> nn{&x};
+
+        const sloppy_not_null<int*> snn1{nn};
+        const sloppy_not_null<int*> snn2 = nn;
+
+        sloppy_helper(nn);
+        sloppy_helper_const(nn);
+
+        CHECK(snn1 == nn);
+        CHECK(snn2 == nn);
+
+        std::hash<sloppy_not_null<int*>> hash_snn;
+        std::hash<not_null<int*>> hash_nn;
+
+        CHECK(hash_nn(snn1) == hash_nn(nn));
+        CHECK(hash_snn(snn1) == hash_nn(nn));
+        CHECK(hash_nn(snn1) == hash_nn(snn2));
+        CHECK(hash_snn(snn1) == hash_snn(nn));
+    }
+
+#ifdef CONFIRM_COMPILATION_ERRORS
+    {
+        sloppy_not_null<int*> p{nullptr};
+    }
+#endif
+}
+
+static_assert(std::is_nothrow_move_constructible<sloppy_not_null<void*>>::value,
+              "sloppy_not_null must be no-throw move constructible");