Dev/annagrin/remove explicit not null constructor (#743)

* Added c++17 test configurations for clang5.0 and clang6.0 * Removed explicit not_null constructor, sloppy_not_null, added strict_not_null We added explicit not_null constructor in version 2.0.0. It proved very difficult to switch to the new version for large code bases that adopted previous versions of gsl, due to not_null used extensively in the code. Still, using explicit constructor is very benefitial for new code, since it encorages better API design and make null checks intentional. To resolve the issue, this change: - removes explicit keyword from not_null constructor - removes unneded sloppy_not_null type - adds strict_not_null type to behave the same way as v2 not_null - updates tests * Removed explicit not_null constructor, sloppy_not_null, added strict_not_null We added explicit not_null constructor in version 2.0.0. It proved very difficult to switch to the new version for large code bases that adopted previous versions of gsl, due to not_null used extensively in the code. Still, using explicit constructor is very benefitial for new code, since it encorages better API design and make null checks intentional. To resolve the issue, this change: - removes explicit keyword from not_null constructor - removes unneded sloppy_not_null type - adds strict_not_null type to behave the same way as v2 not_null - updates tests * fixed build break for gcc7 * added more tests * added more non-compiling tests * Addressed PR comments and suppressed a code analysis warning * Fixed test failure in not_null tests
2019-01-14 16:45:47 -08:00
parent 7a7d025ffa
commit 9ff6e19ea9
8 changed files with 384 additions and 291 deletions
@@ -25,7 +25,7 @@

 #include <catch/catch.hpp> // for AssertionHandler, StringRef, CHECK, TEST_...

-#include <gsl/pointers>       // for not_null, operator<, operator<=, operator>
+#include <gsl/pointers> // for not_null, operator<, operator<=, operator>

 #include <algorithm> // for addressof
 #include <memory>    // for shared_ptr, make_shared, operator<, opera...
@@ -128,47 +128,105 @@ struct NonCopyableNonMovable
 };

 GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
-bool helper(not_null<int*> p)
-{
-    return *p == 12;
-}
-
+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;
-}
+bool helper_const(not_null<const int*> p) { return *p == 12; }
+
+int* return_pointer() { return nullptr; }
+const int* return_pointer_const() { return nullptr; }

 GSL_SUPPRESS(con.4) // NO-FORMAT: attribute
 TEST_CASE("TestNotNullConstructors")
 {
+    {
 #ifdef CONFIRM_COMPILATION_ERRORS
-    not_null<int*> p = nullptr;         // yay...does not compile!
-    not_null<std::vector<char>*> p = 0; // yay...does not compile!
-    not_null<int*> p;                   // yay...does not compile!
-    std::unique_ptr<int> up = std::make_unique<int>(120);
-    not_null<int*> p = up;
+        not_null<int*> p = nullptr;          // yay...does not compile!
+        not_null<std::vector<char>*> p1 = 0; // yay...does not compile!
+        not_null<int*> p2;                   // yay...does not compile!
+        std::unique_ptr<int> up = std::make_unique<int>(120);
+        not_null<int*> p3 = up;

-    // Forbid non-nullptr assignable types
-    not_null<std::vector<int>> f(std::vector<int>{1});
-    not_null<int> z(10);
-    not_null<std::vector<int>> y({1, 2});
+        // Forbid non-nullptr assignable types
+        not_null<std::vector<int>> f(std::vector<int>{1});
+        not_null<int> z(10);
+        not_null<std::vector<int>> y({1, 2});
 #endif
-    int i = 12;
-    auto rp = RefCounted<int>(&i);
-    not_null<int*> p(rp);
-    CHECK(p.get() == &i);
+    }

-    not_null<std::shared_ptr<int>> x(
-        std::make_shared<int>(10)); // shared_ptr<int> is nullptr assignable
+    {
+        // from shared pointer
+        int i = 12;
+        auto rp = RefCounted<int>(&i);
+        not_null<int*> p(rp);
+        CHECK(p.get() == &i);

-#ifdef GSL_THROW_ON_CONTRACT_VIOLATION
-    int* pi = nullptr;
-    CHECK_THROWS_AS(not_null<decltype(pi)>(pi), fail_fast);
-#endif
+        not_null<std::shared_ptr<int>> x(
+            std::make_shared<int>(10)); // shared_ptr<int> is nullptr assignable
+
+        int* pi = nullptr;
+        CHECK_THROWS_AS(not_null<decltype(pi)>(pi), fail_fast);
+    }
+
+    {
+        // from pointer to local
+        int t = 42;
+
+        not_null<int*> x = &t;
+        helper(&t);
+        helper_const(&t);
+
+        CHECK(*x == 42);
+    }
+
+    {
+        // from raw pointer
+        // from not_null pointer
+
+        int t = 42;
+        int* p = &t;
+
+        not_null<int*> x = p;
+        helper(p);
+        helper_const(p);
+        helper(x);
+        helper_const(x);
+
+        CHECK(*x == 42);
+    }
+
+    {
+        // from raw const pointer
+        // from not_null const pointer
+
+        int t = 42;
+        const int* cp = &t;
+
+        not_null<const int*> x = cp;
+        helper_const(cp);
+        helper_const(x);
+
+        CHECK(*x == 42);
+    }
+
+    {
+        // from not_null const pointer, using auto
+        int t = 42;
+        const int* cp = &t;
+
+        auto x = not_null<const int*>{cp};
+
+        CHECK(*x == 42);
+    }
+
+    {
+        // from returned pointer
+
+        CHECK_THROWS_AS(helper(return_pointer()), fail_fast);
+        CHECK_THROWS_AS(helper_const(return_pointer()), fail_fast);
+    }
 }

-template<typename T>
+template <typename T>
 GSL_SUPPRESS(con.4) // NO-FORMAT: attribute
 void ostream_helper(T v)
 {
@@ -474,5 +532,5 @@ TEST_CASE("TestMakeNotNull")
 #endif
 }

-static_assert(std::is_nothrow_move_constructible<not_null<void *>>::value, "not_null must be no-throw move constructible");
-
+static_assert(std::is_nothrow_move_constructible<not_null<void*>>::value,
+              "not_null must be no-throw move constructible");