PR libstdc++/88738 treat shared_ptr and unique_ptr more like plain old pointers

PR libstdc++/88738 Warn about unused comparisons of shared_ptr/unique_ptr * include/bits/c++config [_GLIBCXX_NODISCARD]: Define. * include/bits/shared_ptr.h: Use it for operator ==, !=, <, <=, >, >= for shared_ptr. * include/bits/unique_ptr.h: Likewise for unique_ptr. From-SVN: r267964
2019-01-16 08:01:22 +00:00 · 2019-01-16 08:01:22 +00:00 · ec0d53719f
parent df1de06415
commit ec0d53719f
4 changed files with 53 additions and 36 deletions
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@ -1,3 +1,12 @@
+2019-02-14  Ulrich Drepper  <drepper@redhat.com>
+
+	PR libstdc++/88738
+	Warn about unused comparisons of shared_ptr/unique_ptr
+	* include/bits/c++config [_GLIBCXX_NODISCARD]: Define.
+	* include/bits/shared_ptr.h: Use it for operator ==, !=,
+	<, <=, >, >= for shared_ptr.
+	* include/bits/unique_ptr.h: Likewise for unique_ptr.
+
 2019-01-15  Jonathan Wakely  <jwakely@redhat.com>

 	* include/bits/shared_ptr_base.h (__cpp_lib_shared_ptr_arrays): Define
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@ -99,6 +99,14 @@
 # define _GLIBCXX_ABI_TAG_CXX11 __attribute ((__abi_tag__ ("cxx11")))
 #endif

+// Macro to warn about unused results.
+#if __cplusplus >= 201703L
+# define _GLIBCXX_NODISCARD [[__nodiscard__]]
+#else
+# define _GLIBCXX_NODISCARD
+#endif
+
+

 #if __cplusplus

--- a/libstdc++-v3/include/bits/shared_ptr.h
+++ b/libstdc++-v3/include/bits/shared_ptr.h
@ -380,37 +380,37 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION

  // 20.7.2.2.7 shared_ptr comparisons
  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    { return __a.get() == __b.get(); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    { return !__a; }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    { return !__a; }

  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    { return __a.get() != __b.get(); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    { return (bool)__a; }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    { return (bool)__a; }

  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    {
      using _Tp_elt = typename shared_ptr<_Tp>::element_type;
@ -420,7 +420,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    {
      using _Tp_elt = typename shared_ptr<_Tp>::element_type;
@ -428,7 +428,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    {
      using _Tp_elt = typename shared_ptr<_Tp>::element_type;
@ -436,47 +436,47 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    }

  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    { return !(__b < __a); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    { return !(nullptr < __a); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    { return !(__a < nullptr); }

  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    { return (__b < __a); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    { return nullptr < __a; }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    { return __a < nullptr; }

  template<typename _Tp, typename _Up>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
    { return !(__a < __b); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
    { return !(__a < nullptr); }

  template<typename _Tp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
    { return !(nullptr < __a); }

--- a/libstdc++-v3/include/bits/unique_ptr.h
+++ b/libstdc++-v3/include/bits/unique_ptr.h
@ -707,41 +707,41 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(const unique_ptr<_Tp, _Dp>& __x,
 	       const unique_ptr<_Up, _Ep>& __y)
    { return __x.get() == __y.get(); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
    { return !__x; }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator==(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
    { return !__x; }

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(const unique_ptr<_Tp, _Dp>& __x,
 	       const unique_ptr<_Up, _Ep>& __y)
    { return __x.get() != __y.get(); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
    { return (bool)__x; }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator!=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
    { return (bool)__x; }

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(const unique_ptr<_Tp, _Dp>& __x,
 	      const unique_ptr<_Up, _Ep>& __y)
    {
@ -752,67 +752,67 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
    { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
 								 nullptr); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
    { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
 								 __x.get()); }

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(const unique_ptr<_Tp, _Dp>& __x,
 	       const unique_ptr<_Up, _Ep>& __y)
    { return !(__y < __x); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
    { return !(nullptr < __x); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator<=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
    { return !(__x < nullptr); }

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(const unique_ptr<_Tp, _Dp>& __x,
 	      const unique_ptr<_Up, _Ep>& __y)
    { return (__y < __x); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
    { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
 								 __x.get()); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
    { return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
 								 nullptr); }

  template<typename _Tp, typename _Dp,
 	   typename _Up, typename _Ep>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(const unique_ptr<_Tp, _Dp>& __x,
 	       const unique_ptr<_Up, _Ep>& __y)
    { return !(__x < __y); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
    { return !(__x < nullptr); }

  template<typename _Tp, typename _Dp>
-    inline bool
+    _GLIBCXX_NODISCARD inline bool
    operator>=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
    { return !(nullptr < __x); }