+2019-09-23 Marek Polacek <polacek@redhat.com>
+
+ PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
+ * call.c (reference_related_p): Use similar_type_p instead of
+ same_type_p.
+ (reference_compatible_p): Update implementation to match CWG 2352.
+ * cp-tree.h (similar_type_p): Declare.
+ * typeck.c (similar_type_p): New.
+
2019-09-22 Marek Polacek <polacek@redhat.com>
PR c++/91819 - ICE with operator++ and enum.
/* [dcl.init.ref]
Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
- to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
- of T2. */
- return (same_type_p (t1, t2)
+ to "cv2 T2" if T1 is similar to T2, or T1 is a base class of T2. */
+ return (similar_type_p (t1, t2)
|| (CLASS_TYPE_P (t1) && CLASS_TYPE_P (t2)
&& DERIVED_FROM_P (t1, t2)));
}
/* [dcl.init.ref]
"cv1 T1" is reference compatible with "cv2 T2" if
- * T1 is reference-related to T2 or
- * T2 is "noexcept function" and T1 is "function", where the
- function types are otherwise the same,
- and cv1 is the same cv-qualification as, or greater cv-qualification
- than, cv2. */
- return ((reference_related_p (t1, t2)
- || fnptr_conv_p (t1, t2))
- && at_least_as_qualified_p (t1, t2));
+ a prvalue of type "pointer to cv2 T2" can be converted to the type
+ "pointer to cv1 T1" via a standard conversion sequence. */
+ tree ptype1 = build_pointer_type (t1);
+ tree ptype2 = build_pointer_type (t2);
+ conversion *conv = standard_conversion (ptype1, ptype2, NULL_TREE,
+ /*c_cast_p=*/false, 0, tf_none);
+ if (!conv || conv->bad_p)
+ return false;
+ return true;
}
/* A reference of the indicated TYPE is being bound directly to the
extern bool comp_except_specs (const_tree, const_tree, int);
extern bool comptypes (tree, tree, int);
extern bool same_type_ignoring_top_level_qualifiers_p (tree, tree);
+extern bool similar_type_p (tree, tree);
extern bool compparms (const_tree, const_tree);
extern int comp_cv_qualification (const_tree, const_tree);
extern int comp_cv_qualification (int, int);
return same_type_p (type1, type2);
}
+/* Returns nonzero iff TYPE1 and TYPE2 are similar, as per [conv.qual]. */
+
+bool
+similar_type_p (tree type1, tree type2)
+{
+ if (type1 == error_mark_node || type2 == error_mark_node)
+ return false;
+
+ /* Informally, two types are similar if, ignoring top-level cv-qualification:
+ * they are the same type; or
+ * they are both pointers, and the pointed-to types are similar; or
+ * they are both pointers to member of the same class, and the types of
+ the pointed-to members are similar; or
+ * they are both arrays of the same size or both arrays of unknown bound,
+ and the array element types are similar. */
+
+ if (same_type_ignoring_top_level_qualifiers_p (type1, type2))
+ return true;
+
+ /* FIXME This ought to handle ARRAY_TYPEs too. */
+ if ((TYPE_PTR_P (type1) && TYPE_PTR_P (type2))
+ || (TYPE_PTRDATAMEM_P (type1) && TYPE_PTRDATAMEM_P (type2)))
+ return comp_ptr_ttypes_const (type1, type2);
+
+ return false;
+}
+
/* Returns 1 if TYPE1 is at least as qualified as TYPE2. */
bool
+2019-09-23 Marek Polacek <polacek@redhat.com>
+
+ PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
+ * g++.dg/cpp0x/pr33930.C: Add dg-error.
+ * g++.dg/cpp0x/ref-bind1.C: New test.
+ * g++.dg/cpp0x/ref-bind2.C: New test.
+ * g++.dg/cpp0x/ref-bind3.C: New test.
+ * g++.old-deja/g++.pt/spec35.C: Remove dg-error.
+
2019-09-23 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
* gcc.dg/ucnid-5-utf8.c: Skip unless ucn is supported.
void bar( int* someptr )
{
- int& x = foo( someptr );
+ int& x = foo( someptr ); // { dg-error "cannot bind non-const lvalue reference" }
}
--- /dev/null
+// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
+// { dg-do compile { target c++11 } }
+
+// These should bind directly to ptr, so no -Wreturn-local-addr warnings.
+int *ptr;
+
+const int *const &
+fn1 ()
+{
+ return ptr;
+}
+
+int **const ptr2 = nullptr;
+const int *const *const &
+fn2 ()
+{
+ return ptr2;
+}
+
+int (*ptr3)[10];
+using T = const int (*const)[10];
+
+T&
+fn3 ()
+{
+ return ptr3;
+}
+
+int (**ptr4)[5] = nullptr;
+using T2 = const int (*const *const)[5];
+
+T2&
+fn4 ()
+{
+ return ptr4;
+}
+
+const int **ptr5 = nullptr;
+
+const int *const *const &
+fn5 ()
+{
+ return ptr5;
+}
--- /dev/null
+// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
+// { dg-do compile { target c++11 } }
+
+// "const int *" and "int *" are reference-related, and 5.4.4.
+// says that in that case, if the reference is an rvalue reference,
+// the initializer expression shall not be an lvalue.
+
+int &f (const int *&&);
+
+void
+fn (int *p)
+{
+ const int *&&r = p; // { dg-error "cannot bind rvalue reference" }
+ f (p); // { dg-error "cannot bind rvalue reference" }
+}
--- /dev/null
+// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
+// { dg-do compile { target c++11 } }
+
+template<typename T> int f (const T *const &); // (1)
+template<typename T> int f (T *const &); // (2)
+template<typename T> int f (T *); // (3)
+
+/* Before CWG 2352, (2) was a better match than (1), but (2) and (3) were
+ equally good, so there was an ambiguity. (2) was better than (1) because
+ (1) required a qualification conversion whereas (2) didn't. But with this
+ CWG, (1) no longer requires a qualification conversion, because the types
+ "const int* const" and "int *" are now considered reference-related and we
+ bind directly, and (1) is more specialized than (2). And (1) is also a
+ better match than (3). */
+
+void
+g (int *p, const int *q, const int *const r)
+{
+ f (p); // calls (1)
+ f (q); // calls (1)
+ f (r); // calls (1)
+}
template <typename T> int Qux (T); // { dg-message "note" }
template <typename T> int Qux (T const &); // { dg-message "note" } candidate
-template <typename T> int Bar (T const *const &); // { dg-message "note" }
-template <typename T> int Bar (T *const &); // { dg-message "note" } candidate
-template <typename T> int Bar (T *); // { dg-message "note" } candidate
+template <typename T> int Bar (T const *const &);
+template <typename T> int Bar (T *const &);
+template <typename T> int Bar (T *);
template <typename T> int Baz (T *const &); // { dg-message "note" }
template <typename T> int Baz (T *); // { dg-message "note" } candidate
int Baz (int const *ptr, int *ptr2)
{
Baz (ptr2); // { dg-error "ambiguous" }
- Bar (ptr2); // { dg-error "ambiguous" }
+ Bar (ptr2);
Foo (ptr2); // { dg-error "ambiguous" }
Qux (ptr2); // { dg-error "ambiguous" }
return 0;
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