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. * 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. From-SVN: r276058
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@ -1,3 +1,12 @@
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2019-09-23 Marek Polacek <polacek@redhat.com>
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PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
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* call.c (reference_related_p): Use similar_type_p instead of
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same_type_p.
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(reference_compatible_p): Update implementation to match CWG 2352.
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* cp-tree.h (similar_type_p): Declare.
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* typeck.c (similar_type_p): New.
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2019-09-22 Marek Polacek <polacek@redhat.com>
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PR c++/91819 - ICE with operator++ and enum.
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@ -1530,9 +1530,8 @@ reference_related_p (tree t1, tree t2)
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/* [dcl.init.ref]
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Given types "cv1 T1" and "cv2 T2," "cv1 T1" is reference-related
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to "cv2 T2" if T1 is the same type as T2, or T1 is a base class
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of T2. */
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return (same_type_p (t1, t2)
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to "cv2 T2" if T1 is similar to T2, or T1 is a base class of T2. */
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return (similar_type_p (t1, t2)
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|| (CLASS_TYPE_P (t1) && CLASS_TYPE_P (t2)
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&& DERIVED_FROM_P (t1, t2)));
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}
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@ -1545,14 +1544,15 @@ reference_compatible_p (tree t1, tree t2)
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/* [dcl.init.ref]
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"cv1 T1" is reference compatible with "cv2 T2" if
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* T1 is reference-related to T2 or
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* T2 is "noexcept function" and T1 is "function", where the
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function types are otherwise the same,
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and cv1 is the same cv-qualification as, or greater cv-qualification
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than, cv2. */
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return ((reference_related_p (t1, t2)
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|| fnptr_conv_p (t1, t2))
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&& at_least_as_qualified_p (t1, t2));
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a prvalue of type "pointer to cv2 T2" can be converted to the type
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"pointer to cv1 T1" via a standard conversion sequence. */
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tree ptype1 = build_pointer_type (t1);
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tree ptype2 = build_pointer_type (t2);
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conversion *conv = standard_conversion (ptype1, ptype2, NULL_TREE,
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/*c_cast_p=*/false, 0, tf_none);
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if (!conv || conv->bad_p)
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return false;
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return true;
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}
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/* A reference of the indicated TYPE is being bound directly to the
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@ -7361,6 +7361,7 @@ enum { ce_derived, ce_type, ce_normal, ce_exact };
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extern bool comp_except_specs (const_tree, const_tree, int);
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extern bool comptypes (tree, tree, int);
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extern bool same_type_ignoring_top_level_qualifiers_p (tree, tree);
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extern bool similar_type_p (tree, tree);
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extern bool compparms (const_tree, const_tree);
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extern int comp_cv_qualification (const_tree, const_tree);
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extern int comp_cv_qualification (int, int);
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@ -1530,6 +1530,33 @@ same_type_ignoring_top_level_qualifiers_p (tree type1, tree type2)
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return same_type_p (type1, type2);
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}
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/* Returns nonzero iff TYPE1 and TYPE2 are similar, as per [conv.qual]. */
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bool
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similar_type_p (tree type1, tree type2)
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{
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if (type1 == error_mark_node || type2 == error_mark_node)
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return false;
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/* Informally, two types are similar if, ignoring top-level cv-qualification:
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* they are the same type; or
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* they are both pointers, and the pointed-to types are similar; or
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* they are both pointers to member of the same class, and the types of
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the pointed-to members are similar; or
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* they are both arrays of the same size or both arrays of unknown bound,
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and the array element types are similar. */
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if (same_type_ignoring_top_level_qualifiers_p (type1, type2))
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return true;
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/* FIXME This ought to handle ARRAY_TYPEs too. */
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if ((TYPE_PTR_P (type1) && TYPE_PTR_P (type2))
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|| (TYPE_PTRDATAMEM_P (type1) && TYPE_PTRDATAMEM_P (type2)))
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return comp_ptr_ttypes_const (type1, type2);
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return false;
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}
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/* Returns 1 if TYPE1 is at least as qualified as TYPE2. */
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bool
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@ -1,3 +1,12 @@
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2019-09-23 Marek Polacek <polacek@redhat.com>
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PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
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* g++.dg/cpp0x/pr33930.C: Add dg-error.
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* g++.dg/cpp0x/ref-bind1.C: New test.
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* g++.dg/cpp0x/ref-bind2.C: New test.
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* g++.dg/cpp0x/ref-bind3.C: New test.
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* g++.old-deja/g++.pt/spec35.C: Remove dg-error.
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2019-09-23 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
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* gcc.dg/ucnid-5-utf8.c: Skip unless ucn is supported.
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@ -6,5 +6,5 @@ int& foo( type&& ggg );
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void bar( int* someptr )
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{
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int& x = foo( someptr );
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int& x = foo( someptr ); // { dg-error "cannot bind non-const lvalue reference" }
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}
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@ -0,0 +1,44 @@
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// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
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// { dg-do compile { target c++11 } }
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// These should bind directly to ptr, so no -Wreturn-local-addr warnings.
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int *ptr;
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const int *const &
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fn1 ()
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{
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return ptr;
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}
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int **const ptr2 = nullptr;
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const int *const *const &
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fn2 ()
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{
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return ptr2;
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}
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int (*ptr3)[10];
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using T = const int (*const)[10];
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T&
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fn3 ()
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{
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return ptr3;
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}
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int (**ptr4)[5] = nullptr;
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using T2 = const int (*const *const)[5];
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T2&
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fn4 ()
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{
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return ptr4;
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}
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const int **ptr5 = nullptr;
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const int *const *const &
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fn5 ()
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{
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return ptr5;
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}
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@ -0,0 +1,15 @@
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// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
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// { dg-do compile { target c++11 } }
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// "const int *" and "int *" are reference-related, and 5.4.4.
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// says that in that case, if the reference is an rvalue reference,
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// the initializer expression shall not be an lvalue.
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int &f (const int *&&);
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void
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fn (int *p)
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{
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const int *&&r = p; // { dg-error "cannot bind rvalue reference" }
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f (p); // { dg-error "cannot bind rvalue reference" }
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}
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// PR c++/91844 - Implement CWG 2352, Similar types and reference binding.
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// { dg-do compile { target c++11 } }
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template<typename T> int f (const T *const &); // (1)
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template<typename T> int f (T *const &); // (2)
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template<typename T> int f (T *); // (3)
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/* Before CWG 2352, (2) was a better match than (1), but (2) and (3) were
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equally good, so there was an ambiguity. (2) was better than (1) because
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(1) required a qualification conversion whereas (2) didn't. But with this
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CWG, (1) no longer requires a qualification conversion, because the types
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"const int* const" and "int *" are now considered reference-related and we
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bind directly, and (1) is more specialized than (2). And (1) is also a
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better match than (3). */
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void
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g (int *p, const int *q, const int *const r)
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{
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f (p); // calls (1)
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f (q); // calls (1)
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f (r); // calls (1)
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}
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@ -14,9 +14,9 @@ template <typename T> int Foo (T &); // { dg-message "note" } candidate
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template <typename T> int Qux (T); // { dg-message "note" }
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template <typename T> int Qux (T const &); // { dg-message "note" } candidate
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template <typename T> int Bar (T const *const &); // { dg-message "note" }
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template <typename T> int Bar (T *const &); // { dg-message "note" } candidate
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template <typename T> int Bar (T *); // { dg-message "note" } candidate
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template <typename T> int Bar (T const *const &);
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template <typename T> int Bar (T *const &);
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template <typename T> int Bar (T *);
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template <typename T> int Baz (T *const &); // { dg-message "note" }
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template <typename T> int Baz (T *); // { dg-message "note" } candidate
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int Baz (int const *ptr, int *ptr2)
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{
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Baz (ptr2); // { dg-error "ambiguous" }
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Bar (ptr2); // { dg-error "ambiguous" }
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Bar (ptr2);
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Foo (ptr2); // { dg-error "ambiguous" }
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Qux (ptr2); // { dg-error "ambiguous" }
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return 0;
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