Bootstrapped and regtested on x86_64-pc-linux-gnu, does this
look OK for trunk/14?
-- >8 --
This implements the inherited vs non-inherited guide tiebreaker
specified by P2582R1. In order to track inherited-ness of a guide
it seems natural to reuse the lang_decl_fn::context field that already
tracks inherited-ness of a constructor.
This patch also works around CLASSTYPE_CONSTRUCTORS apparently not
always containing all inherited constructors, by iterating over
TYPE_FIELDS instead.
This patch also makes us recognize another written form of inherited
constructor, 'using Base<T>::Base::Base' whose USING_DECL_SCOPE is a
TYPENAME_TYPE.
PR c++/116276
gcc/cp/ChangeLog:
* call.cc (joust): Implement P2582R1 inherited vs non-inherited
guide tiebreaker.
* cp-tree.h (lang_decl_fn::context): Document usage in
deduction_guide_p FUNCTION_DECLs.
(inherited_guide_p): Declare.
* pt.cc (inherited_guide_p): Define.
(set_inherited_guide_context): Define.
(alias_ctad_tweaks): Use set_inherited_guide_context.
(inherited_ctad_tweaks): Recognize some inherited constructors
whose scope is a TYPENAME_TYPE.
(ctor_deduction_guides_for): For C++23 inherited CTAD, loop
over TYPE_FIELDS instead of using CLASSTYPE_CONSTRUCTORS to
recognize all relevant using-decls.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/class-deduction-inherited4.C: Extend test.
* g++.dg/cpp23/class-deduction-inherited5.C: New test.
---
gcc/cp/call.cc | 22 +++++++++
gcc/cp/cp-tree.h | 8 +++-
gcc/cp/pt.cc | 45 +++++++++++++++----
.../g++.dg/cpp23/class-deduction-inherited4.C | 15 ++++++-
.../g++.dg/cpp23/class-deduction-inherited5.C | 25 +++++++++++
5 files changed, 103 insertions(+), 12 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/class-deduction-inherited5.C
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index a75e2e5e3af..3287f77b59b 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -13261,6 +13261,28 @@ joust (struct z_candidate *cand1, struct z_candidate
*cand2, bool warn,
else if (cand2->rewritten ())
return 1;
+ /* F1 and F2 are generated from class template argument deduction for a class
+ D, and F2 is generated from inheriting constructors from a base class of D
+ while F1 is not, and for each explicit function argument, the
corresponding
+ parameters of F1 and F2 are either both ellipses or have the same type */
+ if (deduction_guide_p (cand1->fn))
+ {
+ bool inherited1 = inherited_guide_p (cand1->fn);
+ bool inherited2 = inherited_guide_p (cand2->fn);
+ if (int diff = inherited2 - inherited1)
+ {
+ for (i = 0; i < len; ++i)
+ {
+ conversion *t1 = cand1->convs[i + off1];
+ conversion *t2 = cand2->convs[i + off2];
+ if (!same_type_p (t1->type, t2->type))
+ break;
+ }
+ if (i == len)
+ return diff;
+ }
+ }
+
/* F1 is generated from a deduction-guide (13.3.1.8) and F2 is not */
if (deduction_guide_p (cand1->fn))
{
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 0c25ec5a04e..0b76fef0df4 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -2973,8 +2973,11 @@ struct GTY(()) lang_decl_fn {
chained here. This pointer thunks to return pointer thunks
will be chained on the return pointer thunk.
For a DECL_CONSTUCTOR_P FUNCTION_DECL, this is the base from
- whence we inherit. Otherwise, it is the class in which a
- (namespace-scope) friend is defined (if any). */
+ whence we inherit.
+ For a deduction_guide_p FUNCTION_DECL, this is the base class
+ from whence we inherited the guide (if any).
+ Otherwise, it is the class in which a (namespace-scope) friend
+ is defined (if any). */
tree context;
union lang_decl_u5
@@ -7655,6 +7658,7 @@ extern bool deduction_guide_p
(const_tree);
extern bool copy_guide_p (const_tree);
extern bool template_guide_p (const_tree);
extern bool builtin_guide_p (const_tree);
+extern bool inherited_guide_p (const_tree);
extern void store_explicit_specifier (tree, tree);
extern tree lookup_explicit_specifier (tree);
extern tree lookup_imported_hidden_friend (tree);
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index d468a3037b6..b518e6d5185 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -29678,6 +29678,26 @@ builtin_guide_p (const_tree fn)
return true;
}
+/* True if FN is a C++23 inherited guide. */
+
+bool
+inherited_guide_p (const_tree fn)
+{
+ gcc_assert (deduction_guide_p (fn));
+ return LANG_DECL_FN_CHECK (fn)->context != NULL_TREE;
+}
+
+/* Set the base class from which this transformed guide was inherited
+ as part of C++23 inherited CTAD. */
+
+static void
+set_inherited_guide_context (const_tree fn, tree context)
+{
+ gcc_assert (deduction_guide_p (fn));
+ LANG_DECL_FN_CHECK (fn)->context = context;
+}
+
+
/* OLDDECL is a _DECL for a template parameter. Return a similar parameter at
LEVEL:INDEX, using tsubst_args and complain for substitution into non-type
template parameter types. Note that the handling of template template
@@ -30448,6 +30468,7 @@ alias_ctad_tweaks (tree tmpl, tree uguides)
TREE_TYPE (fprime) = fntype;
if (TREE_CODE (fprime) == TEMPLATE_DECL)
TREE_TYPE (DECL_TEMPLATE_RESULT (fprime)) = fntype;
+ set_inherited_guide_context (fprime, utype);
}
aguides = lookup_add (fprime, aguides);
@@ -30479,11 +30500,14 @@ inherited_ctad_tweaks (tree tmpl, tree ctor,
tsubst_flags_t complain)
template specialization with the template argument list of A but with C as
the template. */
- /* FIXME: Also recognize inherited constructors of the form 'using C::B::B',
- which seem to be represented with TYPENAME_TYPE C::B as USING_DECL_SCOPE?
- And recognize constructors inherited from a non-dependent base class,
which
- seem to be missing from the overload set entirely? */
tree scope = USING_DECL_SCOPE (ctor);
+ if (TREE_CODE (scope) == TYPENAME_TYPE
+ && (TYPE_IDENTIFIER (TYPE_CONTEXT (scope))
+ == TYPENAME_TYPE_FULLNAME (scope)))
+ /* Recognize using B<T>::B::B; as an inheriting constructor. */
+ /* FIXME: Also recognize using C::B::B; ? We might have to call
+ resolve_typename_type for that. */
+ scope = TYPE_CONTEXT (scope);
if (!CLASS_TYPE_P (scope)
|| !CLASSTYPE_TEMPLATE_INFO (scope)
|| !PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (scope)))
@@ -30617,10 +30641,15 @@ ctor_deduction_guides_for (tree tmpl, tsubst_flags_t
complain)
}
if (cxx_dialect >= cxx23)
- for (tree ctor : ovl_range (CLASSTYPE_CONSTRUCTORS (type)))
- if (TREE_CODE (ctor) == USING_DECL)
- {
- tree uguides = inherited_ctad_tweaks (tmpl, ctor, complain);
+ /* FIXME: CLASSTYPE_CONSTRUCTORS seems to omit (dependent) inherited
+ constructors if e.g. there's a user-defined constructor. So instead
+ iterate over TYPE_FIELDS manually to robustly find all relevant using
+ decls. */
+ for (tree field = TYPE_FIELDS (type); field; field = DECL_CHAIN (field))
+ if (TREE_CODE (field) == USING_DECL
+ && DECL_NAME (field) == ctor_identifier)
+ {
+ tree uguides = inherited_ctad_tweaks (tmpl, field, complain);
if (uguides)
cands = lookup_add (uguides, cands);
}
diff --git a/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited4.C
b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited4.C
index 5e3a7f42919..bc0d5cc53d4 100644
--- a/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited4.C
+++ b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited4.C
@@ -13,10 +13,10 @@ using ty1 = B<int>;
template<class T=void>
struct C : A<int> {
- using A<int>::A; // FIXME: we don't notice this one either
+ using A<int>::A;
};
-using ty2 = decltype(C(0)); // { dg-bogus "" "" { xfail *-*-* } }
+using ty2 = decltype(C(0));
using ty2 = C<void>;
template<class T>
@@ -30,3 +30,14 @@ using ty3 = D<int>;
A(int) -> A<char>; // FIXME: we need to rebuild the guides of D
using ty4 = decltype(D(0));
using ty4 = D<char>; // { dg-bogus "conflicting" "" { xfail *-*-* } }
+
+template<class T>
+struct E { E(T); };
+
+template<class T>
+struct F : E<T> {
+ using E<T>::E::E;
+};
+
+using ty5 = decltype(F(0));
+using ty5 = F<int>;
diff --git a/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited5.C
b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited5.C
new file mode 100644
index 00000000000..7eee8664b10
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/class-deduction-inherited5.C
@@ -0,0 +1,25 @@
+// PR c++/116276
+// { dg-do compile { target c++20 } }
+
+template<class T>
+struct Base1 { };
+
+template<class T>
+struct Base2 { };
+
+template<class T = int>
+struct Derived : public Base1<T>, Base2<T> {
+ using Base1<T>::Base1;
+ using Base2<T>::Base2;
+};
+
+Derived d;
+
+template<class T = int>
+struct Derived2 : public Base1<T>, Base2<T> {
+ using Base1<T>::Base1;
+ using Base2<T>::Base2;
+ Derived2();
+};
+
+Derived2 d2;
--
2.46.0.39.g891ee3b9db
