* Re: C++ PATCH for C++17 class template argument deduction issues
[not found] <CADzB+2ky3hxWhm-JMf8+RAj0hPn0uchY=gv1NwyKQDQ7auirrQ@mail.gmail.com>
@ 2017-03-02 1:58 ` Jason Merrill
2017-03-03 1:27 ` Jason Merrill
0 siblings, 1 reply; 4+ messages in thread
From: Jason Merrill @ 2017-03-02 1:58 UTC (permalink / raw)
To: gcc-patches List
[-- Attachment #1: Type: text/plain, Size: 202 bytes --]
On Tue, Feb 28, 2017 at 1:56 PM, Jason Merrill <jason@redhat.com> wrote:
> This patch implements some proposed resolutions to open issues with
> C++17 class template argument deduction.
And some more:
[-- Attachment #2: ded-new.diff --]
[-- Type: text/plain, Size: 6963 bytes --]
commit 41e5f38da5699736eb02a5b9c65549799c288714
Author: Jason Merrill <jason@redhat.com>
Date: Wed Mar 1 13:15:11 2017 -1000
Class template argument deduction in new-expression
* init.c (build_new): Handle deduction from no initializer.
* parser.c (cp_parser_new_expression): Don't require a single
expression for class template deduction.
* typeck2.c (cxx_incomplete_type_diagnostic): Fix diagnostic for
class template placeholder.
* pt.c (tsubst_copy) [TEMPLATE_DECL]: Handle dependent context.
(tsubst_copy_and_build) [TEMPLATE_ID_EXPR]: Handle SCOPE_REF.
(redeclare_class_template): Set TEMPLATE_TYPE_PARM_FOR_CLASS.
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 7ded37e..191fe13 100644
--- a/gcc/cp/init.c
+++ b/gcc/cp/init.c
@@ -3478,15 +3478,19 @@ build_new (vec<tree, va_gc> **placement, tree type, tree nelts,
if (type == error_mark_node)
return error_mark_node;
- if (nelts == NULL_TREE && vec_safe_length (*init) == 1
+ if (nelts == NULL_TREE
/* Don't do auto deduction where it might affect mangling. */
&& (!processing_template_decl || at_function_scope_p ()))
{
tree auto_node = type_uses_auto (type);
if (auto_node)
{
- tree d_init = (**init)[0];
- d_init = resolve_nondeduced_context (d_init, complain);
+ tree d_init = NULL_TREE;
+ if (vec_safe_length (*init) == 1)
+ {
+ d_init = (**init)[0];
+ d_init = resolve_nondeduced_context (d_init, complain);
+ }
type = do_auto_deduction (type, d_init, auto_node);
}
}
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 50528e2..e684870 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -8228,7 +8228,8 @@ cp_parser_new_expression (cp_parser* parser)
contain a new-initializer of the form ( assignment-expression )".
Additionally, consistently with the spirit of DR 1467, we want to accept
'new auto { 2 }' too. */
- else if (type_uses_auto (type)
+ else if ((ret = type_uses_auto (type))
+ && !CLASS_PLACEHOLDER_TEMPLATE (ret)
&& (vec_safe_length (initializer) != 1
|| (BRACE_ENCLOSED_INITIALIZER_P ((*initializer)[0])
&& CONSTRUCTOR_NELTS ((*initializer)[0]) != 1)))
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index ec9d53a..8144ca6 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5732,6 +5732,9 @@ redeclare_class_template (tree type, tree parms, tree cons)
gcc_assert (DECL_CONTEXT (parm) == NULL_TREE);
DECL_CONTEXT (parm) = tmpl;
}
+
+ if (TREE_CODE (parm) == TYPE_DECL)
+ TEMPLATE_TYPE_PARM_FOR_CLASS (TREE_TYPE (parm)) = true;
}
// Cannot redeclare a class template with a different set of constraints.
@@ -14638,6 +14641,15 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
have to substitute this with one having context `D<int>'. */
tree context = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
+ if (dependent_scope_p (context))
+ {
+ /* When rewriting a constructor into a deduction guide, a
+ non-dependent name can become dependent, so memtmpl<args>
+ becomes context::template memtmpl<args>. */
+ tree type = tsubst (TREE_TYPE (t), args, complain, in_decl);
+ return build_qualified_name (type, context, DECL_NAME (t),
+ /*template*/true);
+ }
return lookup_field (context, DECL_NAME(t), 0, false);
}
else
@@ -16621,6 +16633,14 @@ tsubst_copy_and_build (tree t,
if (targs == error_mark_node)
return error_mark_node;
+ if (TREE_CODE (templ) == SCOPE_REF)
+ {
+ tree name = TREE_OPERAND (templ, 1);
+ tree tid = lookup_template_function (name, targs);
+ TREE_OPERAND (templ, 1) = tid;
+ return templ;
+ }
+
if (variable_template_p (templ))
RETURN (lookup_and_finish_template_variable (templ, targs, complain));
@@ -25144,7 +25164,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
type = TREE_TYPE (most_general_template (tmpl));
}
- bool saw_default = false;
+ bool saw_ctor = false;
bool saw_copy = false;
if (CLASSTYPE_METHOD_VEC (type))
// FIXME cache artificial deduction guides
@@ -25154,9 +25174,9 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
tree guide = build_deduction_guide (fn, outer_args, complain);
cands = ovl_cons (guide, cands);
+ saw_ctor = true;
+
tree parms = FUNCTION_FIRST_USER_PARMTYPE (fn);
- if (sufficient_parms_p (parms))
- saw_default = true;
if (parms && sufficient_parms_p (TREE_CHAIN (parms)))
{
tree pt = TREE_VALUE (parms);
@@ -25167,7 +25187,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
}
}
- if (!saw_default && args->length() == 0)
+ if (!saw_ctor && args->length() == 0)
{
tree guide = build_deduction_guide (type, outer_args, complain);
cands = ovl_cons (guide, cands);
diff --git a/gcc/cp/typeck2.c b/gcc/cp/typeck2.c
index 1e0354d..58a01c9 100644
--- a/gcc/cp/typeck2.c
+++ b/gcc/cp/typeck2.c
@@ -523,8 +523,14 @@ cxx_incomplete_type_diagnostic (location_t loc, const_tree value,
case TEMPLATE_TYPE_PARM:
if (is_auto (type))
- emit_diagnostic (diag_kind, loc, 0,
- "invalid use of %<auto%>");
+ {
+ if (CLASS_PLACEHOLDER_TEMPLATE (type))
+ emit_diagnostic (diag_kind, loc, 0,
+ "invalid use of placeholder %qT", type);
+ else
+ emit_diagnostic (diag_kind, loc, 0,
+ "invalid use of %qT", type);
+ }
else
emit_diagnostic (diag_kind, loc, 0,
"invalid use of template type parameter %qT", type);
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction33.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction33.C
new file mode 100644
index 0000000..d135031
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction33.C
@@ -0,0 +1,13 @@
+// { dg-options -std=c++1z }
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+
+template <class T = void> struct A { };
+template <class T> struct B { B(T,T); };
+
+int main()
+{
+ same<decltype(new A),A<void>*>();
+ same<decltype(new B{1,2}),B<int>*>();
+}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction34.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction34.C
new file mode 100644
index 0000000..b035879
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction34.C
@@ -0,0 +1,13 @@
+// { dg-options -std=c++1z }
+
+template <class T>
+struct A
+{
+ template <class U>
+ static constexpr bool B = U();
+
+ template <class U, bool V = B<U>>
+ A(T, U);
+};
+
+A a (1,2);
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction35.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction35.C
new file mode 100644
index 0000000..b0e53d1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction35.C
@@ -0,0 +1,10 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A;
+
+template <class T> struct A {
+ A(T&&);
+};
+
+int i;
+A a = i; // { dg-error "" }
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: C++ PATCH for C++17 class template argument deduction issues
2017-03-02 1:58 ` C++ PATCH for C++17 class template argument deduction issues Jason Merrill
@ 2017-03-03 1:27 ` Jason Merrill
2017-03-03 7:31 ` Jason Merrill
2017-03-06 14:44 ` Jason Merrill
0 siblings, 2 replies; 4+ messages in thread
From: Jason Merrill @ 2017-03-03 1:27 UTC (permalink / raw)
To: gcc-patches List
[-- Attachment #1: Type: text/plain, Size: 423 bytes --]
On Wed, Mar 1, 2017 at 3:58 PM, Jason Merrill <jason@redhat.com> wrote:
> On Tue, Feb 28, 2017 at 1:56 PM, Jason Merrill <jason@redhat.com> wrote:
>> This patch implements some proposed resolutions to open issues with
>> C++17 class template argument deduction.
>
> And some more:
This patch handles the issues of references to members of the class
template differently, by also allowing explicit guides to refer to
them:
[-- Attachment #2: ded-type.diff --]
[-- Type: text/plain, Size: 10813 bytes --]
commit d32c5f542b7bfe825149fc134b8c5348061f0bfb
Author: Jason Merrill <jason@redhat.com>
Date: Thu Mar 2 13:20:27 2017 -1000
Allow deduction guides to look into primary template.
* cp-tree.h (struct saved_scope): Add deduction_guide_type.
(struct cp_decl_specifier_seq): Add constructor_p.
* parser.c (cp_parser_decl_specifier_seq): Set constructor_p.
(cp_parser_init_declarator): Check it. Set ctor_dtor_or_conv_p.
Clear deduction_guide_type. Don't handle deduction guide names.
(cp_parser_declarator): Don't clear ctor_dtor_or_conv_p.
(cp_parser_direct_declarator): Likewise. Handle deduction guides.
(cp_parser_member_declaration, cp_parser_cache_defarg)
(cp_parser_objc_class_ivars): Set ctor_dtor_or_conv_p.
* pt.c (tsubst_copy, tsubst_copy_and_build): Revert last change.
(build_deduction_guide): Set deduction_guide_type.
(dependent_scope_p): Check deduction_guide_type.
* search.c (lookup_member): Likewise.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index f53f744..31edc5f 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1272,6 +1272,7 @@ struct GTY(()) saved_scope {
vec<tree, va_gc> *lang_base;
tree lang_name;
tree template_parms;
+ tree deduction_guide_type;
cp_binding_level *x_previous_class_level;
tree x_saved_tree;
@@ -5422,6 +5423,9 @@ struct cp_decl_specifier_seq {
BOOL_BITFIELD gnu_thread_keyword_p : 1;
/* True iff the type is a decltype. */
BOOL_BITFIELD decltype_p : 1;
+ /* True iff the declaration declares a constructor or C++17 deduction
+ guide. */
+ BOOL_BITFIELD constructor_p : 1;
};
/* The various kinds of declarators. */
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index e684870..fbe864f 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -13313,6 +13313,8 @@ cp_parser_decl_specifier_seq (cp_parser* parser,
&& constructor_possible_p
&& (cp_parser_constructor_declarator_p
(parser, decl_spec_seq_has_spec_p (decl_specs, ds_friend))));
+ if (constructor_p)
+ decl_specs->constructor_p = true;
/* If we don't have a DECL_SPEC yet, then we must be looking at
a type-specifier. */
@@ -19010,7 +19012,7 @@ cp_parser_init_declarator (cp_parser* parser,
enum cpp_ttype initialization_kind;
bool is_direct_init = false;
bool is_non_constant_init;
- int ctor_dtor_or_conv_p;
+ int ctor_dtor_or_conv_p = decl_specifiers->constructor_p ? -1 : 0;
bool friend_p = cp_parser_friend_p (decl_specifiers);
tree pushed_scope = NULL_TREE;
bool range_for_decl_p = false;
@@ -19048,6 +19050,9 @@ cp_parser_init_declarator (cp_parser* parser,
parser->default_arg_ok_p = saved_default_arg_ok_p;
+ if (cxx_dialect >= cxx1z)
+ scope_chain->deduction_guide_type = NULL_TREE;
+
/* If the DECLARATOR was erroneous, there's no need to go
further. */
if (declarator == cp_error_declarator)
@@ -19095,25 +19100,6 @@ cp_parser_init_declarator (cp_parser* parser,
if (function_declarator_p (declarator))
{
- /* Handle C++17 deduction guides. */
- if (!decl_specifiers->type
- && ctor_dtor_or_conv_p <= 0
- && cxx_dialect >= cxx1z)
- {
- cp_declarator *id = get_id_declarator (declarator);
- tree name = id->u.id.unqualified_name;
- parser->scope = id->u.id.qualifying_scope;
- tree tmpl = cp_parser_lookup_name_simple (parser, name, id->id_loc);
- if (tmpl
- && (DECL_CLASS_TEMPLATE_P (tmpl)
- || DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
- {
- id->u.id.unqualified_name = dguide_name (tmpl);
- id->u.id.sfk = sfk_deduction_guide;
- ctor_dtor_or_conv_p = 1;
- }
- }
-
/* Check to see if the token indicates the start of a
function-definition. */
if (cp_parser_token_starts_function_definition_p (token))
@@ -19432,8 +19418,10 @@ cp_parser_init_declarator (cp_parser* parser,
If CTOR_DTOR_OR_CONV_P is not NULL, *CTOR_DTOR_OR_CONV_P is used to
detect constructors, destructors, deduction guides, or conversion operators.
- It is set to -1 if the declarator is a name, and +1 if it is a
- function. Otherwise it is set to zero. Usually you just want to
+ The caller should set it before the call, to -1 if parsing the
+ decl-specifier-seq determined that we're declaring a constructor or
+ deduction guide, or 0 otherwise. This function sets it to -1 if the
+ declarator is a name, and +1 if it is a function. Usually you just want to
test for >0, but internally the negative value is used.
(The reason for CTOR_DTOR_OR_CONV_P is that a declaration must have
@@ -19464,11 +19452,6 @@ cp_parser_declarator (cp_parser* parser,
tree class_type;
tree gnu_attributes = NULL_TREE, std_attributes = NULL_TREE;
- /* Assume this is not a constructor, destructor, or type-conversion
- operator. */
- if (ctor_dtor_or_conv_p)
- *ctor_dtor_or_conv_p = 0;
-
if (cp_parser_allow_gnu_extensions_p (parser))
gnu_attributes = cp_parser_gnu_attributes_opt (parser);
@@ -19766,9 +19749,6 @@ cp_parser_direct_declarator (cp_parser* parser,
/* Parse an array-declarator. */
tree bounds, attrs;
- if (ctor_dtor_or_conv_p)
- *ctor_dtor_or_conv_p = 0;
-
first = false;
parser->default_arg_ok_p = false;
parser->in_declarator_p = true;
@@ -20023,6 +20003,34 @@ cp_parser_direct_declarator (cp_parser* parser,
*ctor_dtor_or_conv_p = -1;
}
}
+
+ if (cxx_dialect >= cxx1z
+ && sfk == sfk_none
+ && ctor_dtor_or_conv_p
+ && *ctor_dtor_or_conv_p == -1)
+ {
+ /* If *ctor_dtor_or_conv_p is set and we aren't declaring a
+ constructor, we must be declaring a deduction guide. */
+ tree tmpl;
+ if (qualifying_scope)
+ tmpl = (lookup_qualified_name
+ (qualifying_scope, unqualified_name,
+ /*prefer_type*/false, /*complain*/true));
+ else
+ tmpl = lookup_name (unqualified_name);
+ if (tmpl
+ && (DECL_CLASS_TEMPLATE_P (tmpl)
+ || DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
+ {
+ unqualified_name = dguide_name (tmpl);
+ scope_chain->deduction_guide_type
+ = TREE_TYPE (unqualified_name);
+ sfk = sfk_deduction_guide;
+ }
+ else
+ gcc_checking_assert (false);
+ }
+
declarator = make_id_declarator (qualifying_scope,
unqualified_name,
sfk);
@@ -23251,7 +23259,7 @@ cp_parser_member_declaration (cp_parser* parser)
cp_declarator *declarator;
tree initializer;
tree asm_specification;
- int ctor_dtor_or_conv_p;
+ int ctor_dtor_or_conv_p = decl_specifiers.constructor_p ? -1 : 0;
/* Parse the declarator. */
declarator
@@ -28334,7 +28342,7 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
declarator. */
do
{
- int ctor_dtor_or_conv_p;
+ int ctor_dtor_or_conv_p = 0;
cp_lexer_consume_token (parser->lexer);
cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
&ctor_dtor_or_conv_p,
@@ -29655,7 +29663,7 @@ cp_parser_objc_class_ivars (cp_parser* parser)
{
tree width = NULL_TREE, attributes, first_attribute, decl;
cp_declarator *declarator = NULL;
- int ctor_dtor_or_conv_p;
+ int ctor_dtor_or_conv_p = 0;
/* Check for a (possibly unnamed) bitfield declaration. */
token = cp_lexer_peek_token (parser->lexer);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 8144ca6..3b320fc 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14641,15 +14641,6 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
have to substitute this with one having context `D<int>'. */
tree context = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
- if (dependent_scope_p (context))
- {
- /* When rewriting a constructor into a deduction guide, a
- non-dependent name can become dependent, so memtmpl<args>
- becomes context::template memtmpl<args>. */
- tree type = tsubst (TREE_TYPE (t), args, complain, in_decl);
- return build_qualified_name (type, context, DECL_NAME (t),
- /*template*/true);
- }
return lookup_field (context, DECL_NAME(t), 0, false);
}
else
@@ -16633,14 +16624,6 @@ tsubst_copy_and_build (tree t,
if (targs == error_mark_node)
return error_mark_node;
- if (TREE_CODE (templ) == SCOPE_REF)
- {
- tree name = TREE_OPERAND (templ, 1);
- tree tid = lookup_template_function (name, targs);
- TREE_OPERAND (templ, 1) = tid;
- return templ;
- }
-
if (variable_template_p (templ))
RETURN (lookup_and_finish_template_variable (templ, targs, complain));
@@ -23476,6 +23459,9 @@ bool
dependent_scope_p (tree scope)
{
return (scope && TYPE_P (scope) && dependent_type_p (scope)
+ && !(cxx_dialect >= cxx1z
+ && scope_chain->deduction_guide_type
+ && same_type_p (scope, scope_chain->deduction_guide_type))
&& !currently_open_class (scope));
}
@@ -24997,6 +24983,7 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
if (outer_args)
ctor = tsubst (ctor, outer_args, complain, ctor);
type = DECL_CONTEXT (ctor);
+ scope_chain->deduction_guide_type = type;
tree fn_tmpl;
if (TREE_CODE (ctor) == TEMPLATE_DECL)
{
@@ -25089,6 +25076,7 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
current_template_parms = save_parms;
--processing_template_decl;
}
+ scope_chain->deduction_guide_type = NULL_TREE;
}
if (!memtmpl)
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 09c1b4e..6eb4124 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -1279,6 +1279,13 @@ lookup_member (tree xbasetype, tree name, int protect, bool want_type,
if (tree t = currently_open_class (type))
type = t;
+ /* Declaration of a deduction guide can look inside the primary class
+ template; replace a compatible type with the real one. */
+ if (cxx_dialect >= cxx1z
+ && scope_chain->deduction_guide_type
+ && same_type_p (type, scope_chain->deduction_guide_type))
+ type = scope_chain->deduction_guide_type;
+
if (!basetype_path)
basetype_path = TYPE_BINFO (type);
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
new file mode 100644
index 0000000..ee21d14
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
@@ -0,0 +1,16 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A
+{
+ using value_t = T;
+ A(value_t);
+};
+
+template <class T>
+A(typename A<T>::value_t) -> A<double>;
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+
+A a(42);
+same<decltype(a),A<double>> s1;
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: C++ PATCH for C++17 class template argument deduction issues
2017-03-03 1:27 ` Jason Merrill
@ 2017-03-03 7:31 ` Jason Merrill
2017-03-06 14:44 ` Jason Merrill
1 sibling, 0 replies; 4+ messages in thread
From: Jason Merrill @ 2017-03-03 7:31 UTC (permalink / raw)
To: gcc-patches List
[-- Attachment #1: Type: text/plain, Size: 555 bytes --]
On Thu, Mar 2, 2017 at 3:26 PM, Jason Merrill <jason@redhat.com> wrote:
> On Wed, Mar 1, 2017 at 3:58 PM, Jason Merrill <jason@redhat.com> wrote:
>> On Tue, Feb 28, 2017 at 1:56 PM, Jason Merrill <jason@redhat.com> wrote:
>>> This patch implements some proposed resolutions to open issues with
>>> C++17 class template argument deduction.
>>
>> And some more:
>
> This patch handles the issues of references to members of the class
> template differently, by also allowing explicit guides to refer to
> them:
This patch adjusts some overload resolution.
[-- Attachment #2: ded-ovl.diff --]
[-- Type: text/plain, Size: 6056 bytes --]
commit a777aadaf635dc1ef460c5e12d2ead4292eaa6a9
Author: Jason Merrill <jason@redhat.com>
Date: Wed Mar 1 16:11:26 2017 -1000
Update overload resolution with deduction guides.
* pt.c (do_class_deduction): Always build the copy guide.
(copy_guide_p, template_guide_p): New.
(build_deduction_guide): Remember the original constructor.
* call.c (joust): Prefer the copy guide and non-template guides.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index babab00..dc629b96 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -9717,6 +9717,22 @@ joust (struct z_candidate *cand1, struct z_candidate *cand2, bool warn,
int art2 = DECL_ARTIFICIAL (cand2->fn);
if (art1 != art2)
return art2 - art1;
+
+ if (art1)
+ {
+ /* Prefer the special copy guide over a declared copy/move
+ constructor. */
+ if (copy_guide_p (cand1->fn))
+ return 1;
+ if (copy_guide_p (cand2->fn))
+ return -1;
+
+ /* Prefer a candidate generated from a non-template constructor. */
+ int tg1 = template_guide_p (cand1->fn);
+ int tg2 = template_guide_p (cand2->fn);
+ if (tg1 != tg2)
+ return tg2 - tg1;
+ }
}
/* or, if not that, F2 is from a using-declaration, F1 is not, and the
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 31edc5f..7583672 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6288,6 +6288,8 @@ extern tree template_parm_to_arg (tree);
extern tree dguide_name (tree);
extern bool dguide_name_p (tree);
extern bool deduction_guide_p (const_tree);
+extern bool copy_guide_p (const_tree);
+extern bool template_guide_p (const_tree);
/* in repo.c */
extern void init_repo (void);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 3b320fc..13293eb 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -24852,6 +24852,35 @@ deduction_guide_p (const_tree fn)
return false;
}
+/* True if FN is the copy deduction guide, i.e. A(A)->A. */
+
+bool
+copy_guide_p (const_tree fn)
+{
+ gcc_assert (deduction_guide_p (fn));
+ if (!DECL_ARTIFICIAL (fn))
+ return false;
+ tree parms = FUNCTION_FIRST_USER_PARMTYPE (DECL_TI_TEMPLATE (fn));
+ return (TREE_CHAIN (parms) == void_list_node
+ && same_type_p (TREE_VALUE (parms), TREE_TYPE (DECL_NAME (fn))));
+}
+
+/* True if FN is a guide generated from a constructor template. */
+
+bool
+template_guide_p (const_tree fn)
+{
+ gcc_assert (deduction_guide_p (fn));
+ if (!DECL_ARTIFICIAL (fn))
+ return false;
+ if (tree ctor = DECL_ABSTRACT_ORIGIN (fn))
+ {
+ tree tmpl = DECL_TI_TEMPLATE (ctor);
+ return PRIMARY_TEMPLATE_P (tmpl);
+ }
+ return false;
+}
+
/* 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
@@ -25100,6 +25129,8 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
TREE_TYPE (ded_tmpl) = TREE_TYPE (ded_fn);
DECL_TEMPLATE_INFO (ded_fn) = build_template_info (ded_tmpl, targs);
DECL_PRIMARY_TEMPLATE (ded_tmpl) = ded_tmpl;
+ if (DECL_P (ctor))
+ DECL_ABSTRACT_ORIGIN (ded_fn) = ctor;
if (ci)
set_constraints (ded_tmpl, ci);
@@ -25153,7 +25184,6 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
}
bool saw_ctor = false;
- bool saw_copy = false;
if (CLASSTYPE_METHOD_VEC (type))
// FIXME cache artificial deduction guides
for (tree fns = CLASSTYPE_CONSTRUCTORS (type); fns; fns = OVL_NEXT (fns))
@@ -25163,16 +25193,6 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
cands = ovl_cons (guide, cands);
saw_ctor = true;
-
- tree parms = FUNCTION_FIRST_USER_PARMTYPE (fn);
- if (parms && sufficient_parms_p (TREE_CHAIN (parms)))
- {
- tree pt = TREE_VALUE (parms);
- if (TREE_CODE (pt) == REFERENCE_TYPE
- && (same_type_ignoring_top_level_qualifiers_p
- (TREE_TYPE (pt), type)))
- saw_copy = true;
- }
}
if (!saw_ctor && args->length() == 0)
@@ -25180,7 +25200,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
tree guide = build_deduction_guide (type, outer_args, complain);
cands = ovl_cons (guide, cands);
}
- if (!saw_copy && args->length() == 1)
+ if (args->length() == 1)
{
tree guide = build_deduction_guide (build_reference_type (type),
outer_args, complain);
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction36.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction36.C
new file mode 100644
index 0000000..129e29e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction36.C
@@ -0,0 +1,15 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A {
+ A(T&);
+ A(const A&);
+};
+
+int i;
+A a = i;
+A a2 = a;
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+same<decltype(a),A<int>> s1;
+same<decltype(a2),A<int>> s2;
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction38.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction38.C
new file mode 100644
index 0000000..fe6c200
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction38.C
@@ -0,0 +1,27 @@
+// { dg-options -std=c++1z }
+
+template <class T> struct A {
+ using value_type = T;
+ A(value_type); // #1
+ A(const A&); // #2
+ A(T, T, int); // #3
+ template<class U> A(int, T, U); // #4
+}; // A(A); #5, the copy deduction candidate
+
+A x (1, 2, 3); // uses #3, generated from a non-template constructor
+
+template <class T> A(T) -> A<T>; // #6, less specialized than #5
+
+A a (42); // uses #6 to deduce A<int> and #1 to initialize
+A b = a; // uses #5 to deduce A<int> and #2 to initialize
+
+template <class T> A(A<T>) -> A<A<T>>; // #7, as specialized as #5
+
+A b2 = a; // uses #7 to deduce A<A<int>> and #1 to initialize
+
+template <class,class> struct same;
+template <class T> struct same<T,T> {};
+
+same<decltype(a),A<int>> s1;
+same<decltype(b),A<int>> s2;
+same<decltype(b2),A<A<int>>> s3;
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: C++ PATCH for C++17 class template argument deduction issues
2017-03-03 1:27 ` Jason Merrill
2017-03-03 7:31 ` Jason Merrill
@ 2017-03-06 14:44 ` Jason Merrill
1 sibling, 0 replies; 4+ messages in thread
From: Jason Merrill @ 2017-03-06 14:44 UTC (permalink / raw)
To: gcc-patches List
[-- Attachment #1: Type: text/plain, Size: 552 bytes --]
On Thu, Mar 2, 2017 at 3:26 PM, Jason Merrill <jason@redhat.com> wrote:
> On Wed, Mar 1, 2017 at 3:58 PM, Jason Merrill <jason@redhat.com> wrote:
>> On Tue, Feb 28, 2017 at 1:56 PM, Jason Merrill <jason@redhat.com> wrote:
>>> This patch implements some proposed resolutions to open issues with
>>> C++17 class template argument deduction.
>
> This patch handles the issues of references to members of the class
> template differently, by also allowing explicit guides to refer to
> them:
The committee didn't like this direction, so I'm reverting it.
[-- Attachment #2: no-ded-typename.diff --]
[-- Type: text/plain, Size: 9989 bytes --]
commit 522ce181ad77238b7e314377bf21f45579e7b6e8
Author: Jason Merrill <jason@redhat.com>
Date: Sat Mar 4 13:18:47 2017 -1000
Revert "Allow deduction guides to look into primary template."
* cp-tree.h, parser.c, pt.c, search.c: Revert.
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 7583672..68f2722 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1272,7 +1272,6 @@ struct GTY(()) saved_scope {
vec<tree, va_gc> *lang_base;
tree lang_name;
tree template_parms;
- tree deduction_guide_type;
cp_binding_level *x_previous_class_level;
tree x_saved_tree;
@@ -5423,9 +5422,6 @@ struct cp_decl_specifier_seq {
BOOL_BITFIELD gnu_thread_keyword_p : 1;
/* True iff the type is a decltype. */
BOOL_BITFIELD decltype_p : 1;
- /* True iff the declaration declares a constructor or C++17 deduction
- guide. */
- BOOL_BITFIELD constructor_p : 1;
};
/* The various kinds of declarators. */
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index fbe864f..e684870 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -13313,8 +13313,6 @@ cp_parser_decl_specifier_seq (cp_parser* parser,
&& constructor_possible_p
&& (cp_parser_constructor_declarator_p
(parser, decl_spec_seq_has_spec_p (decl_specs, ds_friend))));
- if (constructor_p)
- decl_specs->constructor_p = true;
/* If we don't have a DECL_SPEC yet, then we must be looking at
a type-specifier. */
@@ -19012,7 +19010,7 @@ cp_parser_init_declarator (cp_parser* parser,
enum cpp_ttype initialization_kind;
bool is_direct_init = false;
bool is_non_constant_init;
- int ctor_dtor_or_conv_p = decl_specifiers->constructor_p ? -1 : 0;
+ int ctor_dtor_or_conv_p;
bool friend_p = cp_parser_friend_p (decl_specifiers);
tree pushed_scope = NULL_TREE;
bool range_for_decl_p = false;
@@ -19050,9 +19048,6 @@ cp_parser_init_declarator (cp_parser* parser,
parser->default_arg_ok_p = saved_default_arg_ok_p;
- if (cxx_dialect >= cxx1z)
- scope_chain->deduction_guide_type = NULL_TREE;
-
/* If the DECLARATOR was erroneous, there's no need to go
further. */
if (declarator == cp_error_declarator)
@@ -19100,6 +19095,25 @@ cp_parser_init_declarator (cp_parser* parser,
if (function_declarator_p (declarator))
{
+ /* Handle C++17 deduction guides. */
+ if (!decl_specifiers->type
+ && ctor_dtor_or_conv_p <= 0
+ && cxx_dialect >= cxx1z)
+ {
+ cp_declarator *id = get_id_declarator (declarator);
+ tree name = id->u.id.unqualified_name;
+ parser->scope = id->u.id.qualifying_scope;
+ tree tmpl = cp_parser_lookup_name_simple (parser, name, id->id_loc);
+ if (tmpl
+ && (DECL_CLASS_TEMPLATE_P (tmpl)
+ || DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
+ {
+ id->u.id.unqualified_name = dguide_name (tmpl);
+ id->u.id.sfk = sfk_deduction_guide;
+ ctor_dtor_or_conv_p = 1;
+ }
+ }
+
/* Check to see if the token indicates the start of a
function-definition. */
if (cp_parser_token_starts_function_definition_p (token))
@@ -19418,10 +19432,8 @@ cp_parser_init_declarator (cp_parser* parser,
If CTOR_DTOR_OR_CONV_P is not NULL, *CTOR_DTOR_OR_CONV_P is used to
detect constructors, destructors, deduction guides, or conversion operators.
- The caller should set it before the call, to -1 if parsing the
- decl-specifier-seq determined that we're declaring a constructor or
- deduction guide, or 0 otherwise. This function sets it to -1 if the
- declarator is a name, and +1 if it is a function. Usually you just want to
+ It is set to -1 if the declarator is a name, and +1 if it is a
+ function. Otherwise it is set to zero. Usually you just want to
test for >0, but internally the negative value is used.
(The reason for CTOR_DTOR_OR_CONV_P is that a declaration must have
@@ -19452,6 +19464,11 @@ cp_parser_declarator (cp_parser* parser,
tree class_type;
tree gnu_attributes = NULL_TREE, std_attributes = NULL_TREE;
+ /* Assume this is not a constructor, destructor, or type-conversion
+ operator. */
+ if (ctor_dtor_or_conv_p)
+ *ctor_dtor_or_conv_p = 0;
+
if (cp_parser_allow_gnu_extensions_p (parser))
gnu_attributes = cp_parser_gnu_attributes_opt (parser);
@@ -19749,6 +19766,9 @@ cp_parser_direct_declarator (cp_parser* parser,
/* Parse an array-declarator. */
tree bounds, attrs;
+ if (ctor_dtor_or_conv_p)
+ *ctor_dtor_or_conv_p = 0;
+
first = false;
parser->default_arg_ok_p = false;
parser->in_declarator_p = true;
@@ -20003,34 +20023,6 @@ cp_parser_direct_declarator (cp_parser* parser,
*ctor_dtor_or_conv_p = -1;
}
}
-
- if (cxx_dialect >= cxx1z
- && sfk == sfk_none
- && ctor_dtor_or_conv_p
- && *ctor_dtor_or_conv_p == -1)
- {
- /* If *ctor_dtor_or_conv_p is set and we aren't declaring a
- constructor, we must be declaring a deduction guide. */
- tree tmpl;
- if (qualifying_scope)
- tmpl = (lookup_qualified_name
- (qualifying_scope, unqualified_name,
- /*prefer_type*/false, /*complain*/true));
- else
- tmpl = lookup_name (unqualified_name);
- if (tmpl
- && (DECL_CLASS_TEMPLATE_P (tmpl)
- || DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl)))
- {
- unqualified_name = dguide_name (tmpl);
- scope_chain->deduction_guide_type
- = TREE_TYPE (unqualified_name);
- sfk = sfk_deduction_guide;
- }
- else
- gcc_checking_assert (false);
- }
-
declarator = make_id_declarator (qualifying_scope,
unqualified_name,
sfk);
@@ -23259,7 +23251,7 @@ cp_parser_member_declaration (cp_parser* parser)
cp_declarator *declarator;
tree initializer;
tree asm_specification;
- int ctor_dtor_or_conv_p = decl_specifiers.constructor_p ? -1 : 0;
+ int ctor_dtor_or_conv_p;
/* Parse the declarator. */
declarator
@@ -28342,7 +28334,7 @@ cp_parser_cache_defarg (cp_parser *parser, bool nsdmi)
declarator. */
do
{
- int ctor_dtor_or_conv_p = 0;
+ int ctor_dtor_or_conv_p;
cp_lexer_consume_token (parser->lexer);
cp_parser_declarator (parser, CP_PARSER_DECLARATOR_NAMED,
&ctor_dtor_or_conv_p,
@@ -29663,7 +29655,7 @@ cp_parser_objc_class_ivars (cp_parser* parser)
{
tree width = NULL_TREE, attributes, first_attribute, decl;
cp_declarator *declarator = NULL;
- int ctor_dtor_or_conv_p = 0;
+ int ctor_dtor_or_conv_p;
/* Check for a (possibly unnamed) bitfield declaration. */
token = cp_lexer_peek_token (parser->lexer);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 13293eb..416f132 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14641,6 +14641,15 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
have to substitute this with one having context `D<int>'. */
tree context = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
+ if (dependent_scope_p (context))
+ {
+ /* When rewriting a constructor into a deduction guide, a
+ non-dependent name can become dependent, so memtmpl<args>
+ becomes context::template memtmpl<args>. */
+ tree type = tsubst (TREE_TYPE (t), args, complain, in_decl);
+ return build_qualified_name (type, context, DECL_NAME (t),
+ /*template*/true);
+ }
return lookup_field (context, DECL_NAME(t), 0, false);
}
else
@@ -16624,6 +16633,14 @@ tsubst_copy_and_build (tree t,
if (targs == error_mark_node)
return error_mark_node;
+ if (TREE_CODE (templ) == SCOPE_REF)
+ {
+ tree name = TREE_OPERAND (templ, 1);
+ tree tid = lookup_template_function (name, targs);
+ TREE_OPERAND (templ, 1) = tid;
+ return templ;
+ }
+
if (variable_template_p (templ))
RETURN (lookup_and_finish_template_variable (templ, targs, complain));
@@ -23459,9 +23476,6 @@ bool
dependent_scope_p (tree scope)
{
return (scope && TYPE_P (scope) && dependent_type_p (scope)
- && !(cxx_dialect >= cxx1z
- && scope_chain->deduction_guide_type
- && same_type_p (scope, scope_chain->deduction_guide_type))
&& !currently_open_class (scope));
}
@@ -25012,7 +25026,6 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
if (outer_args)
ctor = tsubst (ctor, outer_args, complain, ctor);
type = DECL_CONTEXT (ctor);
- scope_chain->deduction_guide_type = type;
tree fn_tmpl;
if (TREE_CODE (ctor) == TEMPLATE_DECL)
{
@@ -25105,7 +25118,6 @@ build_deduction_guide (tree ctor, tree outer_args, tsubst_flags_t complain)
current_template_parms = save_parms;
--processing_template_decl;
}
- scope_chain->deduction_guide_type = NULL_TREE;
}
if (!memtmpl)
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 6eb4124..09c1b4e 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -1279,13 +1279,6 @@ lookup_member (tree xbasetype, tree name, int protect, bool want_type,
if (tree t = currently_open_class (type))
type = t;
- /* Declaration of a deduction guide can look inside the primary class
- template; replace a compatible type with the real one. */
- if (cxx_dialect >= cxx1z
- && scope_chain->deduction_guide_type
- && same_type_p (type, scope_chain->deduction_guide_type))
- type = scope_chain->deduction_guide_type;
-
if (!basetype_path)
basetype_path = TYPE_BINFO (type);
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
deleted file mode 100644
index ee21d14..0000000
--- a/gcc/testsuite/g++.dg/cpp1z/class-deduction37.C
+++ /dev/null
@@ -1,16 +0,0 @@
-// { dg-options -std=c++1z }
-
-template <class T> struct A
-{
- using value_t = T;
- A(value_t);
-};
-
-template <class T>
-A(typename A<T>::value_t) -> A<double>;
-
-template <class,class> struct same;
-template <class T> struct same<T,T> {};
-
-A a(42);
-same<decltype(a),A<double>> s1;
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-03-02 1:58 ` C++ PATCH for C++17 class template argument deduction issues Jason Merrill
2017-03-03 1:27 ` Jason Merrill
2017-03-03 7:31 ` Jason Merrill
2017-03-06 14:44 ` Jason Merrill
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