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C++17 class deduction issues

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PR c++/77890
	PR c++/77912
	* pt.c (do_class_deduction): Set cp_unevaluated_operand.
	(tsubst) [TEMPLATE_TYPE_PARM]: Copy CLASS_PLACEHOLDER_TEMPLATE.

From-SVN: r240948
This commit is contained in:
Jason Merrill 2016-10-10 16:48:51 -04:00 committed by Jason Merrill
parent d30078b8e7
commit b7beb16ac1
4 changed files with 58 additions and 5 deletions
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7
gcc/cp/ChangeLog
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@ -1,3 +1,10 @@
2016-10-10 Jason Merrill <jason@redhat.com>
PR c++/77890
PR c++/77912
* pt.c (do_class_deduction): Set cp_unevaluated_operand.
(tsubst) [TEMPLATE_TYPE_PARM]: Copy CLASS_PLACEHOLDER_TEMPLATE.
2016-10-08 Jason Merrill <jason@redhat.com>
* cp-gimplify.c (cp_fold): Add variable name.

15
gcc/cp/pt.c
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@ -13233,11 +13233,15 @@ tsubst (tree t, tree args, tsubst_flags_t complain, tree in_decl)
TYPE_POINTER_TO (r) = NULL_TREE;
TYPE_REFERENCE_TO (r) = NULL_TREE;
/* Propagate constraints on placeholders. */
if (TREE_CODE (t) == TEMPLATE_TYPE_PARM)
if (tree constr = PLACEHOLDER_TYPE_CONSTRAINTS (t))
PLACEHOLDER_TYPE_CONSTRAINTS (r)
= tsubst_constraint (constr, args, complain, in_decl);
{
/* Propagate constraints on placeholders. */
if (tree constr = PLACEHOLDER_TYPE_CONSTRAINTS (t))
PLACEHOLDER_TYPE_CONSTRAINTS (r)
= tsubst_constraint (constr, args, complain, in_decl);
else if (tree pl = CLASS_PLACEHOLDER_TEMPLATE (t))
CLASS_PLACEHOLDER_TEMPLATE (r) = pl;
}
if (TREE_CODE (r) == TEMPLATE_TEMPLATE_PARM)
/* We have reduced the level of the template
@ -24431,9 +24435,10 @@ do_class_deduction (tree tmpl, tree init, tsubst_flags_t complain)
return error_mark_node;
}
++cp_unevaluated_operand;
tree t = build_new_function_call (cands, &args, /*koenig*/false,
complain|tf_decltype);
--cp_unevaluated_operand;
release_tree_vector (args);
return TREE_TYPE (t);

20
gcc/testsuite/g++.dg/cpp1z/class-deduction19.C Normal file
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@ -0,0 +1,20 @@
// PR c++/77912
// { dg-options -std=c++1z }
template<class T> struct S{S(T){}};
//error: invalid use of template type parameter 'S'
template<class T> auto f(T t){return S(t);}
int main()
{
//fails
f(42);
//fails
//error: invalid use of template type parameter 'S'
[](auto a){return S(a);}(42);
//works
[](int a){return S(a);}(42);
}

21
gcc/testsuite/g++.dg/cpp1z/class-deduction20.C Normal file
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@ -0,0 +1,21 @@
// PR c++/77890
// { dg-options -std=c++1z }
template<class F> struct S{S(F&&f){}};
void f()
{
S([]{});
}
template <typename TF>
struct scope_guard : TF
{
scope_guard(TF f) : TF{f} { }
~scope_guard() { (*this)(); }
};
void g()
{
struct K { void operator()() {} };
scope_guard _{K{}};
}