| Message ID | 20210409212548.642159-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: variadic class placeholder template deduction [PR97134] | expand |
On 4/9/21 5:25 PM, Patrick Palka wrote: > do_class_deduction handles specially the case where we're deducing one > placeholder from another equivalent one, but here the initializer passed > to do_class_deduction is wrapped in an EXPR_PACK_EXPANSION (we're being > called from unify during get_partial_spec_bindings). This patch makes > do_class_deduction look through EXPR_PACK_EXPANSIONs so that we detect > this case as well. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk or perhaps stage1? OK for trunk. > gcc/cp/ChangeLog: > > PR c++/97134 > * pt.c (do_class_deduction): Look through EXPR_PACK_EXPANSION > when checking if the initializer is an equivalent class > placeholder template parameter. > > gcc/testsuite/ChangeLog: > > PR c++/97134 > * g++.dg/cpp2a/nontype-class43.C: New test. > --- > gcc/cp/pt.c | 6 +++++- > gcc/testsuite/g++.dg/cpp2a/nontype-class43.C | 11 +++++++++++ > 2 files changed, 16 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/nontype-class43.C > > diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c > index 01c807be1bb..872b08ec9ad 100644 > --- a/gcc/cp/pt.c > +++ b/gcc/cp/pt.c > @@ -29265,7 +29265,11 @@ do_class_deduction (tree ptype, tree tmpl, tree init, > return ptype; > > /* Initializing one placeholder from another. */ > - if (init && TREE_CODE (init) == TEMPLATE_PARM_INDEX > + if (init > + && (TREE_CODE (init) == TEMPLATE_PARM_INDEX > + || (TREE_CODE (init) == EXPR_PACK_EXPANSION > + && (TREE_CODE (PACK_EXPANSION_PATTERN (init)) > + == TEMPLATE_PARM_INDEX))) > && is_auto (TREE_TYPE (init)) > && CLASS_PLACEHOLDER_TEMPLATE (TREE_TYPE (init)) == tmpl) > return cp_build_qualified_type (TREE_TYPE (init), cp_type_quals (ptype)); > diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C > new file mode 100644 > index 00000000000..f51684f7a62 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C > @@ -0,0 +1,11 @@ > +// PR c++/97134 > +// { dg-do compile { target c++20 } } > + > +template<typename T> > +struct templ {}; > + > +template<templ... Vs> > +struct wrapper {}; > + > +template<templ... Vs> requires true > +struct wrapper<Vs...> {}; >
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 01c807be1bb..872b08ec9ad 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -29265,7 +29265,11 @@ do_class_deduction (tree ptype, tree tmpl, tree init, return ptype; /* Initializing one placeholder from another. */ - if (init && TREE_CODE (init) == TEMPLATE_PARM_INDEX + if (init + && (TREE_CODE (init) == TEMPLATE_PARM_INDEX + || (TREE_CODE (init) == EXPR_PACK_EXPANSION + && (TREE_CODE (PACK_EXPANSION_PATTERN (init)) + == TEMPLATE_PARM_INDEX))) && is_auto (TREE_TYPE (init)) && CLASS_PLACEHOLDER_TEMPLATE (TREE_TYPE (init)) == tmpl) return cp_build_qualified_type (TREE_TYPE (init), cp_type_quals (ptype)); diff --git a/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C b/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C new file mode 100644 index 00000000000..f51684f7a62 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class43.C @@ -0,0 +1,11 @@ +// PR c++/97134 +// { dg-do compile { target c++20 } } + +template<typename T> +struct templ {}; + +template<templ... Vs> +struct wrapper {}; + +template<templ... Vs> requires true +struct wrapper<Vs...> {};