Message ID | 87k3rlrrkw.fsf@redhat.com |
---|---|
State | New |
Headers | show |
On Thu, Jan 10, 2013 at 9:22 AM, Dodji Seketeli <dodji@redhat.com> wrote: > > Also, I am not sure if this patch would be appropriate for commit, now > that we are in 'regression-only' mode. But seeing this alias-template > related thing not working hurts me. :) So at worst I'll schedule the > patch for when stage1 opens again. It is certainly a blocker for some people here using both constexpr and template alias. (The code uses a technique documented in the upcoming 4th edition of TC++PL which is due anytime now. It would be embarrassing if GCC-4.8 didn't accept it.) -- Gaby
On Thu, Jan 10, 2013 at 9:22 AM, Dodji Seketeli <dodji@redhat.com> wrote: > But during the instantiation of the *members* of test<int>, we try to > instantiate Alias<the_truth<int>>, without coercing (and thus without > folding) the argument {the_truth<int>}. We do this using > instantiate_alias_template, called from tsubst. > > The patch below makes sure instantiate_alias_template coerces the > arguments it uses to instantiate the alias template, like what I > understood you are suggesting. I have tested it without boostrap and a > full boostrap is currently running. Hmm, is it necessary to coerce all levels as opposed to just the innermost arguments? -- Gaby
On 01/10/2013 11:11 AM, Gabriel Dos Reis wrote: > Hmm, is it necessary to coerce all levels as opposed to just the > innermost arguments? No. But if you read the code, it's really only coercing the innermost level. Just the name is misleading. > If this approach looks acceptable, could I replace (part of) the > template argument coercing code in lookup_class_template_1 with the new > coerce_template_parms_all_level I introduced in this patch? Yes. Jason
Gabriel Dos Reis <gdr@integrable-solutions.net> writes: > On Thu, Jan 10, 2013 at 9:22 AM, Dodji Seketeli <dodji@redhat.com> wrote: >> >> Also, I am not sure if this patch would be appropriate for commit, now >> that we are in 'regression-only' mode. But seeing this alias-template >> related thing not working hurts me. :) So at worst I'll schedule the >> patch for when stage1 opens again. > > It is certainly a blocker for some people here using both constexpr > and template alias. (The code uses a technique documented in the > upcoming 4th edition of TC++PL which is due anytime now. It would be > embarrassing if GCC-4.8 didn't accept it.) /me nods. Hopefully when the review is done, we can ask our friendly release managers to consider interceding for us in this matter. :-)
On Fri, Jan 11, 2013 at 11:41:34AM +0100, Dodji Seketeli wrote: > Gabriel Dos Reis <gdr@integrable-solutions.net> writes: > > > On Thu, Jan 10, 2013 at 9:22 AM, Dodji Seketeli <dodji@redhat.com> wrote: > >> > >> Also, I am not sure if this patch would be appropriate for commit, now > >> that we are in 'regression-only' mode. But seeing this alias-template > >> related thing not working hurts me. :) So at worst I'll schedule the > >> patch for when stage1 opens again. > > > > It is certainly a blocker for some people here using both constexpr > > and template alias. (The code uses a technique documented in the > > upcoming 4th edition of TC++PL which is due anytime now. It would be > > embarrassing if GCC-4.8 didn't accept it.) > > /me nods. > > Hopefully when the review is done, we can ask our friendly release > managers to consider interceding for us in this matter. :-) This is ok for 4.8 from RM POV. Jakub
Jakub Jelinek <jakub@redhat.com> writes: > On Fri, Jan 11, 2013 at 11:41:34AM +0100, Dodji Seketeli wrote: >> Gabriel Dos Reis <gdr@integrable-solutions.net> writes: >> >> > On Thu, Jan 10, 2013 at 9:22 AM, Dodji Seketeli <dodji@redhat.com> wrote: >> >> >> >> Also, I am not sure if this patch would be appropriate for commit, now >> >> that we are in 'regression-only' mode. But seeing this alias-template >> >> related thing not working hurts me. :) So at worst I'll schedule the >> >> patch for when stage1 opens again. >> > >> > It is certainly a blocker for some people here using both constexpr >> > and template alias. (The code uses a technique documented in the >> > upcoming 4th edition of TC++PL which is due anytime now. It would be >> > embarrassing if GCC-4.8 didn't accept it.) >> >> /me nods. >> >> Hopefully when the review is done, we can ask our friendly release >> managers to consider interceding for us in this matter. :-) > > This is ok for 4.8 from RM POV. Thank you!
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index 30bafa0..aadc173 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -130,6 +130,8 @@ static tree tsubst_initializer_list (tree, tree); static tree get_class_bindings (tree, tree, tree, tree); static tree coerce_template_parms (tree, tree, tree, tsubst_flags_t, bool, bool); +static tree coerce_template_parms_all_levels (tree, tree, tree, tsubst_flags_t, + bool, bool); static void tsubst_enum (tree, tree, tree); static tree add_to_template_args (tree, tree); static tree add_outermost_template_args (tree, tree); @@ -6742,6 +6744,58 @@ coerce_template_parms (tree parms, return new_inner_args; } +/* Like coerce_template_parms. If PARMS represents all template + parameters levels, this function returns a vector of vectors + representing all the resulting argument levels. Note that in this + case, only the innermost arguments are coerced because the + outermost ones are supposed to have been coerced already. + + Otherwise, if PARMS represents only (the innermost) vectors of + parameters, returns a vector containing just the innermost + resulting arguments. */ + +static tree +coerce_template_parms_all_levels (tree parms, + tree args, + tree in_decl, + tsubst_flags_t complain, + bool require_all_args, + bool use_default_args) +{ + int parms_depth = TMPL_PARMS_DEPTH (parms); + int args_depth = TMPL_ARGS_DEPTH (args); + tree coerced_args; + + if (parms_depth > 1) + { + coerced_args = make_tree_vec (parms_depth); + tree level; + int cur_depth; + + for (level = parms, cur_depth = parms_depth; + parms_depth > 0 && level != NULL_TREE; + level = TREE_CHAIN (level), --cur_depth) + { + tree l; + if (cur_depth == args_depth) + l = coerce_template_parms (TREE_VALUE (level), + args, in_decl, complain, + require_all_args, + use_default_args); + else + l = TMPL_ARGS_LEVEL (args, cur_depth); + + SET_TMPL_ARGS_LEVEL (coerced_args, cur_depth, l); + } + } + else + coerced_args = coerce_template_parms (INNERMOST_TEMPLATE_PARMS (parms), + args, in_decl, complain, + require_all_args, + use_default_args); + return coerced_args; +} + /* Returns 1 if template args OT and NT are equivalent. */ static int @@ -14637,7 +14691,15 @@ instantiate_alias_template (tree tmpl, tree args, tsubst_flags_t complain) ggc_free (tinst); return error_mark_node; } - tree r = instantiate_template (tmpl, args, complain); + + tree coerced_args = + coerce_template_parms_all_levels (DECL_TEMPLATE_PARMS (tmpl), + args, tmpl, complain, + /*require_all_args=*/true, + /*use_default_args=*/true); + + tree r = instantiate_template (tmpl, coerced_args, complain); + pop_tinst_level (); /* We can't free this if a pending_template entry or last_error_tinst_level is pointing at it. */ diff --git a/gcc/testsuite/g++.dg/cpp0x/alias-decl-31.C b/gcc/testsuite/g++.dg/cpp0x/alias-decl-31.C new file mode 100644 index 0000000..83eea47 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/alias-decl-31.C @@ -0,0 +1,20 @@ +// Origin: PR c++/55663 +// { dg-do compile { target c++11 } } + +template <typename> +constexpr bool the_truth () { return true; } + +template <bool> + struct Takes_bool { }; + +template<bool B> + using Alias = Takes_bool<B>; + +template<typename T> + struct test { using type = Alias<the_truth<T>()>; }; + +int main () { + test<int> a; + + return 0; +}