Hi,
I had tried same approach as Marek. For me it solved the PR, but
caused other regressions on boostrap. So I dropped the way via
dependent_type_p.
Well, this bootstrap-issue might be caused by some local changes I had
forgot to remove, but I doubt it.
Marek, have you tried to do a boostrap with your patch?
Kai
2015-03-31 13:50 GMT+02:00 Marek Polacek <pola...@redhat.com>:
> On Tue, Mar 24, 2015 at 01:14:50AM -0400, Jason Merrill wrote:
>
> Here's my shot at this.
>
>> The problem is that the type is considered dependent in a template but is
>> not actually dependent, so we can see the exact same type outside a template
>
> Yeah, I think this is true...
>
>> and it's not dependent. So, this code is creating the difference:
>
>> > /* We can only call value_dependent_expression_p on integral constant
>> > expressions; treat non-constant expressions as dependent, too. */
>> > if (processing_template_decl
>> > && (type_dependent_expression_p (size)
>> > || !TREE_CONSTANT (size) || value_dependent_expression_p (size)))
>>
>> Now that we have instantiation_dependent_expression_p, we should be able to
>> use that instead of checking type/value dependency separately.
>
> ...but I think there's another place where things go wrong. ISTM that in
> build_cplus_array_type we consider all arrays with non-constant index as
> dependent (when processing_template_decl) -- but as the testcase shows, this
> is not always true. The fix then could look like the following, though I
> wouldn't be surprised if this was a wrong way how to go about this.
>
> Bootstrapped/regtested on x86_64-linux. Not a regression, so we might want to
> defer this patch to the next stage1.
>
> 2015-03-31 Marek Polacek <pola...@redhat.com>
>
> PR c++/65390
> * tree.c (build_cplus_array_type): Use dependent_type_p rather than
> checking for constness.
>
> * g++.dg/template/pr65390.C: New test.
>
> diff --git gcc/cp/tree.c gcc/cp/tree.c
> index ef53aff..97bccc0 100644
> --- gcc/cp/tree.c
> +++ gcc/cp/tree.c
> @@ -822,10 +822,9 @@ build_cplus_array_type (tree elt_type, tree index_type)
> if (elt_type == error_mark_node || index_type == error_mark_node)
> return error_mark_node;
>
> - bool dependent
> - = (processing_template_decl
> - && (dependent_type_p (elt_type)
> - || (index_type && !TREE_CONSTANT (TYPE_MAX_VALUE (index_type)))));
> + bool dependent = (processing_template_decl
> + && (dependent_type_p (elt_type)
> + || (index_type && dependent_type_p (index_type))));
>
> if (elt_type != TYPE_MAIN_VARIANT (elt_type))
> /* Start with an array of the TYPE_MAIN_VARIANT. */
> diff --git gcc/testsuite/g++.dg/template/pr65390.C
> gcc/testsuite/g++.dg/template/pr65390.C
> index e69de29..299d22a 100644
> --- gcc/testsuite/g++.dg/template/pr65390.C
> +++ gcc/testsuite/g++.dg/template/pr65390.C
> @@ -0,0 +1,12 @@
> +// PR c++/65390
> +// { dg-do compile }
> +// { dg-options "" }
> +
> +template<typename T> struct shared_ptr { };
> +
> +template<typename T, typename Arg>
> +shared_ptr<T> make_shared(Arg) { return shared_ptr<T>(); } // { dg-error
> "variably modified type|trying to instantiate" }
> +
> +void f(int n){
> + make_shared<int[n]>(1); // { dg-error "no matching function" }
> +}
>
> Marek
