From: Patrick Palka <ppalka@redhat.com>
To: Patrick Palka <ppalka@redhat.com>
Cc: Nathan Sidwell <nathan@acm.org>,
gcc-patches@gcc.gnu.org, jason@redhat.com
Subject: Re: [PATCH] c++ modules: ICE with class NTTP argument [PR100616]
Date: Mon, 26 Sep 2022 15:05:01 -0400 (EDT) [thread overview]
Message-ID: <9c72067f-c3ff-50d7-cd07-ca1eec819f82@idea> (raw)
In-Reply-To: <8728ddf0-ba58-60b3-9083-781901e350f9@idea>
[-- Attachment #1: Type: text/plain, Size: 12637 bytes --]
On Mon, 26 Sep 2022, Patrick Palka wrote:
> On Mon, 26 Sep 2022, Nathan Sidwell wrote:
>
> > On 9/26/22 10:08, Nathan Sidwell wrote:
> > > On 9/23/22 09:32, Patrick Palka wrote:
> > >
> > > > Judging by the two commits that introduced/modified this part of
> > > > maybe_register_incomplete_var, r196852 and r214333, ISTM the code
> > > > is really only concerned with constexpr static data members (whose
> > > > initializer may contain a pointer-to-member for a currently open class).
> > > > So maybe we ought to restrict the branch like so, which effectively
> > > > disables this part of maybe_register_incomplete_var during stream-in, and
> > > > guarantees that outermost_open_class doesn't return NULL if the branch is
> > > > taken?
> > >
> > > I think the problem is that we're streaming these VAR_DECLs as regular
> > > VAR_DECLS, when we should be handling them as a new kind of object fished
> > > out from the template they're instantiating. (I'm guessing that'll just be a
> > > new tag, a type and an initializer?)
> > >
> > > Then on stream-in we can handle them in the same way as a non-modules
> > > compilation handles such redeclarations. I.e. how does:
> > >
> > > template<auto> struct C { };
> > > struct A { };
> > > C<A{}> c1; // #1
> > > C<A{}> c2; // #2
> > >
> > > work. Presumably at some point #2's A{} gets unified such that we find the
> > > instantation that occurred at #1?
>
> This works because the lookup in get_template_parm_object for #2's A{}
> finds and reuses the VAR_DECL created for #1's A{}.
>
> But IIUC this lookup (performed via get_global_binding) isn't
> import-aware, which I suppose explains why we don't find the VAR_DECL
> from another TU.
>
> > >
> > > I notice the template arg for C<A{}> is a var decl mangled as _ZTAXtl1AEE,
> > > which is a 'template paramete object for A{}'. I see that's a special
> > > mangler 'mangle_template_parm_object', called from
> > > get_template_parm_object. Perhaps these VAR_DECLs need an additional
> > > in-tree flag that the streamer can check for?
> >
> > I wonder if we're setting the module attachment for these variables sanely?
> > They should be attached to the global module. My guess is the
> > pushdecl_top_level_and_finish call in get_templatE_parm_object is not doing
> > what is needed (as well as the other issues).
>
> This is a bit of a shot in the dark, but the following seems to work:
> when pushing the VAR_DECL, we need to call set_originating_module to
> attach it to the global module, and when looking it up, we need to do so
> in an import-aware way. Hopefully something like this is sufficient
> to properly handle these VAR_DECLs and we don't need to stream them
> specially?
Err, rather than changing the behavior of get_namespace_binding (which
has many unrelated callers), I guess we could just use the already
import-aware lookup_qualified_name instead where appropriate. WDYT of
the following? (testing in progress)
-- >8 --
Subject: [PATCH] c++ modules: ICE with class NTTP argument [PR100616]
PR c++/100616
PR c++/102576
gcc/cp/ChangeLog:
* pt.cc (get_template_parm_object): Use lookup_qualified_name
instead of get_global_binding. Call set_originating_module before
pushing the VAR_DECL.
(listify): Use lookup_qualified_name instead of get_global_binding.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr100616_a.C: New test.
* g++.dg/modules/pr100616_b.C: New test.
* g++.dg/modules/pr102576_a.H: New test.
* g++.dg/modules/pr102576_b.C: New test.
---
gcc/cp/pt.cc | 10 ++++++----
gcc/testsuite/g++.dg/modules/pr100616_a.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/pr100616_b.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/pr102576_a.H | 5 +++++
gcc/testsuite/g++.dg/modules/pr102576_b.C | 9 +++++++++
5 files changed, 36 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_b.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr102576_a.H
create mode 100644 gcc/testsuite/g++.dg/modules/pr102576_b.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 1f088fe281e..e030d9db2f6 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -7284,8 +7284,8 @@ get_template_parm_object (tree expr, tsubst_flags_t complain)
gcc_assert (!TREE_HAS_CONSTRUCTOR (expr));
tree name = mangle_template_parm_object (expr);
- tree decl = get_global_binding (name);
- if (decl)
+ tree decl = lookup_qualified_name (global_namespace, name);
+ if (decl != error_mark_node)
return decl;
tree type = cp_build_qualified_type (TREE_TYPE (expr), TYPE_QUAL_CONST);
@@ -7307,6 +7307,7 @@ get_template_parm_object (tree expr, tsubst_flags_t complain)
hash_map_safe_put<hm_ggc> (tparm_obj_values, decl, copy);
}
+ set_originating_module (decl);
pushdecl_top_level_and_finish (decl, expr);
return decl;
@@ -29150,9 +29151,10 @@ finish_concept_definition (cp_expr id, tree init)
static tree
listify (tree arg)
{
- tree std_init_list = get_namespace_binding (std_node, init_list_identifier);
+ tree std_init_list = lookup_qualified_name (std_node, init_list_identifier);
- if (!std_init_list || !DECL_CLASS_TEMPLATE_P (std_init_list))
+ if (std_init_list == error_mark_node
+ || !DECL_CLASS_TEMPLATE_P (std_init_list))
{
gcc_rich_location richloc (input_location);
maybe_add_include_fixit (&richloc, "<initializer_list>", false);
diff --git a/gcc/testsuite/g++.dg/modules/pr100616_a.C b/gcc/testsuite/g++.dg/modules/pr100616_a.C
new file mode 100644
index 00000000000..788af2eb533
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr100616_a.C
@@ -0,0 +1,8 @@
+// PR c++/100616
+// { dg-additional-options "-std=c++20 -fmodules-ts" }
+// { dg-module-cmi pr100616 }
+export module pr100616;
+
+template<auto> struct C { };
+struct A { };
+C<A{}> c1;
diff --git a/gcc/testsuite/g++.dg/modules/pr100616_b.C b/gcc/testsuite/g++.dg/modules/pr100616_b.C
new file mode 100644
index 00000000000..fc89cd08ac5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr100616_b.C
@@ -0,0 +1,8 @@
+// PR c++/100616
+// { dg-additional-options "-std=c++20 -fmodules-ts" }
+module pr100616;
+
+C<A{}> c2;
+
+using type = decltype(c1);
+using type = decltype(c2);
diff --git a/gcc/testsuite/g++.dg/modules/pr102576_a.H b/gcc/testsuite/g++.dg/modules/pr102576_a.H
new file mode 100644
index 00000000000..87ba9b52031
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr102576_a.H
@@ -0,0 +1,5 @@
+// PR c++/102576
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+#include <initializer_list>
diff --git a/gcc/testsuite/g++.dg/modules/pr102576_b.C b/gcc/testsuite/g++.dg/modules/pr102576_b.C
new file mode 100644
index 00000000000..10251ed5304
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr102576_b.C
@@ -0,0 +1,9 @@
+// PR c++/102576
+// { dg-additional-options -fmodules-ts }
+
+import "pr102576_a.H";
+
+int main() {
+ for (int i : {1, 2, 3})
+ ;
+}
--
2.38.0.rc1.2.g4b79ee4b0c
>
> -- >8 --
>
> Subject: [PATCH] c++ modules: ICE with class NTTP argument [PR100616]
>
> The function get_template_parm_object returns an artifical mangled
> VAR_DECL that's unique to the given class NTTP argument. To enforce
> this uniqueness, we first look up the mangled name of the VAR_DECL from
> the global scope via get_global_binding, and only create/push a VAR_DECL
> if this lookup fails.
>
> But with modules, we need to do more to enforce uniqueness: the VAR_DECL
> needs to be attached to the global module, and the lookup needs to be
> import-aware, which get_global_binding currently isn't.
>
> So this patch makes us call set_originating_module from
> get_template_parm_object before pushing, and makes get_namespace_binding
> use name_lookup::search_qualified which does look into imports.
>
> It turns out this change to get_namespace_binding also fixes PR102576
> where we were failing to find an imported std::initializer_list due to
> the function not being import-aware.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
>
> PR c++/100616
> PR c++/102576
>
> gcc/cp/ChangeLog:
>
> * name-lookup.cc (get_namespace_binding): Rewrite in terms of
> name_lookup::search_unqualified.
> * pt.cc (get_template_parm_object): Call set_originating_module
> before pushing the VAR_DECL.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/modules/pr100616_a.C: New test.
> * g++.dg/modules/pr100616_b.C: New test.
> * g++.dg/modules/pr102576_a.H: New test.
> * g++.dg/modules/pr102576_b.C: New test.
> ---
> gcc/cp/name-lookup.cc | 21 ++++++---------------
> gcc/cp/pt.cc | 1 +
> gcc/testsuite/g++.dg/modules/pr100616_a.C | 8 ++++++++
> gcc/testsuite/g++.dg/modules/pr100616_b.C | 8 ++++++++
> gcc/testsuite/g++.dg/modules/pr102576_a.H | 5 +++++
> gcc/testsuite/g++.dg/modules/pr102576_b.C | 9 +++++++++
> 6 files changed, 37 insertions(+), 15 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_a.C
> create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_b.C
> create mode 100644 gcc/testsuite/g++.dg/modules/pr102576_a.H
> create mode 100644 gcc/testsuite/g++.dg/modules/pr102576_b.C
>
> diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
> index 69d555ddf1f..6cd73276cf5 100644
> --- a/gcc/cp/name-lookup.cc
> +++ b/gcc/cp/name-lookup.cc
> @@ -5772,9 +5772,7 @@ do_class_using_decl (tree scope, tree name)
>
> \f
> /* Return the binding for NAME in NS in the current TU. If NS is
> - NULL, look in global_namespace. We will not find declarations
> - from imports. Users of this who, having found nothing, push a new
> - decl must be prepared for that pushing to match an existing decl. */
> + NULL, look in global_namespace. .*/
>
> tree
> get_namespace_binding (tree ns, tree name)
> @@ -5783,19 +5781,12 @@ get_namespace_binding (tree ns, tree name)
> if (!ns)
> ns = global_namespace;
> gcc_checking_assert (!DECL_NAMESPACE_ALIAS (ns));
> - tree ret = NULL_TREE;
>
> - if (tree *b = find_namespace_slot (ns, name))
> - {
> - ret = *b;
> -
> - if (TREE_CODE (ret) == BINDING_VECTOR)
> - ret = BINDING_VECTOR_CLUSTER (ret, 0).slots[0];
> - if (ret)
> - ret = MAYBE_STAT_DECL (ret);
> - }
> -
> - return ret;
> + name_lookup lookup (name);
> + if (lookup.search_qualified (ns))
> + return lookup.value;
> + else
> + return NULL_TREE;
> }
>
> /* Push internal DECL into the global namespace. Does not do the
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 1f088fe281e..95cfc5b70a3 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -7307,6 +7307,7 @@ get_template_parm_object (tree expr, tsubst_flags_t complain)
> hash_map_safe_put<hm_ggc> (tparm_obj_values, decl, copy);
> }
>
> + set_originating_module (decl);
> pushdecl_top_level_and_finish (decl, expr);
>
> return decl;
> diff --git a/gcc/testsuite/g++.dg/modules/pr100616_a.C b/gcc/testsuite/g++.dg/modules/pr100616_a.C
> new file mode 100644
> index 00000000000..788af2eb533
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr100616_a.C
> @@ -0,0 +1,8 @@
> +// PR c++/100616
> +// { dg-additional-options "-std=c++20 -fmodules-ts" }
> +// { dg-module-cmi pr100616 }
> +export module pr100616;
> +
> +template<auto> struct C { };
> +struct A { };
> +C<A{}> c1;
> diff --git a/gcc/testsuite/g++.dg/modules/pr100616_b.C b/gcc/testsuite/g++.dg/modules/pr100616_b.C
> new file mode 100644
> index 00000000000..fc89cd08ac5
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr100616_b.C
> @@ -0,0 +1,8 @@
> +// PR c++/100616
> +// { dg-additional-options "-std=c++20 -fmodules-ts" }
> +module pr100616;
> +
> +C<A{}> c2;
> +
> +using type = decltype(c1);
> +using type = decltype(c2);
> diff --git a/gcc/testsuite/g++.dg/modules/pr102576_a.H b/gcc/testsuite/g++.dg/modules/pr102576_a.H
> new file mode 100644
> index 00000000000..87ba9b52031
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr102576_a.H
> @@ -0,0 +1,5 @@
> +// PR c++/102576
> +// { dg-additional-options -fmodule-header }
> +// { dg-module-cmi {} }
> +
> +#include <initializer_list>
> diff --git a/gcc/testsuite/g++.dg/modules/pr102576_b.C b/gcc/testsuite/g++.dg/modules/pr102576_b.C
> new file mode 100644
> index 00000000000..10251ed5304
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr102576_b.C
> @@ -0,0 +1,9 @@
> +// PR c++/102576
> +// { dg-additional-options -fmodules-ts }
> +
> +import "pr102576_a.H";
> +
> +int main() {
> + for (int i : {1, 2, 3})
> + ;
> +}
> --
> 2.38.0.rc1.2.g4b79ee4b0c
>
next prev parent reply other threads:[~2022-09-26 19:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 18:25 Patrick Palka
2022-09-22 19:13 ` Nathan Sidwell
2022-09-23 13:32 ` Patrick Palka
2022-09-26 14:08 ` Nathan Sidwell
2022-09-26 14:46 ` Nathan Sidwell
2022-09-26 18:26 ` Patrick Palka
2022-09-26 19:05 ` Patrick Palka [this message]
2022-09-27 11:49 ` Nathan Sidwell
2022-09-28 14:42 ` Patrick Palka
2022-09-28 20:51 ` Nathan Sidwell
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