On 10/11/22 10:58, Patrick Palka wrote:
On Mon, 10 Oct 2022, Nathan Sidwell wrote:
On 10/4/22 13:36, Patrick Palka wrote:
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should probably be
clearing processing_template_decl somewhere e.g in lazy_load_binding.
This is sufficient to fix the testcase.
yeah, I remember hitting issues with this, but thought I'd got rid of the need
to override processing_template_decl. Do you also need to override it in
lazy_load_pendings though? that's a lazy loader and my suspicion is it might
be susceptible to the same issues.
Hmm yeah, looks like we need to override it in lazy_load_pendings too:
I ran the testsuite with gcc_assert (!processing_template_decl) added to
module_state::read_cluster and if we don't also override it in
lazy_load_binding then the assert triggers for pr99425-2_b.X.
But it also seems the processing_template_decl test in
note_vague_linkage_fn, added by r8-7539-g977bc3ee11383e for PR84973, is
perhaps too strong: if the intent is to avoid deferring output for
uninstantiated templates, we should make sure that DECL in question is
an uninstantiated template by checking e.g. value_dependent_expression_p.
This too is sufficient to fix the testcase (since f isn't a template)
and survives bootstrap and regtest.
I think this is an orthogonal issue -- can we remove it from this patch?
Done.
-- >8 --
Subject: [PATCH] c++ modules: lazy loading from within template [PR99377]
Here when lazily loading the binding for f at parse time from the
template g, processing_template_decl is set and thus the call to
note_vague_linkage_fn from module_state::read_cluster has no effect,
and we never push f onto deferred_fns and end up never emitting its
definition.
ISTM the behavior of the lazy loading machinery shouldn't be sensitive
to whether we're inside a template, and therefore we should be clearing
processing_template_decl in the entrypoints lazy_load_binding and
lazy_load_pendings.
PR c++/99377
gcc/cp/ChangeLog:
* module.cc (lazy_load_binding): Clear processing_template_decl.
(lazy_load_pendings): Likewise.
ok, thanks
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr99377-2_a.C: New test.
* g++.dg/modules/pr99377-2_b.C: New test.
---
gcc/cp/module.cc | 8 ++++++++
gcc/testsuite/g++.dg/modules/pr99377-2_a.C | 5 +++++
gcc/testsuite/g++.dg/modules/pr99377-2_b.C | 6 ++++++
3 files changed, 19 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr99377-2_b.C
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 94fbee85225..7c48602136c 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -19081,6 +19081,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
timevar_start (TV_MODULE_IMPORT);
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
/* Stop GC happening, even in outermost loads (because our caller
could well be building up a lookup set). */
function_depth++;
@@ -19129,6 +19133,10 @@ lazy_load_binding (unsigned mod, tree ns, tree id,
binding_slot *mslot)
void
lazy_load_pendings (tree decl)
{
+ /* Make sure lazy loading from a template context behaves as if
+ from a non-template context. */
+ processing_template_decl_sentinel ptds;
+
tree key_decl;
pending_key key;
key.ns = find_pending_key (decl, &key_decl);
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
new file mode 100644
index 00000000000..26e2bccbbbe
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_a.C
@@ -0,0 +1,5 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr99377 }
+export module pr99377;
+export inline void f() { }
diff --git a/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
new file mode 100644
index 00000000000..69571952c8a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr99377-2_b.C
@@ -0,0 +1,6 @@
+// PR c++/99377
+// { dg-additional-options -fmodules-ts }
+// { dg-do link }
+import pr99377;
+template<class> void g() { f(); }
+int main() { g<int>(); }
--
Nathan Sidwell
