From patchwork Tue Oct 11 14:58:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Patrick Palka X-Patchwork-Id: 58791 From: ppalka@redhat.com (Patrick Palka) Date: Tue, 11 Oct 2022 10:58:18 -0400 (EDT) Subject: [PATCH] c++ modules: lazy loading from within template [PR99377] In-Reply-To: References: <20221004173631.2958133-1-ppalka@redhat.com> Message-ID: 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. 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 void g() { f(); } +int main() { g(); }