On Thu, 22 Sep 2022, Nathan Sidwell wrote:
> On 9/22/22 14:25, Patrick Palka wrote:
>
> > index 80467c19254..722b64793ed 100644
> > --- a/gcc/cp/decl.cc
> > +++ b/gcc/cp/decl.cc
> > @@ -18235,9 +18235,11 @@ maybe_register_incomplete_var (tree var)
> > {
> > /* When the outermost open class is complete we can resolve any
> > pointers-to-members. */
> > - tree context = outermost_open_class ();
> > - incomplete_var iv = {var, context};
> > - vec_safe_push (incomplete_vars, iv);
> > + if (tree context = outermost_open_class ())
> > + {
> > + incomplete_var iv = {var, context};
> > + vec_safe_push (incomplete_vars, iv);
> > + }
>
> My immediate thought here is eek! during stream in, the outermost_open_class
> could be anything -- to do with the context that wanted to lookup of the thing
> being streamed in, right? So, the above change is I think just papering over
> a problem in this case.
D'oh, makes sense. I suppose this second branch of
maybe_register_incomplete_var shouldn't ever be taken during stream-in.
>
> not sure how to approach this.
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?
Bootstrapped and regtested on x86_64-pc-linux-gnu.
-- >8 --
Subject: [PATCH] c++ modules: ICE with class NTTP argument [PR100616]
PR c++/100616
gcc/cp/ChangeLog:
* decl.cc (maybe_register_incomplete_var): Restrict second branch
to static data members from a currently open class.
gcc/testsuite/ChangeLog:
* g++.dg/modules/pr100616_a.C: New test.
* g++.dg/modules/pr100616_b.C: New test.
---
gcc/cp/decl.cc | 2 ++
gcc/testsuite/g++.dg/modules/pr100616_a.C | 8 ++++++++
gcc/testsuite/g++.dg/modules/pr100616_b.C | 10 ++++++++++
3 files changed, 20 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_a.C
create mode 100644 gcc/testsuite/g++.dg/modules/pr100616_b.C
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 80467c19254..ea616f0e686 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -18230,6 +18230,8 @@ maybe_register_incomplete_var (tree var)
vec_safe_push (incomplete_vars, iv);
}
else if (!(DECL_LANG_SPECIFIC (var) && DECL_TEMPLATE_INFO (var))
+ && DECL_CLASS_SCOPE_P (var)
+ && currently_open_class (DECL_CONTEXT (var))
&& decl_constant_var_p (var)
&& (TYPE_PTRMEM_P (inner_type) || CLASS_TYPE_P (inner_type)))
{
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..a37eb08131b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr100616_b.C
@@ -0,0 +1,10 @@
+// PR c++/100616
+// { dg-additional-options "-std=c++20 -fmodules-ts" }
+module pr100616;
+
+C<A{}> c2;
+
+// FIXME: We don't reuse the artificial VAR_DECL for the class NTTP argument
A{}
+// from the other translation unit, which causes these types to be different.
+using type = decltype(c1);
+using type = decltype(c2); // { dg-bogus "conflicting" "" { xfail *-*-* } }
--
2.38.0.rc1.2.g4b79ee4b0c
