On Tue, 12 Mar 2024, Patrick Palka wrote:
> On Tue, 12 Mar 2024, Jason Merrill wrote:
>
> > On 3/11/24 12:53, Patrick Palka wrote:
> > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look
> > > OK for trunk and release branches?
> > >
> > > -- >8 --
> > >
> > > r13-6452-g341e6cd8d603a3 made build_extra_args walk evaluated contexts
> > > first so that we prefer processing a local specialization in an evaluated
> > > context even if its first use is in an unevaluated context. But this
> > > means we need to avoid walking a tree that already has extra args/specs
> > > saved because the list of saved specs appears to be an evaluated
> > > context. It seems then that we should be calculating the saved specs
> > > from scratch each time, rather than potentially walking the saved specs
> > > list from an earlier partial instantiation when calling build_extra_args
> > > a second time around.
> >
> > Makes sense, but I wonder if we want to approach that by avoiding walking
> > into
> > *_EXTRA_ARGS in extract_locals_r? Or do we still want to walk into any
> > nested
> > extra args? And if so, will we run into this same problem then?
>
> I'm not sure totally but I'd expect a nested extra-args tree to always
> have empty *_EXTRA_ARGS since the outer extra-args tree should intercept
> any substitution before the inner extra-args tree can see it?
... and so in extract_locals_r I think we can assume *_EXTRA_ARGS is
empty, and not have to explicitly avoid walking it.
>
> >
> > > PR c++/114303
> > >
> > > gcc/cp/ChangeLog:
> > >
> > > * constraint.cc (tsubst_requires_expr): Clear
> > > REQUIRES_EXPR_EXTRA_ARGS before calling build_extra_args.
> > > * pt.cc (tsubst_stmt) <case IF_STMT>: Call build_extra_args
> > > on the new IF_STMT instead of t which might already have
> > > IF_STMT_EXTRA_ARGS.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > * g++.dg/cpp1z/constexpr-if-lambda6.C: New test.
> > > ---
> > > gcc/cp/constraint.cc | 1 +
> > > gcc/cp/pt.cc | 2 +-
> > > .../g++.dg/cpp1z/constexpr-if-lambda6.C | 16 ++++++++++++++++
> > > 3 files changed, 18 insertions(+), 1 deletion(-)
> > > create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda6.C
> > >
> > > diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> > > index 49de3211d4c..8a3b5d80ba7 100644
> > > --- a/gcc/cp/constraint.cc
> > > +++ b/gcc/cp/constraint.cc
> > > @@ -2362,6 +2362,7 @@ tsubst_requires_expr (tree t, tree args, sat_info
> > > info)
> > > matching or dguide constraint rewriting), in which case we need
> > > to partially substitute. */
> > > t = copy_node (t);
> > > + REQUIRES_EXPR_EXTRA_ARGS (t) = NULL_TREE;
> > > REQUIRES_EXPR_EXTRA_ARGS (t) = build_extra_args (t, args,
> > > info.complain);
> > > return t;
> > > }
> > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> > > index 8cf0d5b7a8d..37f2392d035 100644
> > > --- a/gcc/cp/pt.cc
> > > +++ b/gcc/cp/pt.cc
> > > @@ -18718,7 +18718,7 @@ tsubst_stmt (tree t, tree args, tsubst_flags_t
> > > complain, tree in_decl)
> > > IF_COND (stmt) = IF_COND (t);
> > > THEN_CLAUSE (stmt) = THEN_CLAUSE (t);
> > > ELSE_CLAUSE (stmt) = ELSE_CLAUSE (t);
> > > - IF_STMT_EXTRA_ARGS (stmt) = build_extra_args (t, args, complain);
> > > + IF_STMT_EXTRA_ARGS (stmt) = build_extra_args (stmt, args, complain);
> > > add_stmt (stmt);
> > > break;
> > > }
> > > diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda6.C
> > > b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda6.C
> > > new file mode 100644
> > > index 00000000000..038c2a41210
> > > --- /dev/null
> > > +++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-if-lambda6.C
> > > @@ -0,0 +1,16 @@
> > > +// PR c++/114303
> > > +// { dg-do compile { target c++17 } }
> > > +
> > > +struct A { static constexpr bool value = true; };
> > > +
> > > +int main() {
> > > + [](auto x1) {
> > > + return [&](auto) {
> > > + return [&](auto x3) {
> > > + if constexpr (decltype(x3)::value) {
> > > + static_assert(decltype(x1)::value);
> > > + }
> > > + }(A{});
> > > + }(0);
> > > + }(A{});
> > > +}
> >
> >
>
