From: Nathan Sidwell <nathan@acm.org>
To: Patrick Palka <ppalka@redhat.com>, gcc-patches@gcc.gnu.org
Cc: jason@redhat.com
Subject: Re: [PATCH 1/2] c++: modules and non-dependent auto deduction
Date: Tue, 20 Sep 2022 16:02:02 -0400 [thread overview]
Message-ID: <2d27e230-6f11-c701-71e1-db45ce247d67@acm.org> (raw)
In-Reply-To: <20220920195431.1527042-1-ppalka@redhat.com>
On 9/20/22 15:54, Patrick Palka wrote:
> The modules streaming code seems to rely on the invariant that a
> TEMPLATE_DECL and its DECL_TEMPLATE_RESULT have the same TREE_TYPE.
It does indeed.
> But for a templated VAR_DECL with deduced non-dependent type, the two
> TREE_TYPEs end up diverging: cp_finish_decl deduces the type of the
> initializer ahead of time and updates the TREE_TYPE of the VAR_DECL, but
> neglects to update the corresponding TEMPLATE_DECL as well, which leads
> to a "conflicting global module declaration" error for each of the
> __phase_alignment decls in the below testcase (and for the xtreme-header
> testcases if we try including <barrier>).
>
> This patch makes cp_finish_decl update the TREE_TYPE of the corresponding
> TEMPLATE_DECL so that the invariant is maintained >
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
Ok, thanks
>
> gcc/cp/ChangeLog:
>
> * decl.cc (cp_finish_decl): After updating the deduced type of a
> VAR_DECL, also update the corresponding TEMPLATE_DECL if there
> is one.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/modules/auto-3.h: New test.
> * g++.dg/modules/auto-3_a.H: New test.
> * g++.dg/modules/auto-3_b.C: New test.
> ---
> gcc/cp/decl.cc | 6 ++++++
> gcc/testsuite/g++.dg/modules/auto-3.h | 10 ++++++++++
> gcc/testsuite/g++.dg/modules/auto-3_a.H | 4 ++++
> gcc/testsuite/g++.dg/modules/auto-3_b.C | 4 ++++
> 4 files changed, 24 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3.h
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_a.H
> create mode 100644 gcc/testsuite/g++.dg/modules/auto-3_b.C
>
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 070f673c3a2..80467c19254 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -8180,6 +8180,12 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
> return;
> }
> cp_apply_type_quals_to_decl (cp_type_quals (type), decl);
> +
> + /* Update the type of the corresponding TEMPLATE_DECL to match. */
> + if (DECL_LANG_SPECIFIC (decl)
> + && DECL_TEMPLATE_INFO (decl)
> + && DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (decl)) == decl)
> + TREE_TYPE (DECL_TI_TEMPLATE (decl)) = type;
> }
>
> if (ensure_literal_type_for_constexpr_object (decl) == error_mark_node)
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3.h b/gcc/testsuite/g++.dg/modules/auto-3.h
> new file mode 100644
> index 00000000000..f129433cbcb
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3.h
> @@ -0,0 +1,10 @@
> +template<class>
> +struct __tree_barrier {
> + static const auto __phase_alignment_1 = 0;
> +
> + template<class>
> + static const auto __phase_alignment_2 = 0;
> +};
> +
> +template<class>
> +inline auto __phase_alignment_3 = 0;
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3_a.H b/gcc/testsuite/g++.dg/modules/auto-3_a.H
> new file mode 100644
> index 00000000000..25a7a73e73e
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3_a.H
> @@ -0,0 +1,4 @@
> +// { dg-additional-options "-fmodule-header" }
> +// { dg-module-cmi {} }
> +
> +#include "auto-3.h"
> diff --git a/gcc/testsuite/g++.dg/modules/auto-3_b.C b/gcc/testsuite/g++.dg/modules/auto-3_b.C
> new file mode 100644
> index 00000000000..03b6d46f476
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/auto-3_b.C
> @@ -0,0 +1,4 @@
> +// { dg-additional-options "-fmodules-ts -fno-module-lazy" }
> +
> +#include "auto-3.h"
> +import "auto-3_a.H";
--
Nathan Sidwell
prev parent reply other threads:[~2022-09-20 20:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-20 19:54 Patrick Palka
2022-09-20 19:54 ` [PATCH 2/2] c++: xtreme-header modules tests cleanups Patrick Palka
2022-09-20 20:02 ` Nathan Sidwell
2022-09-20 20:02 ` Nathan Sidwell [this message]
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