From: Patrick Palka <ppalka@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] c++: return-type-req in constraint using only outer tparms [PR104527]
Date: Tue, 1 Mar 2022 08:13:40 -0500 [thread overview]
Message-ID: <CAMOnLZZzc3av+1+0cwrj3DPTpmKYrduWkyXy0egdxf5GACf=2A@mail.gmail.com> (raw)
In-Reply-To: <508cd6cd-3d60-a846-411e-20599702c9d8@idea>
On Wed, Feb 16, 2022 at 2:56 PM Patrick Palka <ppalka@redhat.com> wrote:
>
> On Tue, 15 Feb 2022, Jason Merrill wrote:
>
> > On 2/14/22 11:32, Patrick Palka wrote:
> > > Here the template context for the atomic constraint has two levels of
> > > template arguments, but since it depends only on the innermost argument
> > > T we use a single-level argument vector during substitution into the
> > > constraint (built by get_mapped_args). We eventually pass this vector
> > > to do_auto_deduction as part of checking the return-type-requirement
> > > inside the atom, but do_auto_deduction expects outer_targs to be a full
> > > set of arguments for sake of satisfaction.
> >
> > Could we note the current number of levels in the map and use that in
> > get_mapped_args instead of the highest level parameter we happened to use?
>
> Ah yeah, that seems to work nicely. IIUC it should suffice to remember
> whether the atomic constraint expression came from a concept definition.
> If it did, then the depth of the argument vector returned by
> get_mapped_args must be one, otherwise (as in the testcase) it must be
> the same as the template depth of the constrained entity, which is the
> depth of ARGS.
>
> How does the following look? Bootstrapped and regtested on
> x86_64-pc-linux-gnu and also on cmcstl2 and range-v3.
Ping.
>
> -- >8 --
>
> Subject: [PATCH] c++: return-type-req in constraint using only outer tparms
> [PR104527]
>
> Here the template context for the atomic constraint has two levels of
> template parameters, but since it depends only on the innermost parameter
> T we use a single-level argument vector (built by get_mapped_args) during
> substitution into the atom. We eventually pass this vector to
> do_auto_deduction as part of checking the return-type-requirement within
> the atom, but do_auto_deduction expects outer_targs to be a full set of
> arguments for sake of satisfaction.
>
> This patch fixes this by making get_mapped_args always return an
> argument vector whose depth corresponds to the template depth of the
> context in which the atomic constraint expression was written, instead
> of the highest parameter level that the expression happens to use.
>
> PR c++/104527
>
> gcc/cp/ChangeLog:
>
> * constraint.cc (normalize_atom): Set
> ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P appropriately.
> (get_mapped_args): Make static, adjust parameters. Always
> return a vector whose depth corresponds to the template depth of
> the context of the atomic constraint expression. Micro-optimize
> by passing false as exact to safe_grow_cleared and by collapsing
> a multi-level depth-one argument vector.
> (satisfy_atom): Adjust call to get_mapped_args and
> diagnose_atomic_constraint.
> (diagnose_atomic_constraint): Replace map parameter with an args
> parameter.
> * cp-tree.h (ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P): Define.
> (get_mapped_args): Remove declaration.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp2a/concepts-return-req4.C: New test.
> ---
> gcc/cp/constraint.cc | 64 +++++++++++--------
> gcc/cp/cp-tree.h | 7 +-
> .../g++.dg/cpp2a/concepts-return-req4.C | 24 +++++++
> 3 files changed, 69 insertions(+), 26 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-return-req4.C
>
> diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
> index 12db7e5cf14..306e28955c6 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -764,6 +764,8 @@ normalize_atom (tree t, tree args, norm_info info)
> tree ci = build_tree_list (t, info.context);
>
> tree atom = build1 (ATOMIC_CONSTR, ci, map);
> + if (info.in_decl && concept_definition_p (info.in_decl))
> + ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P (atom) = true;
> if (!info.generate_diagnostics ())
> {
> /* Cache the ATOMIC_CONSTRs that we return, so that sat_hasher::equal
> @@ -2826,33 +2828,37 @@ satisfaction_value (tree t)
> return boolean_true_node;
> }
>
> -/* Build a new template argument list with template arguments corresponding
> - to the parameters used in an atomic constraint. */
> +/* Build a new template argument vector according to the parameter
> + mapping of the atomic constraint T, using arguments from ARGS. */
>
> -tree
> -get_mapped_args (tree map)
> +static tree
> +get_mapped_args (tree t, tree args)
> {
> + tree map = ATOMIC_CONSTR_MAP (t);
> +
> /* No map, no arguments. */
> if (!map)
> return NULL_TREE;
>
> - /* Find the mapped parameter with the highest level. */
> - int count = 0;
> - for (tree p = map; p; p = TREE_CHAIN (p))
> - {
> - int level;
> - int index;
> - template_parm_level_and_index (TREE_VALUE (p), &level, &index);
> - if (level > count)
> - count = level;
> - }
> + /* Determine the depth of the resulting argument vector. */
> + int depth;
> + if (ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P (t))
> + /* The expression of this atomic constraint comes from a concept definition,
> + whose template depth is always one, so the resulting argument vector
> + will also have depth one. */
> + depth = 1;
> + else
> + /* Otherwise, the expression of this atomic constraint was written in
> + the context of the constrained entity, whose template depth is that
> + of ARGS. */
> + depth = TMPL_ARGS_DEPTH (args);
>
> /* Place each argument at its corresponding position in the argument
> list. Note that the list will be sparse (not all arguments supplied),
> but instantiation is guaranteed to only use the parameters in the
> mapping, so null arguments would never be used. */
> - auto_vec< vec<tree> > lists (count);
> - lists.quick_grow_cleared (count);
> + auto_vec< vec<tree> > lists (depth);
> + lists.quick_grow_cleared (depth);
> for (tree p = map; p; p = TREE_CHAIN (p))
> {
> int level;
> @@ -2862,12 +2868,12 @@ get_mapped_args (tree map)
> /* Insert the argument into its corresponding position. */
> vec<tree> &list = lists[level - 1];
> if (index >= (int)list.length ())
> - list.safe_grow_cleared (index + 1, true);
> + list.safe_grow_cleared (index + 1, /*exact=*/false);
> list[index] = TREE_PURPOSE (p);
> }
>
> /* Build the new argument list. */
> - tree args = make_tree_vec (lists.length ());
> + args = make_tree_vec (lists.length ());
> for (unsigned i = 0; i != lists.length (); ++i)
> {
> vec<tree> &list = lists[i];
> @@ -2879,6 +2885,16 @@ get_mapped_args (tree map)
> }
> SET_NON_DEFAULT_TEMPLATE_ARGS_COUNT (args, 0);
>
> + if (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (args)
> + && TMPL_ARGS_DEPTH (args) == 1)
> + {
> + /* Micro-optimization: represent a depth-one argument vector
> + using a single level. */
> + tree level = TMPL_ARGS_LEVEL (args, 1);
> + ggc_free (args);
> + args = level;
> + }
> +
> return args;
> }
>
> @@ -2933,7 +2949,7 @@ satisfy_atom (tree t, tree args, sat_info info)
> }
>
> /* Rebuild the argument vector from the parameter mapping. */
> - args = get_mapped_args (map);
> + args = get_mapped_args (t, args);
>
> /* Apply the parameter mapping (i.e., just substitute). */
> tree expr = ATOMIC_CONSTR_EXPR (t);
> @@ -2955,7 +2971,7 @@ satisfy_atom (tree t, tree args, sat_info info)
> if (!same_type_p (TREE_TYPE (result), boolean_type_node))
> {
> if (info.noisy ())
> - diagnose_atomic_constraint (t, map, result, info);
> + diagnose_atomic_constraint (t, args, result, info);
> return cache.save (inst_cache.save (error_mark_node));
> }
>
> @@ -2974,7 +2990,7 @@ satisfy_atom (tree t, tree args, sat_info info)
> }
> result = satisfaction_value (result);
> if (result == boolean_false_node && info.diagnose_unsatisfaction_p ())
> - diagnose_atomic_constraint (t, map, result, info);
> + diagnose_atomic_constraint (t, args, result, info);
>
> return cache.save (inst_cache.save (result));
> }
> @@ -3642,11 +3658,10 @@ diagnose_trait_expr (tree expr, tree args)
> }
> }
>
> -/* Diagnose a substitution failure in the atomic constraint T when applied
> - with the instantiated parameter mapping MAP. */
> +/* Diagnose a substitution failure in the atomic constraint T using ARGS. */
>
> static void
> -diagnose_atomic_constraint (tree t, tree map, tree result, sat_info info)
> +diagnose_atomic_constraint (tree t, tree args, tree result, sat_info info)
> {
> /* If the constraint is already ill-formed, we've previously diagnosed
> the reason. We should still say why the constraints aren't satisfied. */
> @@ -3667,7 +3682,6 @@ diagnose_atomic_constraint (tree t, tree map, tree result, sat_info info)
> /* Generate better diagnostics for certain kinds of expressions. */
> tree expr = ATOMIC_CONSTR_EXPR (t);
> STRIP_ANY_LOCATION_WRAPPER (expr);
> - tree args = get_mapped_args (map);
> switch (TREE_CODE (expr))
> {
> case TRAIT_EXPR:
> diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> index f253b32c3f2..dc2429a8406 100644
> --- a/gcc/cp/cp-tree.h
> +++ b/gcc/cp/cp-tree.h
> @@ -466,6 +466,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
> IMPLICIT_CONV_EXPR_NONTYPE_ARG (in IMPLICIT_CONV_EXPR)
> BASELINK_FUNCTIONS_MAYBE_INCOMPLETE_P (in BASELINK)
> BIND_EXPR_VEC_DTOR (in BIND_EXPR)
> + ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P (in ATOMIC_CONSTR)
> 2: IDENTIFIER_KIND_BIT_2 (in IDENTIFIER_NODE)
> ICS_THIS_FLAG (in _CONV)
> DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (in VAR_DECL)
> @@ -1679,6 +1680,11 @@ check_constraint_info (tree t)
> #define ATOMIC_CONSTR_MAP_INSTANTIATED_P(NODE) \
> TREE_LANG_FLAG_0 (ATOMIC_CONSTR_CHECK (NODE))
>
> +/* Whether the expression for this atomic constraint belongs to a
> + concept definition. */
> +#define ATOMIC_CONSTR_EXPR_FROM_CONCEPT_P(NODE) \
> + TREE_LANG_FLAG_1 (ATOMIC_CONSTR_CHECK (NODE))
> +
> /* The expression of an atomic constraint. */
> #define ATOMIC_CONSTR_EXPR(NODE) \
> CONSTR_EXPR (ATOMIC_CONSTR_CHECK (NODE))
> @@ -8306,7 +8312,6 @@ extern tree evaluate_requires_expr (tree);
> extern tree tsubst_constraint (tree, tree, tsubst_flags_t, tree);
> extern tree tsubst_constraint_info (tree, tree, tsubst_flags_t, tree);
> extern tree tsubst_parameter_mapping (tree, tree, tsubst_flags_t, tree);
> -extern tree get_mapped_args (tree);
>
> struct processing_constraint_expression_sentinel
> {
> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-return-req4.C b/gcc/testsuite/g++.dg/cpp2a/concepts-return-req4.C
> new file mode 100644
> index 00000000000..471946bc8eb
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-return-req4.C
> @@ -0,0 +1,24 @@
> +// PR c++/104527
> +// { dg-do compile { target c++20 } }
> +
> +template<class T, class U>
> +concept is_same = __is_same(T, U);
> +
> +template<class T>
> +struct A {
> + template<class...>
> + requires requires { { 0 } -> is_same<T>; }
> + struct B {};
> +
> + template<class...>
> + requires requires { { 1 } -> is_same<T>; }
> + static void f();
> +};
> +
> +A<int>::B<> a1;
> +A<bool>::B<> a2; // { dg-error "constraint" }
> +
> +int main() {
> + A<int>::f();
> + A<bool>::f(); // { dg-error "no match" }
> +}
> --
> 2.35.1.129.gb80121027d
>
next prev parent reply other threads:[~2022-03-01 13:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-14 16:32 Patrick Palka
2022-02-14 16:37 ` Patrick Palka
2022-02-15 23:39 ` Jason Merrill
2022-02-16 19:56 ` Patrick Palka
2022-03-01 13:13 ` Patrick Palka [this message]
2022-03-10 19:43 ` Jason Merrill
2022-03-10 20:57 ` Patrick Palka
2022-03-11 22:19 ` Jason Merrill
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