c++: implicitly_declare_fn and access checks [PR113908]
Checks
Commit Message
Bootstrapped and regtested on x86_64-pc-linux-gnu, are one of
both of these fixes OK for trunk?
-- >8 --
Here during ahead of time checking of the non-dependent new-expr we
synthesize B's copy constructor, which should be defined as deleted
due to A's inaccessible copy constructor. But enforce_access incorrectly
decides to defer the (silent) access check for A::A(const A&) during
synthesization since current_template_parms is still set (before r14-557
it checked processing_template_decl which got cleared from
implicitly_declare_fn), which leads to the access check leaking out to
the template context that needed the synthesization.
This patch narrowly fixes this regression in two sufficient ways:
1. Clear current_template_parms alongside processing_template_decl
in implicitly_declare_fn so that it's more independent of context.
2. Don't defer a silent access check when in a template context,
since such deferred checks will be replayed noisily at instantiation
time which may not be what the caller intended. We need to adjust
cp_parser_make_typename_type since otherwise the diagnostic for
typedef22.C regresses because cp_parser_invalid_type_name otherwise
will emit "invalid combination of multiple type-specifiers" for what
is an inaccessible qualified-id.
PR c++/113908
gcc/cp/ChangeLog:
* method.cc (implicitly_declare_fn): Clear current_template_parms
alongside processing_template_decl.
* parser.cc (cp_parser_make_typename_type): Temporarily defer
access checks around the tf_none call to make_typename_type.
* semantics.cc (enforce_access): Don't defer silent access
checks from a template context.
gcc/testsuite/ChangeLog:
* g++.dg/template/non-dependent31.C: New test.
---
gcc/cp/method.cc | 8 +++++++-
gcc/cp/parser.cc | 2 ++
gcc/cp/semantics.cc | 1 +
.../g++.dg/template/non-dependent31.C | 18 ++++++++++++++++++
4 files changed, 28 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/template/non-dependent31.C
Comments
On 2/13/24 11:49, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, are one of
> both of these fixes OK for trunk?
>
> -- >8 --
>
> Here during ahead of time checking of the non-dependent new-expr we
> synthesize B's copy constructor, which should be defined as deleted
> due to A's inaccessible copy constructor. But enforce_access incorrectly
> decides to defer the (silent) access check for A::A(const A&) during
> synthesization since current_template_parms is still set (before r14-557
> it checked processing_template_decl which got cleared from
> implicitly_declare_fn), which leads to the access check leaking out to
> the template context that needed the synthesization.
>
> This patch narrowly fixes this regression in two sufficient ways:
>
> 1. Clear current_template_parms alongside processing_template_decl
> in implicitly_declare_fn so that it's more independent of context.
Hmm, perhaps it or synthesized_method_walk should use
maybe_push_to_top_level?
> 2. Don't defer a silent access check when in a template context,
> since such deferred checks will be replayed noisily at instantiation
> time which may not be what the caller intended.
True, but returning a possibly incorrect 'false' is probably also not
what the caller intended. It would be better to see that we never call
enforce_access with tf_none in a template. If that's not feasible, I
think we should still conservatively return true.
Jason
On Tue, 13 Feb 2024, Jason Merrill wrote:
> On 2/13/24 11:49, Patrick Palka wrote:
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, are one of
> > both of these fixes OK for trunk?
> >
> > -- >8 --
> >
> > Here during ahead of time checking of the non-dependent new-expr we
> > synthesize B's copy constructor, which should be defined as deleted
> > due to A's inaccessible copy constructor. But enforce_access incorrectly
> > decides to defer the (silent) access check for A::A(const A&) during
> > synthesization since current_template_parms is still set (before r14-557
> > it checked processing_template_decl which got cleared from
> > implicitly_declare_fn), which leads to the access check leaking out to
> > the template context that needed the synthesization.
> >
> > This patch narrowly fixes this regression in two sufficient ways:
> >
> > 1. Clear current_template_parms alongside processing_template_decl
> > in implicitly_declare_fn so that it's more independent of context.
>
> Hmm, perhaps it or synthesized_method_walk should use maybe_push_to_top_level?
That works nicely, and also fixes the other regression PR113332. There
the lambda context triggering synthesization of a default ctor was
causing maybe_dummy_object to misbehave during overload resolution of
one of its member's default ctors, and now synthesization is context
independent.
>
> > 2. Don't defer a silent access check when in a template context,
> > since such deferred checks will be replayed noisily at instantiation
> > time which may not be what the caller intended.
>
> True, but returning a possibly incorrect 'false' is probably also not what the
> caller intended. It would be better to see that we never call enforce_access
> with tf_none in a template. If that's not feasible, I think we should still
> conservatively return true.
Makes sense, I can experiment with that enforce_access access change as
a follow-up.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?
-- >8 --
Subject: [PATCH] c++: synthesized_method_walk context independence [PR113908]
PR c++/113908
PR c++/113332
gcc/cp/ChangeLog:
* method.cc (synthesized_method_walk): Use maybe_push_to_top_level.
gcc/testsuite/ChangeLog:
* g++.dg/template/non-dependent31.C: New test.
* g++.dg/template/non-dependent32.C: New test.
---
gcc/cp/method.cc | 2 ++
.../g++.dg/template/non-dependent31.C | 18 +++++++++++++++++
.../g++.dg/template/non-dependent32.C | 20 +++++++++++++++++++
3 files changed, 40 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/template/non-dependent31.C
create mode 100644 gcc/testsuite/g++.dg/template/non-dependent32.C
diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 957496d3e18..98c10e6a8b5 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -2760,6 +2760,7 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
return;
}
+ bool push_to_top = maybe_push_to_top_level (TYPE_NAME (ctype));
++cp_unevaluated_operand;
++c_inhibit_evaluation_warnings;
push_deferring_access_checks (dk_no_deferred);
@@ -2857,6 +2858,7 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
pop_deferring_access_checks ();
--cp_unevaluated_operand;
--c_inhibit_evaluation_warnings;
+ maybe_pop_from_top_level (push_to_top);
}
/* DECL is a defaulted function whose exception specification is now
diff --git a/gcc/testsuite/g++.dg/template/non-dependent31.C b/gcc/testsuite/g++.dg/template/non-dependent31.C
new file mode 100644
index 00000000000..3fa68f40fe1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent31.C
@@ -0,0 +1,18 @@
+// PR c++/113908
+// { dg-do compile { target c++11 } }
+
+struct A {
+ A();
+private:
+ A(const A&);
+};
+
+struct B {
+ A a;
+
+ template<class T>
+ static void f() { new B(); }
+};
+
+template void B::f<int>();
+static_assert(!__is_constructible(B, const B&), "");
diff --git a/gcc/testsuite/g++.dg/template/non-dependent32.C b/gcc/testsuite/g++.dg/template/non-dependent32.C
new file mode 100644
index 00000000000..246654c5b50
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent32.C
@@ -0,0 +1,20 @@
+// PR c++/113332
+// { dg-do compile { target c++11 } }
+
+struct tuple {
+ template<class _Tp>
+ static constexpr bool __is_implicitly_default_constructible() { return true; }
+
+ template<class _Tp = void,
+ bool = __is_implicitly_default_constructible<_Tp>()>
+ tuple();
+};
+
+struct DBusStruct {
+private:
+ tuple data_;
+};
+
+struct IBusService {
+ int m = [] { DBusStruct{}; return 42; }();
+};
On 2/14/24 08:46, Patrick Palka wrote:
> On Tue, 13 Feb 2024, Jason Merrill wrote:
>
>> On 2/13/24 11:49, Patrick Palka wrote:
>>> Bootstrapped and regtested on x86_64-pc-linux-gnu, are one of
>>> both of these fixes OK for trunk?
>>>
>>> -- >8 --
>>>
>>> Here during ahead of time checking of the non-dependent new-expr we
>>> synthesize B's copy constructor, which should be defined as deleted
>>> due to A's inaccessible copy constructor. But enforce_access incorrectly
>>> decides to defer the (silent) access check for A::A(const A&) during
>>> synthesization since current_template_parms is still set (before r14-557
>>> it checked processing_template_decl which got cleared from
>>> implicitly_declare_fn), which leads to the access check leaking out to
>>> the template context that needed the synthesization.
>>>
>>> This patch narrowly fixes this regression in two sufficient ways:
>>>
>>> 1. Clear current_template_parms alongside processing_template_decl
>>> in implicitly_declare_fn so that it's more independent of context.
>>
>> Hmm, perhaps it or synthesized_method_walk should use maybe_push_to_top_level?
>
> That works nicely, and also fixes the other regression PR113332. There
> the lambda context triggering synthesization of a default ctor was
> causing maybe_dummy_object to misbehave during overload resolution of
> one of its member's default ctors, and now synthesization is context
> independent.
>
>>
>>> 2. Don't defer a silent access check when in a template context,
>>> since such deferred checks will be replayed noisily at instantiation
>>> time which may not be what the caller intended.
>>
>> True, but returning a possibly incorrect 'false' is probably also not what the
>> caller intended. It would be better to see that we never call enforce_access
>> with tf_none in a template. If that's not feasible, I think we should still
>> conservatively return true.
>
> Makes sense, I can experiment with that enforce_access access change as
> a follow-up.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
OK.
> -- >8 --
>
> Subject: [PATCH] c++: synthesized_method_walk context independence [PR113908]
>
> PR c++/113908
> PR c++/113332
>
> gcc/cp/ChangeLog:
>
> * method.cc (synthesized_method_walk): Use maybe_push_to_top_level.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/template/non-dependent31.C: New test.
> * g++.dg/template/non-dependent32.C: New test.
> ---
> gcc/cp/method.cc | 2 ++
> .../g++.dg/template/non-dependent31.C | 18 +++++++++++++++++
> .../g++.dg/template/non-dependent32.C | 20 +++++++++++++++++++
> 3 files changed, 40 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/template/non-dependent31.C
> create mode 100644 gcc/testsuite/g++.dg/template/non-dependent32.C
>
> diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
> index 957496d3e18..98c10e6a8b5 100644
> --- a/gcc/cp/method.cc
> +++ b/gcc/cp/method.cc
> @@ -2760,6 +2760,7 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
> return;
> }
>
> + bool push_to_top = maybe_push_to_top_level (TYPE_NAME (ctype));
> ++cp_unevaluated_operand;
> ++c_inhibit_evaluation_warnings;
> push_deferring_access_checks (dk_no_deferred);
> @@ -2857,6 +2858,7 @@ synthesized_method_walk (tree ctype, special_function_kind sfk, bool const_p,
> pop_deferring_access_checks ();
> --cp_unevaluated_operand;
> --c_inhibit_evaluation_warnings;
> + maybe_pop_from_top_level (push_to_top);
> }
>
> /* DECL is a defaulted function whose exception specification is now
> diff --git a/gcc/testsuite/g++.dg/template/non-dependent31.C b/gcc/testsuite/g++.dg/template/non-dependent31.C
> new file mode 100644
> index 00000000000..3fa68f40fe1
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/non-dependent31.C
> @@ -0,0 +1,18 @@
> +// PR c++/113908
> +// { dg-do compile { target c++11 } }
> +
> +struct A {
> + A();
> +private:
> + A(const A&);
> +};
> +
> +struct B {
> + A a;
> +
> + template<class T>
> + static void f() { new B(); }
> +};
> +
> +template void B::f<int>();
> +static_assert(!__is_constructible(B, const B&), "");
> diff --git a/gcc/testsuite/g++.dg/template/non-dependent32.C b/gcc/testsuite/g++.dg/template/non-dependent32.C
> new file mode 100644
> index 00000000000..246654c5b50
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/non-dependent32.C
> @@ -0,0 +1,20 @@
> +// PR c++/113332
> +// { dg-do compile { target c++11 } }
> +
> +struct tuple {
> + template<class _Tp>
> + static constexpr bool __is_implicitly_default_constructible() { return true; }
> +
> + template<class _Tp = void,
> + bool = __is_implicitly_default_constructible<_Tp>()>
> + tuple();
> +};
> +
> +struct DBusStruct {
> +private:
> + tuple data_;
> +};
> +
> +struct IBusService {
> + int m = [] { DBusStruct{}; return 42; }();
> +};
@@ -3088,6 +3088,7 @@ implicitly_declare_fn (special_function_kind kind, tree type,
tree this_parm;
tree name;
HOST_WIDE_INT saved_processing_template_decl;
+ tree saved_current_template_parms;
bool deleted_p = false;
bool constexpr_p = false;
tree inherited_ctor = (kind == sfk_inheriting_constructor
@@ -3132,6 +3133,10 @@ implicitly_declare_fn (special_function_kind kind, tree type,
when not in a template. */
saved_processing_template_decl = processing_template_decl;
processing_template_decl = 0;
+ /* Also clear CURRENT_TEMPLATE_PARMS so enforce_access immediately checks
+ access even in a template context. */
+ saved_current_template_parms = current_template_parms;
+ current_template_parms = NULL_TREE;
type = TYPE_MAIN_VARIANT (type);
@@ -3341,8 +3346,9 @@ implicitly_declare_fn (special_function_kind kind, tree type,
set_constraints (fn, new_ci);
}
- /* Restore PROCESSING_TEMPLATE_DECL. */
+ /* Restore PROCESSING_TEMPLATE_DECL and CURRENT_TEMPLATE_PARMS. */
processing_template_decl = saved_processing_template_decl;
+ current_template_parms = saved_current_template_parms;
if (inherited_ctor && TREE_CODE (inherited_ctor) == TEMPLATE_DECL)
fn = add_inherited_template_parms (fn, inherited_ctor);
@@ -4350,8 +4350,10 @@ cp_parser_make_typename_type (cp_parser *parser, tree id,
tree result;
if (identifier_p (id))
{
+ push_deferring_access_checks (dk_deferred);
result = make_typename_type (parser->scope, id, typename_type,
/*complain=*/tf_none);
+ pop_to_parent_deferring_access_checks ();
if (result == error_mark_node)
cp_parser_diagnose_invalid_type_name (parser, id, id_location);
return result;
@@ -346,6 +346,7 @@ enforce_access (tree basetype_path, tree decl, tree diag_decl,
tree cs = current_scope ();
if (in_template_context
+ && (complain & tf_error)
&& (CLASS_TYPE_P (cs) || TREE_CODE (cs) == FUNCTION_DECL))
if (tree template_info = get_template_info (cs))
{
new file mode 100644
@@ -0,0 +1,18 @@
+// PR c++/113908
+// { dg-do compile { target c++11 } }
+
+struct A {
+ A();
+private:
+ A(const A&);
+};
+
+struct B {
+ A a;
+
+ template<class T>
+ static void f() { new B(); }
+};
+
+template void B::f<int>();
+static_assert(!__is_constructible(B, const B&), "");