On Fri, Feb 17, 2023 at 04:32:50PM -0500, Patrick Palka wrote:
> On Fri, 17 Feb 2023, Patrick Palka wrote:
>
> > On Fri, 17 Feb 2023, Marek Polacek wrote:
> >
> > > On Fri, Feb 17, 2023 at 03:00:39PM -0500, Patrick Palka wrote:
> > > > On Fri, 17 Feb 2023, Marek Polacek via Gcc-patches wrote:
> > > >
> > > > > Here we crash in is_capture_proxy:
> > > > >
> > > > > /* Location wrappers should be stripped or otherwise handled by the
> > > > > caller before using this predicate. */
> > > > > gcc_checking_assert (!location_wrapper_p (decl));
> > > > >
> > > > > so fixed as the comment suggests. We only crash with the redundant
> > > > > capture:
> > > > >
> > > > > int abyPage = [=, abyPage] { ... }
> > > > >
> > > > > because prune_lambda_captures is only called when there was a default
> > > > > capture, and with [=] only abyPage won't be in
> > > > > LAMBDA_EXPR_CAPTURE_LIST.
> > > >
> > > > It's weird that we even get this far in var_to_maybe_prune. Shouldn't
> > > > LAMBDA_CAPTURE_EXPLICIT_P be true for abyPage?
> > >
> > > Ug, I was seduced by the ostensible obviousness and failed to notice
> > > that check. In that light, the correct fix ought to be this. Thanks!
> > >
> > > Bootstrap/regtest running on x86_64-pc-linux-gnu, ok for trunk if it
> > > passes?
> > >
> > > -- >8 --
> > > Here we crash in is_capture_proxy:
> > >
> > > /* Location wrappers should be stripped or otherwise handled by the
> > > caller before using this predicate. */
> > > gcc_checking_assert (!location_wrapper_p (decl));
> > >
> > > We only crash with the redundant capture:
> > >
> > > int abyPage = [=, abyPage] { ... }
> > >
> > > because prune_lambda_captures is only called when there was a default
> > > capture, and with [=] only abyPage won't be in LAMBDA_EXPR_CAPTURE_LIST.
> > >
> > > The problem is that LAMBDA_CAPTURE_EXPLICIT_P wasn't propagated
> > > correctly and so var_to_maybe_prune proceeded where it shouldn't.
> > >
> > > PR c++/108829
> > >
> > > gcc/cp/ChangeLog:
> > >
> > > * pt.cc (tsubst_lambda_expr): Propagate LAMBDA_CAPTURE_EXPLICIT_P.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > * g++.dg/cpp0x/lambda/lambda-108829.C: New test.
> > > ---
> > > gcc/cp/pt.cc | 4 ++++
> > > gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C | 11 +++++++++++
> > > 2 files changed, 15 insertions(+)
> > > create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C
> > >
> > > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> > > index b1ac7d4beb4..f747ce877b5 100644
> > > --- a/gcc/cp/pt.cc
> > > +++ b/gcc/cp/pt.cc
> > > @@ -19992,6 +19992,10 @@ tsubst_lambda_expr (tree t, tree args,
> > > tsubst_flags_t complain, tree in_decl)
> > > if (id_equal (DECL_NAME (field), "__this"))
> > > LAMBDA_EXPR_THIS_CAPTURE (r) = field;
> > > }
> > > +
> > > + if (LAMBDA_EXPR_CAPTURE_LIST (r))
> > > + LAMBDA_CAPTURE_EXPLICIT_P (LAMBDA_EXPR_CAPTURE_LIST (r))
> > > + = LAMBDA_CAPTURE_EXPLICIT_P (LAMBDA_EXPR_CAPTURE_LIST (t));
> >
> > I'm not sure how the flag works for pack captures but it looks like
> > this would only propagate the flag to the last expanded capture if
> > the capture was originally a pack.
>
> Testcase:
>
> template<int, class... Ts>
> void f(Ts... ts) {
> constexpr int IDX_PAGE_SIZE = 4096;
> int abyPage = [=, ts...] { return IDX_PAGE_SIZE; }();
> }
> void h() {
> f<1>(0, 1);
> }
Thanks a lot for the testacase. Revised patch below. Look OK?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
Here we crash in is_capture_proxy:
/* Location wrappers should be stripped or otherwise handled by the
caller before using this predicate. */
gcc_checking_assert (!location_wrapper_p (decl));
We only crash with the redundant capture:
int abyPage = [=, abyPage] { ... }
because prune_lambda_captures is only called when there was a default
capture, and with [=] only abyPage won't be in LAMBDA_EXPR_CAPTURE_LIST.
The problem is that LAMBDA_CAPTURE_EXPLICIT_P wasn't propagated
correctly and so var_to_maybe_prune proceeded where it shouldn't.
PR c++/108829
gcc/cp/ChangeLog:
* pt.cc (prepend_one_capture): Set LAMBDA_CAPTURE_EXPLICIT_P.
(tsubst_lambda_expr): Pass LAMBDA_CAPTURE_EXPLICIT_P to
prepend_one_capture.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/lambda/lambda-108829-2.C: New test.
* g++.dg/cpp0x/lambda/lambda-108829.C: New test.
Co-Authored by: Patrick Palka <ppa...@redhat.com>
---
gcc/cp/pt.cc | 9 ++++++---
gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829-2.C | 11 +++++++++++
gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C | 11 +++++++++++
3 files changed, 28 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829-2.C
create mode 100644 gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index b1ac7d4beb4..1a071e95004 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -19870,10 +19870,11 @@ tsubst_non_call_postfix_expression (tree t, tree args,
/* Subroutine of tsubst_lambda_expr: add the FIELD/INIT capture pair to the
LAMBDA_EXPR_CAPTURE_LIST passed in LIST. Do deduction for a previously
- dependent init-capture. */
+ dependent init-capture. EXPLICIT_P is true if the original list had
+ explicit captures. */
static void
-prepend_one_capture (tree field, tree init, tree &list,
+prepend_one_capture (tree field, tree init, tree &list, bool explicit_p,
tsubst_flags_t complain)
{
if (tree auto_node = type_uses_auto (TREE_TYPE (field)))
@@ -19893,6 +19894,7 @@ prepend_one_capture (tree field, tree init, tree &list,
cp_apply_type_quals_to_decl (cp_type_quals (type), field);
}
list = tree_cons (field, init, list);
+ LAMBDA_CAPTURE_EXPLICIT_P (list) = explicit_p;
}
/* T is a LAMBDA_EXPR. Generate a new LAMBDA_EXPR for the current
@@ -19982,12 +19984,13 @@ tsubst_lambda_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
prepend_one_capture (TREE_VEC_ELT (field, i),
TREE_VEC_ELT (init, i),
LAMBDA_EXPR_CAPTURE_LIST (r),
+ LAMBDA_CAPTURE_EXPLICIT_P (cap),
complain);
}
else
{
prepend_one_capture (field, init, LAMBDA_EXPR_CAPTURE_LIST (r),
- complain);
+ LAMBDA_CAPTURE_EXPLICIT_P (cap), complain);
if (id_equal (DECL_NAME (field), "__this"))
LAMBDA_EXPR_THIS_CAPTURE (r) = field;
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829-2.C
b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829-2.C
new file mode 100644
index 00000000000..4e24470514d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829-2.C
@@ -0,0 +1,11 @@
+// PR c++/108829
+// { dg-do compile { target c++11 } }
+
+template<int, class... Ts>
+void f(Ts... ts) {
+ constexpr int IDX_PAGE_SIZE = 4096;
+ int abyPage = [=, ts...] { return IDX_PAGE_SIZE; }(); // { dg-error
"redundant" }
+}
+void h() {
+ f<1>(0, 1);
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C
b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C
new file mode 100644
index 00000000000..e621a0d14d0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-108829.C
@@ -0,0 +1,11 @@
+// PR c++/108829
+// { dg-do compile { target c++11 } }
+
+template <int>
+void f(void) {
+ constexpr int IDX_PAGE_SIZE = 4096;
+ int abyPage = [=, abyPage] { return IDX_PAGE_SIZE; }(); // { dg-error
"redundant" }
+}
+void h() {
+ f<1>();
+}
base-commit: 5fea1be820508e1fbc610d1a54b61c1add33c36f
--
2.39.2
