Re: [PATCH v2] c++: ICE with constexpr lambda [PR107280]
On Wed, Mar 15, 2023 at 12:48:27PM -0400, Jason Merrill wrote:
> On 3/15/23 10:37, Marek Polacek wrote:
> > On Fri, Mar 10, 2023 at 01:47:46PM -0500, Jason Merrill wrote:
> > > On 3/10/23 11:17, Marek Polacek wrote:
> > > > We crash here since r10-3661, the store_init_value hunk in particular.
> > > > Before, we called cp_fully_fold_init, so e.g.
> > > >
> > > > {.str=VIEW_CONVERT_EXPR("")}
> > > >
> > > > was folded into
> > > >
> > > > {.str=""}
> > > >
> > > > but now we don't fold and keep the VCE around, and it causes trouble in
> > > > cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
> > > > .str's initializer but since it's wrapped in a VCE, we skip the
> > > > STRING_CST
> > > > check and then crash on the CONSTRUCTOR_NO_CLEARING.
> > > >
> > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/12?
> > > >
> > > > PR c++/107280
> > > >
> > > > gcc/cp/ChangeLog:
> > > >
> > > > * constexpr.cc (cxx_eval_store_expression): Strip location
> > > > wrappers.
> > > >
> > > > gcc/testsuite/ChangeLog:
> > > >
> > > > * g++.dg/cpp1z/constexpr-lambda28.C: New test.
> > > > ---
> > > >gcc/cp/constexpr.cc | 3 ++-
> > > >gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C | 15 +++
> > > >2 files changed, 17 insertions(+), 1 deletion(-)
> > > >create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
> > > >
> > > > diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> > > > index 8683c00596a..abf6ee560c5 100644
> > > > --- a/gcc/cp/constexpr.cc
> > > > +++ b/gcc/cp/constexpr.cc
> > > > @@ -6033,7 +6033,8 @@ cxx_eval_store_expression (const constexpr_ctx
> > > > *ctx, tree t,
> > > > *valp = build_constructor (type, NULL);
> > > > CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init;
> > > > }
> > > > - else if (TREE_CODE (*valp) == STRING_CST)
> > > > + else if (STRIP_ANY_LOCATION_WRAPPER (*valp),
> > > > + TREE_CODE (*valp) == STRING_CST)
> > >
> > > Seems like this is stripping the location wrapper when we try to modify
> > > the
> > > string; I think we want to strip it earlier, when we first initialize the
> > > array member.
> >
> > Hmm, I suppose we don't want to do the stripping too early. I could
> > have put it in get_nsdmi, for instance, but maybe here is good as well?
>
> I guess I was thinking more around the time when the value is imported into
> constant evaluation, i.e. this chunk of cxx_eval_constant_expression:
>
> > if (tree init = DECL_INITIAL (r))
> > {
> > init = cxx_eval_constant_expression (ctx, init, vc_prvalue,
> > non_constant_p,
> > overflow_p);
> > /* Don't share a CONSTRUCTOR that might be changed. */
> > init = unshare_constructor (init);
> > /* Remember that a constant object's constructor has already
> > run. */
> > if (CLASS_TYPE_P (TREE_TYPE (r))
> > && CP_TYPE_CONST_P (TREE_TYPE (r)))
> > TREE_READONLY (init) = true;
> > ctx->global->put_value (r, init);
> > }
Ah, that wouldn't fix the problem as far as I can tell -- here init is
the whole constructor: {.str=VIEW_CONVERT_EXPR("")} so we'd
not have a way to strip the inner init.
> Feel free to pursue that approach or go ahead and push your first patch,
> whichever you prefer.
The original patch it is, then. Thanks.
Marek
Re: [PATCH v2] c++: ICE with constexpr lambda [PR107280]
On 3/15/23 10:37, Marek Polacek wrote:
On Fri, Mar 10, 2023 at 01:47:46PM -0500, Jason Merrill wrote:
On 3/10/23 11:17, Marek Polacek wrote:
We crash here since r10-3661, the store_init_value hunk in particular.
Before, we called cp_fully_fold_init, so e.g.
{.str=VIEW_CONVERT_EXPR("")}
was folded into
{.str=""}
but now we don't fold and keep the VCE around, and it causes trouble in
cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
.str's initializer but since it's wrapped in a VCE, we skip the STRING_CST
check and then crash on the CONSTRUCTOR_NO_CLEARING.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/12?
PR c++/107280
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_store_expression): Strip location wrappers.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-lambda28.C: New test.
---
gcc/cp/constexpr.cc | 3 ++-
gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C | 15 +++
2 files changed, 17 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 8683c00596a..abf6ee560c5 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -6033,7 +6033,8 @@ cxx_eval_store_expression (const constexpr_ctx *ctx, tree
t,
*valp = build_constructor (type, NULL);
CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init;
}
- else if (TREE_CODE (*valp) == STRING_CST)
+ else if (STRIP_ANY_LOCATION_WRAPPER (*valp),
+ TREE_CODE (*valp) == STRING_CST)
Seems like this is stripping the location wrapper when we try to modify the
string; I think we want to strip it earlier, when we first initialize the
array member.
Hmm, I suppose we don't want to do the stripping too early. I could
have put it in get_nsdmi, for instance, but maybe here is good as well?
I guess I was thinking more around the time when the value is imported
into constant evaluation, i.e. this chunk of cxx_eval_constant_expression:
if (tree init = DECL_INITIAL (r))
{
init = cxx_eval_constant_expression (ctx, init, vc_prvalue,
non_constant_p, overflow_p);
/* Don't share a CONSTRUCTOR that might be changed. */
init = unshare_constructor (init);
/* Remember that a constant object's constructor has already
run. */
if (CLASS_TYPE_P (TREE_TYPE (r))
&& CP_TYPE_CONST_P (TREE_TYPE (r)))
TREE_READONLY (init) = true;
ctx->global->put_value (r, init);
}
Feel free to pursue that approach or go ahead and push your first patch,
whichever you prefer.
Jason
[PATCH v2] c++: ICE with constexpr lambda [PR107280]
On Fri, Mar 10, 2023 at 01:47:46PM -0500, Jason Merrill wrote:
> On 3/10/23 11:17, Marek Polacek wrote:
> > We crash here since r10-3661, the store_init_value hunk in particular.
> > Before, we called cp_fully_fold_init, so e.g.
> >
> >{.str=VIEW_CONVERT_EXPR("")}
> >
> > was folded into
> >
> >{.str=""}
> >
> > but now we don't fold and keep the VCE around, and it causes trouble in
> > cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
> > .str's initializer but since it's wrapped in a VCE, we skip the STRING_CST
> > check and then crash on the CONSTRUCTOR_NO_CLEARING.
> >
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/12?
> >
> > PR c++/107280
> >
> > gcc/cp/ChangeLog:
> >
> > * constexpr.cc (cxx_eval_store_expression): Strip location wrappers.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/cpp1z/constexpr-lambda28.C: New test.
> > ---
> > gcc/cp/constexpr.cc | 3 ++-
> > gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C | 15 +++
> > 2 files changed, 17 insertions(+), 1 deletion(-)
> > create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
> >
> > diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
> > index 8683c00596a..abf6ee560c5 100644
> > --- a/gcc/cp/constexpr.cc
> > +++ b/gcc/cp/constexpr.cc
> > @@ -6033,7 +6033,8 @@ cxx_eval_store_expression (const constexpr_ctx *ctx,
> > tree t,
> > *valp = build_constructor (type, NULL);
> > CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init;
> > }
> > - else if (TREE_CODE (*valp) == STRING_CST)
> > + else if (STRIP_ANY_LOCATION_WRAPPER (*valp),
> > + TREE_CODE (*valp) == STRING_CST)
>
> Seems like this is stripping the location wrapper when we try to modify the
> string; I think we want to strip it earlier, when we first initialize the
> array member.
Hmm, I suppose we don't want to do the stripping too early. I could
have put it in get_nsdmi, for instance, but maybe here is good as well?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
We crash here since r10-3661, the store_init_value hunk in particular.
Before, we called cp_fully_fold_init, so e.g.
{.str=VIEW_CONVERT_EXPR("")}
was folded into
{.str=""}
but now we don't fold and keep the VCE around, and it causes trouble in
cxx_eval_store_expression: in the !refs->is_empty () loop we descend on
.str's initializer but since it's wrapped in a VCE, we skip the STRING_CST
check and then crash on the CONSTRUCTOR_NO_CLEARING.
PR c++/107280
gcc/cp/ChangeLog:
* typeck2.cc (process_init_constructor_record): Strip location wrappers.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-lambda28.C: New test.
---
gcc/cp/typeck2.cc | 1 +
gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C | 15 +++
2 files changed, 16 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
index c56b69164e2..d0984910ce4 100644
--- a/gcc/cp/typeck2.cc
+++ b/gcc/cp/typeck2.cc
@@ -1889,6 +1889,7 @@ process_init_constructor_record (tree type, tree init,
int nested, int flags,
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (init) = 1;
CONSTRUCTOR_PLACEHOLDER_BOUNDARY (next) = 0;
}
+ STRIP_ANY_LOCATION_WRAPPER (next);
CONSTRUCTOR_APPEND_ELT (v, field, next);
}
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
new file mode 100644
index 000..aafbfddd8b9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-lambda28.C
@@ -0,0 +1,15 @@
+// PR c++/107280
+// { dg-do compile { target c++17 } }
+
+struct string {
+ char str[8] = "";
+};
+template constexpr void
+test ()
+{
+ string str{};
+ auto append = [&](const char *s) { *str.str = *s; };
+ append("");
+}
+
+static_assert ((test(), true), "");
base-commit: 40c1352c5a4530350012d6a922435cf491663daa
--
2.39.2
