c++: fix ICE with __type_pack_element [PR113834]
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Commit Message
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
-- >8 --
Here we crash on this invalid code because we seem to infinitely recurse
and end up with __type_pack_element with index that doesn't tree_fits_shwi_p
which then crashes on tree_to_shwi.
Thanks to Jakub for suggesting a nicer fix than my original one.
PR c++/113834
gcc/cp/ChangeLog:
* semantics.cc (finish_type_pack_element): Perform range checking
before tree_to_shwi.
gcc/testsuite/ChangeLog:
* g++.dg/ext/type_pack_element4.C: New test.
---
gcc/cp/semantics.cc | 7 +++----
gcc/testsuite/g++.dg/ext/type_pack_element4.C | 17 +++++++++++++++++
2 files changed, 20 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/ext/type_pack_element4.C
base-commit: c9bdcb0c3433ce09f5bb713a51a14130858578a2
Comments
On 2/9/24 13:32, Marek Polacek wrote:
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
> -- >8 --
> Here we crash on this invalid code because we seem to infinitely recurse
> and end up with __type_pack_element with index that doesn't tree_fits_shwi_p
> which then crashes on tree_to_shwi.
>
> Thanks to Jakub for suggesting a nicer fix than my original one.
>
> PR c++/113834
>
> gcc/cp/ChangeLog:
>
> * semantics.cc (finish_type_pack_element): Perform range checking
> before tree_to_shwi.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/ext/type_pack_element4.C: New test.
> ---
> gcc/cp/semantics.cc | 7 +++----
> gcc/testsuite/g++.dg/ext/type_pack_element4.C | 17 +++++++++++++++++
> 2 files changed, 20 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/ext/type_pack_element4.C
>
> diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
> index 3299e270446..57840176863 100644
> --- a/gcc/cp/semantics.cc
> +++ b/gcc/cp/semantics.cc
> @@ -4650,20 +4650,19 @@ finish_type_pack_element (tree idx, tree types, tsubst_flags_t complain)
> error ("%<__type_pack_element%> index is not an integral constant");
> return error_mark_node;
> }
> - HOST_WIDE_INT val = tree_to_shwi (idx);
> - if (val < 0)
> + if (tree_int_cst_sgn (idx) < 0)
> {
> if (complain & tf_error)
> error ("%<__type_pack_element%> index is negative");
> return error_mark_node;
> }
> - if (val >= TREE_VEC_LENGTH (types))
> + if (wi::to_widest (idx) >= TREE_VEC_LENGTH (types))
> {
> if (complain & tf_error)
> error ("%<__type_pack_element%> index is out of range");
> return error_mark_node;
> }
> - return TREE_VEC_ELT (types, val);
> + return TREE_VEC_ELT (types, tree_to_shwi (idx));
> }
>
> /* Implement the __direct_bases keyword: Return the direct base classes
> diff --git a/gcc/testsuite/g++.dg/ext/type_pack_element4.C b/gcc/testsuite/g++.dg/ext/type_pack_element4.C
> new file mode 100644
> index 00000000000..aa508c79090
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ext/type_pack_element4.C
> @@ -0,0 +1,17 @@
> +// PR c++/113834
> +// { dg-do compile { target c++17 } }
> +
> +template <typename... _Elements> class tuple{};
> +template <unsigned long __i, typename... _Elements>
> +__type_pack_element<__i, _Elements...> &get(tuple<_Elements...> &__t) noexcept; // { dg-error "index is out of range" }
> +tuple<int,int> data;
> +template <unsigned long Level>
> +unsigned take_impl(unsigned idx) {
> + if constexpr (Level != -1){
> + return take_impl<Level - 1>(get<Level - 1>(data)); // { dg-error "" }
> + }
> + return 0;
> +}
> +int main() {
> + take_impl<2>(0);
> +}
>
> base-commit: c9bdcb0c3433ce09f5bb713a51a14130858578a2
@@ -4650,20 +4650,19 @@ finish_type_pack_element (tree idx, tree types, tsubst_flags_t complain)
error ("%<__type_pack_element%> index is not an integral constant");
return error_mark_node;
}
- HOST_WIDE_INT val = tree_to_shwi (idx);
- if (val < 0)
+ if (tree_int_cst_sgn (idx) < 0)
{
if (complain & tf_error)
error ("%<__type_pack_element%> index is negative");
return error_mark_node;
}
- if (val >= TREE_VEC_LENGTH (types))
+ if (wi::to_widest (idx) >= TREE_VEC_LENGTH (types))
{
if (complain & tf_error)
error ("%<__type_pack_element%> index is out of range");
return error_mark_node;
}
- return TREE_VEC_ELT (types, val);
+ return TREE_VEC_ELT (types, tree_to_shwi (idx));
}
/* Implement the __direct_bases keyword: Return the direct base classes
new file mode 100644
@@ -0,0 +1,17 @@
+// PR c++/113834
+// { dg-do compile { target c++17 } }
+
+template <typename... _Elements> class tuple{};
+template <unsigned long __i, typename... _Elements>
+__type_pack_element<__i, _Elements...> &get(tuple<_Elements...> &__t) noexcept; // { dg-error "index is out of range" }
+tuple<int,int> data;
+template <unsigned long Level>
+unsigned take_impl(unsigned idx) {
+ if constexpr (Level != -1){
+ return take_impl<Level - 1>(get<Level - 1>(data)); // { dg-error "" }
+ }
+ return 0;
+}
+int main() {
+ take_impl<2>(0);
+}