c++: ICE with auto[] and VLA [PR102414]
Commit Message
Here we ICE in unify_array_domain when we're trying to deduce the type
of an array, as in
auto(*p)[i] = (int(*)[i])0;
but unify_array_domain doesn't arbitrarily complex bounds. Another
test is, e.g.,
auto (*b)[0/0] = &a;
where the type of the array is
<<< Unknown tree: template_type_parm >>>[0:(sizetype) ((ssizetype) (0 / 0) - 1)]
It seems to me that we need not handle these.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
PR c++/102414
PR c++/101874
gcc/cp/ChangeLog:
* decl.cc (create_array_type_for_decl): Use template_placeholder_p.
Sorry on a variable-length array of auto.
gcc/testsuite/ChangeLog:
* g++.dg/cpp23/auto-array3.C: New test.
* g++.dg/cpp23/auto-array4.C: New test.
---
gcc/cp/decl.cc | 14 +++++++++++---
gcc/testsuite/g++.dg/cpp23/auto-array3.C | 17 +++++++++++++++++
gcc/testsuite/g++.dg/cpp23/auto-array4.C | 10 ++++++++++
3 files changed, 38 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-array3.C
create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-array4.C
base-commit: 99f17e996f21d0ed64c36ed1e52977b705143522
Comments
On 1/27/22 20:02, Marek Polacek wrote:
> Here we ICE in unify_array_domain when we're trying to deduce the type
> of an array, as in
>
> auto(*p)[i] = (int(*)[i])0;
>
> but unify_array_domain doesn't arbitrarily complex bounds. Another
> test is, e.g.,
>
> auto (*b)[0/0] = &a;
>
> where the type of the array is
>
> <<< Unknown tree: template_type_parm >>>[0:(sizetype) ((ssizetype) (0 / 0) - 1)]
>
> It seems to me that we need not handle these.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> PR c++/102414
> PR c++/101874
>
> gcc/cp/ChangeLog:
>
> * decl.cc (create_array_type_for_decl): Use template_placeholder_p.
> Sorry on a variable-length array of auto.
>
> gcc/testsuite/ChangeLog:
>
> * g++.dg/cpp23/auto-array3.C: New test.
> * g++.dg/cpp23/auto-array4.C: New test.
> ---
> gcc/cp/decl.cc | 14 +++++++++++---
> gcc/testsuite/g++.dg/cpp23/auto-array3.C | 17 +++++++++++++++++
> gcc/testsuite/g++.dg/cpp23/auto-array4.C | 10 ++++++++++
> 3 files changed, 38 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-array3.C
> create mode 100644 gcc/testsuite/g++.dg/cpp23/auto-array4.C
>
> diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
> index 10e6956117e..4ba8bf3e8a9 100644
> --- a/gcc/cp/decl.cc
> +++ b/gcc/cp/decl.cc
> @@ -11089,7 +11089,7 @@ create_array_type_for_decl (tree name, tree type, tree size, location_t loc)
>
> /* [dcl.type.class.deduct] prohibits forming an array of placeholder
> for a deduced class type. */
> - if (is_auto (type) && CLASS_PLACEHOLDER_TEMPLATE (type))
> + if (template_placeholder_p (type))
> {
> if (name)
> error_at (loc, "%qD declared as array of template placeholder "
> @@ -11159,8 +11159,16 @@ create_array_type_for_decl (tree name, tree type, tree size, location_t loc)
>
> /* Figure out the index type for the array. */
> if (size)
> - itype = compute_array_index_type_loc (loc, name, size,
> - tf_warning_or_error);
> + {
> + itype = compute_array_index_type_loc (loc, name, size,
> + tf_warning_or_error);
> + if (type_uses_auto (type)
> + && !TREE_CONSTANT (maybe_constant_value (size)))
Maybe variably_modified_type_p (itype)?
> + {
> + sorry_at (loc, "variable-length array of %<auto%>");
> + return error_mark_node;
> + }
> + }
>
> return build_cplus_array_type (type, itype);
> }
> diff --git a/gcc/testsuite/g++.dg/cpp23/auto-array3.C b/gcc/testsuite/g++.dg/cpp23/auto-array3.C
> new file mode 100644
> index 00000000000..e383a17d0ee
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp23/auto-array3.C
> @@ -0,0 +1,17 @@
> +// PR c++/102414
> +// { dg-do compile { target c++11 } }
> +// { dg-options "" }
> +
> +constexpr int sz () { return 3; }
> +
> +void f ()
> +{
> + int a[3];
> + auto (*a1)[0/0] = &a; // { dg-message "variable-length array of .auto." }
> +// { dg-warning "division by zero" "" { target *-*-* } .-1 }
Let's move the error into the other testcase?
> + const int N = 3;
> + auto (*a2)[N] = &a;
> + constexpr int M = 3;
> + auto (*a3)[M] = &a;
> + auto (*a4)[sz()] = &a;
> +}
> diff --git a/gcc/testsuite/g++.dg/cpp23/auto-array4.C b/gcc/testsuite/g++.dg/cpp23/auto-array4.C
> new file mode 100644
> index 00000000000..4819472a9ac
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp23/auto-array4.C
> @@ -0,0 +1,10 @@
> +// PR c++/101874
> +// { dg-do compile { target c++11 } }
> +// { dg-options "" }
> +
> +void
> +f (int i)
> +{
> + auto x[i] = { 0 }; // { dg-message "variable-length array of .auto." }
> + auto(*p)[i] = (int(*)[i])0; // { dg-message "variable-length array of .auto." }
> +}
>
> base-commit: 99f17e996f21d0ed64c36ed1e52977b705143522
@@ -11089,7 +11089,7 @@ create_array_type_for_decl (tree name, tree type, tree size, location_t loc)
/* [dcl.type.class.deduct] prohibits forming an array of placeholder
for a deduced class type. */
- if (is_auto (type) && CLASS_PLACEHOLDER_TEMPLATE (type))
+ if (template_placeholder_p (type))
{
if (name)
error_at (loc, "%qD declared as array of template placeholder "
@@ -11159,8 +11159,16 @@ create_array_type_for_decl (tree name, tree type, tree size, location_t loc)
/* Figure out the index type for the array. */
if (size)
- itype = compute_array_index_type_loc (loc, name, size,
- tf_warning_or_error);
+ {
+ itype = compute_array_index_type_loc (loc, name, size,
+ tf_warning_or_error);
+ if (type_uses_auto (type)
+ && !TREE_CONSTANT (maybe_constant_value (size)))
+ {
+ sorry_at (loc, "variable-length array of %<auto%>");
+ return error_mark_node;
+ }
+ }
return build_cplus_array_type (type, itype);
}
new file mode 100644
@@ -0,0 +1,17 @@
+// PR c++/102414
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+constexpr int sz () { return 3; }
+
+void f ()
+{
+ int a[3];
+ auto (*a1)[0/0] = &a; // { dg-message "variable-length array of .auto." }
+// { dg-warning "division by zero" "" { target *-*-* } .-1 }
+ const int N = 3;
+ auto (*a2)[N] = &a;
+ constexpr int M = 3;
+ auto (*a3)[M] = &a;
+ auto (*a4)[sz()] = &a;
+}
new file mode 100644
@@ -0,0 +1,10 @@
+// PR c++/101874
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+void
+f (int i)
+{
+ auto x[i] = { 0 }; // { dg-message "variable-length array of .auto." }
+ auto(*p)[i] = (int(*)[i])0; // { dg-message "variable-length array of .auto." }
+}