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c++: ICE with auto[] and VLA [PR102414]

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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.

	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.
This commit is contained in:
Marek Polacek
2022-01-27 18:11:03 -05:00
parent b1a8b92f8f
commit 874ad5d674
3 changed files with 41 additions and 3 deletions
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14
gcc/cp/decl.cc
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@@ -11099,7 +11099,7 @@ 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 "
@@ -11169,8 +11169,16 @@ 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)
&& variably_modified_type_p (itype, /*fn=*/NULL_TREE))
{
sorry_at (loc, "variable-length array of %<auto%>");
return error_mark_node;
}
}
return build_cplus_array_type (type, itype);
}

16
gcc/testsuite/g++.dg/cpp23/auto-array3.C Normal file
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@@ -0,0 +1,16 @@
// PR c++/102414
// PR c++/101874
// { dg-do compile { target c++11 } }
// { dg-options "" }
constexpr int sz () { return 3; }
void f ()
{
int a[3];
const int N = 3;
auto (*a2)[N] = &a;
constexpr int M = 3;
auto (*a3)[M] = &a;
auto (*a4)[sz()] = &a;
}

14
gcc/testsuite/g++.dg/cpp23/auto-array4.C Normal file
View File

@@ -0,0 +1,14 @@
// PR c++/102414
// 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." }
int a[3];
auto (*a1)[0/0] = &a; // { dg-message "variable-length array of .auto." }
// { dg-warning "division by zero" "" { target *-*-* } .-1 }
}