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From: Marek Polacek <mpolacek@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-6952] c++: ICE with auto[] and VLA [PR102414] Date: Mon, 31 Jan 2022 20:36:34 +0000 (GMT) [thread overview] Message-ID: <20220131203634.B735D3857C46@sourceware.org> (raw) https://gcc.gnu.org/g:874ad5d6745bf3bbe4aa138cef09c669b3fb9b07 commit r12-6952-g874ad5d6745bf3bbe4aa138cef09c669b3fb9b07 Author: Marek Polacek <polacek@redhat.com> Date: Thu Jan 27 18:11:03 2022 -0500 c++: ICE with auto[] and VLA [PR102414] 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. Diff: --- gcc/cp/decl.cc | 14 +++++++++++--- gcc/testsuite/g++.dg/cpp23/auto-array3.C | 16 ++++++++++++++++ gcc/testsuite/g++.dg/cpp23/auto-array4.C | 14 ++++++++++++++ 3 files changed, 41 insertions(+), 3 deletions(-) diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc index 26ce9bfefec..09eed9ceba6 100644 --- a/gcc/cp/decl.cc +++ b/gcc/cp/decl.cc @@ -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); } 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..fdf25470fc2 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/auto-array3.C @@ -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; +} 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..4385c4a6bf9 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp23/auto-array4.C @@ -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 } +}
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