On June 6, 2020 6:17:49 AM GMT+02:00, Jason Merrill via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>The problem in this testcase comes from cloning the constructor into
>complete and base variants. When we clone the body the first time,
>walk_tree_1 calls copy_tree_body_r on the type of the artificial
>TYPE_DECL
>we made for the VLA type without calling it on the decl itself, so we
>overwrite the type of the TYPE_DECL without copying the decl first.
>
>This has been broken since we started inserting a TYPE_DECL for
>anonymous
>VLAs in r7-457.
>
>This patch fixes walk_tree_1 to call the function on the TYPE_DECL, as
>we do
>for other decls of a DECL_EXPR.
>
>Tested x86_64-pc-linux-gnu. OK for trunk? Release branches?
Looks reasonable. Please make sure to bootstrap and test with Ada enabled. Eric
may also have comments here.
In any case please wait a while before backporting.
Thanks,
Richard.
>gcc/ChangeLog:
>
> PR c++/95552
> * tree.c (walk_tree_1): Call func on the TYPE_DECL of a DECL_EXPR.
>
>gcc/testsuite/ChangeLog:
>
> PR c++/95552
> * g++.dg/ext/vla23.C: New test.
>---
> gcc/testsuite/g++.dg/ext/vla23.C | 14 ++++++++++++++
> gcc/tree.c | 5 +++++
> 2 files changed, 19 insertions(+)
> create mode 100644 gcc/testsuite/g++.dg/ext/vla23.C
>
>diff --git a/gcc/testsuite/g++.dg/ext/vla23.C
>b/gcc/testsuite/g++.dg/ext/vla23.C
>new file mode 100644
>index 00000000000..317a824b2f3
>--- /dev/null
>+++ b/gcc/testsuite/g++.dg/ext/vla23.C
>@@ -0,0 +1,14 @@
>+// PR c++/95552
>+// Test for VLA and cloned constructor.
>+// { dg-additional-options -Wno-vla }
>+// { dg-require-effective-target alloca }
>+
>+struct VB { };
>+struct ViewDom: virtual VB
>+{
>+ ViewDom(int i) { char (*a)[i]; }
>+};
>+void element( )
>+{
>+ ViewDom a(2);
>+}
>diff --git a/gcc/tree.c b/gcc/tree.c
>index 7197b4720ce..c8e9680b06c 100644
>--- a/gcc/tree.c
>+++ b/gcc/tree.c
>@@ -12212,6 +12212,11 @@ walk_tree_1 (tree *tp, walk_tree_fn func, void
>*data,
> Note that DECLs get walked as part of processing the BIND_EXPR. */
> if (TREE_CODE (DECL_EXPR_DECL (*tp)) == TYPE_DECL)
> {
>+ /* Call the function for the decl so e.g. inlining can remap it.
>*/
>+ result = (*func) (&DECL_EXPR_DECL (*tp), &walk_subtrees, data);
>+ if (result || !walk_subtrees)
>+ return result;
>+
> tree *type_p = &TREE_TYPE (DECL_EXPR_DECL (*tp));
> if (TREE_CODE (*type_p) == ERROR_MARK)
> return NULL_TREE;
>
>base-commit: 5bc13e5217f687f5d08a7022b4c6081befc54402
