Re: [PATCH] c++: fix ICE on invalid attributes [PR96637]

[Jason Merrill <jason@redhat.com>]

On 4/29/22 10:12, Marek Polacek wrote:
> This patch fixes crashes with invalid attributes.  Arguably it could
> make sense to assert seen_error() too.

So in this testcase we have TREE_CHAIN of a TREE_LIST pointing to 
error_mark_node?  Can we avoid that?

> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk = GCC 13?
> 
> 	PR c++/96637
> 
> gcc/ChangeLog:
> 
> 	* attribs.cc (decl_attributes): Check error_mark_node.
> 
> gcc/cp/ChangeLog:
> 
> 	* decl2.cc (cp_check_const_attributes): Check error_mark_node.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/parse/error64.C: New test.
> ---
>   gcc/attribs.cc                       | 3 +++
>   gcc/cp/decl2.cc                      | 2 ++
>   gcc/testsuite/g++.dg/parse/error64.C | 4 ++++
>   3 files changed, 9 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/parse/error64.C
> 
> diff --git a/gcc/attribs.cc b/gcc/attribs.cc
> index b219f878042..ff157dcf81c 100644
> --- a/gcc/attribs.cc
> +++ b/gcc/attribs.cc
> @@ -700,6 +700,9 @@ decl_attributes (tree *node, tree attributes, int flags,
>        in the same order as in the source.  */
>     for (tree attr = attributes; attr; attr = TREE_CHAIN (attr))
>       {
> +      if (attr == error_mark_node)
> +	continue;
> +
>         tree ns = get_attribute_namespace (attr);
>         tree name = get_attribute_name (attr);
>         tree args = TREE_VALUE (attr);
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index d2b29208ed5..c3ff1962a75 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -1537,6 +1537,8 @@ cp_check_const_attributes (tree attributes)
>         /* As we implement alignas using gnu::aligned attribute and
>   	 alignas argument is a constant expression, force manifestly
>   	 constant evaluation of aligned attribute argument.  */
> +      if (attr == error_mark_node)
> +	continue;
>         bool manifestly_const_eval
>   	= is_attribute_p ("aligned", get_attribute_name (attr));
>         for (arg = TREE_VALUE (attr); arg && TREE_CODE (arg) == TREE_LIST;
> diff --git a/gcc/testsuite/g++.dg/parse/error64.C b/gcc/testsuite/g++.dg/parse/error64.C
> new file mode 100644
> index 00000000000..87848a58c27
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/parse/error64.C
> @@ -0,0 +1,4 @@
> +// PR c++/96637
> +// { dg-do compile }
> +
> +void foo(int[] alignas[1] alignas(1)){} // { dg-error "" }
> 
> base-commit: 9ae8b993cd362e8aea4f65580aaf1453120207f2