Re: [PATCH] Fix ICE with spelling hints within explicit namespace aliases (PR c++/79298)

[Jason Merrill <jason at redhat dot com>]

OK.

On Tue, Jan 31, 2017 at 3:10 PM, David Malcolm <dmalcolm@redhat.com> wrote:
> PR c++/79298 reports a segfault when handling a qualified name lookup error,
> where consider_binding_level dereferences a NULL cp_binding_level *.
>
> The root cause is that suggest_alternative_in_explicit_scope assumes that
> NAMESPACE_LEVEL (scope) is non-NULL, but this can be NULL for namespace aliases.
>
> This patch adds a use of ORIGINAL_NAMESPACE to look through any namespace
> aliases.
>
> Successfully bootstrapped&regrtested on x86_64-pc-linux-gnu.
>
> OK for trunk?
>
> gcc/cp/ChangeLog:
>         PR c++/79298
>         * name-lookup.c (suggest_alternative_in_explicit_scope): Resolve
>         any namespace aliases.
>
> gcc/testsuite/ChangeLog:
>         PR c++/79298
>         * g++.dg/spellcheck-pr79298.C: New test case.
> ---
>  gcc/cp/name-lookup.c                      |  3 +++
>  gcc/testsuite/g++.dg/spellcheck-pr79298.C | 17 +++++++++++++++++
>  2 files changed, 20 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/spellcheck-pr79298.C
>
> diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
> index a3cb7ee..994f7f0 100644
> --- a/gcc/cp/name-lookup.c
> +++ b/gcc/cp/name-lookup.c
> @@ -4545,6 +4545,9 @@ bool
>  suggest_alternative_in_explicit_scope (location_t location, tree name,
>                                        tree scope)
>  {
> +  /* Resolve any namespace aliases.  */
> +  scope = ORIGINAL_NAMESPACE (scope);
> +
>    cp_binding_level *level = NAMESPACE_LEVEL (scope);
>
>    best_match <tree, tree> bm (name);
> diff --git a/gcc/testsuite/g++.dg/spellcheck-pr79298.C b/gcc/testsuite/g++.dg/spellcheck-pr79298.C
> new file mode 100644
> index 0000000..4d7bbf9
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/spellcheck-pr79298.C
> @@ -0,0 +1,17 @@
> +// Ensure that we can offer suggestions for misspellings via a
> +// namespace alias.
> +
> +namespace N { int x; int color; }
> +namespace M = N;
> +namespace O = M;
> +
> +int foo ()
> +{
> +  return M::y; // { dg-error ".y. is not a member of .M." }
> +}
> +
> +int bar ()
> +{
> +  return O::colour; // { dg-error ".colour. is not a member of .O." }
> +  // { dg-message "suggested alternative: .color." "" { target *-*-* } .-1 }
> +}
> --
> 1.8.5.3
>