Re: [PATCH] Fix PR c++/105760: ICE in build_deduction_guide for invalid template

[Jason Merrill]

On 5/6/24 09:20, Simon Martin wrote:

Hi,

We currently ICE upon the following invalid snippet because we fail to properly handle tsubst_arg_types returning error_mark_node in build_deduction_guide.

== cut ==
template<class... Ts, class>
struct A { A(Ts...); };
A a;
== cut ==

This patch fixes this, and has been successfully tested on x86_64-pc-linux-gnu. OK for trunk?

OK, thanks.

Thanks!

-- Simon

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a78d9d546d6..9acef73e7ac 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2024-05-06  Simon Martin  <simar...@gcc.gnu.org>
+
+       PR c++/105760
+       * pt.c (build_deduction_guide): Check for error_mark_node
+       result from tsubst_arg_types.
+
  2024-05-03  Jason Merrill  <ja...@redhat.com>

         PR c++/114935
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index d68d688016d..da5d9b8a665 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc

@@ -30018,6 +30018,8 @@ build_deduction_guide (tree type, tree ctor, tree outer_args, tsubst_flags_t com

              references to members of an unknown specialization.  */
           cp_evaluated ev;

          fparms = tsubst_arg_types (fparms, targs, NULL_TREE, complain, ctor);

+         if (fparms == error_mark_node)
+           ok = false;
           fargs = tsubst (fargs, targs, complain, ctor);
           if (ci)
             {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 03c88bbed07..8c606a8fb4f 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2024-05-06  Simon Martin  <simar...@gcc.gnu.org>
+
+       PR c++/105760
+       * g++.dg/parse/error66.C: New test.
+
  2024-05-05  Harald Anlauf  <anl...@gmx.de>

         PR fortran/114827

diff --git a/gcc/testsuite/g++.dg/parse/error66.C b/gcc/testsuite/g++.dg/parse/error66.C

new file mode 100644
index 00000000000..82f4b8b8a53
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/error66.C
@@ -0,0 +1,6 @@
+// PR c++/105760
+// { dg-do compile { target c++17 } }
+

+template<class... Ts, class> // { dg-error "must be at the end of the template parameter list" }

+struct A { A(Ts...); };
+A a;