[Bug c++/95735] New: ICE on invalid non-type template argument

[Bug c++/95735] New: ICE on invalid non-type template argument

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

            Bug ID: 95735
           Summary: ICE on invalid non-type template argument
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/v7iLPn.
```C++
template <auto F>
    requires requires { F(); }
bool v{};

void f() {
    int x;
    static_assert(v<throw>);
}
```
<source>: In function 'void f()':
<source>:7:19: error: parse error in template argument list
    7 |     static_assert(v<throw>);
      |                   ^~~~~~~~
<source>:7:19: error: template argument 1 is invalid
<source>:7: confused by earlier errors, bailing out
Compiler returned: 1

Less silly example: https://godbolt.org/z/-bWfJ4.
```C++
template <auto F>
    requires requires { F(); }
bool v{};

void f() {
    int x;
    static_assert(v<[&] { x++; }>);
}
```
<source>: In function 'void f()':
<source>:7:19: error: '<lambda closure object>f()::<lambda()>{x}' is not a
constant expression
    7 |     static_assert(v<[&] { x++; }>);
      |                   ^~~~~~~~~~~~~~~
<source>:7: confused by earlier errors, bailing out
Compiler returned: 1

[Bug c++/95735] ICE on invalid non-type template argument

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-06-18
     Ever confirmed|0                           |1
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started to ICE with r10-3735-gcb57504a55015891.

[Bug c++/95735] ICE on invalid non-type template argument

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
The second test ICEs with gcc 6 too.

Patch:
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -10154,6 +10154,8 @@ finish_template_variable (tree var, tsubst_flags_t
complain)
   arglist = coerce_innermost_template_parms (parms, arglist, templ, complain,
                         /*req_all*/true,
                         /*use_default*/true);
+  if (arglist == error_mark_node)
+    return error_mark_node;

   if (flag_concepts && !constraints_satisfied_p (templ, arglist))
     {

[Bug c++/95735] ICE on invalid non-type template argument

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
           Keywords|                            |patch

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Posted.

[Bug c++/95735] ICE on invalid non-type template argument

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:5421fae8b17c7401f3a4ac5b9f414a47f7bda379

commit r11-1516-g5421fae8b17c7401f3a4ac5b9f414a47f7bda379
Author: Marek Polacek <polacek@redhat.com>
Date:   Thu Jun 18 09:38:42 2020 -0400

    c++: ICE in requires-expressions with invalid args [PR95735]

    This ICE-on-invalid goes back to GCC 6.  In finish_template_variable,
    if coerce_innermost_template_parms returns error_mark_node, we pass
    it down to constraints_satisfied_p and that error_mark_node flows
    down to various satisfy_* functions and then to various tsubst_*
    functions, where we crash.  diagnose_constraints also doesn't cope
    with error arglist, so I think we should just return as in the
    patch below.

    gcc/cp/ChangeLog:

            PR c++/95735
            * pt.c (finish_template_variable): Return if
            coerce_innermost_template_parms return error_mark_node.

    gcc/testsuite/ChangeLog:

            PR c++/95735
            * g++.dg/cpp2a/concepts-err2.C: New test.

[Bug c++/95735] ICE on invalid non-type template argument

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95735

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.