[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349
Bug 84349 depends on bug 84798, which changed state.

Bug 84798 Summary: [6/7 Regression] ICE (Segmentation fault) if `auto` appears 
in a template argument
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84798

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |FIXED

[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349

Volker Reichelt  changed:

   What|Removed |Added

 CC||jason at gcc dot gnu.org
 Depends on||84798

--- Comment #3 from Volker Reichelt  ---
This was fixed on trunk by Jason's patch for PR84798.
Do we want to add this as a testcase or close it as a duplicate?


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84798
[Bug 84798] [6/7 Regression] ICE (Segmentation fault) if `auto` appears in a
template argument

[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349

Martin Sebor  changed:

   What|Removed |Added

 Status|NEW |ASSIGNED
   Assignee|unassigned at gcc dot gnu.org  |msebor at gcc dot 
gnu.org

[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349

Martin Sebor  changed:

   What|Removed |Added

  Known to work||4.8.4
  Known to fail||4.9.4, 5.5.0, 6.4.0, 7.2.0,
   ||8.0

--- Comment #2 from Martin Sebor  ---
A slightly simpler test case:

  void *p = (int(*)(auto))0;

The bug seems to be that the auto isn't rejected in this context (namespace
scope).  The same initializer is rejected in local scope.

Accepting it in an initializer expression results in incrementing the
processing_template_decl counter in the test case from its initial value of
zero to 1.  The counter doesn't get decremented back to zero which then
triggers the unpaired call to finish_lambda_scope() below:

  if (!member_p && processing_template_decl)
start_lambda_scope (decl);
  initializer = cp_parser_initializer (parser,
   _direct_init,
   _non_constant_init);
  if (!member_p && processing_template_decl)
finish_lambda_scope ();

AFAICS, the problem is somewhere in cp_parser_decl_specifier_seq() that creates
a decl_specifiers.type for the initializer at global scope for which
type_uses_auto() returns null.

[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349

Richard Biener  changed:

   What|Removed |Added

   Priority|P3  |P2
   Target Milestone|--- |6.5

[Bug c++/84349] [6/7/8 Regression] ICE with auto in function cast

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84349

Martin Sebor  changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
   Last reconfirmed||2018-02-13
 CC||msebor at gcc dot gnu.org
 Ever confirmed|0   |1

--- Comment #1 from Martin Sebor  ---
Confirmed.  The ICE originated with r202540 in GCC 4.9.0:

r202540 | abutcher | 2013-09-12 17:04:52 -0400 (Thu, 12 Sep 2013) | 31 lines

Support using 'auto' in a function parameter list to introduce an implicit
template parameter.

Prior to that, GCC would error out with:

t.C:2:19: error: parameter declared ‘auto’
 int i = (*(int(*)(auto)) p)(0);
   ^
t.C:2:30: error: too many arguments to function
 int i = (*(int(*)(auto)) p)(0);
  ^