[Bug c++/85148] [6/7/8 Regression] ICE with NSDMI and this pointer

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85148

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2018-04-03
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org
   Target Milestone|---                         |6.5
     Ever confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I get ICE already with r185596 when -std=c++1y option has been introduced:
pr85148.C:1:29: internal compiler error: tree check: expected tree that
contains ‘common’ structure, have ‘constructor’ in perform_member_init, at
cp/init.c:661
Then starting with r210653 it is rejected:
pr85148.C: In function ‘void foo()’:
pr85148.C:8:28: error: could not convert ‘(long int)this’ from ‘long int’ to
‘A<long int>’
   A<A<__PTRDIFF_TYPE__>> a{};
                            ^
pr85148.C: In constructor ‘constexpr A<A<long int> >::A()’:
pr85148.C:1:29: error: could not convert ‘(long int)this’ from ‘long int’ to
‘A<long int>’
 template<typename T> struct A
                             ^
pr85148.C: In function ‘void foo()’:
pr85148.C:8:28: note: synthesized method ‘constexpr A<A<long int> >::A()’ first
required here 
   A<A<__PTRDIFF_TYPE__>> a{};
                            ^
Then starting with r216750 it ICEs in tsubst_copy:
pr85148.C: In function ‘void foo()’:
pr85148.C:8:28: internal compiler error: in tsubst_copy, at cp/pt.c:12755
   A<A<__PTRDIFF_TYPE__>> a{};
                            ^
0x71171b tsubst_copy
        ../../gcc/cp/pt.c:12755
0x720a9b tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/cp/pt.c:15464
and finally starting with r234442 in replace_placeholders.

It hasn't been fixed by the r258593 changes, seems the PLACEHOLDER_EXPR refers
to the outer A when it should be refering to the inner A?  Or I'm totally
confused on what exactly it should do.