[Bug c++/72796] New: [7 Regression] Firefox build error: use of deleted function

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72796

            Bug ID: 72796
           Summary: [7 Regression] Firefox build error: use of deleted
                    function
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
  Target Milestone: ---

Created attachment 39053
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39053&action=edit
unreduced testcase

markus@x4 js % clang++ -w -std=c++11 -c jsarray.ii
markus@x4 js % icpc -w -std=c++11 -c jsarray.ii
markus@x4 js % g++-6 -w -std=c++11 -c jsarray.ii
markus@x4 js % g++-trunk -w -std=c++11 -c jsarray.ii
In file included from /var/tmp/gecko-dev/js/src/vm/Runtime.h:48:0,
                 from /var/tmp/gecko-dev/js/src/jscntxt.h:17,
                 from /var/tmp/gecko-dev/js/src/jsarray.cpp:19:
/var/tmp/gecko-dev/js/src/vm/Stack.h: In instantiation of
‘js::detail::FixedArgsBase<Construct, N>::FixedArgsBase(JSContext*) [with
js::MaybeConstruct Construct = (js::MaybeConstruct)1u; long unsigned int N =
1ul]’:
/var/tmp/gecko-dev/js/src/vm/Stack.h:1028:57:   required from
‘js::FixedConstructArgs<N>::FixedConstructArgs(JSContext*) [with long unsigned
int N = 1ul]’
/var/tmp/gecko-dev/js/src/jsarray.cpp:3075:39:   required from here
/var/tmp/gecko-dev/js/src/vm/Stack.h:987:13: error: ‘void
js::AnyConstructArgs::setThis(JS::Value)’ is private within this context
             this->CallArgs::setThis(MagicValue(JS_IS_CONSTRUCTING));
             ^~~~
/var/tmp/gecko-dev/js/src/vm/Stack.h:942:10: note: declared private here
     void setThis(Value v) = delete;
          ^~~~~~~
/var/tmp/gecko-dev/js/src/vm/Stack.h:987:13: error: use of deleted function
‘void js::AnyConstructArgs::setThis(JS::Value)’
             this->CallArgs::setThis(MagicValue(JS_IS_CONSTRUCTING));
             ^~~~
/var/tmp/gecko-dev/js/src/vm/Stack.h:942:10: note: declared here
     void setThis(Value v) = delete;
          ^~~~~~~

Reducing...