[Bug tree-optimization/109945] Escape analysis hates copy elision: different result with -O1 vs -O2

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109945

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org
      Known to fail|4.1.2, 4.5.3, 4.7.4, 4.9.0  |

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The testcase is very related to the old PR and shows the issue manifests itself
also for !TYPE_NEEDS_CONSTRUCTING types.

I wonder whether we need a CTOR at all here to show the issue.

I also wonder how we can query whether the type has a CTOR (as opposed to
"needs" one).  The function type is

 <function_type 0x7ffff6ff3bd0
    type <record_type 0x7ffff6fdef18 Widget sizes-gimplified needs-constructing
cxx-odr-p type_1 type_5 type_6 BLK
        size <integer_cst 0x7ffff6ff6048 constant 160>
        unit-size <integer_cst 0x7ffff6ff6060 constant 20>
        align:32 warn_if_not_align:0 symtab:0 alias-set 2 canonical-type
0x7ffff6fdef18
        fields <function_decl 0x7ffff6ffd000 __dt  type <method_type
0x7ffff6ff3f18>
            public abstract external autoinline decl_3 QI t.ii:1:8 align:16
warn_if_not_align:0 context <record_type 0x7ffff6fdef18 Widget>
            full-name "Widget::~Widget() noexcept (<uninstantiated>)"
            not-really-extern chain <function_decl 0x7ffff6ffd200 __dt_base >>
context <translation_unit_decl 0x7ffff6e3f168 t.ii>
        full-name "struct Widget"
        needs-constructor X() X(constX&) this=(X&) n_parents=0 use_template=0
interface-unknown
        pointer_to_this <pointer_type 0x7ffff6ff30a8> reference_to_this
<reference_type 0x7ffff6ff3930> chain <type_decl 0x7ffff6e64c78 Widget>>

so the type has TYPE_NEEDS_CONSTRUCTING set but it isn't TREE_ADDRESSABLE.