[Bug c++/93711] ICE: [[no_unique_address] when constructing via template helper

[Bug c++/93711] ICE: [[no_unique_address] when constructing via template helper

[leni536 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

Lénárd Szolnoki <leni536 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |leni536 at gmail dot com

--- Comment #3 from Lénárd Szolnoki <leni536 at gmail dot com> ---
A smaller example:

struct S {
    S(S&&) = delete;
};

S foo();

struct A {
    [[no_unique_address]] S s = foo();
};

A a{};

Version:
11.0.0 20200616

Command line options:
-std=c++20 -Wall -Wextra -pedantic

Diagnostics:
during RTL pass: expand
<source>: In function 'void __static_initialization_and_destruction_0(int,
int)':
<source>:11:5: internal compiler error: in assign_temp, at function.c:984
   11 | A a{};
      |     ^

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE: [[no_unique_address]   |[9/10/11 Regression] ICE:
                   |when constructing via       |[[no_unique_address] when
                   |template helper             |constructing via template
                   |                            |helper
                 CC|                            |mpolacek at gcc dot gnu.org
   Last reconfirmed|                            |2020-06-17
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |9.4
     Ever confirmed|0                           |1

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Same backtrace as bug 90254 but it didn't start with the same revision.  This
one started with r264813.

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |boris.staletic at gmail dot com

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
*** Bug 95878 has been marked as a duplicate of this bug. ***

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Another test:

struct istream_iterator {
        istream_iterator() {}
        istream_iterator(const istream_iterator&) {}
};

istream_iterator next(istream_iterator&& bound) {
        return static_cast<istream_iterator>(bound);
}

struct copy_result {
        [[no_unique_address]] istream_iterator in;
};

int main() {
        copy_result result{next(istream_iterator{})};
}

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[boris.staletic at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

--- Comment #7 from Boris Staletic <boris.staletic at gmail dot com> ---
I don't know if this is the same problem, since the actual
`std::istream_iterator<int>` isn't empty, unlike in the other test cases. If
the following is a different problem, sorry up front for the noise.

https://godbolt.org/z/XAM9o7

This is the actual thing I've come across during a pull request for NanoRange
library.

DIfferences from the above test cases:

- ICE is there even at `-Og`, as well as `-O0`
- The bottom example shows that wrapping the call to `fn()` in `std::move()`
avoids the ICE.

If this is a separate issue and thus noise, I'll open a separate issue.

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hewillk at gmail dot com

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 96408 has been marked as a duplicate of this bug. ***

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Another one:

struct A { A(const A&) = delete; };

A f();

struct C
{
  [[no_unique_address]] A a;
};

C c{f()};


during RTL pass: expand
ice.C: In function 'void __static_initialization_and_destruction_0(int, int)':
ice.C:10:8: internal compiler error: in assign_temp, at function.c:984
   10 | C c{f()};
      |        ^
0x6f9772 assign_temp(tree_node*, int, int)
        /home/jwakely/src/gcc/gcc/gcc/function.c:984
0xb56653 expand_call(tree_node*, rtx_def*, int)
        /home/jwakely/src/gcc/gcc/gcc/calls.c:3750
0xc87aaa expand_expr_real_1(tree_node*, rtx_def*, machine_mode,
expand_modifier, rtx_def**, bool)
        /home/jwakely/src/gcc/gcc/gcc/expr.c:11240
0xc9a133 expand_expr_real(tree_node*, rtx_def*, machine_mode, expand_modifier,
rtx_def**, bool)
        /home/jwakely/src/gcc/gcc/gcc/expr.c:8474
0xc9a133 expand_normal
        /home/jwakely/src/gcc/gcc/gcc/expr.h:288
0xc9a133 store_field
        /home/jwakely/src/gcc/gcc/gcc/expr.c:7213
0xc966d6 expand_assignment(tree_node*, tree_node*, bool)
        /home/jwakely/src/gcc/gcc/gcc/expr.c:5448
0xb66553 expand_call_stmt
        /home/jwakely/src/gcc/gcc/gcc/cfgexpand.c:2701
0xb66553 expand_gimple_stmt_1
        /home/jwakely/src/gcc/gcc/gcc/cfgexpand.c:3682
0xb66553 expand_gimple_stmt
        /home/jwakely/src/gcc/gcc/gcc/cfgexpand.c:3847
0xb6bd9a expand_gimple_basic_block
        /home/jwakely/src/gcc/gcc/gcc/cfgexpand.c:5888
0xb6d846 execute
        /home/jwakely/src/gcc/gcc/gcc/cfgexpand.c:6572
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
             Status|NEW                         |ASSIGNED
                 CC|                            |jason at gcc dot gnu.org

[Bug c++/93711] [9/10/11 Regression] ICE: [[no_unique_address] when constructing via template helper

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:320054784250e572cb75d6f69ab44b2330d61d8b

commit r11-2704-g320054784250e572cb75d6f69ab44b2330d61d8b
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Aug 12 05:45:02 2020 -0400

    c++: Copy elision and [[no_unique_address]]. [PR93711]

    We don't elide a copy from a function returning a class by value into a
base
    because that can overwrite data laid out in the tail padding of the base
    class; we need to handle [[no_unique_address]] fields the same way, or we
    ICE when the middle-end wants to create a temporary object of a
    TYPE_NEEDS_CONSTRUCTING type.

    This means that we can't always express initialization of a field with
    INIT_EXPR from a TARGET_EXPR the way we usually do, so I needed
    to change several places that were assuming that was sufficient.

    This also fixes 90254, the same problem with C++17 aggregate initialization
    of a base.

    gcc/cp/ChangeLog:

            PR c++/90254
            PR c++/93711
            * cp-tree.h (unsafe_return_slot_p): Declare.
            * call.c (is_base_field_ref): Rename to unsafe_return_slot_p.
            (build_over_call): Check unsafe_return_slot_p.
            (build_special_member_call): Likewise.
            * init.c (expand_default_init): Likewise.
            * typeck2.c (split_nonconstant_init_1): Likewise.

    gcc/testsuite/ChangeLog:

            PR c++/90254
            PR c++/93711
            * g++.dg/cpp1z/aggr-base10.C: New test.
            * g++.dg/cpp2a/no_unique_address7.C: New test.
            * g++.dg/cpp2a/no_unique_address7a.C: New test.

[Bug c++/93711] [9/10 Regression] ICE: [[no_unique_address] when constructing via template helper

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[9/10/11 Regression] ICE:   |[9/10 Regression] ICE:
                   |[[no_unique_address] when   |[[no_unique_address] when
                   |constructing via template   |constructing via template
                   |helper                      |helper

--- Comment #11 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for GCC 11 so far.

[Bug c++/93711] [9/10 Regression] ICE: [[no_unique_address] when constructing via template helper

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:97014e4ada448aa8978b3cd14ed95e0e56f375d9

commit r10-9168-g97014e4ada448aa8978b3cd14ed95e0e56f375d9
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Aug 12 05:45:02 2020 -0400

    c++: Copy elision and [[no_unique_address]]. [PR93711]

    We don't elide a copy from a function returning a class by value into a
base
    because that can overwrite data laid out in the tail padding of the base
    class; we need to handle [[no_unique_address]] fields the same way, or we
    ICE when the middle-end wants to create a temporary object of a
    TYPE_NEEDS_CONSTRUCTING type.

    This means that we can't always express initialization of a field with
    INIT_EXPR from a TARGET_EXPR the way we usually do, so I needed
    to change several places that were assuming that was sufficient.

    This also fixes 90254, the same problem with C++17 aggregate initialization
    of a base.

    gcc/cp/ChangeLog:

            PR c++/90254
            PR c++/93711
            * cp-tree.h (unsafe_return_slot_p): Declare.
            * call.c (is_base_field_ref): Rename to unsafe_return_slot_p.
            (build_over_call): Check unsafe_return_slot_p.
            (build_special_member_call): Likewise.
            * init.c (expand_default_init): Likewise.
            * typeck2.c (split_nonconstant_init_1): Likewise.

    gcc/testsuite/ChangeLog:

            PR c++/90254
            PR c++/93711
            * g++.dg/cpp1z/aggr-base10.C: New test.
            * g++.dg/cpp2a/no_unique_address7.C: New test.
            * g++.dg/cpp2a/no_unique_address7a.C: New test.

[Bug c++/93711] [9/10 Regression] ICE: [[no_unique_address] when constructing via template helper

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711
Bug 93711 depends on bug 98642, which changed state.

Bug 98642 Summary: [10 Regression] wrong "use of deleted function" error
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98642

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

[Bug c++/93711] [9 Regression] ICE: [[no_unique_address] when constructing via template helper

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |10.2.0
      Known to work|                            |10.2.1
           Priority|P3                          |P2
            Summary|[9/10 Regression] ICE:      |[9 Regression] ICE:
                   |[[no_unique_address] when   |[[no_unique_address] when
                   |constructing via template   |constructing via template
                   |helper                      |helper

[Bug c++/93711] [9 Regression] ICE: [[no_unique_address] when constructing via template helper

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.4                         |9.5

--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.

[Bug c++/93711] [9 Regression] ICE: [[no_unique_address] when constructing via template helper

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93711

Jason Merrill <jason at gcc dot gnu.org> changed:

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

--- Comment #14 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed in 10.2 and later.