[Bug c++/100205] New: [11 Regression] error: invalid use of non-static data member

[Bug c++/100205] New: [11 Regression] error: invalid use of non-static data member

[gcc-bugs at marehr dot dialup.fu-berlin.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

            Bug ID: 100205
           Summary: [11 Regression] error: invalid use of non-static data
                    member
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc-bugs at marehr dot dialup.fu-berlin.de
  Target Milestone: ---

Hi gcc-team,

the following code compiles with gcc-10, but does not compile with gcc-11 any
more:

```cpp
#include <ranges>

struct coordinate_matrix {
  using index_t = size_t;
  struct convert_to_matrix_coordinate {
    index_t column_id;
    index_t operator()(index_t) { return column_id; }
  };
  using iota_view_t = decltype(std::views::iota(0, 1));
  index_t column_id;

  // does not work
  using value_type =
      decltype(std::declval<iota_view_t>() |
std::views::transform(convert_to_matrix_coordinate{column_id}));

  // does not work
  using value_type2 =
      decltype(std::views::transform(std::declval<iota_view_t>(),
convert_to_matrix_coordinate{column_id}));

  // does work
  using value_type3 =
      decltype(std::views::transform(std::declval<iota_view_t>(),
                                     ([](index_t)
                                     {
                                         return [](index_t) -> index_t
                                         {
                                             return 0;
                                         };
                                     })(column_id)));

  // does work
  using value_type4 =
      decltype(std::views::transform(std::declval<iota_view_t>(),
convert_to_matrix_coordinate{0u}));

  // does work
  using value_type5 = decltype(column_id);
};

int main()
{
    // works:
    using index_t = size_t;
    auto view = std::views::iota(0, 1);
    using iota_view_t = decltype(std::views::iota(0, 1));
    index_t column_id = 0;
    view |
std::views::transform(coordinate_matrix::convert_to_matrix_coordinate{column_id});
    using value_type = decltype(std::declval<iota_view_t>() |
                
std::views::transform(coordinate_matrix::convert_to_matrix_coordinate{column_id}));
}
```

https://godbolt.org/z/EPoP3jvab

with the following error:

```
<source>:14:97: error: invalid use of non-static data member
'coordinate_matrix::column_id'
   14 |       decltype(std::declval<iota_view_t>() |
std::views::transform(convert_to_matrix_coordinate{column_id}));
      |                                                                        
                        ^~~~~~~~~
<source>:10:11: note: declared here
   10 |   index_t column_id;
      |           ^~~~~~~~~
```

I know how to work around this, but I'm a bit confused why in some cases it
allows using column_id and some cases don't.

Thank you!

[Bug c++/100205] [11 Regression] error: invalid use of non-static data member

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |10.3.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, it compiles for me just fine with a compiler from Apr. 12th

[Bug c++/100205] [11 Regression] error: invalid use of non-static data member

[gcc-bugs at marehr dot dialup.fu-berlin.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #2 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
Yeah, it compiled for me with a build from two weeks ago, too. I should have
mentioned that :)

[Bug c++/100205] [11 Regression] error: invalid use of non-static data member

[gcc-bugs at marehr dot dialup.fu-berlin.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #3 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
To be more precise my gcc build is:

```
> gcc-git -v

Using built-in specs.
COLLECT_GCC=/opt/gcc/gcc-git//bin/g++
COLLECT_LTO_WRAPPER=/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/marehr/Packages/gcc-git/src/gcc/configure
--prefix=/opt/gcc/gcc-git --libdir=/opt/gcc/gcc-git/lib
--libexecdir=/opt/gcc/gcc-git/lib --mandir=/opt/gcc/gcc-git/share/man
--infodir=/opt/gcc/gcc-git/share/info --with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++ --with-isl --with-linker-hash-style=gnu
--with-system-zlib --enable-__cxa_atexit --enable-cet=auto
--enable-checking=release --enable-clocale=gnu --enable-default-pie
--enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object
--enable-install-libiberty --enable-linker-build-id --enable-lto
--enable-multilib --enable-plugin --enable-shared --enable-threads=posix
--disable-libssp --disable-libstdcxx-pch --disable-libunwind-exceptions
--disable-werror --disable-bootstrap
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.0.1 20210421 (prerelease) (GCC) 
COMPILER_PATH=/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/
LIBRARY_PATH=/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
'-dumpdir' 'a.'
 /opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/collect2 -plugin
/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/liblto_plugin.so
-plugin-opt=/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/lto-wrapper
-plugin-opt=-fresolution=/tmp/cchzTpvd.res -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --build-id
--eh-frame-hdr --hash-style=gnu -m elf_x86_64 -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -pie /lib/../lib/Scrt1.o /lib/../lib/crti.o
/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/crtbeginS.o
-L/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1
-L/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/../../../../lib
-L/lib/../lib -L/usr/lib/../lib
-L/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/../../.. -rpath
/opt/gcc/gcc-git//lib -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
/opt/gcc/gcc-git/lib/gcc/x86_64-pc-linux-gnu/11.0.1/crtendS.o
/lib/../lib/crtn.o
/usr/bin/ld: /lib/../lib/Scrt1.o: in function `_start':
(.text+0x24): undefined reference to `main'
collect2: error: ld returned 1 exit status
```

The build gcc-git-11.0.1.r184220.be8d5f99f50 did work, but the newer build
gcc-git-11.0.1.r184427.e826f7355af doesn't any more.

[Bug c++/100205] [11 Regression] error: invalid use of non-static data member

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Target Milestone|---                         |11.0
             Status|UNCONFIRMED                 |NEW
      Known to fail|                            |11.0
   Last reconfirmed|                            |2021-04-22

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, I can confirm it doesn't work on the gcc-11 branch head.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Started to be rejected with r11-8181

    c++: non-static member, array bound, sizeof [PR93314]

    N2253 allowed referring to non-static data members without an object in
    unevaluated operands like that of sizeof, but in a constant-expression
    context like an array bound or template argument within such an unevaluated
    operand we do actually need a value, so that permission cannot apply.

    gcc/cp/ChangeLog:

            PR c++/93314
            * semantics.c (finish_id_expression_1): Clear
cp_unevaluated_operand
            for a non-static data member in a constant-expression.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Reduced:

struct coordinate_matrix {
  using index_t = unsigned;
  struct convert_to_matrix_coordinate {
    index_t column_id;
  };
  index_t column_id;

  // does not work
  using value_type2 = decltype(convert_to_matrix_coordinate{column_id});

  // does work
  using value_type5 = decltype(column_id);
};

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(I think GCC is correct)

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #7)
> (I think GCC is correct)

clang9 accepts your reduced testcase.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.0                        |11.2

--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 11.1 has been released, retargeting bugs to GCC 11.2.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- 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:8c114759b8c9c9e2ec90b82d92a24b5a71647017

commit r12-886-g8c114759b8c9c9e2ec90b82d92a24b5a71647017
Author: Jason Merrill <jason@redhat.com>
Date:   Tue May 18 12:18:56 2021 -0400

    c++: non-static member, decltype, {} [PR100205]

    This test was fixed by my second patch for PR93314, which distinguishes
    between constant-expression and potentially-constant-evaluated contexts in
a
    way that my first patch did not.

            PR c++/100205
            PR c++/99314

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/decltype-nonstatic1.C: New test.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[gcc-bugs at marehr dot dialup.fu-berlin.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #11 from gcc-bugs at marehr dot dialup.fu-berlin.de ---
Awesome, thank you, Jason!

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:b786dafe9eb933f23686c68c6d7110fef5656985

commit r11-8430-gb786dafe9eb933f23686c68c6d7110fef5656985
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Apr 14 11:24:50 2021 -0400

    c++: constant expressions are evaluated [PR93314]

    My GCC 11 patch for PR93314 turned off cp_unevaluated_operand while
    processing an id-expression that names a non-static data member, but the
    broader issue is that in general, a constant-expression is evaluated even
in
    an unevaluated operand.

    This also fixes 100205, introduced by the earlier patch that couldn't
    distinguish between the different allow_non_constant_p cases.

            PR c++/100205
            PR c++/93314

    gcc/cp/ChangeLog:

            * cp-tree.h (cp_evaluated): Add reset parm to constructor.
            * parser.c (cp_parser_constant_expression): Change
            allow_non_constant_p to int.  Use cp_evaluated.
            (cp_parser_initializer_clause): Pass 2 to allow_non_constant_p.
            * semantics.c (finish_id_expression_1): Don't mess with
            cp_unevaluated_operand here.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/decltype-nonstatic1.C: New test.

[Bug c++/100205] [11/12 Regression] error: invalid use of non-static data member

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100205

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

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

--- Comment #13 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 11.2/12.