[Bug c++/95197] New: libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[Bug c++/95197] New: libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

            Bug ID: 95197
           Summary: libgomp/testsuite/libgomp.c++/for-27.C fails with
                    -std=c++17
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mpolacek at gcc dot gnu.org
  Target Milestone: ---

See <https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545879.html> for why
this fails.  My workaround was

--- a/libgomp/testsuite/libgomp.c++/for-27.C
+++ b/libgomp/testsuite/libgomp.c++/for-27.C
@@ -151,6 +151,12 @@ f4 (const I<int> &x, const I<int> &y)
     else if (results[i])                               \
       abort ()

+// FIXME: OpenMP seems to count on this being instantiated; the copy
+// constructor is called in functions fn2/fn3/fn4.  But in C++17 we
+// elide this copy constructor, so it's never been instantiated.  For
+// now instantiate it explicitly.
+template I<int>::I(const I<int> &);
+
 int
 main ()
 {

Seems that OpenMP has to call mark_used or some such.

[Bug c++/95197] libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For e.g.
void bar (I<int> &a);

void
foo (I<int> &a)
{
  #pragma omp task //firstprivate (a)
  bar (a);
}
with the same templates this is handled by omp_cxx_notice_variable, which will
1068                  get_copy_ctor (type, tf_none);
1069                  get_dtor (type, tf_none);
because when it is done only during gimplification, we don't instantiate it
anymore.
So, I think I need to go through all the lang_hooks.decls.omp_finish_clause
calls in the gimplifier and deal with it similarly during genericization time.

[Bug c++/95197] libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase:

// { dg-do link }

typedef __PTRDIFF_TYPE__ ptrdiff_t;

template <typename T>
class I
{
public:
  typedef ptrdiff_t difference_type;
  I ();
  ~I ();
  I (T *);
  I (const I &);
  T &operator * ();
  T *operator -> ();
  T &operator [] (const difference_type &) const;
  I &operator = (const I &);
  I &operator ++ ();
  I operator ++ (int);
  I &operator -- ();
  I operator -- (int);
  I &operator += (const difference_type &);
  I &operator -= (const difference_type &);
  I operator + (const difference_type &) const;
  I operator - (const difference_type &) const;
  template <typename S> friend bool operator == (I<S> &, I<S> &);
  template <typename S> friend bool operator == (const I<S> &, const I<S> &);
  template <typename S> friend bool operator < (I<S> &, I<S> &);
  template <typename S> friend bool operator < (const I<S> &, const I<S> &);
  template <typename S> friend bool operator <= (I<S> &, I<S> &);
  template <typename S> friend bool operator <= (const I<S> &, const I<S> &);
  template <typename S> friend bool operator > (I<S> &, I<S> &);
  template <typename S> friend bool operator > (const I<S> &, const I<S> &);
  template <typename S> friend bool operator >= (I<S> &, I<S> &);
  template <typename S> friend bool operator >= (const I<S> &, const I<S> &);
  template <typename S> friend typename I<S>::difference_type operator - (I<S>
&, I<S> &);
  template <typename S> friend typename I<S>::difference_type operator - (const
I<S> &, const I<S> &);
  template <typename S> friend I<S> operator + (typename I<S>::difference_type
, const I<S> &);
private:
  T *p;
};
template <typename T> I<T>::I () : p (0) {}
template <typename T> I<T>::~I () {}
template <typename T> I<T>::I (T *x) : p (x) {}
template <typename T> I<T>::I (const I &x) : p (x.p) {}
template <typename T> T &I<T>::operator * () { return *p; }
template <typename T> T *I<T>::operator -> () { return p; }
template <typename T> T &I<T>::operator [] (const difference_type &x) const {
return p[x]; }
template <typename T> I<T> &I<T>::operator = (const I &x) { p = x.p; return
*this; }
template <typename T> I<T> &I<T>::operator ++ () { ++p; return *this; }
template <typename T> I<T> I<T>::operator ++ (int) { return I (p++); }
template <typename T> I<T> &I<T>::operator -- () { --p; return *this; }
template <typename T> I<T> I<T>::operator -- (int) { return I (p--); }
template <typename T> I<T> &I<T>::operator += (const difference_type &x) { p +=
x; return *this; }
template <typename T> I<T> &I<T>::operator -= (const difference_type &x) { p -=
x; return *this; }
template <typename T> I<T> I<T>::operator + (const difference_type &x) const {
return I (p + x); }
template <typename T> I<T> I<T>::operator - (const difference_type &x) const {
return I (p - x); }
template <typename T> bool operator == (I<T> &x, I<T> &y) { return x.p == y.p;
}
template <typename T> bool operator == (const I<T> &x, const I<T> &y) { return
x.p == y.p; }
template <typename T> bool operator != (I<T> &x, I<T> &y) { return !(x == y); }
template <typename T> bool operator != (const I<T> &x, const I<T> &y) { return
!(x == y); }
template <typename T> bool operator < (I<T> &x, I<T> &y) { return x.p < y.p; }
template <typename T> bool operator < (const I<T> &x, const I<T> &y) { return
x.p < y.p; }
template <typename T> bool operator <= (I<T> &x, I<T> &y) { return x.p <= y.p;
}
template <typename T> bool operator <= (const I<T> &x, const I<T> &y) { return
x.p <= y.p; }
template <typename T> bool operator > (I<T> &x, I<T> &y) { return x.p > y.p; }
template <typename T> bool operator > (const I<T> &x, const I<T> &y) { return
x.p > y.p; }
template <typename T> bool operator >= (I<T> &x, I<T> &y) { return x.p >= y.p;
}
template <typename T> bool operator >= (const I<T> &x, const I<T> &y) { return
x.p >= y.p; }
template <typename T> typename I<T>::difference_type operator - (I<T> &x, I<T>
&y) { return x.p - y.p; }
template <typename T> typename I<T>::difference_type operator - (const I<T> &x,
const I<T> &y) { return x.p - y.p; }
template <typename T> I<T> operator + (typename I<T>::difference_type x, const
I<T> &y) { return I<T> (x + y.p); }

void
bar (I<int> &a)
{
}

void
foo (const I<int> &a, const I<int> &b)
{
  I<int> i;
  #pragma omp distribute parallel for
  for (i = a; i < b; i++)
    bar (i);
}

int
main ()
{
  int a[64];
  foo (&a[0], &a[63]);
}

[Bug c++/95197] libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-05-25

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 48597
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48597&action=edit
gcc11-pr95197.patch

Untested fix.

[Bug c++/95197] libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:f1f862aec2c3b93dbd6adfc35b0e1b6034e59c21

commit r11-629-gf1f862aec2c3b93dbd6adfc35b0e1b6034e59c21
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 26 09:35:21 2020 +0200

    openmp: Ensure copy ctor for composite distribute parallel for class
iterators is instantiated [PR95197]

    During gimplification omp_finish_clause langhook is called in several
places
    to add the language specific info to the clause like what default/copy
ctors,
    dtors and assignment operators should be used.

    Unfortunately, if it refers to some not yet instantiated method, during
    gimplification it is too late and the methods will not be instantiated
    anymore.  For other cases, the genericizer has code to detect those and
    instantiate whatever is needed, this change adds the same for
    distribute parallel for class iterators where we under the hood need
    a copy constructor for the iterator to implement it.

    2020-05-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95197
            * gimplify.c (find_combined_omp_for): Move to omp-general.c.
            * omp-general.h (find_combined_omp_for): Declare.
            * omp-general.c: Include tree-iterator.h.
            (find_combined_omp_for): New function, moved from gimplify.c.

            * cp-gimplify.c: Include omp-general.h.
            (cp_genericize_r) <case OMP_DISTRIBUTE>: For class iteration
            variables in composite distribute parallel for, instantiate copy
            ctor of their types.

[Bug c++/95197] libgomp/testsuite/libgomp.c++/for-27.C fails with -std=c++17

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95197

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:6d6df84dc031924cb95599a6c498aa27d3bceac4

commit r10-8294-g6d6df84dc031924cb95599a6c498aa27d3bceac4
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 26 09:35:21 2020 +0200

    openmp: Ensure copy ctor for composite distribute parallel for class
iterators is instantiated [PR95197]

    During gimplification omp_finish_clause langhook is called in several
places
    to add the language specific info to the clause like what default/copy
ctors,
    dtors and assignment operators should be used.

    Unfortunately, if it refers to some not yet instantiated method, during
    gimplification it is too late and the methods will not be instantiated
    anymore.  For other cases, the genericizer has code to detect those and
    instantiate whatever is needed, this change adds the same for
    distribute parallel for class iterators where we under the hood need
    a copy constructor for the iterator to implement it.

    2020-05-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95197
            * gimplify.c (find_combined_omp_for): Move to omp-general.c.
            * omp-general.h (find_combined_omp_for): Declare.
            * omp-general.c: Include tree-iterator.h.
            (find_combined_omp_for): New function, moved from gimplify.c.

            * cp-gimplify.c: Include omp-general.h.
            (cp_genericize_r) <case OMP_DISTRIBUTE>: For class iteration
            variables in composite distribute parallel for, instantiate copy
            ctor of their types.

    (cherry picked from commit f1f862aec2c3b93dbd6adfc35b0e1b6034e59c21)