[Bug fortran/65223] New: Regresion on elemental type-bound procedure's passed object with INTENT(OUT)

[Bug fortran/65223] New: Regresion on elemental type-bound procedure's passed object with INTENT(OUT)

[jwmwalrus at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

            Bug ID: 65223
           Summary: Regresion on elemental type-bound procedure's passed
                    object with INTENT(OUT)
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jwmwalrus at gmail dot com

The code below compiles just fine with gfortran 4.9, but throws an error with
gfortran 5.0:

module storage_mod
    implicit none
    private
    save

    type, public :: StorageClass
        character(20) :: name = 'default'
    contains
        procedure :: destroy => destroyStorage
    end type
contains
    elemental subroutine destroyStorage(this)
        class(StorageClass), intent(OUT) :: this
    end subroutine
end module storage_mod



The output I get is:

$ ll `which gfortran`
lrwxrwxrwx 1 root root 12 Oct 18 04:03 /usr/bin/gfortran -> gfortran-4.9*
$ gfortran -c storage_mod.f90 
$ gfortran-5.0 -c storage_mod.f90 
storage_mod.f90:12:44:

     elemental subroutine destroyStorage(this)
                                            1
Error: INTENT(OUT) argument 'this' of pure procedure 'destroystorage' at (1)
may not be polymorphic



The error goes away by removing the ELEMENTAL attribute, so it seems like a
regression on valid code.

The compiler and system information is:

$ lsb_release -rd
Description:    Debian GNU/Linux 8.0 (jessie)
Release:    8.0

$ gfortran-5.0 -v
Using built-in specs.
COLLECT_GCC=gfortran-5.0
COLLECT_LTO_WRAPPER=/usr/lib/gcc-snapshot/libexec/gcc/x86_64-linux-gnu/5.0.0/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 20150211-1'
--with-bugurl=file:///usr/share/doc/gcc-snapshot/README.Bugs
--enable-languages=c,ada,c++,java,go,fortran,objc,obj-c++
--prefix=/usr/lib/gcc-snapshot --enable-shared --enable-linker-build-id
--disable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --with-default-libstdcxx-abi=c++98
--enable-gnu-unique-object --disable-vtable-verify --enable-plugin
--with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
--enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5.0-snap-amd64/jre
--enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5.0-snap-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5.0-snap-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--disable-werror --enable-checking=yes --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.0.0 20150211 (experimental) [trunk revision 220605] (Debian
20150211-1)

[Bug fortran/65223] Regresion on elemental type-bound procedure's passed object with INTENT(OUT)

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
This is the intended behavior: see the thread starting at
https://gcc.gnu.org/ml/fortran/2014-12/msg00094.html. You must use 'impure
elemental' if there is an INTENT(OUT) polymorphic argument.

[Bug fortran/65223] Regresion on elemental type-bound procedure's passed object with INTENT(OUT)

[jwmwalrus at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

--- Comment #2 from John <jwmwalrus at gmail dot com> ---
Changing the ELEMENTAL attribute to PURE produces the same error. If that's the
intended behavior, then that's the same as saying type-bound procedures cannot
be pure.

The thread mentioned by Dominique d'Humieres seems to only apply to "unlimited
polymorphic", which is not part of the test case I posted.

[Bug fortran/65223] Regresion on elemental type-bound procedure's passed object with INTENT(OUT)

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |WAITING
   Last reconfirmed|                            |2015-02-27
                 CC|                            |janus at gcc dot gnu.org
         Resolution|INVALID                     |---
     Ever confirmed|0                           |1

--- Comment #3 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> The thread mentioned by Dominique d'Humieres seems to only apply to
> "unlimited polymorphic", which is not part of the test case I posted.

Sorry, the pointer should be

https://gcc.gnu.org/ml/fortran/2014-12/msg00098.html

The rationale refers to F08:C1278a, however in my F08 draft it is 'A local
variable of a pure subprogram, or of a BLOCK construct within a pure
subprogram, shall not have the SAVE attribute.'. The only related constraint I
can find is

C534 An assumed-size array with the INTENT (OUT) attribute shall not be
polymorphic, finalizable, of a type with an allocatable ultimate component, or
of a type for which default initialization is specied.

but this does not apply to the test in comment 0, CCed Janus.

Nevertheless replacing 'element' with 'impure elemental' allows the code to
compile.

[Bug fortran/65223] Elemental type-bound procedure's passed object with INTENT(OUT) should be accepted with -std=f2003 (?).

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
            Summary|Regresion on elemental      |Elemental type-bound
                   |type-bound procedure's      |procedure's passed object
                   |passed object with          |with INTENT(OUT) should be
                   |INTENT(OUT)                 |accepted with -std=f2003
                   |                            |(?).

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
AFAICT the condition

if (sym->ts.type == BT_CLASS && sym->attr.intent == INTENT_OUT)

implement the constraints C1290 (from my copy of the f2015 draft, see
fortran.dg/class_dummy_5.f90 for the rationale)

1.6.4 Fortran 2003 compatibility

...

6 Fortran 2003 permitted the function result of a pure function to be
  a polymorphic allocatable variable, and to be finalizable by an impure final
  subroutine. These are not permitted by this part of ISO/IEC 1539.
7 Fortran 2003 permitted an INTENT (OUT) argument of a pure subroutine to be
  polymorphic; that is not permitted by this part of ISO/IEC 1539.

12.7 Pure procedures

...

C1289 An INTENT (OUT) dummy argument of a pure procedure shall not be such that
      finalization of the actual argument would reference an impure procedure.
C1290 An INTENT (OUT) dummy argument of a pure procedure shall not be
polymorphic.

Since the constraints are Fortran 2008, IMO the code should compile with
-std=f2003. In addition I am not sure that constraint C1289 is implemented:
compiling

module storage_mod
    implicit none
    private
    save

    type, public :: StorageClass
        character(20) :: name = 'default'
    contains
        procedure, nopass :: destroy => destroyStorage
    end type
contains
    elemental subroutine destroyStorage(this)
    type(StorageClass), intent(OUT) :: this
    end subroutine
end module storage_mod
end

should give an error(?).

[Bug fortran/65223] Elemental type-bound procedure's passed object with INTENT(OUT) should be accepted with -std=f2003 (?).

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65223

--- Comment #5 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
The patch

--- ../_clean/gcc/fortran/resolve.c     2015-10-07 02:32:16.000000000 +0200
+++ gcc/fortran/resolve.c       2015-10-10 17:01:17.000000000 +0200
@@ -415,7 +415,7 @@ resolve_formal_arglist (gfc_symbol *proc
            }

          /* F08:C1278a.  */
-         if (sym->ts.type == BT_CLASS && sym->attr.intent == INTENT_OUT)
+         if ( !gfc_notification_std (GFC_STD_F2008) && sym->ts.type ==
BT_CLASS && sym->attr.intent == INTENT_OUT)
            {
              gfc_error ("INTENT(OUT) argument %qs of pure procedure %qs at %L"
                         " may not be polymorphic", sym->name, proc->name,

allows the code to compile with -std=f2003.