[Bug fortran/43169] New: gfortran rejects pure procedure with select type construct

[Bug fortran/43169] New: gfortran rejects pure procedure with select type construct

[haymaker at mail dot utexas dot edu]

The following code fails to compile with gcc version 4.5.0-pre9999 20100224
(experimental) rev. 157053. However, if lines 22, 23 and 27 (i.e. 'select
type(x)', 'class is (myType)', and 'end select') are removed it compiles fine
and the executable gives the expected output '2.0000 1.0000'.

Source compiled with ifort v. 11.1 behaves as expected with 'select type'
construct included. 

$ cat test.f90 && gfortran test.f90                             
program testPure
implicit none
type :: myType
    real :: a,b
end type myType
type(myType),target :: y
class(myType),pointer :: x

x=>y
x%a=1.
x%b=2.
call swap(x)
print *, x%a,x%b

contains

pure subroutine swap(x)
implicit none
class(myType), intent(inout) :: x
real :: work

select type(x)
class is (myType)
    work=x%a
    x%a=x%b
    x%b=work
end select
end subroutine swap
end program testPure
test.f90:25.4:

    x%a=x%b
    1
Error: Cannot assign to variable 'tmp$class$mytype' in PURE procedure at (1)
test.f90:26.4:

    x%b=work
    1
Error: Cannot assign to variable 'tmp$class$mytype' in PURE procedure at (1)

********************
Now with 'select type' construct removed


$ cat test.f90 && gfortran test.f90 && ./a.out                   
--(Wed,Feb24)--
program testPure
implicit none
type :: myType
    real :: a,b
end type myType
type(myType),target :: y
class(myType),pointer :: x

x=>y
x%a=1.
x%b=2.
call swap(x)
print *, x%a,x%b

contains

pure subroutine swap(x)
implicit none
class(myType), intent(inout) :: x
real :: work

    work=x%a
    x%a=x%b
    x%b=work
end subroutine swap
end program testPure

   2.0000000       1.0000000


-------------------------------------
gcc configure options:
$ gcc -v
gcc -v                                                          
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.0-pre9999/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.0-pre9999/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-4.5.0_pre9999/work/gcc-4.5.0-9999/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.0-pre9999
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.0-pre9999/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.0-pre9999
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.0-pre9999/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.0-pre9999/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.0-pre9999/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --with-ppl --with-cloog --enable-nls
--without-included-gettext --with-system-zlib --disable-checking
--disable-werror --enable-secureplt --enable-multilib --enable-libmudflap
--disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.0-pre9999/python
--disable-libgcj --enable-languages=c,c++,fortran --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo SVN'
--enable-lto --disable-checking
Thread model: posix
gcc version 4.5.0-pre9999 20100224 (experimental) rev. 157053 (Gentoo SVN)


-- 
           Summary: gfortran rejects pure procedure with select type
                    construct
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: haymaker at mail dot utexas dot edu
 GCC build triplet: x86_64-pc-linux-gnu
  GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #1 from janus at gcc dot gnu dot org  2010-02-25 08:38 -------
Confirmed. Here is a reduced test case:

  pure subroutine swap(x)
    implicit none
    type :: myType
      real :: a
    end type myType
    class(myType), intent(inout) :: x
    select type(x)
    class is (myType)
      x%a = 42.
    end select
  end subroutine

Thanks for the report!


-- 

janus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-02-25 08:38:03
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #2 from janus at gcc dot gnu dot org  2010-02-25 09:08 -------
The problem lies in gfc_impure_variable (resolve.c), where it is checked if the
namespace of the variable equals the local namespace of the pure procedure.
This check fails if the procedure has sub-namespaces.

We have sub-namespaces e.g. in the following cases:
1) BLOCK
2) SELECT TYPE
3) contained procedures
4) ...?

Comment #0 shows the failure for case (2), but the others may also be affected.
I'll check this.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #3 from janus at gcc dot gnu dot org  2010-02-25 09:13 -------
Regarding BLOCK, it seems there is an additional problem: Assignments inside a
BLOCK are not checked at all, as the following case shows ...

  implicit none
  real :: glob

contains

  pure subroutine swap
    implicit none
    real :: r1
    r1 = 42.
    block
      real :: r2
      r2 = 43.
      glob = 0.
    end block
  end subroutine

end

The assignment to 'glob' is clearly invalid, but is not being caught.
'gfc_impure_variable' is only called for 'r1', the other two are left
unchecked. Seems like statements inside a BLOCK are not being resolved at
all?!?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #4 from janus at gcc dot gnu dot org  2010-02-25 09:19 -------
Contained procedures are not affected by this bug, since a procedure contained
in a pure procedure must itself be pure. Therefore something like this is
invalid (as gfortran correctly detects):

module m

  implicit none

contains

  pure subroutine swap
    implicit none
    real :: r1

  contains

    pure subroutine cont
      real :: r2
      r1 = 42.
      r2 = 43.
    end subroutine

  end subroutine

end


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #5 from janus at gcc dot gnu dot org  2010-02-25 12:16 -------
(In reply to comment #3)
> Seems like statements inside a BLOCK are not being resolved at all?!?

Sorry, this is wrong. They are resolved alright. The problem is just that
'gfc_pure' does not work (checking if we're inside a pure function).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #6 from janus at gcc dot gnu dot org  2010-02-25 12:54 -------
(In reply to comment #2)
> The problem lies in gfc_impure_variable (resolve.c), where it is checked if the
> namespace of the variable equals the local namespace of the pure procedure.
> This check fails if the procedure has sub-namespaces.

Actually it seems that 'gfc_impure_variable' works fine, but for SELECT TYPE
the 'gfc_current_ns' is not set correctly.

Setting the namespace happens in 'resolve_codes', but the pureness check
happens inside 'gfc_resolve_blocks'.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #7 from janus at gcc dot gnu dot org  2010-02-25 13:40 -------
(In reply to comment #5)
> (In reply to comment #3)
> > Seems like statements inside a BLOCK are not being resolved at all?!?
> 
> Sorry, this is wrong. They are resolved alright. The problem is just that
> 'gfc_pure' does not work (checking if we're inside a pure function).

The BLOCK issue in comment #3 is fixed by the following patch:

Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c       (revision 157055)
+++ gcc/fortran/resolve.c       (working copy)
@@ -11689,18 +11695,30 @@ gfc_impure_variable (gfc_symbol *sym)
 }


-/* Test whether a symbol is pure or not.  For a NULL pointer, checks the
-   symbol of the current procedure.  */
+/* Test whether a symbol is pure or not.  For a NULL pointer, checks if the
+   current namespace is inside a pure procedure.  */

 int
 gfc_pure (gfc_symbol *sym)
 {
   symbol_attribute attr;
+  gfc_namespace *ns;

   if (sym == NULL)
-    sym = gfc_current_ns->proc_name;
-  if (sym == NULL)
-    return 0;
+    {
+      /* Check if the current namespace or one of its parents
+        belongs to a pure procedure.  */
+      for (ns = gfc_current_ns; ns; ns = ns->parent)
+       {
+         sym = ns->proc_name;
+         if (sym == NULL)
+           return 0;
+         attr = sym->attr;
+         if (attr.flavor == FL_PROCEDURE && (attr.pure || attr.elemental))
+           return 1;
+       }
+      return 0;
+    }

   attr = sym->attr;


-- 

janus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |janus at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2010-02-25 08:38:03         |2010-02-25 13:40:15
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[domob at gcc dot gnu dot org]

------- Comment #8 from domob at gcc dot gnu dot org  2010-02-28 15:07 -------
*** Bug 42912 has been marked as a duplicate of this bug. ***


-- 

domob at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #9 from janus at gcc dot gnu dot org  2010-03-01 12:47 -------
Even with the patch from comment #7, another thing goes wrong with BLOCK
statements:

  pure subroutine swap
    implicit none
    real :: r1
    block
      real :: r2
      r1 = 42.
      r2 = 43.
    end block
  end subroutine


      r1 = 42.
      1
Error: Cannot assign to variable 'r1' in PURE procedure at (1)

This is rejected although it is valid.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #10 from janus at gcc dot gnu dot org  2010-03-03 15:13 -------
Subject: Bug 43169

Author: janus
Date: Wed Mar  3 15:12:40 2010
New Revision: 157196

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=157196
Log:
2010-03-03  Janus Weil  <janus@gcc.gnu.org>

        PR fortran/43169
        * resolve.c (resolve_code): Correctly set gfc_current_ns for
        EXEC_SELECT_TYPE.
        (gfc_impure_variable): Make it work with sub-namespaces (BLOCK etc).
        (gfc_pure): Ditto.


2010-03-03  Janus Weil  <janus@gcc.gnu.org>

        PR fortran/43169
        * gfortran.dg/impure_assignment_3.f90: New.

Added:
    trunk/gcc/testsuite/gfortran.dg/impure_assignment_3.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/resolve.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169

[Bug fortran/43169] [OOP] gfortran rejects pure procedure with select type construct

[janus at gcc dot gnu dot org]

------- Comment #11 from janus at gcc dot gnu dot org  2010-03-03 15:17 -------
Fixed with r157196. Closing.


-- 

janus at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43169