[Bug fortran/66113] New: Variable n cannot appear in the expression with nested blocks

[Bug fortran/66113] New: Variable n cannot appear in the expression with nested blocks

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

            Bug ID: 66113
           Summary: Variable n cannot appear in the expression with nested
                    blocks
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

ig25@linux-fd1f:~/Krempel/Block> cat block.f90
program main
  integer :: n
  n = 3
  block
    block
      block
        real, dimension(n) :: a
      end block
    end block
  end block
end program main

ig25@linux-fd1f:~/Krempel/Block> gfortran block.f90
block.f90:7:24:

         real, dimension(n) :: a
                        1
Error: Variable »n« cannot appear in the expression at (1)

This is bogus.

Any solution should include the case of an arbitrary number
of nested blocks.
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From: "jens.gustedt at inria dot fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/65471] type interpretation in _Generic
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide471

--- Comment #2 from Jens Gustedt <jens.gustedt at inria dot fr> ---
For referece, I have now a paper at the ISO committee:

http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1930.htm

we will look at it in the automn session to decide what to do with it.

[Bug fortran/66113] Variable n cannot appear in the expression with nested blocks

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Is not the code invalid?

[Bug fortran/66113] Variable n cannot appear in the expression with nested blocks

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

--- Comment #2 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Dominique d'Humieres from comment #1)
> Is not the code invalid?

I don't think it is invalid.

This works as expected:

program main
  integer :: n
  n = 3
    block
      block
        real, dimension(n) :: a
      end block
    end block
end program main

[Bug fortran/66113] Variable n cannot appear in the expression with nested blocks

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

Mikael Morin <mikael at gcc dot gnu.org> changed:

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

--- Comment #3 from Mikael Morin <mikael at gcc dot gnu.org> ---
Some people write strange code. ;-)
This is related to the inline matmul patch isn't it?

[Bug fortran/66113] Variable n cannot appear in the expression with nested blocks

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

--- Comment #4 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
The reason is that I want to make creation of temporary
variables for arrays more sane.

Currently, temporary arrays are handled using an allocatable array
variable. This obviously does not work if -fno-realloc-lhs is
specified, and introduces unneeded complexity in the generated
code, which is hard for the middle-end optimizers to remove.

What I want to do is, if I want to create a temporary variable for
an array, is to change

   real, dimension(something,other) :: a

   a(f(x),1:3)

into

   block
     freeze = f(x)
     size_1 = 1;
     size_2 = 3;
       block
          real, dimension(size_1, size_2) :: a_tmp
          a_tmp(:,;) = a(freeze, 1:3)
          ...
       end block
   end block

While this might work in the most simple cases, I don't want
to introduce instability by hitting a bug with too many nesting
levels.

[Bug fortran/66113] Variable n cannot appear in the expression with nested blocks

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66113

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

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

--- Comment #6 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Fixed on trunk, closing.