BUG: allow extension of common blocks in numpy.f2py

Lack of this feature resulted in the generation of incorrect *.pyf
files.

For example, the pyf file created by:

      subroutine sub3 (some arguments)
      real a, b, c, d
      common /coeff/ a, b
      common /coeff/ c, d

      <do stuff>

      return
      end

Should contain both common statements the declaration of all four
variables a, b, c, and d.

Closes #5876.

1 files changed, 7 insertions, 6 deletions

diff --git a/doc/source/f2py/signature-file.rst b/doc/source/f2py/signature-file.rst
index cfc35ebda..54b8736f1 100644
--- a/doc/source/f2py/signature-file.rst
+++ b/doc/source/f2py/signature-file.rst
@@ -178,12 +178,13 @@ Common block statements:
 
     <shortentitydecl> := <name> [ ( <arrayspec> ) ] [ , <shortentitydecl> ]
 
-  One ``python module`` block should not contain two or more
-  ``common`` blocks with the same name. Otherwise, the latter ones are
-  ignored. The types of variables in ``<shortentitydecl>`` are defined
-  using ``<argument type declarations>``. Note that the corresponding
-  ``<argument type declarations>`` may contain array specifications;
-  then you don't need to specify these in ``<shortentitydecl>``.
+  If a ``python module`` block contains two or more ``common`` blocks
+  with the same name, the variables from the additional declarations
+  are appened.  The types of variables in ``<shortentitydecl>`` are
+  defined using ``<argument type declarations>``. Note that the
+  corresponding ``<argument type declarations>`` may contain array
+  specifications; then you don't need to specify these in
+  ``<shortentitydecl>``.
 
 Other statements:
   The ``<other statement>`` part refers to any other Fortran language