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Subject: [Bug fortran/100972] New: Missing error with "implicit none
 (external)"
Date: Tue, 08 Jun 2021 17:17:14 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100972

            Bug ID: 100972
           Summary: Missing error with "implicit none (external)"
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

In the following example function g has no known interface and is
not declared external. implicit none (external) does not catch it.
Affects versions down to at least r5.


$ cat z1.f90
program p
   implicit none (external)
   real, external :: f
   real :: a, b
   a =3D f()
   b =3D g()
end


$ gfortran-12-20210606 -c z1.f90
$

BTW, ifort/ifx 2021.2 gets it right with
error #8889: Explicit declaration of the EXTERNAL attribute is required. [G=
]=