https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109275
Bug ID: 109275
Summary: Bad error messages for interfaces describing
surrounding program unit
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: rhidalgochar at bloomberg dot net
Target Milestone: ---
The following example, where an interface is defined for the surrounding
program unit fails to compile:
function foo(arg1) result(res)
interface foo
function foo(arg1)
integer*2 foo(3)
integer*8 arg1
end function foo
end interface
integer*2 res(3)
integer*8 arg1
res = (/1,2,int(arg1,4)/)
end function
Giving the error:
recursive-interface.f:4:8:
4 | function foo(arg1)
| 1
Error: Procedure pointer result ‘foo’ at (1) is missing the pointer attribute
Given you can use this function with that interface, this appears to be an
incorrect warning.
It gives even stranger warnings if you follow its advice and add the pointer
attribute to foo in the interface (i.e. integer*2, pointer :: foo(3)):
recursive-interface.f:4:8:
4 | function foo(arg1)
| 1
Error: Array pointer ‘ppr@’ at (1) must have a deferred shape or assumed rank
recursive-interface.f:1:6:
1 | function foo(arg1) result(res)
| 1
Error: Array pointer ‘foo’ at (1) must have a deferred shape or assumed rank
It appears that "ppr@" is some internal return variable that should not be
getting exposed. Following this advice further and making foo assumed shape
(foo(:)) it goes back to complaining about it not having the pointer attribute
even though it does.
While I don't see any reason why a correctly defined interface would not be
allowed, especially if it's not even used and result is used to disambiguate
the symbol, other compilers do fail to compile and complain about using an
interface with the same name as the surrounding program unit. XLF complained
for normal interfaces, while Sun Studio just complains for generic interface.
GFortrans error message should at least be more informative, explicitly saying
it's not allowed if this is the case.
I came across this issue because a library had an include with many interfaces,
and was then trying to use some of those interfaces in the definitions of those
program units.
