https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111521
Bug ID: 111521
Summary: Polymorphic variable loses information about the
actual type assigned when passed as function result
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: dcesari69 at gmail dot com
Target Milestone: ---
Created attachment 55961
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55961&action=edit
Program showing the described behavior
Hello, the attached program shows an anomalous behavior since gcc-gfortran
version 13, in the previous gfortran versions it worked as expected.
gcc version:
GNU Fortran (GCC) 13.2.1 20230728 (Red Hat 13.2.1-1)
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
OS (Fedora 38):
Linux trentotto 6.3.8-200.fc38.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Jun 15
02:15:40 UTC 2023 x86_64 GNU/Linux
Build command line:
gfortran -g -fcheck=all -o testpoli testpoli.f90
Actual program stdout:
1.integer
1.integer
2.unknown type
3.unknown type
8 -1
Expected program stdout (e.g. when compiled with gfortran 12.2.1):
1.integer
2.integer
3.integer
8 8
Description:
The unlimited polymorphic derived type member %val is initialised with an
integer, but when passed back as a result of a chain of functions, it loses its
type. Additionally, the debugging print show that the function link_getval is
apparently executed twice, while it is called only once.
By executing the commented line `v => this%curr%getval()` instead of `v =>
this%getcurr()` the program gives the expected result with version 13, however
the original code was obviously more complex and this chained function call was
necessary.
The bug could be somehow related to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110415 also appearing in version
13.
