Bizarrely, since the fix for pr101625, the testcase compiles and runs
correctly with s/select type (y => x)/select type (y => (x))/ !

The fix is straightforward and appears to be one of those wrinkles arising
from the use of associate variables as a selector. The fault is reasonable
since the expression is a reference to the _data field, which is of derived
type. However, being a select type selector, the selector must be a
class with that declared type.

Regtests fine. OK for mainline?

Paul

Fortran: Fix a problem with SELECT TYPE selectors [PR104555].

2023-10-29  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
PR fortran/104555
* resolve.cc (resolve_select_type): If the selector expression
has no class component references and the expression is a
derived type, copy the typespec of the symbol to that of the
expression.

gcc/testsuite/
PR fortran/104555
* gfortran.dg/pr104555.f90: New test.