[gcc r14-5003] Fortran: Fix a problem with SELECT TYPE selectors [PR104555].

[gcc r14-5003] Fortran: Fix a problem with SELECT TYPE selectors [PR104555].

[Paul Thomas]

https://gcc.gnu.org/g:f3e44d079747daf56307ada8a2e2e56b64934014

commit r14-5003-gf3e44d079747daf56307ada8a2e2e56b64934014
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Mon Oct 30 07:12:40 2023 +0000

    Fortran: Fix a problem with SELECT TYPE selectors [PR104555].
    
    2023-10-30  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.

Diff:
---
 gcc/fortran/resolve.cc                 |  6 ++++++
 gcc/testsuite/gfortran.dg/pr104555.f90 | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 9f4dc0726457..81a14653a044 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -9578,6 +9578,12 @@ resolve_select_type (gfc_code *code, gfc_namespace *old_ns)
 	{
 	  if (code->expr1->symtree->n.sym->attr.untyped)
 	    code->expr1->symtree->n.sym->ts = code->expr2->ts;
+	  /* Sometimes the selector expression is given the typespec of the
+	     '_data' field, which is logical enough but inappropriate here. */
+	  if (code->expr2->ts.type == BT_DERIVED
+	      && code->expr2->symtree
+	      && code->expr2->symtree->n.sym->ts.type == BT_CLASS)
+	    code->expr2->ts = code->expr2->symtree->n.sym->ts;
 	  selector_type = CLASS_DATA (code->expr2)
 	    ? CLASS_DATA (code->expr2)->ts.u.derived : code->expr2->ts.u.derived;
 	}
diff --git a/gcc/testsuite/gfortran.dg/pr104555.f90 b/gcc/testsuite/gfortran.dg/pr104555.f90
new file mode 100644
index 000000000000..1fc5b5bb977b
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr104555.f90
@@ -0,0 +1,32 @@
+! { dg-do compile }
+!
+! Test the fix for PR104555 in which the select type statement caused an
+! ICE because the selector expression was type(t) rather than class(t).
+!
+! Contributed by Gerhard Steinmetz  <gscfq@t-online.de>
+!
+program p
+   type t
+      character(:), allocatable :: a
+   end type
+   call s(t("abcd"))
+   call s([t("efgh")])
+contains
+   subroutine s(x)
+      class(t) :: x(..)
+      select rank (x)
+      rank (0)
+         print *, "|", x%a, "|"
+         select type (y => x)
+         type is (t)
+           print *, "|", y%a, "|"
+         end select
+      rank (1)
+         print *, "|", x(1)%a, "|"
+         select type (y => x)
+         type is (t)
+           print *, "|", y(1)%a, "|"
+         end select
+      end select
+   end
+end