Fortran: improve error recovery for EXTENDS_TYPE_OF() [PR106121]

gcc/fortran/ChangeLog:

	PR fortran/106121
	* simplify.cc (gfc_simplify_extends_type_of): Do not attempt to
	simplify when one of the arguments is a CLASS variable that was
	not properly declared.

gcc/testsuite/ChangeLog:

	PR fortran/106121
	* gfortran.dg/extends_type_of_4.f90: New test.

Co-authored-by: Steven G. Kargl <kargl@gcc.gnu.org>

diff --git a/gcc/fortran/simplify.cc b/gcc/fortran/simplify.cc
index e8e3ec6..ab59fbc 100644 (file)
--- a/gcc/fortran/simplify.cc
+++ b/gcc/fortran/simplify.cc
@@ -3096,6 +3096,10 @@ gfc_simplify_extends_type_of (gfc_expr *a, gfc_expr *mold)
   if (UNLIMITED_POLY (a) || UNLIMITED_POLY (mold))
     return NULL;
 
+  if ((a->ts.type == BT_CLASS && !gfc_expr_attr (a).class_ok)
+      || (mold->ts.type == BT_CLASS && !gfc_expr_attr (mold).class_ok))
+    return NULL;
+
   /* Return .false. if the dynamic type can never be an extension.  */
   if ((a->ts.type == BT_CLASS && mold->ts.type == BT_CLASS
        && !gfc_type_is_extension_of

diff --git a/gcc/testsuite/gfortran.dg/extends_type_of_4.f90 b/gcc/testsuite/gfortran.dg/extends_type_of_4.f90
new file mode 100644 (file)
index 0000000..6437332
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/extends_type_of_4.f90
@@ -0,0 +1,20 @@
+! { dg-do compile }
+! PR fortran/106121 - ICE in gfc_simplify_extends_type_of
+! Contributed by G.Steinmetz
+
+program p
+   type t
+   end type
+   type(t)  :: x
+   class(t) :: y               ! { dg-error "dummy, allocatable or pointer" }
+   print *, extends_type_of (x, y)
+end
+
+subroutine s
+   type t
+      integer :: i
+   end type
+   type(t)  :: x
+   class(t) :: y               ! { dg-error "dummy, allocatable or pointer" }
+   stop extends_type_of (x, y) ! { dg-error "STOP code" }
+end