[gcc r13-2834] fortran: Fix invalid function decl clobber ICE [PR105012]

[Mikael Morin <mikael@gcc.gnu.org>]

https://gcc.gnu.org/g:edaf1e005c90b311c39b46d85cea17befbece112

commit r13-2834-gedaf1e005c90b311c39b46d85cea17befbece112
Author: Mikael Morin <mikael@gcc.gnu.org>
Date:   Mon Aug 29 11:19:29 2022 +0200

    fortran: Fix invalid function decl clobber ICE [PR105012]
    
    The fortran frontend, as result symbol for a function without
    declared result symbol, uses the function symbol itself.  This caused
    an invalid clobber of a function decl to be emitted, leading to an
    ICE, whereas the intended behaviour was to clobber the function result
    variable.  This change fixes the problem by getting the decl from the
    just-retrieved variable reference after the call to
    gfc_conv_expr_reference, instead of copying it from the frontend symbol.
    
            PR fortran/105012
    
    gcc/fortran/ChangeLog:
    
            * trans-expr.cc (gfc_conv_procedure_call): Retrieve variable
            from the just calculated variable reference.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/intent_out_15.f90: New test.

Diff:
---
 gcc/fortran/trans-expr.cc                   |  3 ++-
 gcc/testsuite/gfortran.dg/intent_out_15.f90 | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 7cdab1cc9b4..8fb63359ba5 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -6528,7 +6528,8 @@ gfc_conv_procedure_call (gfc_se * se, gfc_symbol * sym,
 			  tree var;
 			  /* FIXME: This fails if var is passed by reference, see PR
 			     41453.  */
-			  var = e->symtree->n.sym->backend_decl;
+			  var = build_fold_indirect_ref_loc (input_location,
+							     parmse.expr);
 			  tree clobber = build_clobber (TREE_TYPE (var));
 			  gfc_add_modify (&se->pre, var, clobber);
 			}
diff --git a/gcc/testsuite/gfortran.dg/intent_out_15.f90 b/gcc/testsuite/gfortran.dg/intent_out_15.f90
new file mode 100644
index 00000000000..64334e6f038
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/intent_out_15.f90
@@ -0,0 +1,27 @@
+! { dg-do compile }
+! { dg-additional-options "-fdump-tree-original" }
+!
+! PR fortran/105012
+! The following case was triggering an ICE because of a clobber
+! on the DERFC function decl instead of its result.
+
+module error_function
+integer, parameter :: r8 = selected_real_kind(12) ! 8 byte real
+contains
+SUBROUTINE CALERF_r8(ARG, RESULT, JINT)
+   integer, parameter :: rk = r8
+   real(rk), intent(in)  :: arg
+   real(rk), intent(out) :: result
+   IF (Y .LE. THRESH) THEN
+   END IF
+end SUBROUTINE CALERF_r8
+FUNCTION DERFC(X)
+   integer, parameter :: rk = r8 ! 8 byte real
+   real(rk), intent(in) :: X
+   real(rk) :: DERFC
+   CALL CALERF_r8(X, DERFC, JINT)
+END FUNCTION DERFC
+end module error_function
+
+! { dg-final { scan-tree-dump-times "CLOBBER" 1 "original" } }
+! { dg-final { scan-tree-dump "__result_derfc = {CLOBBER};" "original" } }