[PATCH, pushed] Fortran: fix ICE with use with rename of namelist member [PR116530]

[Harald Anlauf]

Dear all,

the attached simple & obvious patch fixes a NULL pointer dereference
when USEing with rename a namelist member and reading/writing the
namelist.

Patch was OK'ed in the PR by Steve and is pushed to mainline as:

r15-3308-g6bfeba12c86b4d0dae27d99b484f64774dd49398

As this is a 14/15 regression, I plan to backport when it has
successfully passed the testers.

Thanks,
Harald


From 6bfeba12c86b4d0dae27d99b484f64774dd49398 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anl...@gmx.de>
Date: Thu, 29 Aug 2024 21:21:39 +0200
Subject: [PATCH] Fortran: fix ICE with use with rename of namelist member
 [PR116530]

gcc/fortran/ChangeLog:

	PR fortran/116530
	* trans-io.cc (transfer_namelist_element): Prevent NULL pointer
	dereference.

gcc/testsuite/ChangeLog:

	PR fortran/116530
	* gfortran.dg/use_rename_12.f90: New test.
---
 gcc/fortran/trans-io.cc                     |  3 ++-
 gcc/testsuite/gfortran.dg/use_rename_12.f90 | 27 +++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/use_rename_12.f90

diff --git a/gcc/fortran/trans-io.cc b/gcc/fortran/trans-io.cc
index 7ab82fa2f5b..c0baa718ef6 100644
--- a/gcc/fortran/trans-io.cc
+++ b/gcc/fortran/trans-io.cc
@@ -1692,7 +1692,8 @@ transfer_namelist_element (stmtblock_t * block, const char * var_name,
   gcc_assert (sym || c);

   /* Build the namelist object name.  */
-  if (sym && !sym->attr.use_only && sym->attr.use_rename)
+  if (sym && !sym->attr.use_only && sym->attr.use_rename
+      && sym->ns->use_stmts->rename)
     string = gfc_build_cstring_const (sym->ns->use_stmts->rename->local_name);
   else
     string = gfc_build_cstring_const (var_name);
diff --git a/gcc/testsuite/gfortran.dg/use_rename_12.f90 b/gcc/testsuite/gfortran.dg/use_rename_12.f90
new file mode 100644
index 00000000000..0447d5fe150
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/use_rename_12.f90
@@ -0,0 +1,27 @@
+! { dg-do compile }
+! PR fortran/116530 - ICE with member of namelist renamed by use module
+!
+! Reported by philippe.wautelet at cnrs.fr
+
+module mod_nml1
+  implicit none
+  logical :: ldiag
+  namelist /nam_nml1/ldiag
+end module mod_nml1
+
+module mod_interm
+  use mod_nml1
+end module mod_interm
+
+program ice_nml
+  use mod_nml1,        ldiag_nml1 => ldiag
+  use mod_nml1, only : ldiag_only => ldiag
+  use mod_interm
+  implicit none
+  integer :: ilu = 10
+  read(unit=ilu,nml=nam_nml1)
+  write(unit=*,nml=nam_nml1)
+  print *, ldiag
+  print *, ldiag_nml1
+  print *, ldiag_only
+end program ice_nml
--
2.35.3