From a5da50ed65a835dc1ed6179e3f2b6164fd6e4969 Mon Sep 17 00:00:00 2001
From: Thomas Koenig <tkoenig@gcc.gnu.org>
Date: Mon, 10 Aug 2020 19:10:26 +0200
Subject: [PATCH] Fix NULL pointer dereference in
 doloop_contained_function_call.

gcc/fortran/ChangeLog:

	PR fortran/96556
	* frontend-passes.c (doloop_contained_function_call):
	Do not dereference a NULL pointer for value.function.esym.

gcc/testsuite/ChangeLog:

	PR fortran/96556
	* gfortran.dg/do_check_15.f90: New test.
---
 gcc/fortran/frontend-passes.c             |  3 +-
 gcc/testsuite/gfortran.dg/do_check_15.f90 | 58 +++++++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/do_check_15.f90

diff --git a/gcc/fortran/frontend-passes.c b/gcc/fortran/frontend-passes.c
index 6bcb1f06b1c..83f6fd804b1 100644
--- a/gcc/fortran/frontend-passes.c
+++ b/gcc/fortran/frontend-passes.c
@@ -2329,7 +2329,8 @@ doloop_contained_function_call (gfc_expr **e,
   gfc_symbol *sym, *do_var;
   contained_info *info;
 
-  if (expr->expr_type != EXPR_FUNCTION || expr->value.function.isym)
+  if (expr->expr_type != EXPR_FUNCTION || expr->value.function.isym
+      || expr->value.function.esym == NULL)
     return 0;
 
   sym = expr->value.function.esym;
diff --git a/gcc/testsuite/gfortran.dg/do_check_15.f90 b/gcc/testsuite/gfortran.dg/do_check_15.f90
new file mode 100644
index 00000000000..f67452b4660
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/do_check_15.f90
@@ -0,0 +1,58 @@
+! { dg-do compile }
+! PR fortran/96556 - this used to cause an ICE.
+! Test case by Juergen Reuter.
+module polarizations
+
+  implicit none
+  private
+
+  type :: smatrix_t
+     private
+     integer :: dim = 0
+     integer :: n_entry = 0
+     integer, dimension(:,:), allocatable :: index
+   contains
+     procedure :: write => smatrix_write
+  end type smatrix_t
+
+  type, extends (smatrix_t) :: pmatrix_t
+     private
+   contains
+     procedure :: write => pmatrix_write
+     procedure :: normalize => pmatrix_normalize
+  end type pmatrix_t
+
+contains
+
+  subroutine msg_error (string)
+    character(len=*), intent(in), optional :: string
+  end subroutine msg_error
+  
+  subroutine smatrix_write (object)
+    class(smatrix_t), intent(in) :: object
+  end subroutine smatrix_write
+
+  subroutine pmatrix_write (object)
+    class(pmatrix_t), intent(in) :: object
+    call object%smatrix_t%write ()
+  end subroutine pmatrix_write
+
+  subroutine pmatrix_normalize (pmatrix)
+    class(pmatrix_t), intent(inout) :: pmatrix
+    integer :: i, hmax
+    logical :: fermion, ok
+    do i = 1, pmatrix%n_entry
+       associate (index => pmatrix%index(:,i))
+         if (index(1) == index(2)) then
+            call error ("diagonal must be real")
+         end if
+       end associate
+    end do
+  contains
+    subroutine error (msg)
+      character(*), intent(in) :: msg
+      call pmatrix%write ()
+    end subroutine error
+  end subroutine pmatrix_normalize
+
+end module polarizations
-- 
2.30.2