From 892c7f03ae63121766a8be48f7e3b672547fd627 Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Tue, 29 Mar 2022 23:33:23 +0200
Subject: [PATCH] Fortran: improve error recovery for invalid coarray function
 declarations

gcc/fortran/ChangeLog:

	PR fortran/104210
	* arith.cc (eval_intrinsic): Avoid NULL pointer dereference.
	(gfc_zero_size_array): Likewise.

gcc/testsuite/ChangeLog:

	PR fortran/104210
	* gfortran.dg/pr104210.f90: New test.
---
 gcc/fortran/arith.cc                   |  9 ++++++---
 gcc/testsuite/gfortran.dg/pr104210.f90 | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/pr104210.f90

diff --git a/gcc/fortran/arith.cc b/gcc/fortran/arith.cc
index 06e032e22db..d57059a375f 100644
--- a/gcc/fortran/arith.cc
+++ b/gcc/fortran/arith.cc
@@ -1489,6 +1489,9 @@ eval_intrinsic (gfc_intrinsic_op op,
   int unary;
   arith rc;
 
+  if (!op1)
+    return NULL;
+
   gfc_clear_ts (&temp.ts);
 
   switch (op)
@@ -1703,11 +1706,11 @@ eval_type_intrinsic0 (gfc_intrinsic_op iop, gfc_expr *op)
 
 /* Return nonzero if the expression is a zero size array.  */
 
-static int
+static bool
 gfc_zero_size_array (gfc_expr *e)
 {
-  if (e->expr_type != EXPR_ARRAY)
-    return 0;
+  if (e == NULL || e->expr_type != EXPR_ARRAY)
+    return false;
 
   return e->value.constructor == NULL;
 }
diff --git a/gcc/testsuite/gfortran.dg/pr104210.f90 b/gcc/testsuite/gfortran.dg/pr104210.f90
new file mode 100644
index 00000000000..182404c265b
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr104210.f90
@@ -0,0 +1,15 @@
+! { dg-do compile }
+! { dg-options "-fcoarray=single" }
+! PR fortran/104210
+! Contributed by G.Steinmetz
+
+function f()      ! { dg-error "shall not be a coarray" }
+  integer :: f[*]
+end
+program p
+  interface
+     function f() ! { dg-error "shall not be a coarray" }
+       integer :: f[*]
+     end
+  end interface
+end