[gcc/devel/ranger] Fix PR fortran/93500, ICE on invalid.

[Aldy Hernandez]

https://gcc.gnu.org/g:4dc6437183aec5439b88b076315ad8f31794d24b

commit 4dc6437183aec5439b88b076315ad8f31794d24b
Author: Thomas König <tkoenig@gcc.gnu.org>
Date:   Sun Apr 19 12:56:32 2020 +0200

    Fix PR fortran/93500, ICE on invalid.
    
    Returning &gfc_bad_expr when simplifying bounds after a divisin by zero
    happened results in the division by zero error actually reaching the user.
    
    2020-04-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
    
            PR fortran/93500
            * resolve.c (resolve_operator): If both operands are
            NULL, return false.
            * simplify.c (simplify_bound): If a division by zero
            was seen during bound simplification, free the
            corresponcing expression and return &gfc_bad_expr.
    
    2020-04-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
    
            PR fortran/93500
            * arith_divide_3.f90: New test.

Diff:
---
 gcc/fortran/ChangeLog                        |  9 +++++++++
 gcc/fortran/resolve.c                        |  3 +++
 gcc/fortran/simplify.c                       |  6 +++++-
 gcc/testsuite/ChangeLog                      |  5 +++++
 gcc/testsuite/gfortran.dg/arith_divide_3.f90 | 17 +++++++++++++++++
 5 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 2f99ce24599..336ce49090e 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,12 @@
+2020-04-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/93500
+	* resolve.c (resolve_operator): If both operands are
+	NULL, return false.
+	* simplify.c (simplify_bound): If a division by zero
+	was seen during bound simplification, free the
+	corresponcing expression and return &gfc_bad_expr.
+
 2020-04-17  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/94090
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 2371ab23645..fd3b025a84f 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -3992,6 +3992,9 @@ resolve_operator (gfc_expr *e)
 
   op1 = e->value.op.op1;
   op2 = e->value.op.op2;
+  if (op1 == NULL && op2 == NULL)
+    return false;
+
   dual_locus_error = false;
 
   /* op1 and op2 cannot both be BOZ.  */
diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index d5703e38251..c7a4f77e70b 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -4251,7 +4251,11 @@ simplify_bound (gfc_expr *array, gfc_expr *dim, gfc_expr *kind, int upper)
 
 	      for (j = 0; j < d; j++)
 		gfc_free_expr (bounds[j]);
-	      return bounds[d];
+
+	      if (gfc_seen_div0)
+		return &gfc_bad_expr;
+	      else
+		return bounds[d];
 	    }
 	}
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 9f8ae6ccccb..e8742902d12 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-19  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/93500
+	* arith_divide_3.f90: New test.
+
 2020-04-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR objc/94637
diff --git a/gcc/testsuite/gfortran.dg/arith_divide_3.f90 b/gcc/testsuite/gfortran.dg/arith_divide_3.f90
new file mode 100644
index 00000000000..95682dfdda7
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/arith_divide_3.f90
@@ -0,0 +1,17 @@
+! { dg-do compile }
+! { dg-options "-fcoarray=single" }
+! PR 93500 - this used to cause an ICE
+
+program p
+  integer :: a(min(2,0)/0) ! { dg-error "Division by zero" }
+  integer, save :: c[min(2,0)/0,*] ! { dg-error "Division by zero|must have constant shape" }
+  integer :: b = lbound(a) ! { dg-error "must be an array" }
+  print *,lcobound(c)
+end program p
+
+subroutine s
+  integer :: a(min(2,0)/0)  ! { dg-error "Division by zero" }
+  integer, save :: c[min(2,0)/0,*] ! { dg-error "Division by zero" }
+  integer :: b = lbound(a)
+  print *,lcobound(c)
+end subroutine s