Catch division by zero errors in array sizes.

2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/92961
	* gfortran.h (gfc_seen_div0): Add declaration.
	* arith.h (gfc_seen_div0): Add definition.
	(eval_intrinsic): For integer division by zero, set gfc_seen_div0.
	* decl.c (variable_decl):  If resolution resp. simplification
	fails for array spec and a division of zero error has been
	seen, return MATCH_ERROR.

2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/92961
	* gfortran.dg/arith_divide_2.f90: New test.

From-SVN: r279762

6 files changed, 59 insertions, 4 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index 63a6de6..5b92597 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,13 @@
+2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/92961
+	* gfortran.h (gfc_seen_div0): Add declaration.
+	* arith.h (gfc_seen_div0): Add definition.
+	(eval_intrinsic): For integer division by zero, set gfc_seen_div0.
+	* decl.c (variable_decl):  If resolution resp. simplification
+	fails for array spec and a division of zero error has been
+	seen, return MATCH_ERROR.
+
 2019-12-21  Harald Anlauf  <anlauf@gmx.de>
 
 	PR fortran/92990
diff --git a/gcc/fortran/arith.c b/gcc/fortran/arith.c
index 7f048da..b7699e4 100644
--- a/gcc/fortran/arith.c
+++ b/gcc/fortran/arith.c
@@ -32,6 +32,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "target-memory.h"
 #include "constructor.h"
 
+bool gfc_seen_div0;
+
 /* MPFR does not have a direct replacement for mpz_set_f() from GMP.
    It's easily implemented with a few calls though.  */
 
@@ -1620,6 +1622,10 @@ eval_intrinsic (gfc_intrinsic_op op,
       gfc_error (gfc_arith_error (rc), &op1->where);
       if (rc == ARITH_OVERFLOW)
 	goto done;
+
+      if (rc == ARITH_DIV0 && op2->ts.type == BT_INTEGER)
+	gfc_seen_div0 = true;
+
       return NULL;
     }
 
diff --git a/gcc/fortran/decl.c b/gcc/fortran/decl.c
index affdbf6..b43dc2c 100644
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -2535,6 +2535,8 @@ variable_decl (int elem)
 	  goto cleanup;
 	}
 
+      gfc_seen_div0 = false;
+      
       /* F2018:C830 (R816) An explicit-shape-spec whose bounds are not
 	 constant expressions shall appear only in a subprogram, derived
 	 type definition, BLOCK construct, or interface body.  */
@@ -2551,7 +2553,12 @@ variable_decl (int elem)
 	  for (int i = 0; i < as->rank; i++)
 	    {
 	      e = gfc_copy_expr (as->lower[i]);
-	      gfc_resolve_expr (e);
+	      if (!gfc_resolve_expr (e) && gfc_seen_div0)
+		{
+		  m = MATCH_ERROR;
+		  goto cleanup;
+		}
+
 	      gfc_simplify_expr (e, 0);
 	      if (e && (e->expr_type != EXPR_CONSTANT))
 		{
@@ -2561,7 +2568,12 @@ variable_decl (int elem)
 	      gfc_free_expr (e);
 
 	      e = gfc_copy_expr (as->upper[i]);
-	      gfc_resolve_expr (e);
+	      if (!gfc_resolve_expr (e)  && gfc_seen_div0)
+		{
+		  m = MATCH_ERROR;
+		  goto cleanup;
+		}
+
 	      gfc_simplify_expr (e, 0);
 	      if (e && (e->expr_type != EXPR_CONSTANT))
 		{
@@ -2587,7 +2599,12 @@ variable_decl (int elem)
 	      if (e->expr_type != EXPR_CONSTANT)
 		{
 		  n = gfc_copy_expr (e);
-		  gfc_simplify_expr (n, 1);
+		  if (!gfc_simplify_expr (n, 1)  && gfc_seen_div0) 
+		    {
+		      m = MATCH_ERROR;
+		      goto cleanup;
+		    }
+
 		  if (n->expr_type == EXPR_CONSTANT)
 		    gfc_replace_expr (e, n);
 		  else
@@ -2597,7 +2614,12 @@ variable_decl (int elem)
 	      if (e->expr_type != EXPR_CONSTANT)
 		{
 		  n = gfc_copy_expr (e);
-		  gfc_simplify_expr (n, 1);
+		  if (!gfc_simplify_expr (n, 1)  && gfc_seen_div0) 
+		    {
+		      m = MATCH_ERROR;
+		      goto cleanup;
+		    }
+		  
 		  if (n->expr_type == EXPR_CONSTANT)
 		    gfc_replace_expr (e, n);
 		  else
@@ -2934,6 +2956,7 @@ variable_decl (int elem)
 
 cleanup:
   /* Free stuff up and return.  */
+  gfc_seen_div0 = false;
   gfc_free_expr (initializer);
   gfc_free_array_spec (as);
 
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index b38238a..8e414c4 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -2995,6 +2995,8 @@ void gfc_arith_done_1 (void);
 arith gfc_check_integer_range (mpz_t p, int kind);
 bool gfc_check_character_range (gfc_char_t, int);
 
+extern bool gfc_seen_div0;
+
 /* trans-types.c */
 bool gfc_check_any_c_kind (gfc_typespec *);
 int gfc_validate_kind (bt, int, bool);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index dcc0ec9..d704451 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-30  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/92961
+	* gfortran.dg/arith_divide_2.f90: New test.
+
 2019-12-30  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/92745
diff --git a/gcc/testsuite/gfortran.dg/arith_divide_2.f90 b/gcc/testsuite/gfortran.dg/arith_divide_2.f90
new file mode 100644
index 0000000..ffafa26
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/arith_divide_2.f90
@@ -0,0 +1,9 @@
+! { dg-do compile }
+! PR 92961 - this used to ICE. Original test case by Gerhard Steinmetz.
+program p
+   integer :: a((0)/0)    ! { dg-error "Division by zero" }
+   integer :: b(0/(0))    ! { dg-error "Division by zero" }
+   integer :: c((0)/(0))  ! { dg-error "Division by zero" }
+   integer :: d(0/0)      ! { dg-error "Division by zero" }
+   integer :: x = ubound(a,1) ! { dg-error "must be an array" }
+end