Fortran: improve checking of array specifications

gcc/fortran/ChangeLog:

	PR fortran/103505
	* array.c (match_array_element_spec): Try to simplify array
	element specifications to improve early checking.
	* expr.c (gfc_try_simplify_expr): New.  Try simplification of an
	expression via gfc_simplify_expr.  When an error occurs, roll
	back.
	* gfortran.h (gfc_try_simplify_expr): Declare it.

gcc/testsuite/ChangeLog:

	PR fortran/103505
	* gfortran.dg/pr103505.f90: New test.

Co-authored-by: Steven G. Kargl <kargl@gcc.gnu.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index 4084d18..8708932 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -2331,6 +2331,31 @@ gfc_simplify_expr (gfc_expr *p, int type)
 }
 
 
+/* Try simplification of an expression via gfc_simplify_expr.
+   When an error occurs (arithmetic or otherwise), roll back.  */
+
+bool
+gfc_try_simplify_expr (gfc_expr *e, int type)
+{
+  gfc_expr *n;
+  bool t, saved_div0;
+
+  if (e == NULL || e->expr_type == EXPR_CONSTANT)
+    return true;
+
+  saved_div0 = gfc_seen_div0;
+  gfc_seen_div0 = false;
+  n = gfc_copy_expr (e);
+  t = gfc_simplify_expr (n, type) && !gfc_seen_div0;
+  if (t)
+    gfc_replace_expr (e, n);
+  else
+    gfc_free_expr (n);
+  gfc_seen_div0 = saved_div0;
+  return t;
+}
+
+
 /* Returns the type of an expression with the exception that iterator
    variables are automatically integers no matter what else they may
    be declared as.  */