fortran: ICE in gfc_match_assignment PR93600

This patch builds on the original patch by Steve Kargl that fixed the
ICE and produced an "Unclassifiable statement at (1)" error. The
processing of parameter variables now correctly handles zero length
arrays used with %kind and %len. A side affect is that "Unclassifiable"
error now says "Assignment to constant expression at (1)". It also
fixes PR93365.

gcc/fortran/ChangeLog:

	PR fortran/93600
	* expr.c (simplify_parameter_variable): Check whether the ref
	chain contains INQUIRY_LEN or INQUIRY_KIND and set inquiry
	boolean. When an empty array has been identified and a new
	new EXPR_ARRAY expression has been created only return that
	expression if inquiry is not set. This allows the new
	expression to drop through to be simplified into a
	EXPR_CONSTANT representing %kind or %len.
	* match.c (gfc_match_assignment): If lvalue doesn't have a
	symtree free both lvalue and rvalue expressions and return
	an error.
	* resolv.c (gfc_resolve_ref): Ensure that code to handle
	INQUIRY_LEN is only performed for arrays with deferred types.

gcc/testsuite/ChangeLog:

	PR fortran/93365
	PR fortran/93600
	* gfortran.dg/pr93365.f90: New test.
	* gfortran.dg/pr93600_1.f90: New test.
	* gfortran.dg/pr93600_2.f90: New test.

4 files changed, 52 insertions, 9 deletions

diff --git a/gcc/fortran/ChangeLog b/gcc/fortran/ChangeLog
index db79f05..0591579 100644
--- a/gcc/fortran/ChangeLog
+++ b/gcc/fortran/ChangeLog
@@ -1,3 +1,20 @@
+2020-03-23  Mark Eggleston  <mark.eggleston@codethink.com>
+	Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/93600
+	* expr.c (simplify_parameter_variable): Check whether the ref
+	chain contains INQUIRY_LEN or INQUIRY_KIND and set inquiry
+	boolean. When an empty array has been identified and a new
+	new EXPR_ARRAY expression has been created only return that
+	expression if inquiry is not set. This allows the new
+	expression to drop through to be simplified into a
+	EXPR_CONSTANT representing %kind or %len.
+	* matc.c (gfc_match_assignment): If lvalue doesn't have a
+	symtree free both lvalue and rvalue expressions and return
+	an error.
+	* resolv.c (gfc_resolve_ref): Ensure that code to handle
+	INQUIRY_LEN is only performed for arrays with deferred types.
+
 2020-03-18  Jakub Jelinek  <jakub@redhat.com>
 
 	* class.c (generate_finalization_wrapper): Fix up duplicated word
diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
index 79e00b4..08b0a92 100644
--- a/gcc/fortran/expr.c
+++ b/gcc/fortran/expr.c
@@ -2057,6 +2057,18 @@ simplify_parameter_variable (gfc_expr *p, int type)
     }
   gfc_expression_rank (p);
 
+  /* Is this an inquiry?  */
+  bool inquiry = false;
+  gfc_ref* ref = p->ref;
+  while (ref)
+    {
+      if (ref->type == REF_INQUIRY)
+	break;
+      ref = ref->next;
+    }
+  if (ref && ref->type == REF_INQUIRY)
+    inquiry = ref->u.i == INQUIRY_LEN || ref->u.i == INQUIRY_KIND;
+
   if (gfc_is_size_zero_array (p))
     {
       if (p->expr_type == EXPR_ARRAY)
@@ -2069,15 +2081,22 @@ simplify_parameter_variable (gfc_expr *p, int type)
       e->value.constructor = NULL;
       e->shape = gfc_copy_shape (p->shape, p->rank);
       e->where = p->where;
-      gfc_replace_expr (p, e);
-      return true;
+      /* If %kind and %len are not used then we're done, otherwise
+	 drop through for simplification.  */
+      if (!inquiry)
+	{
+	  gfc_replace_expr (p, e);
+	  return true;
+	}
     }
+  else
+    {
+      e = gfc_copy_expr (p->symtree->n.sym->value);
+      if (e == NULL)
+	return false;
 
-  e = gfc_copy_expr (p->symtree->n.sym->value);
-  if (e == NULL)
-    return false;
-
-  e->rank = p->rank;
+      e->rank = p->rank;
+    }
 
   if (e->ts.type == BT_CHARACTER && e->ts.u.cl == NULL)
     e->ts.u.cl = gfc_new_charlen (gfc_current_ns, p->ts.u.cl);
@@ -2126,7 +2145,6 @@ gfc_simplify_expr (gfc_expr *p, int type)
   gfc_actual_arglist *ap;
   gfc_intrinsic_sym* isym = NULL;
 
-
   if (p == NULL)
     return true;
 
diff --git a/gcc/fortran/match.c b/gcc/fortran/match.c
index 753a5f1..3a0c097 100644
--- a/gcc/fortran/match.c
+++ b/gcc/fortran/match.c
@@ -1373,6 +1373,14 @@ gfc_match_assignment (void)
       return m;
     }
 
+  if (!lvalue->symtree)
+    {
+      gfc_free_expr (lvalue);
+      gfc_free_expr (rvalue);
+      return MATCH_ERROR;
+    }
+
+
   gfc_set_sym_referenced (lvalue->symtree->n.sym);
 
   new_st.op = EXEC_ASSIGN;
diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 23b5a2b..2dcb261 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -5314,7 +5314,7 @@ gfc_resolve_ref (gfc_expr *expr)
 	case REF_INQUIRY:
 	  /* Implement requirement in note 9.7 of F2018 that the result of the
 	     LEN inquiry be a scalar.  */
-	  if (ref->u.i == INQUIRY_LEN && array_ref)
+	  if (ref->u.i == INQUIRY_LEN && array_ref && expr->ts.deferred)
 	    {
 	      array_ref->u.ar.type = AR_ELEMENT;
 	      expr->rank = 0;