[Ada] Fix tree sharing issue with slices

[Eric Botcazou]

This can happen because we build an array type on the fly in case there is an 
apparent type inconsistency in the construct.

Tested on x86-64/Linux, applied on the mainline.


2020-05-09  Eric Botcazou  <ebotca...@adacore.com>

        * gcc-interface/utils2.c (build_binary_op) <ARRAY_RANGE_REF>: Use
        build_nonshared_array_type to build the common type and declare it.

-- 
Eric Botcazou
diff --git a/gcc/ada/gcc-interface/utils2.c b/gcc/ada/gcc-interface/utils2.c
index 2ff865434b9..0d612056384 100644
--- a/gcc/ada/gcc-interface/utils2.c
+++ b/gcc/ada/gcc-interface/utils2.c
@@ -1040,8 +1040,15 @@ build_binary_op (enum tree_code op_code, tree result_type,
       /* For a range, make sure the element type is consistent.  */
       if (op_code == ARRAY_RANGE_REF
 	  && TREE_TYPE (operation_type) != TREE_TYPE (left_type))
-	operation_type = build_array_type (TREE_TYPE (left_type),
-					   TYPE_DOMAIN (operation_type));
+	{
+	  operation_type
+	    = build_nonshared_array_type (TREE_TYPE (left_type),
+					  TYPE_DOMAIN (operation_type));
+	  /* Declare it now since it will never be declared otherwise.  This
+	     is necessary to ensure that its subtrees are properly marked.  */
+	  create_type_decl (TYPE_NAME (operation_type), operation_type, true,
+			    false, Empty);
+	}
 
       /* Then convert the right operand to its base type.  This will prevent
 	 unneeded sign conversions when sizetype is wider than integer.  */