Add is_array_like and to_array to language_defn

This adds new is_array_like and to_array methods to language_defn.
This will be used in a subsequent patch that generalizes the new
Python array- and string-handling code.

gdb/ada-lang.c

@@ -13830,6 +13830,19 @@ public:
 
   /* See language.h.  */
 
+  bool is_array_like (struct type *type) const override
+  {
+    return (ada_is_constrained_packed_array_type (type)
+	    || ada_is_array_descriptor_type (type));
+  }
+
+  /* See language.h.  */
+
+  struct value *to_array (struct value *val) const override
+  { return ada_coerce_to_simple_array (val); }
+
+  /* See language.h.  */
+
   const char *struct_too_deep_ellipsis () const override
   { return "(...)"; }
 

gdb/language.h

@@ -568,6 +568,17 @@ struct language_defn
   /* Return true if TYPE is a string type.  */
   virtual bool is_string_type_p (struct type *type) const;
 
+  /* Return true if TYPE is array-like.  */
+  virtual bool is_array_like (struct type *type) const
+  { return false; }
+
+  /* Underlying implementation of value_to_array.  Return a value of
+     array type that corresponds to VAL.  The caller must ensure that
+     is_array_like is true for VAL's type.  Return nullptr if the type
+     cannot be handled.  */
+  virtual struct value *to_array (struct value *val) const
+  { return nullptr; }
+
   /* Return a string that is used by the 'set print max-depth' setting.
      When GDB replaces a struct or union (during value printing) that is
      "too deep" this string is displayed instead.  The default value here

gdb/rust-lang.h

@@ -196,6 +196,16 @@ public:
 
   /* See language.h.  */
 
+  bool is_array_like (struct type *type) const override
+  { return rust_slice_type_p (type); }
+
+  /* See language.h.  */
+
+  struct value *to_array (struct value *val) const override
+  { return rust_slice_to_array (val); }
+
+  /* See language.h.  */
+
   bool range_checking_on_by_default () const override
   { return true; }