gdb: Convert language la_pass_by_reference field to a method

This commit changes the language_data::la_pass_by_reference function
pointer member variable into a member function of language_defn.

The interesting thing in this commit is that I have removed the
default_pass_by_reference function entirely.  This function only ever
returned a language_pass_by_ref_info struct in its default state, so
all uses of this function can be replaced by just default
initialisation of a language_pass_by_ref_info variable.

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* ada-lang.c (ada_language_data): Delete la_pass_by_reference
	initializer.
	* c-lang.c (c_language_data): Likewise.
	(cplus_language_data): Likewise.
	(cplus_language::pass_by_reference_info): New method.
	(asm_language_data): Delete la_pass_by_reference initializer.
	(minimal_language_data): Likewise.
	* cp-abi.c (cp_pass_by_reference): Remove use of
	default_pass_by_reference.
	* d-lang.c (d_language_data): Likewise.
	* f-lang.c (f_language_data): Likewise.
	* gnu-v3-abi.c (gnuv3_pass_by_reference): Remove use of
	default_pass_by_reference.
	* go-lang.c (go_language_data): Likewise.
	* language.c (language_pass_by_reference): Update.
	(default_pass_by_reference): Delete.
	(unknown_language_data): Delete la_pass_by_reference
	initializer.
	(auto_language_data): Likewise.
	* language.h (struct language_data): Delete la_pass_by_reference
	field.
	(language_defn::pass_by_reference_info): New member function.
	(default_pass_by_reference): Delete declaration.
	* m2-lang.c (m2_language_data): Delete la_pass_by_reference
	initializer.
	* objc-lang.c (objc_language_data): Likewise.
	* opencl-lang.c (opencl_language_data): Likewise.
	* p-lang.c (pascal_language_data): Likewise.
	* rust-lang.c (rust_language_data): Likewise.

1 files changed, 11 insertions, 10 deletions

diff --git a/gdb/language.h b/gdb/language.h
index 56260fb..cc0d0ff 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -372,11 +372,6 @@ struct language_data
     void (*la_language_arch_info) (struct gdbarch *,
 				   struct language_arch_info *);
 
-    /* Return information about whether TYPE should be passed
-       (and returned) by reference at the language level.  */
-    struct language_pass_by_ref_info (*la_pass_by_reference)
-      (struct type *type);
-
     /* Return an expression that can be used for a location
        watchpoint.  TYPE is a pointer type that points to the memory
        to watch, and ADDR is the address of the watched memory.  */
@@ -497,6 +492,17 @@ struct language_defn : language_data
 					const struct block *var_block,
 					struct frame_info *frame) const;
 
+  /* Return information about whether TYPE should be passed
+     (and returned) by reference at the language level.  The default
+     implementation returns a LANGUAGE_PASS_BY_REF_INFO initialised in its
+     default state.  */
+
+  virtual struct language_pass_by_ref_info pass_by_reference_info
+	(struct type *type) const
+  {
+    return {};
+  }
+
   /* List of all known languages.  */
   static const struct language_defn *languages[nr_languages];
 };
@@ -669,11 +675,6 @@ extern const char *default_word_break_characters (void);
    (and returned) by reference at the language level.  */
 struct language_pass_by_ref_info language_pass_by_reference (struct type *type);
 
-/* Return a default struct that provides pass-by-reference information
-   about the given TYPE.  Languages should update the default values
-   as appropriate.  */
-struct language_pass_by_ref_info default_pass_by_reference (struct type *type);
-
 /* The default implementation of la_print_typedef.  */
 void default_print_typedef (struct type *type, struct symbol *new_symbol,
 			    struct ui_file *stream);