gdb: Convert language la_read_var_value field to a method

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

An interesting aspect of this change is that the implementation of
language_defn::read_var_value is actually in findvar.c.  This is
partly historical, the new language_defn::read_var_value is a rename
of default_read_var_value, which was already in that file, but also,
that is the file that contains the helper functions needed by the
read_var_value method, so it makes sens that the method implementation
should continue to live there (I think).

There should be no user visible changes after this commit.

gdb/ChangeLog:

	* ada-lang.c (ada_read_var_value): Delete function, move
	implementation to...
	(ada_language::read_var_value): ...here.
	(ada_language_data): Delete la_read_var_value initializer.
	* c-lang.c (c_language_data): Likewise.
	(cplus_language_data): Likewise.
	(minimal_language_data): Likewise.
	* d-lang.c (d_language_data): Likewise.
	* f-lang.c (f_language_data): Likewise.
	* findvar.c (default_read_var_value): Rename to...
	(language_defn::read_var_value): ...this.
	* findvar.c (read_var_value): Update header comment, and change to
	call member function instead of function pointer.
	* go-lang.c (go_language_data): Likewise.
	* language.c (unknown_language_data): Delete la_read_var_value
	initializer.
	(auto_language_data): Likewise.
	* language.h (struct language_data): Delete la_read_var_value
	field.
	(language_defn::read_var_value): New member function.
	(default_read_var_value): Delete declaration.
	* m2-lang.c (m2_language_data): Delete la_read_var_value
	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.
	* value.h (default_read_var_value): Delete declaration.

1 files changed, 15 insertions, 15 deletions

diff --git a/gdb/language.h b/gdb/language.h
index 8960f1e..56260fb 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -272,21 +272,6 @@ struct language_data
     void (*la_value_print) (struct value *, struct ui_file *,
 			    const struct value_print_options *);
 
-    /* Given a symbol VAR, the corresponding block VAR_BLOCK (if any) and a
-       stack frame id FRAME, read the value of the variable and return (pointer
-       to a) struct value containing the value.
-
-       VAR_BLOCK is needed if there's a possibility for VAR to be outside
-       FRAME.  This is what happens if FRAME correspond to a nested function
-       and VAR is defined in the outer function.  If callers know that VAR is
-       located in FRAME or is global/static, NULL can be passed as VAR_BLOCK.
-
-       Throw an error if the variable cannot be found.  */
-
-    struct value *(*la_read_var_value) (struct symbol *var,
-					const struct block *var_block,
-					struct frame_info *frame);
-
     /* PC is possibly an unknown languages trampoline.
        If that PC falls in a trampoline belonging to this language,
        return the address of the first pc in the real function, or 0
@@ -497,6 +482,21 @@ struct language_defn : language_data
 				  struct ui_file *stream,
 				  const value_print_options *options) const;
 
+  /* Given a symbol VAR, the corresponding block VAR_BLOCK (if any) and a
+     stack frame id FRAME, read the value of the variable and return (pointer
+     to a) struct value containing the value.
+
+     VAR_BLOCK is needed if there's a possibility for VAR to be outside
+     FRAME.  This is what happens if FRAME correspond to a nested function
+     and VAR is defined in the outer function.  If callers know that VAR is
+     located in FRAME or is global/static, NULL can be passed as VAR_BLOCK.
+
+     Throw an error if the variable cannot be found.  */
+
+  virtual struct value *read_var_value (struct symbol *var,
+					const struct block *var_block,
+					struct frame_info *frame) const;
+
   /* List of all known languages.  */
   static const struct language_defn *languages[nr_languages];
 };