Fix build with Python 3.4 (PR python/16784)

The type of the function pointer PyOS_ReadlineFunctionPointer (part of the
Python C API), which we use, slightly changed starting with Python 3.4. The
signature went from

PyAPI_DATA(char) *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, char *);

to

PyAPI_DATA(char) *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, const char *);

The parameter that changed is the prompt text.

This commits adjust gdb accordingly by making the prompt_arg parameter
const, as well as the fallouts of that. I needed to rework how
annotations are added to the prompt, since the it is now const. If
annotations are enabled, it will make a copy of the prompt overwrite the
prompt variable that is used throughout the function. Otherwise, no copy
is done and the original prompt_arg value is passed.

I changed the signature of deprecated_readline_hook. I would've changed any
user of it, but it seems like nothing is using it,

Built-tested with python 2.7.x, 3.3.y and 3.4.z.

gdb/ChangeLog:

	* defs.h (gdb_readline): Constify argument.
	(gdb_readline_wrapper): Same.
	(command_line_input): Same.
	(deprecated_readline_hook): Same.
	* top.c (deprecated_readline_hook): Same.
	(gdb_readline): Same.
	(gdb_readline_wrapper): Same.
	(command_line_input): Constify argument. Pass prompt to
	called functions instead of local_prompt, overwriting prompt
	if using annotations.
	* event-top.h (display_gdb_prompt): Constify argument.
	* event-top.c (display_gdb_prompt): Same.
	* python/py-gdb-readline.c (gdbpy_readline_wrapper): Constify
	argument if building with Python 3.4 and up.

Signed-off-by: Simon Marchi <simon.marchi@ericsson.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/gdb/defs.h b/gdb/defs.h
index 7920938d18e..7b5bc0628a3 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -277,11 +277,11 @@ extern void print_transfer_performance (struct ui_file *stream,
 
 typedef void initialize_file_ftype (void);
 
-extern char *gdb_readline (char *);
+extern char *gdb_readline (const char *);
 
-extern char *gdb_readline_wrapper (char *);
+extern char *gdb_readline_wrapper (const char *);
 
-extern char *command_line_input (char *, int, char *);
+extern char *command_line_input (const char *, int, char *);
 
 extern void print_prompt (void);
 
@@ -664,7 +664,7 @@ extern void (*deprecated_warning_hook) (const char *, va_list)
 extern void (*deprecated_interactive_hook) (void);
 extern void (*deprecated_readline_begin_hook) (char *, ...)
      ATTRIBUTE_FPTR_PRINTF_1;
-extern char *(*deprecated_readline_hook) (char *);
+extern char *(*deprecated_readline_hook) (const char *);
 extern void (*deprecated_readline_end_hook) (void);
 extern void (*deprecated_register_changed_hook) (int regno);
 extern void (*deprecated_context_hook) (int);