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Fix PR 20559 - "eval" command and $arg0...$arg9/$argc substitution

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It'd be handy to be able to iterate over command arguments in
user-defined commands, in order to support optional arguments
($arg0..$argN).

I thought I could make it work with "eval", but alas, it doesn't work
currently.  E.g., with:

 define test
   set $i = 0
   while $i < $argc
     eval "print $arg%d", $i
     set $i = $i + 1
   end
 end

we get:

 (gdb) test 1
 $1 = void
 (gdb) test 1 2 3
 $2 = void
 $3 = void
 $4 = void
 (gdb)

The problem is that "eval" doesn't do user-defined command arguments
substitution after expanding its own argument.  This patch fixes that,
which makes the example above work:

 (gdb) test 1
 $1 = 1
 (gdb) test 1 2 3
 $2 = 1
 $3 = 2
 $4 = 3
 (gdb)

New test included, similar the above, but also exercises expanding
$argc.

I think this is likely to simplify many scripts out there, so I'm
adding an example to the manual and mentioning it in NEWS as well.

gdb/ChangeLog:
2016-12-02  Pedro Alves  <palves@redhat.com>

	PR cli/20559
	* NEWS: Mention "eval" expands user-defined command arguments.
	* cli/cli-script.c (execute_control_command): Adjust to rename.
	(insert_args): Rename to ...
	(insert_user_defined_cmd_args): ... this, and make extern.
	* cli/cli-script.h (insert_user_defined_cmd_args): New
	declaration.
	* printcmd.c: Include "cli/cli-script.h".
	(eval_command): Call insert_user_defined_cmd_args.

gdb/doc/ChangeLog:
2016-12-02  Pedro Alves  <palves@redhat.com>

	PR cli/20559
	* gdb.texinfo (Define): Add example of using "eval" to process a
	variable number of arguments.
	(Output) <eval>: Add anchor.

gdb/testsuite/ChangeLog:
2016-12-02  Pedro Alves  <palves@redhat.com>

	PR cli/20559
	* gdb.base/commands.exp (user_defined_command_args_eval): New
	procedure.
	(top level): Call it.
This commit is contained in:
Pedro Alves
2016-12-02 19:17:13 +00:00
parent 7ed7e438bf
commit 01770bbde9
9 changed files with 102 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
gdb/cli/cli-script.c
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@@ -41,8 +41,6 @@ recurse_read_control_structure (char * (*read_next_line_func) (void),
void (*validator)(char *, void *),
void *closure);
static std::string insert_args (const char *line);
static struct cleanup * setup_user_args (char *p);
static char *read_next_line (void);
@@ -455,7 +453,7 @@ execute_control_command (struct command_line *cmd)
case simple_control:
{
/* A simple command, execute it and return. */
std::string new_line = insert_args (cmd->line);
std::string new_line = insert_user_defined_cmd_args (cmd->line);
execute_command (&new_line[0], 0);
ret = cmd->control_type;
break;
@@ -486,7 +484,7 @@ execute_control_command (struct command_line *cmd)
print_command_trace (buffer);
/* Parse the loop control expression for the while statement. */
std::string new_line = insert_args (cmd->line);
std::string new_line = insert_user_defined_cmd_args (cmd->line);
expression_up expr = parse_expression (new_line.c_str ());
ret = simple_control;
@@ -551,7 +549,7 @@ execute_control_command (struct command_line *cmd)
print_command_trace (buffer);
/* Parse the conditional for the if statement. */
std::string new_line = insert_args (cmd->line);
std::string new_line = insert_user_defined_cmd_args (cmd->line);
expression_up expr = parse_expression (new_line.c_str ());
current = NULL;
@@ -591,7 +589,7 @@ execute_control_command (struct command_line *cmd)
{
/* Breakpoint commands list, record the commands in the
breakpoint's command list and return. */
std::string new_line = insert_args (cmd->line);
std::string new_line = insert_user_defined_cmd_args (cmd->line);
ret = commands_from_control_command (new_line.c_str (), cmd);
break;
}
@@ -782,13 +780,12 @@ locate_arg (const char *p)
return NULL;
}
/* Insert the user defined arguments stored in user_arg into the $arg
arguments found in line. */
/* See cli-script.h. */
static std::string
insert_args (const char *line)
std::string
insert_user_defined_cmd_args (const char *line)
{
/* If we are not in a user-defined function, treat $argc, $arg0, et
/* If we are not in a user-defined command, treat $argc, $arg0, et
cetera as normal convenience variables. */
if (user_args == NULL)
return line;