Allow to document user-defined aliases.

Compared to the previous version, this version fixes the comments reported by
Tom Tromey and ensures that the 'help some-user-documented-alias'
shows the alias definition to ensure the user understands this is an
alias even if specifically documented.

When using 'help ALIASNAME', GDB shows the help of the aliased command.
This is a good default behaviour.

However, GDB alias command allows to define aliases with arguments
possibly changing or tuning significantly the behaviour of
the aliased command.  In such a case, showing the help of the aliased
command might not be ideal.

This is particularly true when defining an alias as a set of
nested 'with' followed by a last command to launch, such as:
  (gdb) alias pp10 = with print pretty -- with print elements 10 -- print
Asking 'help pp10' shows the help of the 'with' command, which is
not particularly useful:
  (gdb) help pp10
  with, pp10, w
    alias pp10 = with print pretty -- with print elements 10 -- print
  Temporarily set SETTING to VALUE, run COMMAND, and restore SETTING.
  Usage: with SETTING [VALUE] [-- COMMAND]
  ....

Such an alias can now be documented by the user:
  (gdb) document pp10
  >Pretty printing an expressiong, printing 10 elements.
  >Usage: pp10 [PRINT-COMMAND-OPTIONS] EXP
  >See 'help print' for more information.
  >end
  (gdb) help pp10
    alias pp10 = with print pretty -- with print elements 10 -- print
  Pretty printing an expressiong, printing 10 elements.
  Usage: pp10 [PRINT-COMMAND-OPTIONS] EXP
  See 'help print' for more information.
  (gdb)

When a user-defined alias is documented specifically, help and apropos
use the provided alias documentation instead of the documentation of
the aliased command.

Such a documented alias is also not shown anymore in the help of the
aliased command, and the alias is not listed anymore in the help
of the aliased command.  In particular for cases such as pp10 example above,
indicating that pp10 is an alias of the 'with' command is confusing.
This commit is contained in:
Philippe Waroquiers 2022-04-18 11:21:09 +02:00
parent 8b1a24e546
commit effcf7b144
5 changed files with 146 additions and 34 deletions

View file

@ -99,6 +99,16 @@ maintenance print frame-id [ LEVEL ]
* Changed commands
document user-defined
It is now possible to document user-defined aliases.
When a user-defined alias is documented, the help and apropos commands
use the provided documentation instead of the documentation of the
aliased command.
Documenting a user-defined alias is particularly useful when the alias
is a set of nested 'with' commands to avoid showing the help of
the with command for an alias that will in fact launch the
last command given in the nested commands.
maintenance info line-table
Add a PROLOGUE-END column to the output which indicates that an
entry corresponds to an address where a breakpoint should be placed

View file

@ -1349,6 +1349,18 @@ fput_command_name_styled (const cmd_list_element &c, struct ui_file *stream)
prefixname.c_str (), c.name);
}
/* True if ALIAS has a user-defined documentation. */
static bool
user_documented_alias (const cmd_list_element &alias)
{
gdb_assert (alias.is_alias ());
/* Alias is user documented if it has an allocated documentation
that differs from the aliased command. */
return (alias.doc_allocated
&& strcmp (alias.doc, alias.alias_target->doc) != 0);
}
/* Print the definition of alias C using title style for alias
and aliased command. */
@ -1364,20 +1376,22 @@ fput_alias_definition_styled (const cmd_list_element &c,
gdb_printf (stream, " %s\n", c.default_args.c_str ());
}
/* Print the definition of the aliases of CMD that have default args. */
/* Print the definition of CMD aliases not deprecated and having default args
and not specifically documented by the user. */
static void
fput_aliases_definition_styled (const cmd_list_element &cmd,
struct ui_file *stream)
{
for (const cmd_list_element &alias : cmd.aliases)
if (!alias.cmd_deprecated && !alias.default_args.empty ())
if (!alias.cmd_deprecated
&& !user_documented_alias (alias)
&& !alias.default_args.empty ())
fput_alias_definition_styled (alias, stream);
}
/* If C has one or more aliases, style print the name of C and
the name of its aliases, separated by commas.
/* If C has one or more aliases, style print the name of C and the name of its
aliases not documented specifically by the user, separated by commas.
If ALWAYS_FPUT_C_NAME, print the name of C even if it has no aliases.
If one or more names are printed, POSTFIX is printed after the last name.
*/
@ -1389,11 +1403,11 @@ fput_command_names_styled (const cmd_list_element &c,
{
/* First, check if we are going to print something. That is, either if
ALWAYS_FPUT_C_NAME is true or if there exists at least one non-deprecated
alias. */
alias not documented specifically by the user. */
auto print_alias = [] (const cmd_list_element &alias)
{
return !alias.cmd_deprecated;
return !alias.cmd_deprecated && !user_documented_alias (alias);
};
bool print_something = always_fput_c_name;
@ -1474,11 +1488,11 @@ apropos_cmd (struct ui_file *stream,
/* Walk through the commands. */
for (c=commandlist;c;c=c->next)
{
if (c->is_alias ())
if (c->is_alias () && !user_documented_alias (*c))
{
/* Command aliases/abbreviations are skipped to ensure we print the
doc of a command only once, when encountering the aliased
command. */
/* Command aliases/abbreviations not specifically documented by the
user are skipped to ensure we print the doc of a command only once,
when encountering the aliased command. */
continue;
}
@ -1571,11 +1585,24 @@ help_cmd (const char *command, struct ui_file *stream)
number of this class so that the commands in the class will be
listed. */
if (alias == nullptr || !user_documented_alias (*alias))
{
/* Case of a normal command, or an alias not explictly
documented by the user. */
/* If the user asked 'help somecommand' and there is no alias,
the false indicates to not output the (single) command name. */
fput_command_names_styled (*c, false, "\n", stream);
fput_aliases_definition_styled (*c, stream);
gdb_puts (c->doc, stream);
}
else
{
/* Case of an alias explictly documented by the user.
Only output the alias definition and its explicit documentation. */
fput_alias_definition_styled (*alias, stream);
fput_command_names_styled (*alias, false, "\n", stream);
gdb_puts (alias->doc, stream);
}
gdb_puts ("\n", stream);
if (!c->is_prefix () && !c->is_command_class_help ())

View file

@ -1500,26 +1500,35 @@ define_command (const char *comname, int from_tty)
do_define_command (comname, from_tty, nullptr);
}
/* Document a user-defined command. If COMMANDS is NULL, then this is a
top-level call and the document will be read using read_command_lines.
Otherwise, it is a "document" command in an existing command and the
commands are provided. */
/* Document a user-defined command or user defined alias. If COMMANDS is NULL,
then this is a top-level call and the document will be read using
read_command_lines. Otherwise, it is a "document" command in an existing
command and the commands are provided. */
static void
do_document_command (const char *comname, int from_tty,
const counted_command_line *commands)
{
struct cmd_list_element *c, **list;
const char *tem;
struct cmd_list_element *alias, *prefix_cmd, *c;
const char *comfull;
comfull = comname;
list = validate_comname (&comname);
validate_comname (&comname);
tem = comname;
c = lookup_cmd (&tem, *list, "", NULL, 0, 1);
lookup_cmd_composition (comfull, &alias, &prefix_cmd, &c);
if (c->theclass != class_user)
if (c->theclass != class_user
&& (alias == nullptr || alias->theclass != class_alias))
{
if (alias == nullptr)
error (_("Command \"%s\" is built-in."), comfull);
else
error (_("Alias \"%s\" is built-in."), comfull);
}
/* If we found an alias of class_alias, the user is documenting this
user-defined alias. */
if (alias != nullptr)
c = alias;
counted_command_line doclines;
@ -1532,6 +1541,7 @@ do_document_command (const char *comname, int from_tty,
else
doclines = *commands;
if (c->doc_allocated)
xfree ((char *) c->doc);
{
@ -1553,6 +1563,7 @@ do_document_command (const char *comname, int from_tty,
}
c->doc = doc;
c->doc_allocated = 1;
}
}
@ -1681,8 +1692,8 @@ _initialize_cli_script ()
its prefixes. */
document_cmd_element = add_com ("document", class_support, document_command,
_("\
Document a user-defined command.\n\
Give command name as argument. Give documentation on following lines.\n\
Document a user-defined command or user-defined alias.\n\
Give command or alias name as argument. Give documentation on following lines.\n\
End with a line of just \"end\"."));
set_cmd_completer (document_cmd_element, command_completer);
define_cmd_element = add_com ("define", class_support, define_command, _("\

View file

@ -2265,11 +2265,20 @@ one or more aliases, @value{GDBN} will display a first line with
the command name and all its aliases separated by commas.
This first line will be followed by the full definition of all aliases
having default arguments.
When asking the help for an alias, the documentation for the aliased
command is shown.
A user-defined alias can optionally be documented using the
@code{document} command (@pxref{Define, document}). @value{GDBN} then
considers this alias as different from the aliased command: this alias
is not listed in the aliased command help output, and asking help for
this alias will show the documentation provided for the alias instead of
the documentation of the aliased command.
@kindex apropos
@item apropos [-v] @var{regexp}
The @code{apropos} command searches through all of the @value{GDBN}
commands, and their documentation, for the regular expression specified in
commands and aliases, and their documentation, for the regular expression specified in
@var{args}. It prints out all matches found. The optional flag @samp{-v},
which stands for @samp{verbose}, indicates to output the full documentation
of the matching commands and highlight the parts of the documentation
@ -27967,6 +27976,13 @@ You may use the @code{document} command again to change the
documentation of a command. Redefining the command with @code{define}
does not change the documentation.
It is also possible to document user-defined aliases. The alias documentation
will then be used by the @code{help} and @code{apropos} commands
instead of the documentation of the aliased command.
Documenting a user-defined alias is particularly useful when defining
an alias as a set of nested @code{with} commands
(@pxref{Command aliases default args}).
@kindex define-prefix
@item define-prefix @var{commandname}
Define or mark the command @var{commandname} as a user-defined prefix
@ -28641,6 +28657,14 @@ by the user.
For more information about the @code{with} command usage,
see @ref{Command Settings}.
By default, asking the help for an alias shows the documentation of
the aliased command. When the alias is a set of nested commands, @code{help}
of an alias shows the documentation of the first command. This help
is not particularly useful for an alias such as @code{pp10}.
For such an alias, it is useful to give a specific documentation
using the @code{document} command (@pxref{Define, document}).
@c Python docs live in a separate file.
@include python.texi

View file

@ -128,8 +128,48 @@ gdb_test "apropos handle signal" "handle -- Specify how to handle signals\."
gdb_test "apropos apropos" "apropos -- Search for commands matching a REGEXP.*"
# Test apropos for commands having aliases.
gdb_test_no_output "alias mybt = backtrace" "define mybt alias"
gdb_test_no_output "alias mybt10 = backtrace 10" "define mybt10 alias"
gdb_test "apropos Print backtrace of all stack frames, or innermost COUNT frames\." \
"backtrace, where, bt -- Print backtrace of all stack frames, or innermost COUNT frames\."
"backtrace, mybt10, mybt, where, bt -- Print backtrace of all stack frames, or innermost COUNT frames\.\[\r\n\]+ alias mybt10 = backtrace 10"
# Test help for commands having aliases.
gdb_test "help bt" "backtrace, where, bt\[\r\n\]+Print backtrace of all stack frames, or innermost COUNT frames\..*"
gdb_test "help bt" "backtrace, mybt10, mybt, where, bt\[\r\n\]+ alias mybt10 = backtrace 10\[\r\n\]+Print backtrace of all stack frames, or innermost COUNT frames\..*"
# Document the aliases. The apropos and help commands should then consider them
# as "standalone" commands.
gdb_test_multiple "document mybt" "document alias: mybt" {
-re "Type documentation for \"mybt\".\r\nEnd with a line saying just \"end\".\r\n>$" {
gdb_test "An alias of command backtrace without any args.\nend" \
"" \
"document alias: mybt"
}
}
gdb_test_multiple "document mybt10" "document alias: mybt10" {
-re "Type documentation for \"mybt10\".\r\nEnd with a line saying just \"end\".\r\n>$" {
gdb_test "An alias of command backtrace with arg 10.\nend" \
"" \
"document alias: mybt10"
}
}
# As the aliases are now documented, they do not appear in apropos/help backtrace output anymore.
gdb_test "apropos Print backtrace of all stack frames, or innermost COUNT frames\." \
"backtrace, where, bt -- Print backtrace of all stack frames, or innermost COUNT frames\." \
"apropos after documenting aliases"
gdb_test "help bt" "backtrace, where, bt\[\r\n\]+Print backtrace of all stack frames, or innermost COUNT frames\..*" \
"help after documenting aliases"
# Check apropos and help use the alias documentation.
gdb_test "apropos An alias of command backtrace with arg 10" \
"mybt10 -- An alias of command backtrace with arg 10\." \
"apropos after documenting aliases showing mybt10 doc"
gdb_test "help mybt" " alias mybt = backtrace \[\r\n\]+An alias of command backtrace without any args\." \
"help mybt after documenting aliases showing mybt doc"
# Check pre-defined aliases cannot be documented.
gdb_test "document where" "Alias \"where\" is built-in.*" \
"documenting builtin where alias disallowed"