[PATCH 0/2] Improving tab completion for watch commands

[PATCH 0/2] Improving tab completion for watch commands

[Andrew Burgess]

The good stuff is in patch #2.

Thanks,
Andrew

---

Andrew Burgess (2):
  gdb: convert some function arguments from int to bool
  gdb: update command completion for watch, awatch, and rwatch

 gdb/ChangeLog                         |  27 +++++
 gdb/breakpoint.c                      | 146 +++++++++++++++++++-------
 gdb/breakpoint.h                      |   6 +-
 gdb/eval.c                            |   2 +-
 gdb/mi/mi-cmd-break.c                 |   6 +-
 gdb/ppc-linux-nat.c                   |   4 +-
 gdb/testsuite/ChangeLog               |   4 +
 gdb/testsuite/gdb.base/completion.exp |  16 +++
 gdb/value.h                           |   2 +-
 9 files changed, 164 insertions(+), 49 deletions(-)

-- 
2.25.4

[PATCH 1/2] gdb: convert some function arguments from int to bool

[Andrew Burgess]

A little int to bool conversion around the 'watch' type commands.
There should be no user visible changes after this commit.

gdb/ChangeLog:

	* breakpoint.c (update_watchpoint): Pass 'false' not '0'.
	(watch_command_1): Update parameter types.  Convert locals to
	bool.
	(watch_command_wrapper): Change parameter type.
	(watch_maybe_just_location): Change locals to bool.
	(rwatch_command_wrapper): Update parameter type.
	(awatch_command_wrapper): Update parameter type.
	* breakpoint.h (watch_command_wrapper): Change parameter type.
	(rwatch_command_wrapper): Update parameter type.
	(awatch_command_wrapper): Update parameter type.
	* eval.c (fetch_subexp_value): Change parameter type.
	* ppc-linux-nat.c (ppc_linux_nat_target::check_condition): Pass
	'false' not '0'.
	* value.h (fetch_subexp_value): Change parameter type in
	declaration.
---
 gdb/ChangeLog         | 18 ++++++++++++++++++
 gdb/breakpoint.c      | 22 +++++++++++-----------
 gdb/breakpoint.h      |  6 +++---
 gdb/eval.c            |  2 +-
 gdb/mi/mi-cmd-break.c |  6 +++---
 gdb/ppc-linux-nat.c   |  4 ++--
 gdb/value.h           |  2 +-
 7 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 23278320d9d..a4ae8b2d8c9 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -1905,7 +1905,7 @@ update_watchpoint (struct watchpoint *b, int reparse)
       struct value *v, *result;
       struct program_space *frame_pspace;
 
-      fetch_subexp_value (b->exp.get (), &pc, &v, &result, &val_chain, 0);
+      fetch_subexp_value (b->exp.get (), &pc, &v, &result, &val_chain, false);
 
       /* Avoid setting b->val if it's already set.  The meaning of
 	 b->val is 'the last value' user saw, and we should update
@@ -4969,7 +4969,7 @@ watchpoint_check (bpstat bs)
 	return WP_VALUE_CHANGED;
 
       mark = value_mark ();
-      fetch_subexp_value (b->exp.get (), &pc, &new_val, NULL, NULL, 0);
+      fetch_subexp_value (b->exp.get (), &pc, &new_val, NULL, NULL, false);
 
       if (b->val_bitsize != 0)
 	new_val = extract_bitfield_from_watchpoint_value (b, new_val);
@@ -10676,7 +10676,7 @@ is_masked_watchpoint (const struct breakpoint *b)
 		hw_access: watch access (read or write) */
 static void
 watch_command_1 (const char *arg, int accessflag, int from_tty,
-		 int just_location, int internal)
+		 bool just_location, bool internal)
 {
   struct breakpoint *scope_breakpoint = NULL;
   const struct block *exp_valid_block = NULL, *cond_exp_valid_block = NULL;
@@ -10693,7 +10693,7 @@ watch_command_1 (const char *arg, int accessflag, int from_tty,
   int pc = 0;
   /* Flag to indicate whether we are going to use masks for
      the hardware watchpoint.  */
-  int use_mask = 0;
+  bool use_mask = false;
   CORE_ADDR mask = 0;
 
   /* Make sure that we actually have parameters to parse.  */
@@ -10760,7 +10760,7 @@ watch_command_1 (const char *arg, int accessflag, int from_tty,
 	      if (use_mask)
 		error(_("You can specify only one mask."));
 
-	      use_mask = just_location = 1;
+	      use_mask = just_location = true;
 
 	      mark = value_mark ();
 	      mask_value = parse_to_comma_and_eval (&value_start);
@@ -11077,7 +11077,7 @@ can_use_hardware_watchpoint (const std::vector<value_ref_ptr> &vals)
 }
 
 void
-watch_command_wrapper (const char *arg, int from_tty, int internal)
+watch_command_wrapper (const char *arg, int from_tty, bool internal)
 {
   watch_command_1 (arg, hw_write, from_tty, 0, internal);
 }
@@ -11088,14 +11088,14 @@ watch_command_wrapper (const char *arg, int from_tty, int internal)
 static void
 watch_maybe_just_location (const char *arg, int accessflag, int from_tty)
 {
-  int just_location = 0;
+  bool just_location = false;
 
   if (arg
       && (check_for_argument (&arg, "-location", sizeof ("-location") - 1)
 	  || check_for_argument (&arg, "-l", sizeof ("-l") - 1)))
-    just_location = 1;
+    just_location = true;
 
-  watch_command_1 (arg, accessflag, from_tty, just_location, 0);
+  watch_command_1 (arg, accessflag, from_tty, just_location, false);
 }
 
 static void
@@ -11105,7 +11105,7 @@ watch_command (const char *arg, int from_tty)
 }
 
 void
-rwatch_command_wrapper (const char *arg, int from_tty, int internal)
+rwatch_command_wrapper (const char *arg, int from_tty, bool internal)
 {
   watch_command_1 (arg, hw_read, from_tty, 0, internal);
 }
@@ -11117,7 +11117,7 @@ rwatch_command (const char *arg, int from_tty)
 }
 
 void
-awatch_command_wrapper (const char *arg, int from_tty, int internal)
+awatch_command_wrapper (const char *arg, int from_tty, bool internal)
 {
   watch_command_1 (arg, hw_access, from_tty, 0, internal);
 }
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index b13522e236b..4a65dd2dd43 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -1300,9 +1300,9 @@ const char *bpdisp_text (enum bpdisp disp);
 
 extern void break_command (const char *, int);
 
-extern void watch_command_wrapper (const char *, int, int);
-extern void awatch_command_wrapper (const char *, int, int);
-extern void rwatch_command_wrapper (const char *, int, int);
+extern void watch_command_wrapper (const char *, int, bool);
+extern void awatch_command_wrapper (const char *, int, bool);
+extern void rwatch_command_wrapper (const char *, int, bool);
 extern void tbreak_command (const char *, int);
 
 extern struct breakpoint_ops base_breakpoint_ops;
diff --git a/gdb/eval.c b/gdb/eval.c
index 308f4771482..2626ee6d876 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -183,7 +183,7 @@ void
 fetch_subexp_value (struct expression *exp, int *pc, struct value **valp,
 		    struct value **resultp,
 		    std::vector<value_ref_ptr> *val_chain,
-		    int preserve_errors)
+		    bool preserve_errors)
 {
   struct value *mark, *new_mark, *result;
 
diff --git a/gdb/mi/mi-cmd-break.c b/gdb/mi/mi-cmd-break.c
index 3835c02650d..ed311a6ba33 100644
--- a/gdb/mi/mi-cmd-break.c
+++ b/gdb/mi/mi-cmd-break.c
@@ -463,13 +463,13 @@ mi_cmd_break_watch (const char *command, char **argv, int argc)
   switch (type)
     {
     case REG_WP:
-      watch_command_wrapper (expr, FROM_TTY, 0);
+      watch_command_wrapper (expr, FROM_TTY, false);
       break;
     case READ_WP:
-      rwatch_command_wrapper (expr, FROM_TTY, 0);
+      rwatch_command_wrapper (expr, FROM_TTY, false);
       break;
     case ACCESS_WP:
-      awatch_command_wrapper (expr, FROM_TTY, 0);
+      awatch_command_wrapper (expr, FROM_TTY, false);
       break;
     default:
       error (_("-break-watch: Unknown watchpoint type."));
diff --git a/gdb/ppc-linux-nat.c b/gdb/ppc-linux-nat.c
index 7131134c10a..095ed577a09 100644
--- a/gdb/ppc-linux-nat.c
+++ b/gdb/ppc-linux-nat.c
@@ -2484,13 +2484,13 @@ ppc_linux_nat_target::check_condition (CORE_ADDR watch_addr,
   if (cond->elts[0].opcode != BINOP_EQUAL)
     return 0;
 
-  fetch_subexp_value (cond, &pc, &left_val, NULL, &left_chain, 0);
+  fetch_subexp_value (cond, &pc, &left_val, NULL, &left_chain, false);
   num_accesses_left = num_memory_accesses (left_chain);
 
   if (left_val == NULL || num_accesses_left < 0)
     return 0;
 
-  fetch_subexp_value (cond, &pc, &right_val, NULL, &right_chain, 0);
+  fetch_subexp_value (cond, &pc, &right_val, NULL, &right_chain, false);
   num_accesses_right = num_memory_accesses (right_chain);
 
   if (right_val == NULL || num_accesses_right < 0)
diff --git a/gdb/value.h b/gdb/value.h
index bc57f4f9012..2bd1999dc8f 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -928,7 +928,7 @@ extern value *eval_skip_value (expression *exp);
 extern void fetch_subexp_value (struct expression *exp, int *pc,
 				struct value **valp, struct value **resultp,
 				std::vector<value_ref_ptr> *val_chain,
-				int preserve_errors);
+				bool preserve_errors);
 
 extern const char *extract_field_op (struct expression *exp, int *subexp);
 
-- 
2.25.4

[PATCH 2/2] gdb: update command completion for watch, awatch, and rwatch

[Andrew Burgess]

Switch over to using new option processing mechanism for watch,
awatch, and rwatch commands.  Add command completion function.

This means that expression completion now works correctly when the
-location flag is used.  So previously:

  (gdb) watch var.<TAB><TAB>
  .... list fields of var ....

But,

  (gdb) watch -location var.<TAB><TAB>
  .... list all symbols ....

After this commit only the fields of 'var' are listed even when
'-location' is passed.

Another benefit of this change is that '-location' will now complete.

One thing to note is that previous these commands accepted both
'-location' or '-l' (these being synonyms).  The new option scheme
doesn't really allow for official short form flags, however, it does
allow for non-ambiguous sub-strings to be used.  What this means is
that currently (as these commands only have the '-location' flag) the
user can still use '-l', so there's no change there.

The interactive help text for these commands now emphasises
'-location' as the real option, but does mention that '-l' can also be
used.

gdb/ChangeLog:

	* breakpoint.c (struct watch_options): New struct.
	(watch_option_defs): New static global.
	(make_watch_options_def_group): New function.
	(watch_maybe_just_location): Convert option parsing.
	(watch_command_completer): New function.
	(_initialize_breakpoint): Build help text using options mechanism.

gdb/testsuite/ChangeLog:

	* gdb.base/completion.exp: Add new completion tests.
---
 gdb/ChangeLog                         |   9 ++
 gdb/breakpoint.c                      | 130 ++++++++++++++++++++------
 gdb/testsuite/ChangeLog               |   4 +
 gdb/testsuite/gdb.base/completion.exp |  16 ++++
 4 files changed, 128 insertions(+), 31 deletions(-)

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index a4ae8b2d8c9..27324a0c08d 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -11082,20 +11082,74 @@ watch_command_wrapper (const char *arg, int from_tty, bool internal)
   watch_command_1 (arg, hw_write, from_tty, 0, internal);
 }
 
+/* Options for the watch, awatch, and rwatch commands.  */
+
+struct watch_options
+{
+  /* For -location.  */
+  bool location = false;
+};
+
+/* Definitions of options for the "watch", "awatch", and "rwatch" commands.
+
+   Historically GDB always accepted both '-location' and '-l' flags for
+   these commands (both flags being synonyms).  When converting to the
+   newer option scheme only '-location' is added here.  That's fine (for
+   backward compatibility) as any non-ambiguous prefix of a flag will be
+   accepted, so '-l', '-loc', are now all accepted.
+
+   What this means is that, if in the future, we add any new flag here
+   that starts with '-l' then this will break backward compatibility, so
+   please, don't do that!  */
+
+static const gdb::option::option_def watch_option_defs[] = {
+  gdb::option::flag_option_def<watch_options> {
+    "location",
+    [] (watch_options *opt) { return &opt->location; },
+    N_("\
+This evaluates EXPRESSION and watches the memory to which is refers.\n\
+-l can be used as a short form of -location."),
+  },
+};
+
+/* Returns the option group used by 'watch', 'awatch', and 'rwatch'
+   commands.  */
+
+static gdb::option::option_def_group
+make_watch_options_def_group (watch_options *opts)
+{
+  return {{watch_option_defs}, opts};
+}
+
 /* A helper function that looks for the "-location" argument and then
    calls watch_command_1.  */
 
 static void
 watch_maybe_just_location (const char *arg, int accessflag, int from_tty)
 {
-  bool just_location = false;
+  watch_options opts;
+  auto grp = make_watch_options_def_group (&opts);
+  gdb::option::process_options
+    (&arg, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, grp);
+  if (arg != nullptr && *arg == '\0')
+    arg = nullptr;
+
+  watch_command_1 (arg, accessflag, from_tty, opts.location, false);
+}
 
-  if (arg
-      && (check_for_argument (&arg, "-location", sizeof ("-location") - 1)
-	  || check_for_argument (&arg, "-l", sizeof ("-l") - 1)))
-    just_location = true;
+/* Command completion for 'watch', 'awatch', and 'rwatch' commands.   */
+static void
+watch_command_completer (struct cmd_list_element *ignore,
+			 completion_tracker &tracker,
+			 const char *text, const char * /*word*/)
+{
+  const auto group = make_watch_options_def_group (nullptr);
+  if (gdb::option::complete_options
+      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_OPERAND, group))
+    return;
 
-  watch_command_1 (arg, accessflag, from_tty, just_location, false);
+  const char *word = advance_to_expression_complete_word_point (tracker, text);
+  expression_completer (ignore, tracker, text, word);
 }
 
 static void
@@ -15914,32 +15968,46 @@ If REGEX is given, only stop for libraries matching the regular expression."),
 		     CATCH_PERMANENT,
 		     CATCH_TEMPORARY);
 
-  c = add_com ("watch", class_breakpoint, watch_command, _("\
-Set a watchpoint for an expression.\n\
-Usage: watch [-l|-location] EXPRESSION\n\
-A watchpoint stops execution of your program whenever the value of\n\
-an expression changes.\n\
-If -l or -location is given, this evaluates EXPRESSION and watches\n\
-the memory to which it refers."));
-  set_cmd_completer (c, expression_completer);
-
-  c = add_com ("rwatch", class_breakpoint, rwatch_command, _("\
-Set a read watchpoint for an expression.\n\
-Usage: rwatch [-l|-location] EXPRESSION\n\
-A watchpoint stops execution of your program whenever the value of\n\
-an expression is read.\n\
-If -l or -location is given, this evaluates EXPRESSION and watches\n\
-the memory to which it refers."));
-  set_cmd_completer (c, expression_completer);
-
-  c = add_com ("awatch", class_breakpoint, awatch_command, _("\
-Set a watchpoint for an expression.\n\
-Usage: awatch [-l|-location] EXPRESSION\n\
+  const auto opts = make_watch_options_def_group (nullptr);
+
+  static const std::string watch_help = gdb::option::build_help (_("\
+Set a watchpoint for EXPRESSION.\n\
+Usage: watch [-location] EXPRESSION\n\
+\n\
+Options:\n\
+%OPTIONS%\n\
+\n\
 A watchpoint stops execution of your program whenever the value of\n\
-an expression is either read or written.\n\
-If -l or -location is given, this evaluates EXPRESSION and watches\n\
-the memory to which it refers."));
-  set_cmd_completer (c, expression_completer);
+an expression changes."), opts);
+  c = add_com ("watch", class_breakpoint, watch_command,
+	       watch_help.c_str ());
+  set_cmd_completer_handle_brkchars (c, watch_command_completer);
+
+  static const std::string rwatch_help = gdb::option::build_help (_("\
+Set a read watchpoint for EXPRESSION.\n\
+Usage: rwatch [-location] EXPRESSION\n\
+\n\
+Options:\n\
+%OPTIONS%\n\
+\n\
+A read watchpoint stops execution of your program whenever the value of\n\
+an expression is read."), opts);
+  c = add_com ("rwatch", class_breakpoint, rwatch_command,
+	       rwatch_help.c_str ());
+  set_cmd_completer_handle_brkchars (c, watch_command_completer);
+
+  static const std::string awatch_help = gdb::option::build_help (_("\
+Set an access watchpoint for EXPRESSION.\n\
+Usage: awatch [-location] EXPRESSION\n\
+\n\
+Options:\n\
+%OPTIONS%\n\
+\n\
+An access watchpoint stops execution of your program whenever the value\n\
+of an expression is either read or written."), opts);
+  c = add_com ("awatch", class_breakpoint, awatch_command,
+	       awatch_help.c_str ());
+  set_cmd_completer_handle_brkchars (c, watch_command_completer);
 
   add_info ("watchpoints", info_watchpoints_command, _("\
 Status of specified watchpoints (all watchpoints if no argument)."));
diff --git a/gdb/testsuite/gdb.base/completion.exp b/gdb/testsuite/gdb.base/completion.exp
index ac7f61ddfbc..5bbfda21b25 100644
--- a/gdb/testsuite/gdb.base/completion.exp
+++ b/gdb/testsuite/gdb.base/completion.exp
@@ -172,6 +172,11 @@ if { ![readline_is_used] } {
     return -1
 }
 
+# The bulk of this test script pre-dates the completion-support
+# library, and should probably (where possible) be converted.
+# However, for now, new tests are being added using this library.
+load_lib completion-support.exp
+
 set test "complete 'hfgfh'"
 send_gdb "hfgfh\t"
 gdb_test_multiple "" "$test" {
@@ -922,3 +927,14 @@ gdb_test_multiple "" "$test" {
 	pass "$test"
     }
 }
+
+# Check the watch commands can all complete, with and without flags.
+foreach_with_prefix cmd { "watch" "awatch" "rwatch" } {
+    foreach_with_prefix opt { "" "-l" "-location" } {
+	test_gdb_complete_multiple "${cmd} ${opt} some_union_global." \
+	    "" "f" {
+		"f1"
+		"f2"
+	    }
+    }
+}
-- 
2.25.4

Re: [PATCH 1/2] gdb: convert some function arguments from int to bool

[Tom Tromey]

>>>>> "Andrew" == Andrew Burgess <andrew.burgess@embecosm.com> writes:

Andrew> A little int to bool conversion around the 'watch' type commands.
Andrew> There should be no user visible changes after this commit.

Looks good, thanks for doing this.

Tom

Re: [PATCH 2/2] gdb: update command completion for watch, awatch, and rwatch

[Tom Tromey]

>>>>> "Andrew" == Andrew Burgess <andrew.burgess@embecosm.com> writes:

Andrew> The interactive help text for these commands now emphasises
Andrew> '-location' as the real option, but does mention that '-l' can also be
Andrew> used.

Andrew> gdb/ChangeLog:

Andrew> 	* breakpoint.c (struct watch_options): New struct.
Andrew> 	(watch_option_defs): New static global.
Andrew> 	(make_watch_options_def_group): New function.
Andrew> 	(watch_maybe_just_location): Convert option parsing.
Andrew> 	(watch_command_completer): New function.
Andrew> 	(_initialize_breakpoint): Build help text using options mechanism.

Thank you for doing this.  This looks good to me.

Andrew> +Usage: watch [-location] EXPRESSION\n\

Not relevant for this patch, but I've wondered if these Usage lines
should explain the full syntax, like '[if EXPRESSION]' and '[thread ID]'

Tom