Re: [RFA] Remove a cleanup from parse_expression_for_completion

Tom Tromey
2018-02-20T04:39:26Z

>>>>> "Simon" == Simon Marchi <simon.marchi@polymtl.ca> writes:

Simon> On 2018-02-16 18:02, Tom Tromey wrote:
>> This removes a cleanup from parse_expression_for_completion, by
>> changing various expression-completion functions to use std::string
>> rather than explicit malloc+free.

Simon> That looks good to me. You can go a bit further if you want and make
Simon> add_struct_fields take a const std::string reference as well.

Here's an updated patch. Let me know what you think.

Tom

commit a922232c1fc11a5f932140d8dfa8fcea963cecad
Author: Tom Tromey <tom@tromey.com>
Date: Thu Feb 15 22:41:03 2018 -0700

Remove a cleanup from parse_expression_for_completion

This removes a cleanup from parse_expression_for_completion, by
changing various expression-completion functions to use std::string
rather than explicit malloc+free.

Regression tested by the buildbot.

gdb/ChangeLog
2018-02-19 Tom Tromey <tom@tromey.com>

* value.h: (extract_field_op): Update.
* eval.c (extract_field_op): Return a const char *.
* expression.h (parse_expression_for_completion): Update.
* completer.c (complete_expression): Update.
(add_struct_fields): Make fieldname std::string. Remove namelen.
* parse.c (expout_completion_name): Now a std::string.
(mark_completion_tag, parse_exp_in_context_1): Update.
(parse_expression_for_completion): Change "name" to std::string*.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cd8ef6653d..ac2840d0cb 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,14 @@
+2018-02-19 Tom Tromey <tom@tromey.com>
+
+ * value.h: (extract_field_op): Update.
+ * eval.c (extract_field_op): Return a const char *.
+ * expression.h (parse_expression_for_completion): Update.
+ * completer.c (complete_expression): Update.
+ (add_struct_fields): Make fieldname std::string. Remove namelen.
+ * parse.c (expout_completion_name): Now a std::string.
+ (mark_completion_tag, parse_exp_in_context_1): Update.
+ (parse_expression_for_completion): Change "name" to std::string*.
+
2018-02-19 Alan Hayward <alan.hayward@arm.com>

* Makefile.in: (COMMON_SFILES): Add common/*.c files.
diff --git a/gdb/completer.c b/gdb/completer.c
index a71bd368ff..6d6d52a109 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -962,7 +962,7 @@ location_completer_handle_brkchars (struct cmd_list_element *ignore,

static void
add_struct_fields (struct type *type, completion_list &output,
- char *fieldname, int namelen)
+ const std::string &fieldname)
{
int i;
int computed_type_name = 0;
@@ -973,20 +973,20 @@ add_struct_fields (struct type *type, completion_list &output,
{
if (i < TYPE_N_BASECLASSES (type))
add_struct_fields (TYPE_BASECLASS (type, i),
- output, fieldname, namelen);
+ output, fieldname);
else if (TYPE_FIELD_NAME (type, i))
{
if (TYPE_FIELD_NAME (type, i)[0] != '\0')
{
if (! strncmp (TYPE_FIELD_NAME (type, i),
- fieldname, namelen))
+ fieldname.c_str (), fieldname.size ()))
output.emplace_back (xstrdup (TYPE_FIELD_NAME (type, i)));
}
else if (TYPE_CODE (TYPE_FIELD_TYPE (type, i)) == TYPE_CODE_UNION)
{
/* Recurse into anonymous unions. */
add_struct_fields (TYPE_FIELD_TYPE (type, i),
- output, fieldname, namelen);
+ output, fieldname);
}
}
}
@@ -995,7 +995,7 @@ add_struct_fields (struct type *type, completion_list &output,
{
const char *name = TYPE_FN_FIELDLIST_NAME (type, i);

- if (name && ! strncmp (name, fieldname, namelen))
+ if (name && ! strncmp (name, fieldname.c_str (), fieldname.size ()))
{
if (!computed_type_name)
{
@@ -1016,12 +1016,11 @@ complete_expression (completion_tracker &tracker,
const char *text, const char *word)
{
struct type *type = NULL;
- char *fieldname;
+ std::string fieldname;
enum type_code code = TYPE_CODE_UNDEF;

/* Perform a tentative parse of the expression, to see whether a
field completion is required. */
- fieldname = NULL;
TRY
{
type = parse_expression_for_completion (text, &fieldname, &code);
@@ -1032,7 +1031,7 @@ complete_expression (completion_tracker &tracker,
}
END_CATCH

- if (fieldname && type)
+ if (!fieldname.empty () && type)
{
for (;;)
{
@@ -1045,25 +1044,19 @@ complete_expression (completion_tracker &tracker,
if (TYPE_CODE (type) == TYPE_CODE_UNION
|| TYPE_CODE (type) == TYPE_CODE_STRUCT)
{
- int flen = strlen (fieldname);
completion_list result;

- add_struct_fields (type, result, fieldname, flen);
- xfree (fieldname);
+ add_struct_fields (type, result, fieldname);
tracker.add_completions (std::move (result));
return;
}
}
- else if (fieldname && code != TYPE_CODE_UNDEF)
+ else if (!fieldname.empty () && code != TYPE_CODE_UNDEF)
{
- struct cleanup *cleanup = make_cleanup (xfree, fieldname);
-
- collect_symbol_completion_matches_type (tracker, fieldname, fieldname,
- code);
- do_cleanups (cleanup);
+ collect_symbol_completion_matches_type (tracker, fieldname.c_str (),
+ fieldname.c_str (), code);
return;
}
- xfree (fieldname);

complete_files_symbols (tracker, text, word);
}
diff --git a/gdb/eval.c b/gdb/eval.c
index 6f74c41b9f..4899011a58 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -272,7 +272,7 @@ fetch_subexp_value (struct expression *exp, int *pc, struct value **valp,
subexpression of the left-hand-side of the dereference. This is
used when completing field names. */

-char *
+const char *
extract_field_op (struct expression *exp, int *subexp)
{
int tem;
diff --git a/gdb/expression.h b/gdb/expression.h
index 030f2f08e7..f9b5b1e820 100644
--- a/gdb/expression.h
+++ b/gdb/expression.h
@@ -101,7 +101,8 @@ extern expression_up parse_expression (const char *);
extern expression_up parse_expression_with_language (const char *string,
enum language lang);

-extern struct type *parse_expression_for_completion (const char *, char **,
+extern struct type *parse_expression_for_completion (const char *,
+ std::string *,
enum type_code *);

extern expression_up parse_exp_1 (const char **, CORE_ADDR pc,
diff --git a/gdb/parse.c b/gdb/parse.c
index e3f1306a17..4c09ebec7d 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -88,7 +88,7 @@ static int expout_last_struct = -1;
static enum type_code expout_tag_completion_type = TYPE_CODE_UNDEF;

/* The token for tagged type name completion. */
-static char *expout_completion_name;
+static std::string expout_completion_name;

\f
static unsigned int expressiondebug = 0;
@@ -569,15 +569,13 @@ mark_completion_tag (enum type_code tag, const char *ptr, int length)
{
gdb_assert (parse_completion
&& expout_tag_completion_type == TYPE_CODE_UNDEF
- && expout_completion_name == NULL
+ && expout_completion_name.empty ()
&& expout_last_struct == -1);
gdb_assert (tag == TYPE_CODE_UNION
|| tag == TYPE_CODE_STRUCT
|| tag == TYPE_CODE_ENUM);
expout_tag_completion_type = tag;
- expout_completion_name = (char *) xmalloc (length + 1);
- memcpy (expout_completion_name, ptr, length);
- expout_completion_name[length] = '\0';
+ expout_completion_name = std::string (ptr, length);
}

\f
@@ -1137,8 +1135,7 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
type_stack.depth = 0;
expout_last_struct = -1;
expout_tag_completion_type = TYPE_CODE_UNDEF;
- xfree (expout_completion_name);
- expout_completion_name = NULL;
+ expout_completion_name.clear ();

comma_terminates = comma;

@@ -1277,11 +1274,10 @@ parse_expression_with_language (const char *string, enum language lang)
reference; furthermore, if the parsing ends in the field name,
return the field name in *NAME. If the parsing ends in the middle
of a field reference, but the reference is somehow invalid, throw
- an exception. In all other cases, return NULL. Returned non-NULL
- *NAME must be freed by the caller. */
+ an exception. In all other cases, return NULL. */

struct type *
-parse_expression_for_completion (const char *string, char **name,
+parse_expression_for_completion (const char *string, std::string *name,
enum type_code *code)
{
expression_up exp;
@@ -1306,23 +1302,21 @@ parse_expression_for_completion (const char *string, char **name,
if (expout_tag_completion_type != TYPE_CODE_UNDEF)
{
*code = expout_tag_completion_type;
- *name = expout_completion_name;
- expout_completion_name = NULL;
+ *name = std::move (expout_completion_name);
return NULL;
}

if (expout_last_struct == -1)
return NULL;

- *name = extract_field_op (exp.get (), &subexp);
- if (!*name)
+ const char *fieldname = extract_field_op (exp.get (), &subexp);
+ if (fieldname == NULL)
return NULL;

+ *name = fieldname;