Re: [PATCH v3 14/16] softmmu/vl: Clean up global variable shadowing

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@linaro.org> writes:

> Fix:
>
>   softmmu/vl.c:1069:44: error: declaration shadows a variable in the global 
> scope [-Werror,-Wshadow]
>   static void parse_display_qapi(const char *optarg)
>                                              ^
>   softmmu/vl.c:1224:39: error: declaration shadows a variable in the global 
> scope [-Werror,-Wshadow]
>   static void monitor_parse(const char *optarg, const char *mode, bool pretty)
>                                         ^
>   softmmu/vl.c:1634:17: error: declaration shadows a variable in the global 
> scope [-Werror,-Wshadow]
>       const char *optarg = qdict_get_try_str(qdict, "type");
>                   ^
>   softmmu/vl.c:1784:45: error: declaration shadows a variable in the global 
> scope [-Werror,-Wshadow]
>   static void object_option_parse(const char *optarg)
>                                               ^
>   
> /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/getopt.h:77:14:
>  note: previous declaration is here
>   extern char *optarg;                    /* getopt(3) external variables */
>                ^
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

How much we care about the shadowing is unclear, but that doesn't matter
if the patches make sense even if we pretend global @optarg doesn't
exist.  Let's check that.

> ---
>  softmmu/vl.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index 98e071e63b..ae1ff9887d 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -1066,12 +1066,12 @@ static void select_vgahw(const MachineClass 
> *machine_class, const char *p)
>      }
>  }
>  
> -static void parse_display_qapi(const char *optarg)
> +static void parse_display_qapi(const char *optstr)
>  {
>      DisplayOptions *opts;
>      Visitor *v;
>  
> -    v = qobject_input_visitor_new_str(optarg, "type", &error_fatal);
> +    v = qobject_input_visitor_new_str(optstr, "type", &error_fatal);
>  
>      visit_type_DisplayOptions(v, NULL, &opts, &error_fatal);
>      QAPI_CLONE_MEMBERS(DisplayOptions, &dpy, opts);

The actual argument is a string that is either JSON or KEY=VALUE,...
The fact that it's always an option argument now (actually the value of
global @optarg) is irrelevant here.

parse_display_qapi() passes its parameter to
qobject_input_visitor_new_str() parameter @str, which passes it to
qobject_from_json() parameter @string if JSON, or else to keyval_parse()
parameter @params.

I'd rename @optarg to @str here, like you do in the next hunk, to not
suggest a connection to CLI.  Not a demand.

> @@ -1221,21 +1221,21 @@ static int mon_init_func(void *opaque, QemuOpts 
> *opts, Error **errp)
>      return monitor_init_opts(opts, errp);
>  }
>  
> -static void monitor_parse(const char *optarg, const char *mode, bool pretty)
> +static void monitor_parse(const char *str, const char *mode, bool pretty)
>  {
>      static int monitor_device_index = 0;
>      QemuOpts *opts;
>      const char *p;
>      char label[32];
>  
> -    if (strstart(optarg, "chardev:", &p)) {
> +    if (strstart(str, "chardev:", &p)) {
>          snprintf(label, sizeof(label), "%s", p);
>      } else {
>          snprintf(label, sizeof(label), "compat_monitor%d",
>                   monitor_device_index);
> -        opts = qemu_chr_parse_compat(label, optarg, true);
> +        opts = qemu_chr_parse_compat(label, str, true);
>          if (!opts) {
> -            error_report("parse error: %s", optarg);
> +            error_report("parse error: %s", str);
>              exit(1);
>          }
>      }

The actual argument is either @optarg or a string literal, but that's
again irrelevant here.

> @@ -1631,13 +1631,13 @@ static const QEMUOption *lookup_opt(int argc, char 
> **argv,
>  
>  static MachineClass *select_machine(QDict *qdict, Error **errp)
>  {
> -    const char *optarg = qdict_get_try_str(qdict, "type");
> +    const char *machine_type = qdict_get_try_str(qdict, "type");
>      GSList *machines = object_class_get_list(TYPE_MACHINE, false);
>      MachineClass *machine_class;
>      Error *local_err = NULL;
>  
> -    if (optarg) {
> -        machine_class = find_machine(optarg, machines);
> +    if (machine_type) {
> +        machine_class = find_machine(machine_type, machines);
>          qdict_del(qdict, "type");
>          if (!machine_class) {
>              error_setg(&local_err, "unsupported machine type");

Obvious improvement.

> @@ -1781,20 +1781,20 @@ static void object_option_add_visitor(Visitor *v)
>      QTAILQ_INSERT_TAIL(&object_opts, opt, next);
>  }
>  
> -static void object_option_parse(const char *optarg)
> +static void object_option_parse(const char *optstr)
>  {
>      QemuOpts *opts;
>      const char *type;
>      Visitor *v;
>  
> -    if (optarg[0] == '{') {
> -        QObject *obj = qobject_from_json(optarg, &error_fatal);
> +    if (optstr[0] == '{') {
> +        QObject *obj = qobject_from_json(optstr, &error_fatal);
>  
>          v = qobject_input_visitor_new(obj);
>          qobject_unref(obj);
>      } else {
>          opts = qemu_opts_parse_noisily(qemu_find_opts("object"),
> -                                       optarg, true);
> +                                       optstr, true);
>          if (!opts) {
>              exit(1);
>          }

Same argument as for parse_display_qapi(), and same suggestion.

If this goes though my tree, I can implement my two suggestions, if you
agree.

Reviewed-by: Markus Armbruster <armbru@redhat.com>