options: handle choice -> flag fallback automatically

In the past it happened quite often that flag options (yes/no) were
changed to choice options (yes/no/some more). The problem with this was
that while flag options don't need a parameter, this wasn't the case
with choice options. A hack was introduced to compensate for this:
setting M_OPT_OPTIONAL_PARAM on the option, and an empty string ("") was
added as choice, so that the choice could be used like a flag. So, for
example, "--mute" would set the choice "".

Fix this by 1. not requiring a parameter if there's a "yes" choice, and
2. redirect an empty parameter to "yes". The effect is that a choice
option with the choices ["yes", "no"] is pretty much equivalent to a
flag option.

1 files changed, 17 insertions, 3 deletions

diff --git a/options/m_option.c b/options/m_option.c
index 699ecb4539..b5f9930068 100644
--- a/options/m_option.c
+++ b/options/m_option.c
@@ -74,9 +74,15 @@ char *m_option_strerror(int code)
 
 int m_option_required_params(const m_option_t *opt)
 {
-    if (((opt->flags & M_OPT_OPTIONAL_PARAM) ||
-            (opt->type->flags & M_OPT_TYPE_OPTIONAL_PARAM)))
+    if (opt->type->flags & M_OPT_TYPE_OPTIONAL_PARAM)
         return 0;
+    if (opt->type == &m_option_type_choice) {
+        struct m_opt_choice_alternatives *alt;
+        for (alt = opt->priv; alt->name; alt++) {
+            if (strcmp(alt->name, "yes") == 0)
+                return 0;
+        }
+    }
     return 1;
 }
 
@@ -535,9 +541,17 @@ static int parse_choice(struct mp_log *log, const struct m_option *opt,
                         struct bstr name, struct bstr param, void *dst)
 {
     struct m_opt_choice_alternatives *alt = opt->priv;
-    for ( ; alt->name; alt++)
+    for ( ; alt->name; alt++) {
         if (!bstrcmp0(param, alt->name))
             break;
+    }
+    if (!alt->name && param.len == 0) {
+        // allow flag-style options, e.g. "--mute" implies "--mute=yes"
+        for (alt = opt->priv; alt->name; alt++) {
+            if (!strcmp("yes", alt->name))
+                break;
+        }
+    }
     if (!alt->name) {
         if (param.len == 0)
             return M_OPT_MISSING_PARAM;