path: start special espansion with ~~name instead of ~name

Since commit 7381db60, strings like "~desktop/" were expanded as
platform-specific paths by mpv. Apparently this similarity to standard
Unix shell expansion caused confusion, so change it to "~~desktop/". The
shell doesn't expand this, so it should be better.

DOCS/man/mpv.rst

@@ -332,14 +332,14 @@ Some mpv options interpret paths starting with ``~``. Currently, the prefix
 ``~/`` expands to the user's home directory. (The trailing ``/`` is always
 required.) There are the following paths as well:
 
-=============== ================================================================
-Name            Meaning
-=============== ================================================================
-``~home/``      same as ``~~/``
-``~global/``    the global config path, if available
-``~osxbundle/`` the OSX bundle resource path (OSX only)
-``~desktop/``   the path to the desktop (win32, OSX)
-=============== ================================================================
+================ ===============================================================
+Name             Meaning
+================ ===============================================================
+``~~home/``      same as ``~~/``
+``~~global/``    the global config path, if available (not on win32)
+``~~osxbundle/`` the OSX bundle resource path (OSX only)
+``~~desktop/``   the path to the desktop (win32, OSX)
+================ ===============================================================
 
 
 Per-File Options
@@ -648,7 +648,7 @@ the ``pseudo-gui`` profile being predefined with the following contents:
     terminal=no
     force-window=yes
     idle=once
-    screenshot-directory=~desktop/
+    screenshot-directory=~~desktop/
 
 This follows the mpv config file format. To customize pseudo-GUI mode, you can
 put your own ``pseudo-gui`` profile into your ``mpv.conf``. This profile will

options/path.c

@@ -182,7 +182,7 @@ char *mp_get_user_path(void *talloc_ctx, struct mpv_global *global,
                 res = mp_find_config_file(talloc_ctx, global, rest0);
             } else if (bstr_equals0(prefix, "")) {
                 res = mp_path_join(talloc_ctx, bstr0(getenv("HOME")), rest);
-            } else {
+            } else if (bstr_eatstart0(&prefix, "~")) {
                 char type[80];
                 snprintf(type, sizeof(type), "%.*s", BSTR_P(prefix));
                 const char *p = mp_get_platform_path(talloc_ctx, type);

player/main.c

@@ -100,7 +100,7 @@ static const char def_config[] =
     "terminal=no\n"
     "force-window=yes\n"
     "idle=once\n"
-    "screenshot-directory=~desktop/\n";
+    "screenshot-directory=~~desktop/\n";
 
 static pthread_mutex_t terminal_owner_lock = PTHREAD_MUTEX_INITIALIZER;
 static struct MPContext *terminal_owner;