[glib/wip/baedert/fallthrough] Replace a bunch of fallthrough comments with an attribute

[Timm Bäder <baedert src gnome org>]

commit aeed676c0852c51429c261149cb1293698c9a3a0
Author: Timm Bäder <mail baedert org>
Date:   Fri Aug 21 05:50:02 2020 +0200

    Replace a bunch of fallthrough comments with an attribute
    
    Parsing comments is hack and clang doesn't do it, so switch to
    G_GNUC_FALLTHROUGH, which exists for exactly this case.

 glib/giounix.c  | 2 +-
 glib/gscanner.c | 4 ++--
 glib/gvariant.c | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/glib/giounix.c b/glib/giounix.c
index 6ba442f15..b86d79db7 100644
--- a/glib/giounix.c
+++ b/glib/giounix.c
@@ -491,7 +491,7 @@ g_io_channel_new_file (const gchar *filename,
             mode_num |= MODE_PLUS;
             break;
           }
-        /* Fall through */
+        G_GNUC_FALLTHROUGH;
       default:
         g_warning ("Invalid GIOFileMode %s.", mode);
         return NULL;
diff --git a/glib/gscanner.c b/glib/gscanner.c
index e2c6aa4c4..b77514afe 100644
--- a/glib/gscanner.c
+++ b/glib/gscanner.c
@@ -1378,7 +1378,7 @@ g_scanner_unexp_token (GScanner           *scanner,
          _g_snprintf (token_string, token_string_len, "(unknown) token <%d>", scanner->token);
          break;
        }
-      /* fall through */
+      G_GNUC_FALLTHROUGH;
     case G_TOKEN_SYMBOL:
       if (expected_token == G_TOKEN_SYMBOL ||
          (scanner->config->symbol_2_token &&
@@ -1523,7 +1523,7 @@ g_scanner_unexp_token (GScanner           *scanner,
          _g_snprintf (expected_string, expected_string_len, "(unknown) token <%d>", expected_token);
          break;
        }
-      /* fall through */
+      G_GNUC_FALLTHROUGH;
     case G_TOKEN_SYMBOL:
       need_valid = (scanner->token == G_TOKEN_SYMBOL ||
                    (scanner->config->symbol_2_token &&
diff --git a/glib/gvariant.c b/glib/gvariant.c
index e4b1d4574..6b460d843 100644
--- a/glib/gvariant.c
+++ b/glib/gvariant.c
@@ -4930,7 +4930,7 @@ g_variant_valist_get_nnp (const gchar **str,
 
     case '@':
       g_variant_type_string_scan (*str, NULL, str);
-      /* fall through */
+      G_GNUC_FALLTHROUGH;
 
     case '*':
     case '?':