[PATCH] index: explicitly follow GObject conventions

[Daniel Kahn Gillmor]

Use explicit labels for GTypeInfo member initializers, rather than
relying on comments and ordering.  This is both easier to read, and
harder to screw up.  This also makes it clear that we're mis-casting
GObject class initializers for gcc.

Without this patch, g++ 8.2.0-7 produces this warning:

CXX  -g -O2 lib/index.o
lib/index.cc: In function ‘GMimeFilter* notmuch_filter_discard_non_term_new(GMimeContentType*)’:
lib/index.cc:252:23: warning: cast between incompatible function types from ‘void (*)(NotmuchFilterDiscardNonTermClass*)’ {aka ‘void (*)(_NotmuchFilterDiscardNonTermClass*)’} to ‘GClassInitFunc’ {aka ‘void (*)(void*, void*)’} [-Wcast-function-type]
      (GClassInitFunc) notmuch_filter_discard_non_term_class_init,
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The definition of GClassInitFunc in
/usr/include/glib-2.0/gobject/gtype.h suggests that this function will
always be called with the class_data member of the GTypeInfo.  We set
that value to NULL in both GObject definitions in notmuch. So we mark
it as explicitly unused.

There is no functional change here, just code cleanup.
---
 gmime-filter-reply.c | 25 +++++++++++++------------
 lib/index.cc         | 23 ++++++++++++-----------
 2 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/gmime-filter-reply.c b/gmime-filter-reply.c
index f673c0a2..480d9381 100644
--- a/gmime-filter-reply.c
+++ b/gmime-filter-reply.c
@@ -19,6 +19,7 @@
 #include <stdbool.h>
 
 #include "gmime-filter-reply.h"
+#include "notmuch-client.h"
 
 /**
  * SECTION: gmime-filter-reply
@@ -29,7 +30,7 @@
  **/
 
 
-static void g_mime_filter_reply_class_init (GMimeFilterReplyClass *klass);
+static void g_mime_filter_reply_class_init (GMimeFilterReplyClass *klass, void *class_data);
 static void g_mime_filter_reply_init (GMimeFilterReply *filter, GMimeFilterReplyClass *klass);
 static void g_mime_filter_reply_finalize (GObject *object);
 
@@ -50,16 +51,16 @@ g_mime_filter_reply_get_type (void)
 
 	if (!type) {
 		static const GTypeInfo info = {
-			sizeof (GMimeFilterReplyClass),
-			NULL, /* base_class_init */
-			NULL, /* base_class_finalize */
-			(GClassInitFunc) g_mime_filter_reply_class_init,
-			NULL, /* class_finalize */
-			NULL, /* class_data */
-			sizeof (GMimeFilterReply),
-			0,    /* n_preallocs */
-			(GInstanceInitFunc) g_mime_filter_reply_init,
-			NULL	/* value_table */
+			.class_size = sizeof (GMimeFilterReplyClass),
+			.base_init = NULL,
+			.base_finalize = NULL,
+			.class_init = (GClassInitFunc) g_mime_filter_reply_class_init,
+			.class_finalize = NULL,
+			.class_data = NULL,
+			.instance_size = sizeof (GMimeFilterReply),
+			.n_preallocs = 0,
+			.instance_init = (GInstanceInitFunc) g_mime_filter_reply_init,
+			.value_table = NULL,
 		};
 
 		type = g_type_register_static (GMIME_TYPE_FILTER, "GMimeFilterReply", &info, (GTypeFlags) 0);
@@ -70,7 +71,7 @@ g_mime_filter_reply_get_type (void)
 
 
 static void
-g_mime_filter_reply_class_init (GMimeFilterReplyClass *klass)
+g_mime_filter_reply_class_init (GMimeFilterReplyClass *klass, unused (void *class_data))
 {
 	GObjectClass *object_class = G_OBJECT_CLASS (klass);
 	GMimeFilterClass *filter_class = GMIME_FILTER_CLASS (klass);
diff --git a/lib/index.cc b/lib/index.cc
index 3f694387..efd9da4c 100644
--- a/lib/index.cc
+++ b/lib/index.cc
@@ -142,7 +142,8 @@ static void filter_reset (GMimeFilter *filter);
 static GMimeFilterClass *parent_class = NULL;
 
 static void
-notmuch_filter_discard_non_term_class_init (NotmuchFilterDiscardNonTermClass *klass)
+notmuch_filter_discard_non_term_class_init (NotmuchFilterDiscardNonTermClass *klass,
+					    unused (void *class_data))
 {
     GObjectClass *object_class = G_OBJECT_CLASS (klass);
     GMimeFilterClass *filter_class = GMIME_FILTER_CLASS (klass);
@@ -246,16 +247,16 @@ notmuch_filter_discard_non_term_new (GMimeContentType *content_type)
 
     if (!type) {
 	static const GTypeInfo info = {
-	    sizeof (NotmuchFilterDiscardNonTermClass),
-	    NULL, /* base_class_init */
-	    NULL, /* base_class_finalize */
-	    (GClassInitFunc) notmuch_filter_discard_non_term_class_init,
-	    NULL, /* class_finalize */
-	    NULL, /* class_data */
-	    sizeof (NotmuchFilterDiscardNonTerm),
-	    0,    /* n_preallocs */
-	    NULL, /* instance_init */
-	    NULL  /* value_table */
+	    .class_size = sizeof (NotmuchFilterDiscardNonTermClass),
+	    .base_init = NULL,
+	    .base_finalize = NULL,
+	    .class_init = (GClassInitFunc) notmuch_filter_discard_non_term_class_init,
+	    .class_finalize = NULL,
+	    .class_data = NULL,
+	    .instance_size = sizeof (NotmuchFilterDiscardNonTerm),
+	    .n_preallocs = 0,
+	    .instance_init = NULL,
+	    .value_table = NULL,
 	};
 
 	type = g_type_register_static (GMIME_TYPE_FILTER, "NotmuchFilterDiscardNonTerm", &info, (GTypeFlags) 0);
-- 
2.19.0