patch 7.4.2101
Problem:    Looping over windows, buffers and tab pages is inconsistant.
Solution:   Use FOR_ALL_ macros everywhere. (Yegappan Lakshmanan)
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index adc5352..83305b2 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -1721,7 +1721,7 @@
 
     if (!(p_aw || p_awa) || !p_write)
 	return;
-    for (buf = firstbuf; buf; buf = buf->b_next)
+    FOR_ALL_BUFFERS(buf)
 	if (bufIsChanged(buf) && !buf->b_p_ro)
 	{
 #ifdef FEAT_AUTOCMD
@@ -1764,7 +1764,7 @@
 	    int		count = 0;
 
 	    if (flags & CCGD_ALLBUF)
-		for (buf2 = firstbuf; buf2 != NULL; buf2 = buf2->b_next)
+		FOR_ALL_BUFFERS(buf2)
 		    if (bufIsChanged(buf2)
 				     && (buf2->b_ffname != NULL
 # ifdef FEAT_BROWSE
@@ -1868,7 +1868,7 @@
 	 * Skip readonly buffers, these need to be confirmed
 	 * individually.
 	 */
-	for (buf2 = firstbuf; buf2 != NULL; buf2 = buf2->b_next)
+	FOR_ALL_BUFFERS(buf2)
 	{
 	    if (bufIsChanged(buf2)
 		    && (buf2->b_ffname != NULL
@@ -1904,7 +1904,7 @@
 	/*
 	 * mark all buffers as unchanged
 	 */
-	for (buf2 = firstbuf; buf2 != NULL; buf2 = buf2->b_next)
+	FOR_ALL_BUFFERS(buf2)
 	    unchanged(buf2, TRUE);
     }
 }
@@ -1964,7 +1964,7 @@
     win_T	*wp;
 #endif
 
-    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
+    FOR_ALL_BUFFERS(buf)
 	++bufcount;
 
     if (bufcount == 0)
@@ -1983,13 +1983,13 @@
 	    add_bufnum(bufnrs, &bufnum, wp->w_buffer->b_fnum);
 
     /* buf in other tab */
-    for (tp = first_tabpage; tp != NULL; tp = tp->tp_next)
+    FOR_ALL_TABPAGES(tp)
 	if (tp != curtab)
 	    for (wp = tp->tp_firstwin; wp != NULL; wp = wp->w_next)
 		add_bufnum(bufnrs, &bufnum, wp->w_buffer->b_fnum);
 #endif
     /* any other buf */
-    for (buf = firstbuf; buf != NULL; buf = buf->b_next)
+    FOR_ALL_BUFFERS(buf)
 	add_bufnum(bufnrs, &bufnum, buf->b_fnum);
 
     for (i = 0; i < bufnum; ++i)
@@ -2924,7 +2924,7 @@
 		if (next_fnum < 0 || next_fnum > eap->line2)
 		    break;
 		/* Check if the buffer still exists. */
-		for (buf = firstbuf; buf != NULL; buf = buf->b_next)
+		FOR_ALL_BUFFERS(buf)
 		    if (buf->b_fnum == next_fnum)
 			break;
 		if (buf == NULL)