branches/zip: ibuf_use_t: Add the constant IBUF_USE_COUNT, to eliminate

a gcc warning about an assertion that trivially holds.
The warning was introduced in r4061, in the merge of
branches/innodb+ -r4053.

ibuf_insert(): Let an assertion fail if ibuf_use is unknown.

handler/ha_innodb.cc

@@ -188,7 +188,7 @@ bool nw_panic = FALSE;
 #endif
 
 /** Allowed values of innodb_change_buffering */
-static const char* innobase_change_buffering_values[IBUF_USE_INSERT + 1] = {
+static const char* innobase_change_buffering_values[IBUF_USE_COUNT] = {
 	"none",		/* IBUF_USE_NONE */
 	"inserts"	/* IBUF_USE_INSERT */
 };
@@ -9421,7 +9421,7 @@ innodb_change_buffering_update(
 {
 	ut_a(var_ptr != NULL);
 	ut_a(save != NULL);
-	ut_a((*(ibuf_use_t*) save) <= IBUF_USE_INSERT);
+	ut_a((*(ibuf_use_t*) save) < IBUF_USE_COUNT);
 
 	ibuf_use = *(const ibuf_use_t*) save;
 

ibuf/ibuf0ibuf.c

@@ -2768,13 +2768,18 @@ ibuf_insert(
 
 	ut_a(!dict_index_is_clust(index));
 
-	switch (ibuf_use) {
+	switch (UNIV_EXPECT(ibuf_use, IBUF_USE_INSERT)) {
 	case IBUF_USE_NONE:
 		return(FALSE);
 	case IBUF_USE_INSERT:
+		goto do_insert;
+	case IBUF_USE_COUNT:
 		break;
 	}
 
+	ut_error; /* unknown value of ibuf_use */
+
+do_insert:
 	entry_size = rec_get_converted_size(index, entry, 0);
 
 	if (entry_size

include/ibuf0ibuf.h

@@ -17,10 +17,14 @@ Created 7/19/1997 Heikki Tuuri
 #include "ibuf0types.h"
 #include "fsp0fsp.h"
 
-/** Combinations of operations that can be buffered. */
+/** Combinations of operations that can be buffered.  Because the enum
+values are used for indexing innobase_change_buffering_values[], they
+should start at 0 and there should not be any gaps. */
 typedef enum {
 	IBUF_USE_NONE = 0,
-	IBUF_USE_INSERT		/* insert */
+	IBUF_USE_INSERT,	/* insert */
+
+	IBUF_USE_COUNT		/* number of entries in ibuf_use_t */
 } ibuf_use_t;
 
 /** Operations that can currently be buffered. */