include/bluetooth: rearrange for standard use of extern "C"

Consistently place C++ use of extern "C" after all include directives,
within the negative branch of _ASMLANGUAGE if used.

Background from issue #17997:

Declarations that use C linkage should be placed within extern "C"
so the language linkage is correct when the header is included by
a C++ compiler.

Similarly #include directives should be outside the extern "C" to
ensure the language-specific default linkage is applied to any
declarations provided by the included header.

See: https://en.cppreference.com/w/cpp/language/language_linkage
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>

include/bluetooth/a2dp.h

@@ -10,12 +10,12 @@
 #ifndef ZEPHYR_INCLUDE_BLUETOOTH_A2DP_H_
 #define ZEPHYR_INCLUDE_BLUETOOTH_A2DP_H_
 
+#include <bluetooth/avdtp.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <bluetooth/avdtp.h>
-
 /** @brief Stream Structure */
 struct bt_a2dp_stream {
 	/* TODO */

include/bluetooth/att.h

@@ -10,12 +10,12 @@
 #ifndef ZEPHYR_INCLUDE_BLUETOOTH_ATT_H_
 #define ZEPHYR_INCLUDE_BLUETOOTH_ATT_H_
 
+#include <sys/slist.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <sys/slist.h>
-
 /* Error codes for Error response PDU */
 #define BT_ATT_ERR_INVALID_HANDLE		0x01
 #define BT_ATT_ERR_READ_NOT_PERMITTED		0x02

include/bluetooth/conn.h

@@ -17,15 +17,15 @@
  * @{
  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #include <stdbool.h>
 
 #include <bluetooth/bluetooth.h>
 #include <bluetooth/hci.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /** Opaque type representing a connection to a remote device */
 struct bt_conn;
 

include/bluetooth/gatt.h

@@ -17,10 +17,6 @@
  * @{
  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #include <stddef.h>
 #include <sys/types.h>
 #include <sys/util.h>
@@ -28,6 +24,10 @@ extern "C" {
 #include <bluetooth/uuid.h>
 #include <bluetooth/att.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* GATT attribute permission bit field values */
 enum {
 	/** No operations supported, e.g. for notify-only */

include/bluetooth/l2cap.h

@@ -17,15 +17,15 @@
  * @{
  */
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 #include <sys/atomic.h>
 #include <bluetooth/buf.h>
 #include <bluetooth/conn.h>
 #include <bluetooth/hci.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* L2CAP header size, used for buffer size calculations */
 #define BT_L2CAP_HDR_SIZE               4
 

include/bluetooth/rfcomm.h

@@ -17,13 +17,13 @@
  * @{
  */
 
+#include <bluetooth/buf.h>
+#include <bluetooth/conn.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <bluetooth/buf.h>
-#include <bluetooth/conn.h>
-
 /* RFCOMM channels (1-30): pre-allocated for profiles to avoid conflicts */
 enum {
 	BT_RFCOMM_CHAN_HFP_HF = 1,

include/bluetooth/sdp.h

@@ -17,13 +17,13 @@
  * @{
  */
 
+#include <bluetooth/uuid.h>
+#include <bluetooth/conn.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <bluetooth/uuid.h>
-#include <bluetooth/conn.h>
-
 /*
  * All definitions are based on Bluetooth Assigned Numbers
  * of the Bluetooth Specification
@@ -601,6 +601,7 @@ int bt_sdp_get_profile_version(const struct net_buf *buf, u16_t profile,
  *  @return 0 on success if feature found and valid, negative in case any error
  */
 int bt_sdp_get_features(const struct net_buf *buf, u16_t *features);
+
 #ifdef __cplusplus
 }
 #endif

include/bluetooth/services/bas.h

@@ -18,12 +18,12 @@
  * as a part of ongoing development.
  */
 
+#include <zephyr/types.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <zephyr/types.h>
-
 /** @brief Read battery level value.
  *
  * Read the characteristic value of the battery level

subsys/bluetooth/common/log.h

@@ -14,6 +14,7 @@
 #include <linker/sections.h>
 #include <offsets.h>
 #include <zephyr.h>
+#include <logging/log.h>
 
 #include <bluetooth/bluetooth.h>
 #include <bluetooth/hci.h>
@@ -32,8 +33,6 @@ extern "C" {
 #define LOG_LEVEL CONFIG_BT_LOG_LEVEL
 #endif
 
-#include <logging/log.h>
-
 LOG_MODULE_REGISTER(LOG_MODULE_NAME);
 
 #define BT_DBG(fmt, ...) LOG_DBG(fmt, ##__VA_ARGS__)
@@ -62,4 +61,3 @@ const char *bt_addr_le_str_real(const bt_addr_le_t *addr);
 #endif
 
 #endif /* __BT_LOG_H */
-