From 416e8ce8e6415e99fc5522a61a0b35b2482ed7fa Mon Sep 17 00:00:00 2001
From: Gunar Schorcht <gunar@schorcht.net>
Date: Thu, 16 Jan 2020 13:03:49 +0100
Subject: [PATCH] cpu/esp32: fix C linkage compilatio error

With the new toolchain version required to fix issue #13133, the compilation of `examples/posix_socket` fails due to a C linkage error in `atomic_base.h`. The reason is that including `drivers/include/mtd.h` in `boards/esp32/board_common.h` inside the `extern C` block finally leads to including `atomic_base.h` inside the `extern C` block which in turn to the C linkage error for the template definitions in this file.
---
 boards/common/esp32/include/board_common.h | 7 +++++--
 cpu/esp32/include/sdk_conf.h               | 4 ++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/boards/common/esp32/include/board_common.h b/boards/common/esp32/include/board_common.h
index 3b5143eb5961..a81ffd7c2f03 100644
--- a/boards/common/esp32/include/board_common.h
+++ b/boards/common/esp32/include/board_common.h
@@ -35,8 +35,12 @@
 #include "periph/gpio.h"
 #include "sdk_conf.h"
 
+#if MODULE_MTD
+#include "mtd.h"
+#endif
+
 #ifdef __cplusplus
- extern "C" {
+extern "C" {
 #endif
 
 /**
@@ -103,7 +107,6 @@
  * Built-in SPI flash memory is used as MTD system drive.
  * @{
  */
-#include "mtd.h"
 
 /**
  * @brief   MTD drive start address in SPI flash memory
diff --git a/cpu/esp32/include/sdk_conf.h b/cpu/esp32/include/sdk_conf.h
index 2e5fecbb3e19..5f417be778cc 100644
--- a/cpu/esp32/include/sdk_conf.h
+++ b/cpu/esp32/include/sdk_conf.h
@@ -24,12 +24,12 @@
 
 #ifndef DOXYGEN
 
+#include "board.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include "board.h"
-
 /**
  * @brief   Defines the CPU frequency [values = 2, 40, 80, 160 and 240]
  */