Application to showcase build problem when including mbed.h from .cpp and .c -files. Folder structure and nested #includes inside #ifndefX+#defineX+#endif obfuscate the reason. Compiler error is about 'keyword namespace not found', which happens when mbed.h is included from .c.

Revision:
0:7c2be109ea78
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Sep 27 07:13:58 2016 +0000
@@ -0,0 +1,9 @@
+#include "foldertest2/foldertest2/foldertest2.h"
+//#include "mbed.h"
+int main() {
+    bool led1 = false;
+    while (true) {
+        led1 = !led1;
+        Thread::wait(500);
+    }
+}