input/Error: work around clang bug leading to crash

Closes #373

src/input/Error.hxx

@@ -30,7 +30,15 @@
  * exist?  This function attempts to recognize exceptions thrown by
  * various input plugins.
  */
+#ifndef __clang__
+/* the "pure" attribute must be disabled because it triggers a clang
+   bug, wrongfully leading to std::terminate() even though the
+   function catches all exceptions thrown by std::rethrow_exception();
+   this can be reproduced with clang 7 from Android NDK r18b and on
+   clang 6 on FreeBSD
+   (https://github.com/MusicPlayerDaemon/MPD/issues/373) */
 gcc_pure
+#endif
 bool
 IsFileNotFound(std::exception_ptr e);