[Buildroot] [PATCH] modem-manager: remove -Werror from CFLAGS

[Carlos Santos <casantos@datacom.ind.br>]

We are aproaching the 2018.05 release and modem-manager is still broken
due to warnings like this:

  mm-base-manager.c: In function 'handle_set_logging':
  mm-base-manager.c:680:15: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
       ctx->self = g_object_ref (manager);
                 ^

There is a macro defined in build/libglib2-2.56.1/gobject/gobject.h
which leads to the assignment errors:

  511 /* Make reference APIs type safe with macros */
  512 #define g_object_ref(Obj)      ((__typeof__(Obj)) (g_object_ref) (Obj))

The problem can be easily reproduced with this sample code:

  $ cat test.c
  extern void *g_object_ref(void *);
  #define g_object_ref(Obj) ((__typeof__(Obj)) (g_object_ref) (Obj))
  extern double *new_double(int *);
  double *new_double(int *ip) {
    double *dp;
    dp = g_object_ref(ip);
    return dp;
  }

  $ gcc -Wall -Werror -c /tmp/test.c -o /tmp/test.o
  /tmp/test.c: In function ?new_context?:
  /tmp/test.c:19:13: error: assignment from incompatible pointer type [-Werror=incompatible-pointer-types]
     ctx->self = g_object_ref(om);
               ^
  cc1: all warnings being treated as errors

Fixing the code would require either changing the 120 ofending calls to
g_object_ref or a refactoring to make all types assignment compatible.
Let's take a simpler approach, disabling -Werror, and wait for the next
release of ModemManager.

Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
---
 package/modem-manager/modem-manager.mk | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/package/modem-manager/modem-manager.mk b/package/modem-manager/modem-manager.mk
index 100c4a2941..ba4711b6c2 100644
--- a/package/modem-manager/modem-manager.mk
+++ b/package/modem-manager/modem-manager.mk
@@ -19,6 +19,12 @@ else
 MODEM_MANAGER_CONF_OPTS += --without-qmi
 endif
 
+define MODEM_MANAGER_REMOVE_WERROR
+	$(SED) 's: -Werror::' $(@D)/configure
+endef
+
+MODEM_MANAGER_POST_PATCH_HOOKS += MODEM_MANAGER_REMOVE_WERROR
+
 ifeq ($(BR2_PACKAGE_MODEM_MANAGER_LIBMBIM),y)
 MODEM_MANAGER_DEPENDENCIES += libmbim
 MODEM_MANAGER_CONF_OPTS += --with-mbim
-- 
2.17.0