Tell the compiler that gos_errstr() ia an observer.

All regression tests pass.  Patch due to Jon Schlueter.

3 files changed, 3 insertions, 3 deletions

diff --git a/gps.h b/gps.h
index 73be4ded..736a35a7 100644
--- a/gps.h
+++ b/gps.h
@@ -1427,7 +1427,7 @@ extern int gps_send(struct gps_data_t *, const char *, ... );
 extern int gps_read(/*@out@*/struct gps_data_t *);
 extern bool gps_waiting(struct gps_data_t *);
 extern int gps_stream(struct gps_data_t *, unsigned int, /*@null@*/void *);
-extern char /*@observer@*/ *gps_errstr(const int);
+extern const char /*@observer@*/ *gps_errstr(const int);
 
 /* this only needs to be visible for the unit tests */
 extern int gps_unpack(char *, struct gps_data_t *);
diff --git a/libgps.xml b/libgps.xml
index b8b21756..959fac80 100644
--- a/libgps.xml
+++ b/libgps.xml
@@ -56,7 +56,7 @@ C:
     <paramdef>void *<parameter>data</parameter></paramdef>
 </funcprototype>
 <funcprototype>
-<funcdef>char *<function>gps_errstr</function></funcdef>
+<funcdef>const char *<function>gps_errstr</function></funcdef>
     <paramdef>int <parameter>err</parameter></paramdef>
 </funcprototype>
 <funcsynopsisinfo>
diff --git a/libgps_core.c b/libgps_core.c
index 3cb523f3..8a95f409 100644
--- a/libgps_core.c
+++ b/libgps_core.c
@@ -698,7 +698,7 @@ int gps_stream(struct gps_data_t *gpsdata, unsigned int flags,
     }
 }
 
-extern char /*@observer@*/ *gps_errstr(const int err)
+extern const char /*@observer@*/ *gps_errstr(const int err)
 {
     /* 
      * We might add our own error codes in the future, e.g for