misc: Update sources to more modern C

The code fails to build when having enabled (gcc) warnings:
   -Werror=implicit
   -Werror=implicit-function-declaration
   -Werror=implicit-int
   -Werror=int-conversion
   -Werror=old-style-definition
   -Werror=strict-prototypes

5 files changed, 7 insertions, 9 deletions

diff --git a/src/libical/caldate.c b/src/libical/caldate.c
index e26926b4..f3d600c2 100644
--- a/src/libical/caldate.c
+++ b/src/libical/caldate.c
@@ -55,8 +55,7 @@
  *
  */
 
-long caldat( date )
-struct ut_instant * date;
+long caldat( struct ut_instant * date )
 {
 	double frac;
 	long jd;
@@ -129,8 +128,7 @@ struct ut_instant * date;
  *	50 Year canon of solar eclipses: 1986-2035
  */
 
-double juldat( date )
-struct ut_instant * date;
+double juldat( struct ut_instant * date )
 {
 	double frac, gyr;
 	long iy0, im0;
diff --git a/src/libical/icalduration.c b/src/libical/icalduration.c
index d142c0d5..3f9516da 100644
--- a/src/libical/icalduration.c
+++ b/src/libical/icalduration.c
@@ -301,7 +301,7 @@ int icaldurationtype_is_null_duration(struct icaldurationtype d)
    following the philosophy of unix errno. we set the is_neg
    to -1 to indicate that this is a bad duration.
 */
-struct icaldurationtype icaldurationtype_bad_duration()
+struct icaldurationtype icaldurationtype_bad_duration(void)
 {
     struct icaldurationtype d;
 
diff --git a/src/libical/icalerror.c b/src/libical/icalerror.c
index e10fd72e..e6081c2b 100644
--- a/src/libical/icalerror.c
+++ b/src/libical/icalerror.c
@@ -92,7 +92,7 @@ void icalerror_crash_here(void)
     assert(*p);
 }
 
-void icalerror_clear_errno()
+void icalerror_clear_errno(void)
 {
     icalerrno = ICAL_NO_ERROR;
 }
@@ -108,7 +108,7 @@ void icalerror_set_errors_are_fatal(int fatal)
     icalerror_errors_are_fatal = (fatal != 0);
 }
 
-int icalerror_get_errors_are_fatal()
+int icalerror_get_errors_are_fatal(void)
 {
     return icalerror_errors_are_fatal;
 }
diff --git a/src/libical/icalmemory.c b/src/libical/icalmemory.c
index 6c1bd9ca..db4fe4ea 100644
--- a/src/libical/icalmemory.c
+++ b/src/libical/icalmemory.c
@@ -224,7 +224,7 @@ void *icalmemory_tmp_buffer(size_t size)
     return buf;
 }
 
-void icalmemory_free_ring()
+void icalmemory_free_ring(void)
 {
     buffer_ring *br;
 
diff --git a/src/libical/pvl.c b/src/libical/pvl.c
index 960941a7..726ff835 100644
--- a/src/libical/pvl.c
+++ b/src/libical/pvl.c
@@ -76,7 +76,7 @@ typedef struct pvl_list_t
  * @return  Pointer to the new list, 0 if there is no available memory.
  */
 
-pvl_list pvl_newlist()
+pvl_list pvl_newlist(void)
 {
     struct pvl_list_t *L;