Add set/hashmap helpers for non-trivial freeing and use where straighforward

A macro is needed because otherwise we couldn't ensure type safety.
Some simple tests are included.
No functional change intended.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/cgtop/cgtop.c b/src/cgtop/cgtop.c
index 8add7e73e4..fe339eb493 100644
--- a/src/cgtop/cgtop.c
+++ b/src/cgtop/cgtop.c
@@ -105,10 +105,7 @@ static void group_free(Group *g) {
 }
 
 static void group_hashmap_clear(Hashmap *h) {
-        Group *g;
-
-        while ((g = hashmap_steal_first(h)))
-                group_free(g);
+        hashmap_clear_with_destructor(h, group_free);
 }
 
 static void group_hashmap_free(Hashmap *h) {