reflect: add Cap and Len support for map and chan

src/runtime/hashmap.go

@@ -1,7 +1,7 @@
 package runtime
 
 // This is a hashmap implementation for the map[T]T type.
-// It is very rougly based on the implementation of the Go hashmap:
+// It is very roughly based on the implementation of the Go hashmap:
 //
 //     https://golang.org/src/runtime/map.go
 
@@ -80,6 +80,7 @@ func hashmapMake(keySize, valueSize uint8, sizeHint uintptr) *hashmap {
 
 // Return the number of entries in this hashmap, called from the len builtin.
 // A nil hashmap is defined as having length 0.
+//go:inline
 func hashmapLen(m *hashmap) int {
 	if m == nil {
 		return 0
@@ -87,6 +88,12 @@ func hashmapLen(m *hashmap) int {
 	return int(m.count)
 }
 
+// wrapper for use in reflect
+func hashmapLenUnsafePointer(p unsafe.Pointer) int {
+	m := (*hashmap)(p)
+	return hashmapLen(m)
+}
+
 // Set a specified key to a given value. Grow the map if necessary.
 //go:nobounds
 func hashmapSet(m *hashmap, key unsafe.Pointer, value unsafe.Pointer, hash uint32, keyEqual func(x, y unsafe.Pointer, n uintptr) bool) {