compiler,runtime: implement maps for arbitrary keys

This implementation simply casts types without special support to an
interface, to make the implementation simpler and possibly reducing the
code size too. It will likely be slower than the canonical Go
implementation though (which builds special compare and hash functions
at compile time).

testdata/map.go

@@ -24,6 +24,11 @@ var testMapArrayKey = map[ArrayKey]int{
 }
 var testmapIntInt = map[int]int{1: 1, 2: 4, 3: 9}
 
+type namedFloat struct {
+	s string
+	f float32
+}
+
 func main() {
 	m := map[string]int{"answer": 42, "foo": 3}
 	readMap(m, "answer")
@@ -48,6 +53,44 @@ func main() {
 	testMapArrayKey[arrKey] = 5555
 	println(testMapArrayKey[arrKey])
 
+	// test maps with interface keys
+	itfMap := map[interface{}]int{
+		3.14:         3,
+		8:            8,
+		uint8(8):     80,
+		"eight":      800,
+		[2]int{5, 2}: 52,
+		true:         1,
+	}
+	println("itfMap[3]:", itfMap[3]) // doesn't exist
+	println("itfMap[3.14]:", itfMap[3.14])
+	println("itfMap[8]:", itfMap[8])
+	println("itfMap[uint8(8)]:", itfMap[uint8(8)])
+	println(`itfMap["eight"]:`, itfMap["eight"])
+	println(`itfMap[[2]int{5, 2}]:`, itfMap[[2]int{5, 2}])
+	println("itfMap[true]:", itfMap[true])
+	delete(itfMap, 8)
+	println("itfMap[8]:", itfMap[8])
+
+	// test map with float keys
+	floatMap := map[float32]int{
+		42: 84,
+	}
+	println("floatMap[42]:", floatMap[42])
+	println("floatMap[43]:", floatMap[43])
+	delete(floatMap, 42)
+	println("floatMap[42]:", floatMap[42])
+
+	// test maps with struct keys
+	structMap := map[namedFloat]int{
+		namedFloat{"tau", 6.28}: 5,
+	}
+	println(`structMap[{"tau", 6.28}]:`, structMap[namedFloat{"tau", 6.28}])
+	println(`structMap[{"Tau", 6.28}]:`, structMap[namedFloat{"Tau", 6.28}])
+	println(`structMap[{"tau", 3.14}]:`, structMap[namedFloat{"tau", 3.14}])
+	delete(structMap, namedFloat{"tau", 6.28})
+	println(`structMap[{"tau", 6.28}]:`, structMap[namedFloat{"tau", 6.28}])
+
 	// test preallocated map
 	squares := make(map[int]int, 200)
 	testBigMap(squares, 100)
@@ -79,7 +122,7 @@ func testBigMap(squares map[int]int, n int) {
 		if len(squares) != i {
 			println("unexpected length:", len(squares), "at i =", i)
 		}
-		squares[i] = i*i
+		squares[i] = i * i
 		for j := 0; j <= i; j++ {
 			if v, ok := squares[j]; !ok || v != j*j {
 				if !ok {