Fix duration multiplication by integer

expr_test.go

@@ -976,6 +976,18 @@ func TestExpr(t *testing.T) {
 			`duration("1h") + duration("1m")`,
 			time.Hour + time.Minute,
 		},
+		{
+			`7 * duration("1h")`,
+			7 * time.Hour,
+		},
+		{
+			`duration("1h") * 7`,
+			7 * time.Hour,
+		},
+		{
+			`duration("1s") * .5`,
+			5e8,
+		},
 		{
 			`1 /* one */ + 2 // two`,
 			3,

vm/runtime/helpers/main.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"go/format"
+	"os"
 	"strings"
 	"text/template"
 )
@@ -13,11 +14,14 @@ func main() {
 	err := template.Must(
 		template.New("helpers").
 			Funcs(template.FuncMap{
-				"cases":          func(op string) string { return cases(op, false) },
-				"cases_int_only": func(op string) string { return cases(op, true) },
+				"cases":          func(op string) string { return cases(op, uints, ints, floats) },
+				"cases_int_only": func(op string) string { return cases(op, uints, ints) },
+				"cases_with_duration": func(op string) string {
+					return cases(op, uints, ints, floats, []string{"time.Duration"})
+				},
 			}).
 			Parse(helpers),
-	).Execute(&b, types)
+	).Execute(&b, nil)
 	if err != nil {
 		panic(err)
 	}
@@ -29,40 +33,48 @@ func main() {
 	fmt.Print(string(formatted))
 }
 
-var types = []string{
-	"uint",
-	"uint8",
-	"uint16",
-	"uint32",
-	"uint64",
+var ints = []string{
 	"int",
 	"int8",
 	"int16",
 	"int32",
 	"int64",
+}
+
+var uints = []string{
+	"uint",
+	"uint8",
+	"uint16",
+	"uint32",
+	"uint64",
+}
+
+var floats = []string{
 	"float32",
 	"float64",
 }
 
-func cases(op string, noFloat bool) string {
+func cases(op string, xs ...[]string) string {
+	var types []string
+	for _, x := range xs {
+		types = append(types, x...)
+	}
+
+	_, _ = fmt.Fprintf(os.Stderr, "Generating %s cases for %v\n", op, types)
+
 	var out string
 	echo := func(s string, xs ...any) {
 		out += fmt.Sprintf(s, xs...) + "\n"
 	}
 	for _, a := range types {
-		aIsFloat := strings.HasPrefix(a, "float")
-		if noFloat && aIsFloat {
-			continue
-		}
 		echo(`case %v:`, a)
 		echo(`switch y := b.(type) {`)
 		for _, b := range types {
-			bIsFloat := strings.HasPrefix(b, "float")
-			if noFloat && bIsFloat {
-				continue
-			}
 			t := "int"
-			if aIsFloat || bIsFloat {
+			if isDuration(a) || isDuration(b) {
+				t = "time.Duration"
+			}
+			if isFloat(a) || isFloat(b) {
 				t = "float64"
 			}
 			echo(`case %v:`, b)
@@ -77,6 +89,18 @@ func cases(op string, noFloat bool) string {
 	return strings.TrimRight(out, "\n")
 }
 
+func isFloat(t string) bool {
+	return strings.HasPrefix(t, "float")
+}
+
+func isInt(t string) bool {
+	return strings.HasPrefix(t, "int")
+}
+
+func isDuration(t string) bool {
+	return t == "time.Duration"
+}
+
 const helpers = `// Code generated by vm/runtime/helpers/main.go. DO NOT EDIT.
 
 package runtime
@@ -245,7 +269,7 @@ func Subtract(a, b interface{}) interface{} {
 
 func Multiply(a, b interface{}) interface{} {
 	switch x := a.(type) {
-	{{ cases "*" }}
+	{{ cases_with_duration "*" }}
 	}
 	panic(fmt.Sprintf("invalid operation: %T * %T", a, b))
 }