lang: funcs: core: Add a second panic signature

This modifies the panic feature to accept a boolean or a string. If true
or not empty, then it will cause the panic. This makes some of the error
code a little less ugly.

examples/lang/panic/main.mcl

@@ -1,4 +1,10 @@
 class foo() {
+	panic(false) # should NOT panic
+	panic(false) # should NOT panic
+	panic("") # should NOT panic
+	panic("") # should NOT panic
+	panic(true) # should panic
+	panic(true) # should panic
 	panic("fail3") # should panic
 	panic("fail4") # should panic
 

examples/lang/panic0.mcl

@@ -1,7 +1,11 @@
 import "panic/" as nested # local, relative module to prove it can nest
 
+panic(false) # should NOT panic
+panic(false) # should NOT panic
 panic("") # should NOT panic
 panic("") # should NOT panic
+panic(true) # should panic
+panic(true) # should panic
 panic("fail1") # should panic
 panic("fail2") # should panic
 

lang/funcs/core/panic_func.go

@@ -20,23 +20,40 @@ package core
 import (
 	"fmt"
 
-	"github.com/purpleidea/mgmt/lang/funcs/simple"
+	"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
 	"github.com/purpleidea/mgmt/lang/types"
 )
 
 func init() {
-	simple.Register("panic", &types.FuncValue{
+	simplepoly.Register("panic", []*types.FuncValue{
+		{
+			T: types.NewType("func(x bool) bool"),
+			V: Panic,
+		},
+		{
 			T: types.NewType("func(x str) bool"),
 			V: Panic,
+		},
 	})
 }
 
-// Panic returns an error when it receives a non-empty string. The error should
-// cause the function engine to shutdown. If there's no error, it returns false.
+// Panic returns an error when it receives a non-empty string or a true boolean.
+// The error should cause the function engine to shutdown. If there's no error,
+// it returns false.
 func Panic(input []types.Value) (types.Value, error) {
-	if s := input[0].Str(); s != "" {
-		return nil, fmt.Errorf("panic occurred: %s", s)
+	switch k := input[0].Type().Kind; k {
+	case types.KindBool:
+		if input[0].Bool() {
+			return nil, fmt.Errorf("bool panic occurred")
 		}
+	case types.KindStr:
+		if s := input[0].Str(); s != "" {
+			return nil, fmt.Errorf("str panic occurred: %s", s)
+		}
+	default:
+		return nil, fmt.Errorf("unsupported kind: %+v", k)
+	}
+
 	return &types.BoolValue{
 		V: false,
 	}, nil

lang/interpret_test/TestAstFunc2/panic0.txtar

@@ -1,5 +1,7 @@
 -- main.mcl --
 # This should not panic.
+panic(false)
+panic(false)
 panic("")
 panic("")
 # Empty graph, no output.

lang/interpret_test/TestAstFunc2/panic1.txtar

@@ -1,5 +1,6 @@
 -- main.mcl --
 # This should not panic.
+panic(false)
 panic("")
 test "hello" {}
 -- OUTPUT --

lang/interpret_test/TestAstFunc2/panic2.txtar

@@ -1,6 +1,6 @@
 -- main.mcl --
 # This should panic!
-panic("please panic")
+panic(true)
 test "hello" {}
 -- OUTPUT --
 # err: errStream: func `panic @ 0x0000000000` stopped before it was loaded

lang/interpret_test/TestAstFunc2/panic3.txtar

@@ -0,0 +1,6 @@
+-- main.mcl --
+# This should panic!
+panic("please panic")
+test "hello" {}
+-- OUTPUT --
+# err: errStream: func `panic @ 0x0000000000` stopped before it was loaded

lang/interpret_test/TestAstFunc2/panic4.txtar

@@ -0,0 +1,10 @@
+-- main.mcl --
+# This should panic!
+panic(true)
+panic(true)
+panic("please panic")
+panic("please panic")
+panic("please panic!")
+test "hello" {}
+-- OUTPUT --
+# err: errStream: func `panic @ 0x0000000000` stopped before it was loaded