fix: continue statement was not applied correctly

_test/for8.go

@@ -0,0 +1,18 @@
+package main
+
+func main() {
+	for i := 0; i < 4; i++ {
+		for {
+			break
+		}
+		if i == 1 {
+			continue
+		}
+		println(i)
+	}
+}
+
+// Output:
+// 0
+// 2
+// 3

_test/primes.go

@@ -0,0 +1,26 @@
+package main
+
+func Primes(n int) int {
+	var xs []int
+	for i := 2; len(xs) < n; i++ {
+		ok := true
+		for _, x := range xs {
+			if i%x == 0 {
+				ok = false
+				break
+			}
+		}
+		if !ok {
+			continue
+		}
+		xs = append(xs, i)
+	}
+	return xs[n-1]
+}
+
+func main() {
+	println(Primes(3))
+}
+
+// Output:
+// 5

interp/cfg.go

@@ -44,7 +44,6 @@ var identifier = regexp.MustCompile(`([\pL_][\pL_\d]*)$`)
 // Following this pass, the CFG is ready to run
 func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 	sc, pkgName := interp.initScopePkg(root)
-	var loop, loopRestart *node
 	var initNodes []*node
 	var iotaValue int
 	var err error
@@ -236,12 +235,12 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			}
 
 		case forStmt0, forRangeStmt:
-			loop, loopRestart = n, n.child[0]
 			sc = sc.pushBloc()
+			sc.loop, sc.loopRestart = n, n.child[0]
 
 		case forStmt1, forStmt2, forStmt3, forStmt3a, forStmt4:
-			loop, loopRestart = n, n.lastChild()
 			sc = sc.pushBloc()
+			sc.loop, sc.loopRestart = n, n.lastChild()
 
 		case funcLit:
 			n.typ = nil // to force nodeType to recompute the type
@@ -313,7 +312,7 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 				c[i], c[l] = c[l], c[i]
 			}
 			sc = sc.pushBloc()
-			loop = n
+			sc.loop = n
 
 		case importSpec:
 			var name, ipath string
@@ -698,14 +697,14 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			if len(n.child) > 0 {
 				gotoLabel(n.sym)
 			} else {
-				n.tnext = loop
+				n.tnext = sc.loop
 			}
 
 		case continueStmt:
 			if len(n.child) > 0 {
 				gotoLabel(n.sym)
 			} else {
-				n.tnext = loopRestart
+				n.tnext = sc.loopRestart
 			}
 
 		case gotoStmt:
@@ -829,7 +828,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			body := n.child[0]
 			n.start = body.start
 			body.tnext = n.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forStmt1: // for cond {}
@@ -841,7 +839,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			cond.tnext = body.start
 			cond.fnext = n
 			body.tnext = cond.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forStmt2: // for init; cond; {}
@@ -854,7 +851,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			cond.tnext = body.start
 			cond.fnext = n
 			body.tnext = cond.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forStmt3: // for ; cond; post {}
@@ -867,7 +863,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			cond.fnext = n
 			body.tnext = post.start
 			post.tnext = cond.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forStmt3a: // for int; ; post {}
@@ -876,7 +871,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			init.tnext = body.start
 			body.tnext = post.start
 			post.tnext = body.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forStmt4: // for init; cond; post {}
@@ -890,11 +884,9 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 			cond.fnext = n
 			body.tnext = post.start
 			post.tnext = cond.start
-			loop, loopRestart = nil, nil
 			sc = sc.pop()
 
 		case forRangeStmt:
-			loop, loopRestart = nil, nil
 			n.start = n.child[0].start
 			n.child[0].fnext = n
 			sc = sc.pop()
@@ -1320,7 +1312,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 				n.start = sbn.start
 			}
 			sc = sc.pop()
-			loop = nil
 
 		case switchIfStmt: // like an if-else chain
 			sbn := n.lastChild() // switch block node
@@ -1357,7 +1348,6 @@ func (interp *Interpreter) cfg(root *node) ([]*node, error) {
 				n.start = sbn.start
 			}
 			sc = sc.pop()
-			loop = nil
 
 		case typeAssertExpr:
 			if len(n.child) > 1 {

interp/scope.go

@@ -74,12 +74,14 @@ type symbol struct {
 // execution to the index in frame, created exactly from the types layout.
 //
 type scope struct {
-	anc    *scope             // Ancestor upper scope
+	anc         *scope             // Ancestor upper scope
-	def    *node              // function definition node this scope belongs to, or nil
+	def         *node              // function definition node this scope belongs to, or nil
-	types  []reflect.Type     // Frame layout, may be shared by same level scopes
+	loop        *node              // loop exit node for break statement
-	level  int                // Frame level: number of frame indirections to access var during execution
+	loopRestart *node              // loop restart node for continue statement
-	sym    map[string]*symbol // Map of symbols defined in this current scope
+	types       []reflect.Type     // Frame layout, may be shared by same level scopes
-	global bool               // true if scope refers to global space (single frame for universe and package level scopes)
+	level       int                // Frame level: number of frame indirections to access var during execution
+	sym         map[string]*symbol // Map of symbols defined in this current scope
+	global      bool               // true if scope refers to global space (single frame for universe and package level scopes)
 }
 
 // push creates a new scope and chain it to the current one
@@ -95,6 +97,8 @@ func (s *scope) push(indirect bool) *scope {
 		sc.global = s.global
 		sc.level = s.level
 	}
+	// inherit loop state from ancestor
+	sc.loop, sc.loopRestart = s.loop, s.loopRestart
 	return &sc
 }