2973: fix switch branch stmts

gnovm/pkg/gnolang/nodes.go

@@ -2118,13 +2118,14 @@ func (x *BasicLitExpr) GetInt() int {
 type GnoAttribute string
 
 const (
-	ATTR_PREPROCESSED GnoAttribute = "ATTR_PREPROCESSED"
-	ATTR_PREDEFINED   GnoAttribute = "ATTR_PREDEFINED"
-	ATTR_TYPE_VALUE   GnoAttribute = "ATTR_TYPE_VALUE"
-	ATTR_TYPEOF_VALUE GnoAttribute = "ATTR_TYPEOF_VALUE"
-	ATTR_IOTA         GnoAttribute = "ATTR_IOTA"
-	ATTR_LOCATIONED   GnoAttribute = "ATTR_LOCATIONED"
-	ATTR_SHIFT_RHS    GnoAttribute = "ATTR_SHIFT_RHS"
+	ATTR_PREPROCESSED    GnoAttribute = "ATTR_PREPROCESSED"
+	ATTR_PREDEFINED      GnoAttribute = "ATTR_PREDEFINED"
+	ATTR_TYPE_VALUE      GnoAttribute = "ATTR_TYPE_VALUE"
+	ATTR_TYPEOF_VALUE    GnoAttribute = "ATTR_TYPEOF_VALUE"
+	ATTR_IOTA            GnoAttribute = "ATTR_IOTA"
+	ATTR_LOCATIONED      GnoAttribute = "ATTR_LOCATIONED"
+	ATTR_SHIFT_RHS       GnoAttribute = "ATTR_SHIFT_RHS"
+	ATTR_LAST_BLOCK_STMT GnoAttribute = "ATTR_LAST_BLOCK_STMT"
 )
 
 var rePkgName = regexp.MustCompile(`^[a-z][a-z0-9_]+$`)

gnovm/pkg/gnolang/op_exec.go

@@ -676,25 +676,15 @@ EXEC_SWITCH:
 			bs.Active = bs.Body[cs.BodyIndex] // prefill
 		case FALLTHROUGH:
 			ss, ok := m.LastFrame().Source.(*SwitchStmt)
+			// this is handled in the preprocessor
+			// should never happen
 			if !ok {
-				// fallthrough is only allowed in a switch statement
 				panic("fallthrough statement out of place")
 			}
-			if ss.IsTypeSwitch {
-				// fallthrough is not allowed in type switches
-				panic("cannot fallthrough in type switch")
-			}
+
 			b := m.LastBlock()
-			if b.bodyStmt.NextBodyIndex != len(b.bodyStmt.Body) {
-				// fallthrough is not the final statement
-				panic("fallthrough statement out of place")
-			}
 			// compute next switch clause from BodyIndex (assigned in preprocess)
 			nextClause := cs.BodyIndex + 1
-			if nextClause >= len(ss.Clauses) {
-				// no more clause after the one executed, this is not allowed
-				panic("cannot fallthrough final case in switch")
-			}
 			// expand block size
 			cl := ss.Clauses[nextClause]
 			if nn := cl.GetNumNames(); int(nn) > len(b.Values) {

gnovm/pkg/gnolang/preprocess.go

@@ -311,6 +311,11 @@ func initStaticBlocks(store Store, ctx BlockNode, bn BlockNode) {
 					last.Predefine(false, n.VarName)
 				}
 			case *SwitchClauseStmt:
+				blen := len(n.Body)
+				if blen > 0 {
+					n.Body[blen-1].SetAttribute(ATTR_LAST_BLOCK_STMT, true)
+				}
+
 				pushInitRealBlock(n, &last, &stack)
 				// parent switch statement.
 				ss := ns[len(ns)-1].(*SwitchStmt)
@@ -2106,8 +2111,19 @@ func Preprocess(store Store, ctx BlockNode, n Node) Node {
 
 			// TRANS_LEAVE -----------------------
 			case *BranchStmt:
+
+				notAllowedFunc := func(s string) {
+					_, isFunc := last.(*FuncLitExpr)
+
+					if isFunc {
+						panic(fmt.Sprintf("%s statement out of place", s))
+					}
+				}
+
 				switch n.Op {
 				case BREAK:
+					notAllowedFunc("break")
+
 					if n.Label == "" {
 						if !findBreakableNode(ns) {
 							panic("cannot break with no parent loop or switch")
@@ -2120,6 +2136,8 @@ func Preprocess(store Store, ctx BlockNode, n Node) Node {
 						}
 					}
 				case CONTINUE:
+					notAllowedFunc("continue")
+
 					if n.Label == "" {
 						if !findContinuableNode(ns) {
 							panic("cannot continue with no parent loop")
@@ -2135,17 +2153,32 @@ func Preprocess(store Store, ctx BlockNode, n Node) Node {
 					n.Depth = depth
 					n.BodyIndex = index
 				case FALLTHROUGH:
-					if swchC, ok := last.(*SwitchClauseStmt); ok {
-						// last is a switch clause, find its index in the switch and assign
-						// it to the fallthrough node BodyIndex. This will be used at
-						// runtime to determine the next switch clause to run.
-						swch := lastSwitch(ns)
-						for i := range swch.Clauses {
-							if &swch.Clauses[i] == swchC {
-								// switch clause found
-								n.BodyIndex = i
-								break
-							}
+					swchC, ok := last.(*SwitchClauseStmt)
+					if !ok {
+						// fallthrough is only allowed in a switch statement
+						panic("fallthrough statement out of place")
+					}
+
+					if n.GetAttribute(ATTR_LAST_BLOCK_STMT) != true {
+						// no more clause after the one executed, this is not allowed
+						panic("cannot fallthrough final case in switch")
+					}
+
+					// last is a switch clause, find its index in the switch and assign
+					// it to the fallthrough node BodyIndex. This will be used at
+					// runtime to determine the next switch clause to run.
+					swch := lastSwitch(ns)
+
+					if swch.IsTypeSwitch {
+						// fallthrough is not allowed in type switches
+						panic("cannot fallthrough in type switch")
+					}
+
+					for i := range swch.Clauses {
+						if &swch.Clauses[i] == swchC {
+							// switch clause found
+							n.BodyIndex = i
+							break
 						}
 					}
 				default:

gnovm/tests/files/for21.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+    for i := 0; i < 10; i++ {
+        if i == 1 {
+            _ = func() int {
+                continue
+                return 11
+            }()
+        }
+        println(i)
+    }
+    println("wat???")
+}
+
+// Error:
+// continue statement out of place

gnovm/tests/files/for22.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+    for i := 0; i < 10; i++ {
+        if i == 1 {
+            _ = func() int {
+                fallthrough
+                return 11
+            }()
+        }
+        println(i)
+    }
+    println("wat???")
+}
+
+// Error:
+// fallthrough statement out of place

gnovm/tests/files/for23.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+    for i := 0; i < 10; i++ {
+        if i == 1 {
+            _ = func() int {
+                break
+                return 11
+            }()
+        }
+        println(i)
+    }
+    println("wat???")
+}
+
+// Error:
+// break statement out of place