fix(gnovm): alternative way(of #4444) to get last line

gnovm/pkg/gnolang/machine.go

@@ -39,6 +39,7 @@ type Machine struct {
 	GCCycle       int64         // number of "gc" cycles
 	Stage         Stage         // pre for static eval, add for package init, run otherwise
 	ReviveEnabled bool          // true if revive() enabled (only in testing mode for now)
+	Lastline      int           // the line the VM is currently executing
 
 	Debugger Debugger
 
@@ -426,32 +427,17 @@ func (m *Machine) Stacktrace() (stacktrace Stacktrace) {
 	if m.LastFrame().Func != nil && m.LastFrame().Func.IsNative() {
 		stacktrace.LastLine = -1 // special line for native.
 	} else {
-		if len(m.Stmts) > 0 {
-			ls := m.PeekStmt(1)
-			if bs, ok := ls.(*bodyStmt); ok {
-				stacktrace.LastLine = bs.LastStmt().GetLine()
-			} else {
-				goto NOTPANIC // not a panic call
-			}
-		} else {
-			goto NOTPANIC // not a panic call
+		if m.Lastline != 0 {
+			stacktrace.LastLine = m.Lastline
+			return
 		}
-	NOTPANIC:
-		if len(m.Exprs) > 0 {
-			stacktrace.LastLine = m.PeekExpr(1).GetLine()
-		} else if len(m.Stmts) > 0 {
-			stmt := m.PeekStmt(1)
-			if bs, ok := stmt.(*bodyStmt); ok {
-				if 0 <= bs.NextBodyIndex-1 {
-					stmt = bs.Body[bs.NextBodyIndex-1]
-				}
-			}
-			stacktrace.LastLine = stmt.GetLine()
-		} else {
-			stacktrace.LastLine = 0 // dunno
+
+		ls := m.PeekStmt(1)
+		if bs, ok := ls.(*bodyStmt); ok {
+			stacktrace.LastLine = bs.LastStmt().GetLine()
+			return
 		}
 	}
-
 	return
 }
 
@@ -1670,6 +1656,7 @@ func (m *Machine) PushStmt(s Stmt) {
 	if debug {
 		m.Printf("+s %v\n", s)
 	}
+	m.Lastline = s.GetLine()
 	m.Stmts = append(m.Stmts, s)
 }
 
@@ -1679,6 +1666,7 @@ func (m *Machine) PushStmts(ss ...Stmt) {
 			m.Printf("+s %v\n", s)
 		}
 	}
+	// XXX, also set lastLine here?
 	m.Stmts = append(m.Stmts, ss...)
 }
 
@@ -1726,6 +1714,7 @@ func (m *Machine) PopExpr() Expr {
 	if debug {
 		m.Printf("-x %v\n", x)
 	}
+	m.Lastline = x.GetLine()
 	m.Exprs = m.Exprs[:numExprs-1]
 	return x
 }

gnovm/tests/files/access2.gno

@@ -12,3 +12,8 @@ func main(cur realm) {
 
 // Error:
 // cannot directly modify readonly tainted object (w/o method): (const (ref(gno.land/p/nt/testutils) package{})).TestVar1
+
+// Stacktrace:
+// panic: cannot directly modify readonly tainted object (w/o method): (const (ref(gno.land/p/nt/testutils) package{})).TestVar1
+// main<VPBlock(1,0)>(struct{( .uverse.address),("gno.land/r/access" string),(nil .uverse..grealm)})
+//     gno.land/r/access/access2.gno:9

gnovm/tests/files/panic3.gno

@@ -0,0 +1,19 @@
+package main
+
+var a = 0
+func foo()int{
+	return 1/a
+}
+func main() {
+	foo()
+}
+
+// Error:
+// division by zero
+
+// Stacktrace:
+// panic: division by zero
+// foo<VPBlock(3,1)>()
+//     main/panic3.gno:5
+// main<VPBlock(1,2)>()
+//     main/panic3.gno:8

gnovm/tests/files/panic4.gno

@@ -0,0 +1,13 @@
+package main
+
+func main() {
+	panic("===")
+}
+
+// Stacktrace:
+// panic: ===
+// main<VPBlock(1,0)>()
+//     main/panic4.gno:4
+
+// Error:
+// ===

gnovm/tests/files/panic5.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+	a := 0
+	if i := 1; true && 
+		i/a == 2 {
+		println("ok")
+	}
+}
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/panic5.gno:6
+
+// Error:
+// division by zero

gnovm/tests/files/panic5a.gno

@@ -0,0 +1,16 @@
+package main
+
+func main() {
+	a := 0
+	if i := 0; true && i/a == 1 {
+		println("ok")
+	}
+}
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/panic5a.gno:5
+
+// Error:
+// division by zero

gnovm/tests/files/panic5b.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+	a := 0
+	if i := 1; i ==
+		2/a {
+		println("ok")
+	}
+}
+
+// Error:
+// division by zero
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/panic5b.gno:6

gnovm/tests/files/panic5c.gno

@@ -0,0 +1,17 @@
+package main
+
+func main() {
+	a := 0
+	b := 1/a
+}
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/panic5c.gno:5
+
+// Error:
+// division by zero
+
+// TypeCheckError:
+// main/panic5c.gno:5:2: declared and not used: b

gnovm/tests/files/panic5d.gno

@@ -0,0 +1,16 @@
+package main
+
+func main() {
+	a := 0
+	if i := 1/a; true  {
+		println(i)
+	}
+}
+
+// Error:
+// division by zero
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/panic5d.gno:5

gnovm/tests/files/panic6.gno

@@ -0,0 +1,28 @@
+package main
+
+import "fmt"
+
+func main() {
+	// A pointer to a pointer, initialized to nil
+	var doublePtr **int = nil
+
+	fmt.Println("1. Attempting to evaluate **doublePtr")
+
+	// The expression is: *(*doublePtr)
+	// The VM/Runtime must evaluate the INNER (*doublePtr) first
+	// to get the address for the OUTER (*).
+
+	// CRASH OCCURS HERE inside the first dereference.
+	val := **doublePtr 
+
+	// This line is never reached
+	fmt.Println("2. Success:", val)
+}
+
+// Stacktrace:
+// panic: nil pointer dereference
+// main<VPBlock(1,0)>()
+//     main/panic6.gno:16
+
+// Error:
+// nil pointer dereference

gnovm/tests/files/panic7.gno

@@ -0,0 +1,14 @@
+package main
+
+func main() {
+	var p *int
+	println(*p)	
+}
+
+// Stacktrace:
+// panic: nil pointer dereference
+// main<VPBlock(1,0)>()
+//     main/panic7.gno:5
+
+// Error:
+// nil pointer dereference

gnovm/tests/files/recover/recover3.gno

@@ -0,0 +1,15 @@
+package main
+
+func main() {
+	for i := 0; 1/i >= 0; i++ {
+		break
+	}
+}
+
+// Error:
+// division by zero
+
+// Stacktrace:
+// panic: division by zero
+// main<VPBlock(1,0)>()
+//     main/recover3.gno:4