Fix a bug for 'for' loop without condition: "for {}" (#100)

d5 · Feb 12, 2019 · cb1c8a4 · cb1c8a4
1 parent fc4e358
commit cb1c8a4
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Showing 2 changed files with 144 additions and 5 deletions.
diff --git a/compiler/compiler_for.go b/compiler/compiler_for.go
@@ -21,11 +21,14 @@ func (c *Compiler) compileForStmt(stmt *ast.ForStmt) error {
 	preCondPos := len(c.currentInstructions())
 
 	// condition expression
-	if err := c.Compile(stmt.Cond); err != nil {
-		return err
+	postCondPos := -1
+	if stmt.Cond != nil {
+		if err := c.Compile(stmt.Cond); err != nil {
+			return err
+		}
+		// condition jump position
+		postCondPos = c.emit(OpJumpFalsy, 0)
 	}
-	// condition jump position
-	postCondPos := c.emit(OpJumpFalsy, 0)
 
 	// enter loop
 	loop := c.enterLoop()
@@ -53,7 +56,9 @@ func (c *Compiler) compileForStmt(stmt *ast.ForStmt) error {
 
 	// post-statement position
 	postStmtPos := len(c.currentInstructions())
-	c.changeOperand(postCondPos, postStmtPos)
+	if postCondPos >= 0 {
+		c.changeOperand(postCondPos, postStmtPos)
+	}
 
 	// update all break/continue jump positions
 	for _, pos := range loop.Breaks {

diff --git a/runtime/vm_for_test.go b/runtime/vm_for_test.go
@@ -5,6 +5,40 @@ import (
 )
 
 func TestFor(t *testing.T) {
+	expect(t, `
+	for {
+		out++
+		if out == 5 {
+			break
+		}
+	}`, 5)
+
+	expect(t, `
+	for {
+		out++
+		if out == 5 {
+			break
+		}
+	}`, 5)
+
+	expect(t, `
+	a := 0
+	for {
+		a++
+		if a == 3 { continue }
+		if a == 5 { break }
+		out += a
+	}`, 7) // 1 + 2 + 4
+
+	expect(t, `
+	a := 0
+	for {
+		a++
+		if a == 3 { continue }
+		out += a
+		if a == 5 { break }
+	}`, 12) // 1 + 2 + 4 + 5
+
 	expect(t, `
 	for true {
 		out++
@@ -13,6 +47,34 @@ func TestFor(t *testing.T) {
 		}
 	}`, 5)
 
+	expect(t, `
+	a := 0
+	for true {
+		a++
+		if a == 5 {
+			break
+		}
+	}
+	out = a`, 5)
+
+	expect(t, `
+	a := 0
+	for true {
+		a++
+		if a == 3 { continue }
+		if a == 5 { break }
+		out += a
+	}`, 7) // 1 + 2 + 4
+
+	expect(t, `
+	a := 0
+	for true {
+		a++
+		if a == 3 { continue }
+		out += a
+		if a == 5 { break }
+	}`, 12) // 1 + 2 + 4 + 5
+
 	expect(t, `
 	func() {
 		for true {
@@ -35,6 +97,78 @@ func TestFor(t *testing.T) {
 		}
 	}`, 54)
 
+	expect(t, `
+	func() {
+		for {
+			out++
+			if out == 5 {
+				break
+			}
+		}
+	}()`, 5)
+
+	expect(t, `
+	func() {
+		for true {
+			out++
+			if out == 5 {
+				break
+			}
+		}
+	}()`, 5)
+
+	expect(t, `
+	out = func() {
+		a := 0
+		for {
+			a++
+			if a == 5 {
+				break
+			}
+		}
+		return a
+	}()`, 5)
+
+	expect(t, `
+	out = func() {
+		a := 0
+		for true {
+			a++
+			if a== 5 {
+				break
+			}
+		}
+		return a
+	}()`, 5)
+
+	expect(t, `
+	out = func() {
+		a := 0
+		func() {
+			for {
+				a++
+				if a == 5 {
+					break
+				}
+			}
+		}()
+		return a
+	}()`, 5)
+
+	expect(t, `
+	out = func() {
+		a := 0
+		func() {
+			for true {
+				a++
+				if a == 5 {
+					break
+				}
+			}
+		}()
+		return a
+	}()`, 5)
+
 	expect(t, `
 	out = func() {
 		sum := 0