Merge pull request #1084 from nevkontakte/double-defer

nevkontakte · web-flow · commit 55c718a57440 · 2021-11-08T12:03:34.000Z
Use object identity to detect how far to unwind stack after panic recovery.
diff --git a/compiler/package.go b/compiler/package.go
@@ -831,7 +831,7 @@ func translateFunction(typ *ast.FuncType, recv *ast.Ident, body *ast.BlockStmt,
 	}
 
 	if c.HasDefer {
-		prefix = prefix + " $deferred = []; $deferred.index = $curGoroutine.deferStack.length; $curGoroutine.deferStack.push($deferred);"
+		prefix = prefix + " $deferred = []; $curGoroutine.deferStack.push($deferred);"
 	}
 
 	if prefix != "" {
diff --git a/compiler/prelude/goroutines.go b/compiler/prelude/goroutines.go
@@ -12,7 +12,7 @@ var $getStackDepth = function() {
 
 var $panicStackDepth = null, $panicValue;
 var $callDeferred = function(deferred, jsErr, fromPanic) {
-  if (!fromPanic && deferred !== null && deferred.index >= $curGoroutine.deferStack.length) {
+  if (!fromPanic && deferred !== null && $curGoroutine.deferStack.indexOf(deferred) == -1) {
     throw jsErr;
   }
   if (jsErr !== null) {
@@ -88,6 +88,18 @@ var $callDeferred = function(deferred, jsErr, fromPanic) {
         return;
       }
     }
+  } catch(e) {
+    // Deferred function threw a JavaScript exception or tries to unwind stack
+    // to the point where a panic was handled.
+    if (fromPanic) {
+      // Re-throw the exception to reach deferral execution call at the end
+      // of the function.
+      throw e;
+    }
+    // We are at the end of the function, handle the error or re-throw to
+    // continue unwinding if necessary, or simply stop unwinding if we got far
+    // enough.
+    $callDeferred(deferred, e, fromPanic);
   } finally {
     if (localPanicValue !== undefined) {
       if ($panicStackDepth !== null) {
diff --git a/compiler/prelude/prelude_min.go b/compiler/prelude/prelude_min.go
diff --git a/tests/deferblock_test.go b/tests/deferblock_test.go
@@ -1,6 +1,8 @@
 package tests
 
 import (
+	"errors"
+	"fmt"
 	"testing"
 	"time"
 )
@@ -40,3 +42,75 @@ func TestBlockingInDefer(t *testing.T) {
 
 	outer(ch, b)
 }
+
+func TestIssue1083(t *testing.T) {
+	// https://github.com/gopherjs/gopherjs/issues/1083
+	var block = make(chan bool)
+
+	recoverCompleted := false
+
+	recoverAndBlock := func() {
+		defer func() {}()
+		recover()
+		block <- true
+		recoverCompleted = true
+	}
+
+	handle := func() {
+		defer func() {}()
+		panic("expected panic")
+	}
+
+	serve := func() {
+		defer recoverAndBlock()
+		handle()
+		t.Fatal("This line must never execute.")
+	}
+
+	go func() { <-block }()
+
+	serve()
+	if !recoverCompleted {
+		t.Fatal("Recovery function did not execute fully.")
+	}
+}
+
+func TestIssue780(t *testing.T) {
+	// https://github.com/gopherjs/gopherjs/issues/780
+	want := errors.New("expected error")
+	var got error
+
+	catch := func() {
+		if r := recover(); r != nil {
+			got = r.(error)
+		}
+	}
+	throw := func() { panic(want) }
+
+	catchAndThrow := func() {
+		t.Logf("catchAndThrow: %v", recover())
+		panic(want)
+	}
+
+	execute := func(x int) (err error) {
+		defer catch() // Final recovery.
+
+		for i := 0; i < x; i++ {
+			// Test that several deferred panics can be handled.
+			defer catchAndThrow()
+		}
+
+		defer throw() // Emulates a panicing cleanup.
+
+		return nil
+	}
+
+	for _, x := range []int{0, 1, 2, 5, 10} {
+		t.Run(fmt.Sprint(x), func(t *testing.T) {
+			execute(x)
+			if !errors.Is(got, want) {
+				t.Errorf("process() returned error %v, want %v", got, want)
+			}
+		})
+	}
+}
diff --git a/tests/gorepo/run.go b/tests/gorepo/run.go
@@ -68,7 +68,6 @@ var knownFails = map[string]failReason{
 	"fixedbugs/issue6899.go":  {desc: "incorrect output -0"},
 	"fixedbugs/issue7550.go":  {category: neverTerminates, desc: "FATAL ERROR: invalid table size Allocation failed - process out of memory"},
 	"fixedbugs/issue7690.go":  {desc: "Error: runtime error: slice bounds out of range"},
-	"fixedbugs/issue8047.go":  {desc: "null"},
 	"fixedbugs/issue8047b.go": {desc: "Error: [object Object]"},
 
 	// Failing due to use of os/exec.Command, which is unsupported. Now skipped via !nacl build tag.

Original file line number	Diff line number	Diff line change
`@@ -831,7 +831,7 @@ func translateFunction(typ ast.FuncType, recv ast.Ident, body *ast.BlockStmt,`
`831`	`831`	`}`
`832`	`832`
`833`	`833`	`if c.HasDefer {`
`834`		`- prefix = prefix + " $deferred = []; $deferred.index = $curGoroutine.deferStack.length; $curGoroutine.deferStack.push($deferred);"`
	`834`	`+ prefix = prefix + " $deferred = []; $curGoroutine.deferStack.push($deferred);"`
`835`	`835`	`}`
`836`	`836`
`837`	`837`	`if prefix != "" {`