[FIX] issue with delayed renders being left pending forever

tests/components/__snapshots__/concurrency.test.ts.snap

@@ -52,6 +52,50 @@ exports[`Cascading renders after microtaskTick 3`] = `
 }"
 `;
 
+exports[`another scenario with delayed rendering 1`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    let b2,b3;
+    b2 = text(\`A\`);
+    if (ctx['state'].value<15) {
+      b3 = component(\`B\`, {value: ctx['state'].value}, key + \`__1\`, node, ctx);
+    }
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`another scenario with delayed rendering 2`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  return function template(ctx, node, key = \\"\\") {
+    const b2 = text(ctx['props'].value);
+    const b3 = component(\`C\`, {}, key + \`__1\`, node, ctx);
+    return multi([b2, b3]);
+  }
+}"
+`;
+
+exports[`another scenario with delayed rendering 3`] = `
+"function anonymous(bdom, helpers
+) {
+  let { text, createBlock, list, multi, html, toggler, component, comment } = bdom;
+  
+  let block1 = createBlock(\`<button block-handler-0=\\"click\\"><block-text-1/></button>\`);
+  
+  return function template(ctx, node, key = \\"\\") {
+    let hdlr1 = [ctx['increment'], ctx];
+    let txt1 = ctx['state'].val;
+    return block1([hdlr1, txt1]);
+  }
+}"
+`;
+
 exports[`async rendering destroying a widget before start is over 1`] = `
 "function anonymous(bdom, helpers
 ) {

tests/components/concurrency.test.ts

@@ -3591,6 +3591,105 @@ test("delayed rendering, reusing fiber then component is destroyed and  stuff",
   ]).toBeLogged();
 });
 
+test("another scenario with delayed rendering", async () => {
+  let prom1 = makeDeferred();
+  let onSecondRenderA = makeDeferred();
+
+  class C extends Component {
+    static template = xml`<button t-on-click="increment"><t t-esc="state.val"/></button>`;
+    state = useState({ val: 1 });
+    setup() {
+      useLogLifecycle();
+    }
+    increment() {
+      this.state.val++;
+    }
+  }
+
+  class B extends Component {
+    static template = xml`<t t-esc="props.value"/><C />`;
+    static components = { C };
+    setup() {
+      useLogLifecycle();
+      onWillUpdateProps(() => prom1);
+    }
+  }
+
+  class A extends Component {
+    static template = xml`A<t t-if="state.value lt 15"><B value="state.value"/></t>`;
+    static components = { B };
+    state = useState({ value: 3 });
+    setup() {
+      useLogLifecycle();
+      let n = 0;
+      onRendered(() => {
+        n++;
+        if (n === 2) {
+          onSecondRenderA.resolve();
+        }
+      });
+    }
+  }
+
+  const parent = await mount(A, fixture);
+  expect(fixture.innerHTML).toBe("A3<button>1</button>");
+  expect([
+    "A:setup",
+    "A:willStart",
+    "A:willRender",
+    "B:setup",
+    "B:willStart",
+    "A:rendered",
+    "B:willRender",
+    "C:setup",
+    "C:willStart",
+    "B:rendered",
+    "C:willRender",
+    "C:rendered",
+    "C:mounted",
+    "B:mounted",
+    "A:mounted",
+  ]).toBeLogged();
+
+  // initiate a render in A, but is blocked in B
+  parent.state.value = 5;
+  await nextTick();
+  expect(["A:willRender", "B:willUpdateProps", "A:rendered"]).toBeLogged();
+
+  // initiate a render in C (will be delayed because of render in A)
+  fixture.querySelector("button")!.click();
+  await nextTick();
+  expect([]).toBeLogged();
+
+  // initiate a render in A, that will destroy B
+  parent.state.value = 23;
+  await onSecondRenderA;
+  await nextMicroTick();
+  expect(["A:willRender", "A:rendered"]).toBeLogged();
+
+  // rerender A, but without destroying B
+  parent.state.value = 7;
+  await nextTick();
+  expect(["A:willRender", "B:willUpdateProps", "A:rendered"]).toBeLogged();
+
+  prom1.resolve();
+  await nextTick();
+  expect(fixture.innerHTML).toBe("A7<button>2</button>");
+
+  expect([
+    "B:willRender",
+    "B:rendered",
+    "C:willRender",
+    "C:rendered",
+    "A:willPatch",
+    "B:willPatch",
+    "B:patched",
+    "A:patched",
+    "C:willPatch",
+    "C:patched",
+  ]).toBeLogged();
+});
+
 //   test.skip("components with shouldUpdate=false", async () => {
 //     const state = { p: 1, cc: 10 };