fix(ivy): ensure template styles/classes are applied before directives are instantiated (#29269)

Angular Ivy interprets inline static style/class attribute values as instructions that
are processed whilst an element gets created. Because these inline style values are
referenced by style/class bindings, their inline style values are applied at a later
stage. Despite them being eventually applied, their values should be applied earlier
before any directives are instantiated so that directive code can rely on any inline
style/class changes.

This patch ensures that all static style/class attribute values are applied (rendered)
on the element before directives are instantiated.

Jira Issue: FW-1133

PR Close #29269

packages/core/src/render3/instructions.ts

@@ -619,10 +619,13 @@ export function elementStart(
   ngDevMode && ngDevMode.rendererCreateElement++;
 
   const native = elementCreate(name);
+  const renderer = lView[RENDERER];
 
   ngDevMode && assertDataInRange(lView, index - 1);
 
   const tNode = createNodeAtIndex(index, TNodeType.Element, native !, name, attrs || null);
+  let initialStylesIndex = 0;
+  let initialClassesIndex = 0;
 
   if (attrs) {
     const lastAttrIndex = setUpAttributes(native, attrs);
@@ -640,6 +643,14 @@ export function elementStart(
         tNode.stylingTemplate = initializeStaticStylingContext(attrs, stylingAttrsStartIndex);
       }
     }
+
+    if (tNode.stylingTemplate) {
+      // the initial style/class values are rendered immediately after having been
+      // initialized into the context so the element styling is ready when directives
+      // are initialized (since they may read style/class values in their constructor)
+      initialStylesIndex = renderInitialStyles(native, tNode.stylingTemplate, renderer);
+      initialClassesIndex = renderInitialClasses(native, tNode.stylingTemplate, renderer);
+    }
   }
 
   appendChild(native, tNode, lView);
@@ -667,11 +678,11 @@ export function elementStart(
     }
   }
 
-  // There is no point in rendering styles when a class directive is present since
-  // it will take that over for us (this will be removed once #FW-882 is in).
+  // we render the styling again below in case any directives have set any `style` and/or
+  // `class` host attribute values...
   if (tNode.stylingTemplate) {
-    renderInitialClasses(native, tNode.stylingTemplate, lView[RENDERER]);
-    renderInitialStyles(native, tNode.stylingTemplate, lView[RENDERER]);
+    renderInitialClasses(native, tNode.stylingTemplate, renderer, initialClassesIndex);
+    renderInitialStyles(native, tNode.stylingTemplate, renderer, initialStylesIndex);
   }
 
   const currentQueries = lView[QUERIES];

packages/core/src/render3/interfaces/styling.ts

@@ -470,6 +470,12 @@ export const enum InitialStylingValuesIndex {
    */
   DirectiveOwnerOffset = 2,
 
+  /**
+   * The first bit set aside to mark if the initial style was already rendere
+   */
+  AppliedFlagBitPosition = 0b0,
+  AppliedFlagBitLength = 1,
+
   /**
    * The total size for each style/class entry (prop + value + directiveOwner)
    */

packages/core/src/render3/styling/class_and_style_bindings.ts

@@ -139,47 +139,53 @@ function patchInitialStylingValue(
 }
 
 /**
- * Runs through the initial style data present in the context and renders
- * them via the renderer on the element.
- */
-export function renderInitialStyles(
-    element: RElement, context: StylingContext, renderer: Renderer3) {
-  const initialStyles = context[StylingIndex.InitialStyleValuesPosition];
-  renderInitialStylingValues(element, renderer, initialStyles, false);
-}
-
-/**
- * Runs through the initial class data present in the context and renders
- * them via the renderer on the element.
+ * Runs through the initial class values present in the provided
+ * context and renders them via the provided renderer on the element.
+ *
+ * @param element the element the styling will be applied to
+ * @param context the source styling context which contains the initial class values
+ * @param renderer the renderer instance that will be used to apply the class
+ * @returns the index that the classes were applied up until
  */
 export function renderInitialClasses(
-    element: RElement, context: StylingContext, renderer: Renderer3) {
+    element: RElement, context: StylingContext, renderer: Renderer3, startIndex?: number): number {
   const initialClasses = context[StylingIndex.InitialClassValuesPosition];
-  renderInitialStylingValues(element, renderer, initialClasses, true);
+  let i = startIndex || InitialStylingValuesIndex.KeyValueStartPosition;
+  while (i < initialClasses.length) {
+    const value = initialClasses[i + InitialStylingValuesIndex.ValueOffset];
+    if (value) {
+      setClass(
+          element, initialClasses[i + InitialStylingValuesIndex.PropOffset] as string, true,
+          renderer, null);
+    }
+    i += InitialStylingValuesIndex.Size;
+  }
+  return i;
 }
 
 /**
- * This is a helper function designed to render each entry present within the
- * provided list of initialStylingValues.
+ * Runs through the initial styles values present in the provided
+ * context and renders them via the provided renderer on the element.
+ *
+ * @param element the element the styling will be applied to
+ * @param context the source styling context which contains the initial class values
+ * @param renderer the renderer instance that will be used to apply the class
+ * @returns the index that the styles were applied up until
  */
-function renderInitialStylingValues(
-    element: RElement, renderer: Renderer3, initialStylingValues: InitialStylingValues,
-    isEntryClassBased: boolean) {
-  for (let i = InitialStylingValuesIndex.KeyValueStartPosition; i < initialStylingValues.length;
-       i += InitialStylingValuesIndex.Size) {
-    const value = initialStylingValues[i + InitialStylingValuesIndex.ValueOffset];
+export function renderInitialStyles(
+    element: RElement, context: StylingContext, renderer: Renderer3, startIndex?: number) {
+  const initialStyles = context[StylingIndex.InitialStyleValuesPosition];
+  let i = startIndex || InitialStylingValuesIndex.KeyValueStartPosition;
+  while (i < initialStyles.length) {
+    const value = initialStyles[i + InitialStylingValuesIndex.ValueOffset];
     if (value) {
-      if (isEntryClassBased) {
-        setClass(
-            element, initialStylingValues[i + InitialStylingValuesIndex.PropOffset] as string, true,
-            renderer, null);
-      } else {
-        setStyle(
-            element, initialStylingValues[i + InitialStylingValuesIndex.PropOffset] as string,
-            value as string, renderer, null);
-      }
+      setStyle(
+          element, initialStyles[i + InitialStylingValuesIndex.PropOffset] as string,
+          value as string, renderer, null);
     }
+    i += InitialStylingValuesIndex.Size;
   }
+  return i;
 }
 
 export function allowNewBindingsForStylingContext(context: StylingContext): boolean {
@@ -375,7 +381,7 @@ export function updateContextWithBindings(
     }
 
     // if a property is not found in the initial style values list then it
-    // is ALWAYS added incase a follow-up directive introduces the same initial
+    // is ALWAYS added in case a follow-up directive introduces the same initial
     // style/class value later on.
     let initialValuesToLookup = entryIsClassBased ? initialClasses : initialStyles;
     let indexForInitial = getInitialStylingValuesIndexOf(initialValuesToLookup, propName);
@@ -765,7 +771,7 @@ function patchStylingMapIntoContext(
       const mapProp = props[i];
 
       if (!mapProp) {
-        // this is an early exit incase a value was already encountered above in the
+        // this is an early exit in case a value was already encountered above in the
         // previous loop (which means that the property was applied or rejected)
         continue;
       }
@@ -801,7 +807,7 @@ function patchStylingMapIntoContext(
               // SKIP IF INITIAL CHECK
               // If the former `value` is `null` then it means that an initial value
               // could be being rendered on screen. If that is the case then there is
-              // no point in updating the value incase it matches. In other words if the
+              // no point in updating the value in case it matches. In other words if the
               // new value is the exact same as the previously rendered value (which
               // happens to be the initial value) then do nothing.
               if (distantCtxValue !== null ||
@@ -872,7 +878,7 @@ function patchStylingMapIntoContext(
   // reapply their values into the object. For this to happen, the cached array needs to be updated
   // with dirty flags so that follow-up calls to `updateStylingMap` will reapply their styling code.
   // the reapplication of styling code within the context will reshape it and update the offset
-  // values (also follow-up directives can write new values incase earlier directives set anything
+  // values (also follow-up directives can write new values in case earlier directives set anything
   // to null due to removals or falsy values).
   valuesEntryShapeChange = valuesEntryShapeChange || existingCachedValueCount !== totalUniqueValues;
   updateCachedMapValue(
@@ -1074,7 +1080,7 @@ export function renderStyling(
 
         // VALUE DEFER CASE 2: Use the initial value if all else fails (is falsy)
         // the initial value will always be a string or null,
-        // therefore we can safely adopt it incase there's nothing else
+        // therefore we can safely adopt it in case there's nothing else
         // note that this should always be a falsy check since `false` is used
         // for both class and style comparisons (styles can't be false and false
         // classes are turned off and should therefore defer to their initial values)
@@ -1742,7 +1748,7 @@ function allowValueChange(
   // directive is the parent component directive (the template) and each directive
   // that is added after is considered less important than the previous entry. This
   // prioritization of directives enables the styling algorithm to decide if a style
-  // or class should be allowed to be updated/replaced incase an earlier directive
+  // or class should be allowed to be updated/replaced in case an earlier directive
   // already wrote to the exact same style-property or className value. In other words
   // this decides what to do if and when there is a collision.
   if (currentValue != null) {
@@ -1751,7 +1757,7 @@ function allowValueChange(
       // previous directive's value...
       return newDirectiveOwner <= currentDirectiveOwner;
     } else {
-      // only write a null value incase it's the same owner writing it.
+      // only write a null value in case it's the same owner writing it.
       // this avoids having a higher-priority directive write to null
       // only to have a lesser-priority directive change right to a
       // non-null value immediately afterwards.
@@ -1955,7 +1961,7 @@ function registerMultiMapEntry(
     while (cachedValues.length < limit) {
       // this means that ONLY directive class styling (like ngClass) was used
       // therefore the root directive will still need to be filled in as well
-      // as any other directive spaces incase they only used static values
+      // as any other directive spaces in case they only used static values
       cachedValues.push(0, startPosition, null, 0);
     }
   }

packages/core/test/acceptance/styling_spec.ts

@@ -5,7 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-import {Component, HostBinding} from '@angular/core';
+import {Component, Directive, ElementRef, HostBinding} from '@angular/core';
 import {TestBed} from '@angular/core/testing';
 import {expect} from '@angular/platform-browser/testing/src/matchers';
 import {ivyEnabled, onlyInIvy} from '@angular/private/testing';
@@ -96,4 +96,61 @@ describe('acceptance integration tests', () => {
     expect(element.classList.contains('foo')).toBeTruthy();
     expect(element.classList.contains('baz')).toBeTruthy();
   });
+
+  it('should render inline style and class attribute values on the element before a directive is instantiated',
+     () => {
+       @Component({
+         template: `
+        <div directive-expecting-styling style="width:200px" class="abc xyz"></div>
+      `
+       })
+       class Cmp {
+       }
+
+       @Directive({selector: '[directive-expecting-styling]'})
+       class DirectiveExpectingStyling {
+         constructor(elm: ElementRef) {
+           const native = elm.nativeElement;
+           native.setAttribute('data-captured-width', native.style.width);
+           native.setAttribute('data-captured-classes', native.className);
+         }
+       }
+
+       TestBed.configureTestingModule({declarations: [Cmp, DirectiveExpectingStyling]});
+       const fixture = TestBed.createComponent(Cmp);
+       fixture.detectChanges();
+
+       const element = fixture.nativeElement.querySelector('div');
+       expect(element.style.width).toEqual('200px');
+       expect(element.getAttribute('data-captured-width')).toEqual('200px');
+       expect(element.className.trim()).toEqual('abc xyz');
+       expect(element.getAttribute('data-captured-classes')).toEqual('abc xyz');
+     });
+
+  it('should only render the same initial styling values once before a directive runs', () => {
+    @Component({
+      template: `
+        <div directive-expecting-styling style="width:200px" class="abc"></div>
+      `
+    })
+    class Cmp {
+    }
+
+    @Directive({selector: '[directive-expecting-styling]'})
+    class DirectiveExpectingStyling {
+      constructor(elm: ElementRef) {
+        const native = elm.nativeElement;
+        native.style.width = '300px';
+        native.classList.remove('abc');
+      }
+    }
+
+    TestBed.configureTestingModule({declarations: [Cmp, DirectiveExpectingStyling]});
+    const fixture = TestBed.createComponent(Cmp);
+    fixture.detectChanges();
+
+    const element = fixture.nativeElement.querySelector('div');
+    expect(element.style.width).toEqual('300px');
+    expect(element.classList.contains('abc')).toBeFalsy();
+  });
 });

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -605,9 +605,6 @@
   {
     "name": "renderInitialStyles"
   },
-  {
-    "name": "renderInitialStylingValues"
-  },
   {
     "name": "renderStringify"
   },

packages/core/test/bundling/hello_world/bundle.golden_symbols.json

@@ -425,9 +425,6 @@
   {
     "name": "renderInitialStyles"
   },
-  {
-    "name": "renderInitialStylingValues"
-  },
   {
     "name": "renderStringify"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -1178,9 +1178,6 @@
   {
     "name": "renderInitialStyles"
   },
-  {
-    "name": "renderInitialStylingValues"
-  },
   {
     "name": "renderStringify"
   },

tools/material-ci/angular_material_test_blocklist.js

@@ -104,14 +104,6 @@ window.testBlocklist = {
   "MatSnackBar with TemplateRef should be able to open a snack bar using a TemplateRef": {
     "error": "Error: Expected ' Fries Pizza  ' to contain 'Pasta'.",
     "notes": "Breaking change: Change detection follows insertion tree only, not declaration tree (MatSnackBarContainer is OnPush)"
-  },
-  "MatTooltip special cases should clear the `user-select` when a tooltip is set on a text field": {
-    "error": "Error: Expected 'none' to be falsy.",
-    "notes": "FW-1133: Inline styles are not applied before constructor is run"
-  },
-  "MatTooltip special cases should clear the `-webkit-user-drag` on draggable elements": {
-    "error": "Error: Expected 'none' to be falsy.",
-    "notes": "FW-1133: Inline styles are not applied before constructor is run"
   }
 };
-// clang-format on
+// clang-format on