fix(ivy): handling className as an input properly

packages/compiler/src/render3/view/styling_builder.ts

@@ -201,6 +201,10 @@ export class StylingBuilder {
     const entry:
         BoundStylingEntry = {name: property, value, sourceSpan, hasOverrideFlag, unit: null};
     if (isMapBased) {
+      if (this._classMapInput) {
+        throw new Error(
+            '[class] and [className] bindings cannot be used on the same element simultaneously');
+      }
       this._classMapInput = entry;
     } else {
       (this._singleClassInputs = this._singleClassInputs || []).push(entry);

packages/core/src/render3/instructions/element.ts

@@ -19,7 +19,7 @@ import {assertNodeType} from '../node_assert';
 import {appendChild} from '../node_manipulation';
 import {decreaseElementDepthCount, getElementDepthCount, getIsParent, getLView, getNamespace, getPreviousOrParentTNode, getSelectedIndex, increaseElementDepthCount, setIsNotParent, setPreviousOrParentTNode} from '../state';
 import {setUpAttributes} from '../util/attrs_utils';
-import {getInitialStylingValue, hasClassInput, hasStyleInput} from '../util/styling_utils';
+import {getInitialStylingValue, hasClassInput, hasStyleInput, selectClassBasedInputName} from '../util/styling_utils';
 import {getNativeByTNode, getTNode} from '../util/view_utils';
 
 import {createDirectivesInstances, elementCreate, executeContentQueries, getOrCreateTNode, renderInitialStyling, resolveDirectives, saveResolvedLocalsInData, setInputsForProperty} from './shared';
@@ -132,7 +132,8 @@ export function ɵɵelementEnd(): void {
   }
 
   if (hasClassInput(tNode)) {
-    setDirectiveStylingInput(tNode.classes, lView, tNode.inputs !['class']);
+    const inputName: string = selectClassBasedInputName(tNode.inputs !);
+    setDirectiveStylingInput(tNode.classes, lView, tNode.inputs ![inputName]);
   }
 
   if (hasStyleInput(tNode)) {

packages/core/src/render3/instructions/shared.ts

@@ -849,7 +849,7 @@ function initializeInputAndOutputAliases(tView: TView, tNode: TNode): void {
   }
 
   if (inputsStore !== null) {
-    if (inputsStore.hasOwnProperty('class')) {
+    if (inputsStore.hasOwnProperty('class') || inputsStore.hasOwnProperty('className')) {
       tNode.flags |= TNodeFlags.hasClassInput;
     }
     if (inputsStore.hasOwnProperty('style')) {

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

@@ -19,7 +19,7 @@ import {activateStylingMapFeature} from '../styling/map_based_bindings';
 import {attachStylingDebugObject} from '../styling/styling_debug';
 import {NO_CHANGE} from '../tokens';
 import {renderStringify} from '../util/misc_utils';
-import {addItemToStylingMap, allocStylingMapArray, allocTStylingContext, allowDirectStyling, concatString, forceClassesAsString, forceStylesAsString, getInitialStylingValue, getStylingMapArray, hasClassInput, hasStyleInput, hasValueChanged, isContextLocked, isHostStylingActive, isStylingContext, normalizeIntoStylingMap, patchConfig, setValue, stylingMapToString} from '../util/styling_utils';
+import {addItemToStylingMap, allocStylingMapArray, allocTStylingContext, allowDirectStyling, concatString, forceClassesAsString, forceStylesAsString, getInitialStylingValue, getStylingMapArray, hasClassInput, hasStyleInput, hasValueChanged, isContextLocked, isHostStylingActive, isStylingContext, normalizeIntoStylingMap, patchConfig, selectClassBasedInputName, setValue, stylingMapToString} from '../util/styling_utils';
 import {getNativeByTNode, getTNode} from '../util/view_utils';
 
 
@@ -402,7 +402,7 @@ function updateDirectiveInputValue(
     // directive input(s) in the event that it is falsy during the
     // first update pass.
     if (newValue || isContextLocked(context, false)) {
-      const inputName = isClassBased ? 'class' : 'style';
+      const inputName: string = isClassBased ? selectClassBasedInputName(tNode.inputs !) : 'style';
       const inputs = tNode.inputs ![inputName] !;
       const initialValue = getInitialStylingValue(context);
       const value = normalizeStylingDirectiveInputValue(initialValue, newValue, isClassBased);

packages/core/src/render3/util/styling_utils.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 {TNode, TNodeFlags} from '../interfaces/node';
+import {PropertyAliases, TNode, TNodeFlags} from '../interfaces/node';
 import {LStylingData, StylingMapArray, StylingMapArrayIndex, TStylingConfig, TStylingContext, TStylingContextIndex, TStylingContextPropConfigFlags} from '../interfaces/styling';
 import {NO_CHANGE} from '../tokens';
 
@@ -433,3 +433,9 @@ export function normalizeIntoStylingMap(
 
   return stylingMapArr;
 }
+
+// TODO (matsko|AndrewKushnir): refactor this once we figure out how to generate separate
+// `input('class') + classMap()` instructions.
+export function selectClassBasedInputName(inputs: PropertyAliases): string {
+  return inputs.hasOwnProperty('class') ? 'class' : 'className';
+}

packages/core/test/acceptance/styling_spec.ts

@@ -551,6 +551,74 @@ describe('styling', () => {
     expect(capturedMyClassBindingCount).toEqual(1);
   });
 
+  it('should write to a `className` input binding', () => {
+    @Component({
+      selector: 'comp',
+      template: `{{className}}`,
+    })
+    class Comp {
+      @Input() className: string = '';
+    }
+    @Component({
+      template: `<comp [className]="'my-className'"></comp>`,
+    })
+    class App {
+    }
+
+    TestBed.configureTestingModule({declarations: [Comp, App]});
+    const fixture = TestBed.createComponent(App);
+    fixture.detectChanges();
+    expect(fixture.debugElement.nativeElement.firstChild.innerHTML).toBe('my-className');
+  });
+
+  onlyInIvy('only ivy combines static and dynamic class-related attr values')
+      .it('should write to a `className` input binding, when static `class` is present', () => {
+        @Component({
+          selector: 'comp',
+          template: `{{className}}`,
+        })
+        class Comp {
+          @Input() className: string = '';
+        }
+
+        @Component({
+          template: `<comp class="static" [className]="'my-className'"></comp>`,
+        })
+        class App {
+        }
+
+        TestBed.configureTestingModule({declarations: [Comp, App]});
+        const fixture = TestBed.createComponent(App);
+        fixture.detectChanges();
+        expect(fixture.debugElement.nativeElement.firstChild.innerHTML).toBe('static my-className');
+      });
+
+  onlyInIvy('in Ivy [class] and [className] bindings on the same element are not allowed')
+      .it('should throw an error in case [class] and [className] bindings are used on the same element',
+          () => {
+            @Component({
+              selector: 'comp',
+              template: `{{class}} - {{className}}`,
+            })
+            class Comp {
+              @Input() class: string = '';
+              @Input() className: string = '';
+            }
+            @Component({
+              template: `<comp [class]="'my-class'" [className]="'className'"></comp>`,
+            })
+            class App {
+            }
+
+            TestBed.configureTestingModule({declarations: [Comp, App]});
+            expect(() => {
+              const fixture = TestBed.createComponent(App);
+              fixture.detectChanges();
+            })
+                .toThrowError(
+                    '[class] and [className] bindings cannot be used on the same element simultaneously');
+          });
+
   onlyInIvy('only ivy persists static class/style attrs with their binding counterparts')
       .it('should write to a `class` input binding if there is a static class value and there is a binding value',
           () => {

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

@@ -584,6 +584,9 @@
   {
     "name": "saveResolvedLocalsInData"
   },
+  {
+    "name": "selectClassBasedInputName"
+  },
   {
     "name": "selectIndexInternal"
   },

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

@@ -1181,6 +1181,9 @@
   {
     "name": "searchTokensOnInjector"
   },
+  {
+    "name": "selectClassBasedInputName"
+  },
   {
     "name": "selectIndexInternal"
   },