fix(compiler): do not remove whitespace wrapping i18n expansions (#31962)

Similar to interpolation, we do not want to completely remove whitespace
nodes that are siblings of an expansion.

For example, the following template

```html
<div>
  <strong>items left<strong> {count, plural, =1 {item} other {items}}
</div>
```

was being collapsed to

```html
<div><strong>items left<strong>{count, plural, =1 {item} other {items}}</div>
```

which results in the text looking like

```
items left4
```

instead it should be collapsed to

```html
<div><strong>items left<strong> {count, plural, =1 {item} other {items}}</div>
```

which results in the text looking like

```
items left 4
```

---

**Analysis of the code and manual testing has shown that this does not cause
the generated ids to change, so there is no breaking change here.**

PR Close #31962

packages/compiler-cli/test/compliance/r3_view_compiler_i18n_spec.ts

@@ -2600,14 +2600,16 @@ describe('i18n support in the view compiler', () => {
         function MyComponent_div_2_Template(rf, ctx) {
           if (rf & 1) {
             $r3$.ɵɵelementStart(0, "div", $_c2$);
-            $r3$.ɵɵi18n(1, $I18N_3$);
+            i0.ɵɵtext(1, " ");
+            $r3$.ɵɵi18n(2, $I18N_3$);
+            i0.ɵɵtext(3, " ");
             $r3$.ɵɵelementEnd();
           }
           if (rf & 2) {
             const $ctx_r0$ = $r3$.ɵɵnextContext();
-            $r3$.ɵɵselect(1);
+            $r3$.ɵɵselect(2);
             $r3$.ɵɵi18nExp($ctx_r0$.age);
-            $r3$.ɵɵi18nApply(1);
+            $r3$.ɵɵi18nApply(2);
           }
         }
         const $_c3$ = ["title", "icu and text"];
@@ -2646,7 +2648,7 @@ describe('i18n support in the view compiler', () => {
             $r3$.ɵɵelementStart(0, "div");
             $r3$.ɵɵi18n(1, $I18N_0$);
             $r3$.ɵɵelementEnd();
-            $r3$.ɵɵtemplate(2, MyComponent_div_2_Template, 2, 1, "div", $_c0$);
+            $r3$.ɵɵtemplate(2, MyComponent_div_2_Template, 4, 1, "div", $_c0$);
             $r3$.ɵɵtemplate(3, MyComponent_div_3_Template, 4, 2, "div", $_c1$);
           }
           if (rf & 2) {
@@ -2730,7 +2732,7 @@ describe('i18n support in the view compiler', () => {
         const $_c2$ = [1, "other"];
         var $I18N_0$;
         if (ngI18nClosureMode) {
-            const $MSG_EXTERNAL_5791551881115084301$$APP_SPEC_TS_0$ = goog.getMsg("{$icu}{$startBoldText}Other content{$closeBoldText}{$startTagDiv}{$startItalicText}Another content{$closeItalicText}{$closeTagDiv}", {
+            const $MSG_EXTERNAL_5791551881115084301$$APP_SPEC_TS_0$ = goog.getMsg(" {$icu} {$startBoldText}Other content{$closeBoldText}{$startTagDiv}{$startItalicText}Another content{$closeItalicText}{$closeTagDiv}", {
               "startBoldText": "\uFFFD#2\uFFFD",
               "closeBoldText": "\uFFFD/#2\uFFFD",
               "startTagDiv": "\uFFFD#3\uFFFD",
@@ -2742,7 +2744,7 @@ describe('i18n support in the view compiler', () => {
             $I18N_0$ = $MSG_EXTERNAL_5791551881115084301$$APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{$icu}{$startBoldText}Other content{$closeBoldText}{$startTagDiv}{$startItalicText}Another content{$closeItalicText}{$closeTagDiv}", {
+            $I18N_0$ = $r3$.ɵɵi18nLocalize(" {$icu} {$startBoldText}Other content{$closeBoldText}{$startTagDiv}{$startItalicText}Another content{$closeItalicText}{$closeTagDiv}", {
               "startBoldText": "\uFFFD#2\uFFFD",
               "closeBoldText": "\uFFFD/#2\uFFFD",
               "startTagDiv": "\uFFFD#3\uFFFD",
@@ -2848,14 +2850,14 @@ describe('i18n support in the view compiler', () => {
         });
         var $I18N_0$;
         if (ngI18nClosureMode) {
-            const $MSG_EXTERNAL_2967249209167308918$$APP_SPEC_TS_0$ = goog.getMsg("{$icu}{$icu_1}", {
+            const $MSG_EXTERNAL_2967249209167308918$$APP_SPEC_TS_0$ = goog.getMsg(" {$icu} {$icu_1} ", {
               "icu": $I18N_1$,
               "icu_1": $I18N_2$
             });
             $I18N_0$ = $MSG_EXTERNAL_2967249209167308918$$APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{$icu}{$icu_1}", {
+            $I18N_0$ = $r3$.ɵɵi18nLocalize(" {$icu} {$icu_1} ", {
               "icu": $I18N_1$,
               "icu_1": $I18N_2$
             });
@@ -2930,7 +2932,7 @@ describe('i18n support in the view compiler', () => {
         });
         var $I18N_0$;
         if (ngI18nClosureMode) {
-            const $MSG_APP_SPEC_TS_0$ = goog.getMsg("{$icu}{$startTagDiv}{$icu}{$closeTagDiv}{$startTagDiv_1}{$icu}{$closeTagDiv}", {
+            const $MSG_APP_SPEC_TS_0$ = goog.getMsg(" {$icu} {$startTagDiv} {$icu} {$closeTagDiv}{$startTagDiv_1} {$icu} {$closeTagDiv}", {
               "startTagDiv": "\uFFFD#2\uFFFD",
               "closeTagDiv": "[\uFFFD/#2\uFFFD|\uFFFD/#1:1\uFFFD\uFFFD/*3:1\uFFFD]",
               "startTagDiv_1": "\uFFFD*3:1\uFFFD\uFFFD#1:1\uFFFD",
@@ -2939,7 +2941,7 @@ describe('i18n support in the view compiler', () => {
             $I18N_0$ = $MSG_APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{$icu}{$startTagDiv}{$icu}{$closeTagDiv}{$startTagDiv_1}{$icu}{$closeTagDiv}", {
+            $I18N_0$ = $r3$.ɵɵi18nLocalize(" {$icu} {$startTagDiv} {$icu} {$closeTagDiv}{$startTagDiv_1} {$icu} {$closeTagDiv}", {
               "startTagDiv": "\uFFFD#2\uFFFD",
               "closeTagDiv": "[\uFFFD/#2\uFFFD|\uFFFD/#1:1\uFFFD\uFFFD/*3:1\uFFFD]",
               "startTagDiv_1": "\uFFFD*3:1\uFFFD\uFFFD#1:1\uFFFD",
@@ -3000,19 +3002,26 @@ describe('i18n support in the view compiler', () => {
       `;
 
       const output = String.raw `
-        var $I18N_0$;
+        var $I18N_1$;
         if (ngI18nClosureMode) {
             const $MSG_EXTERNAL_343563413083115114$$APP_SPEC_TS_0$ = goog.getMsg("{VAR_SELECT_1, select, male {male of age: {VAR_SELECT, select, 10 {ten} 20 {twenty} 30 {thirty} other {other}}} female {female} other {other}}");
-            $I18N_0$ = $MSG_EXTERNAL_343563413083115114$$APP_SPEC_TS_0$;
+            $I18N_1$ = $MSG_EXTERNAL_343563413083115114$$APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{VAR_SELECT_1, select, male {male of age: {VAR_SELECT, select, 10 {ten} 20 {twenty} 30 {thirty} other {other}}} female {female} other {other}}");
+            $I18N_1$ = $r3$.ɵɵi18nLocalize("{VAR_SELECT_1, select, male {male of age: {VAR_SELECT, select, 10 {ten} 20 {twenty} 30 {thirty} other {other}}} female {female} other {other}}");
         }
-        $I18N_0$ = $r3$.ɵɵi18nPostprocess($I18N_0$, {
+        $I18N_1$ = $r3$.ɵɵi18nPostprocess($I18N_1$, {
           "VAR_SELECT": "\uFFFD0\uFFFD",
           "VAR_SELECT_1": "\uFFFD1\uFFFD"
         });
-        …
+        var $I18N_0$;
+        if (ngI18nClosureMode) {
+            const $MSG_EXTERNAL_3052001905251380936$$APP_SPEC_TS_3$ = goog.getMsg(" {$icu} ", { "icu": $I18N_1$ });
+            $I18N_0$ = $MSG_EXTERNAL_3052001905251380936$$APP_SPEC_TS_3$;
+        }
+        else {
+            $I18N_0$ = i0.ɵɵi18nLocalize(" {$icu} ", { "icu": $I18N_1$ });
+        }        …
         consts: 2,
         vars: 2,
         template: function MyComponent_Template(rf, ctx) {
@@ -3117,7 +3126,7 @@ describe('i18n support in the view compiler', () => {
         });
         var $I18N_0$;
         if (ngI18nClosureMode) {
-            const $MSG_EXTERNAL_1194472282609532229$$APP_SPEC_TS_0$ = goog.getMsg("{$icu}{$startTagSpan}{$icu_1}{$closeTagSpan}", {
+            const $MSG_EXTERNAL_1194472282609532229$$APP_SPEC_TS_0$ = goog.getMsg(" {$icu} {$startTagSpan} {$icu_1} {$closeTagSpan}", {
               "startTagSpan": "\uFFFD*2:1\uFFFD\uFFFD#1:1\uFFFD",
               "closeTagSpan": "\uFFFD/#1:1\uFFFD\uFFFD/*2:1\uFFFD",
               "icu": $I18N_1$,
@@ -3126,7 +3135,7 @@ describe('i18n support in the view compiler', () => {
             $I18N_0$ = $MSG_EXTERNAL_1194472282609532229$$APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{$icu}{$startTagSpan}{$icu_1}{$closeTagSpan}", {
+            $I18N_0$ = $r3$.ɵɵi18nLocalize(" {$icu} {$startTagSpan} {$icu_1} {$closeTagSpan}", {
               "startTagSpan": "\uFFFD*2:1\uFFFD\uFFFD#1:1\uFFFD",
               "closeTagSpan": "\uFFFD/#1:1\uFFFD\uFFFD/*2:1\uFFFD",
               "icu": $I18N_1$,
@@ -3207,7 +3216,7 @@ describe('i18n support in the view compiler', () => {
         });
         var $I18N_0$;
         if (ngI18nClosureMode) {
-            const $MSG_EXTERNAL_7186042105600518133$$APP_SPEC_TS_0$ = goog.getMsg("{$icu}{$startTagSpan}{$icu_1}{$closeTagSpan}", {
+            const $MSG_EXTERNAL_7186042105600518133$$APP_SPEC_TS_0$ = goog.getMsg(" {$icu} {$startTagSpan} {$icu_1} {$closeTagSpan}", {
               "startTagSpan": "\uFFFD*2:1\uFFFD\uFFFD#1:1\uFFFD",
               "closeTagSpan": "\uFFFD/#1:1\uFFFD\uFFFD/*2:1\uFFFD",
               "icu": $I18N_1$,
@@ -3216,7 +3225,7 @@ describe('i18n support in the view compiler', () => {
             $I18N_0$ = $MSG_EXTERNAL_7186042105600518133$$APP_SPEC_TS_0$;
         }
         else {
-            $I18N_0$ = $r3$.ɵɵi18nLocalize("{$icu}{$startTagSpan}{$icu_1}{$closeTagSpan}", {
+            $I18N_0$ = $r3$.ɵɵi18nLocalize(" {$icu} {$startTagSpan} {$icu_1} {$closeTagSpan}", {
               "startTagSpan": "\uFFFD*2:1\uFFFD\uFFFD#1:1\uFFFD",
               "closeTagSpan": "\uFFFD/#1:1\uFFFD\uFFFD/*2:1\uFFFD",
               "icu": $I18N_1$,

packages/compiler/src/ml_parser/html_whitespaces.ts

@@ -60,18 +60,20 @@ export class WhitespaceVisitor implements html.Visitor {
     }
 
     return new html.Element(
-        element.name, element.attrs, html.visitAll(this, element.children), element.sourceSpan,
+        element.name, element.attrs, visitAllWithSiblings(this, element.children),
-        element.startSourceSpan, element.endSourceSpan, element.i18n);
+        element.sourceSpan, element.startSourceSpan, element.endSourceSpan, element.i18n);
   }
 
   visitAttribute(attribute: html.Attribute, context: any): any {
     return attribute.name !== PRESERVE_WS_ATTR_NAME ? attribute : null;
   }
 
-  visitText(text: html.Text, context: any): any {
+  visitText(text: html.Text, context: SiblingVisitorContext|null): any {
     const isNotBlank = text.value.match(NO_WS_REGEXP);
+    const hasExpansionSibling = context &&
+        (context.prev instanceof html.Expansion || context.next instanceof html.Expansion);
 
-    if (isNotBlank) {
+    if (isNotBlank || hasExpansionSibling) {
       return new html.Text(
           replaceNgsp(text.value).replace(WS_REPLACE_REGEXP, ' '), text.sourceSpan, text.i18n);
     }
@@ -91,3 +93,21 @@ export function removeWhitespaces(htmlAstWithErrors: ParseTreeResult): ParseTree
       html.visitAll(new WhitespaceVisitor(), htmlAstWithErrors.rootNodes),
       htmlAstWithErrors.errors);
 }
+
+interface SiblingVisitorContext {
+  prev: html.Node|undefined;
+  next: html.Node|undefined;
+}
+
+function visitAllWithSiblings(visitor: WhitespaceVisitor, nodes: html.Node[]): any[] {
+  const result: any[] = [];
+
+  nodes.forEach((ast, i) => {
+    const context: SiblingVisitorContext = {prev: nodes[i - 1], next: nodes[i + 1]};
+    const astResult = ast.visit(visitor, context);
+    if (astResult) {
+      result.push(astResult);
+    }
+  });
+  return result;
+}

packages/compiler/test/i18n/i18n_parser_spec.ts

@@ -40,7 +40,7 @@ import {DEFAULT_INTERPOLATION_CONFIG} from '@angular/compiler/src/ml_parser/inte
       it('should not create a message for plain elements',
          () => { expect(_humanizeMessages('<div></div>')).toEqual([]); });
 
-      it('should suppoprt void elements', () => {
+      it('should support void elements', () => {
         expect(_humanizeMessages('<div i18n="m|d"><p><br></p></div>')).toEqual([
           [
             [
@@ -173,6 +173,13 @@ import {DEFAULT_INTERPOLATION_CONFIG} from '@angular/compiler/src/ml_parser/inte
         ]);
       });
 
+      it('should extract as ICU + ph when wrapped in whitespace in an element', () => {
+        expect(_humanizeMessages('<div i18n="m|d"> {count, plural, =0 {zero}} </div>')).toEqual([
+          [[' ', '<ph icu name="ICU">{count, plural, =0 {[zero]}}</ph>', ' '], 'm', 'd'],
+          [['{count, plural, =0 {[zero]}}'], '', ''],
+        ]);
+      });
+
       it('should extract as ICU when single child of a block', () => {
         expect(_humanizeMessages('<!-- i18n:m|d -->{count, plural, =0 {zero}}<!-- /i18n -->'))
             .toEqual([

packages/compiler/test/ml_parser/html_whitespaces_spec.ts

@@ -9,14 +9,15 @@
 import * as html from '../../src/ml_parser/ast';
 import {HtmlParser} from '../../src/ml_parser/html_parser';
 import {PRESERVE_WS_ATTR_NAME, removeWhitespaces} from '../../src/ml_parser/html_whitespaces';
+import {TokenizeOptions} from '../../src/ml_parser/lexer';
 
 import {humanizeDom} from './ast_spec_utils';
 
 {
   describe('removeWhitespaces', () => {
 
-    function parseAndRemoveWS(template: string): any[] {
+    function parseAndRemoveWS(template: string, options?: TokenizeOptions): any[] {
-      return humanizeDom(removeWhitespaces(new HtmlParser().parse(template, 'TestComp')));
+      return humanizeDom(removeWhitespaces(new HtmlParser().parse(template, 'TestComp', options)));
     }
 
     it('should remove blank text nodes', () => {
@@ -97,6 +98,17 @@ import {humanizeDom} from './ast_spec_utils';
       ]);
     });
 
+    it('should preserve whitespaces around ICU expansions', () => {
+      expect(parseAndRemoveWS(`<span> {a, b, =4 {c}} </span>`, {tokenizeExpansionForms: true}))
+          .toEqual([
+            [html.Element, 'span', 0],
+            [html.Text, ' ', 1],
+            [html.Expansion, 'a', 'b', 1],
+            [html.ExpansionCase, '=4', 2],
+            [html.Text, ' ', 1],
+          ]);
+    });
+
     it('should preserve whitespaces inside <pre> elements', () => {
       expect(parseAndRemoveWS(`<pre><strong>foo</strong>\n<strong>bar</strong></pre>`)).toEqual([
         [html.Element, 'pre', 0],

packages/compiler/test/ml_parser/lexer_spec.ts

@@ -798,6 +798,30 @@ import {ParseLocation, ParseSourceFile, ParseSourceSpan} from '../../src/parse_u
             ]);
       });
 
+      it('should parse an expansion form with whitespace surrounding it', () => {
+        expect(tokenizeAndHumanizeParts(
+                   '<div><span> {a, b, =4 {c}} </span></div>', {tokenizeExpansionForms: true}))
+            .toEqual([
+              [lex.TokenType.TAG_OPEN_START, '', 'div'],
+              [lex.TokenType.TAG_OPEN_END],
+              [lex.TokenType.TAG_OPEN_START, '', 'span'],
+              [lex.TokenType.TAG_OPEN_END],
+              [lex.TokenType.TEXT, ' '],
+              [lex.TokenType.EXPANSION_FORM_START],
+              [lex.TokenType.RAW_TEXT, 'a'],
+              [lex.TokenType.RAW_TEXT, 'b'],
+              [lex.TokenType.EXPANSION_CASE_VALUE, '=4'],
+              [lex.TokenType.EXPANSION_CASE_EXP_START],
+              [lex.TokenType.TEXT, 'c'],
+              [lex.TokenType.EXPANSION_CASE_EXP_END],
+              [lex.TokenType.EXPANSION_FORM_END],
+              [lex.TokenType.TEXT, ' '],
+              [lex.TokenType.TAG_CLOSE, '', 'span'],
+              [lex.TokenType.TAG_CLOSE, '', 'div'],
+              [lex.TokenType.EOF],
+            ]);
+      });
+
       it('should parse an expansion forms with elements in it', () => {
         expect(tokenizeAndHumanizeParts(
                    '{one.two, three, =4 {four <b>a</b>}}', {tokenizeExpansionForms: true}))

packages/core/test/acceptance/i18n_spec.ts

@@ -606,10 +606,11 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
               '{VAR_SELECT, select, 10 {dix} 20 {vingt} other {autre}}'
         }
       });
-      const fixture = initWithTemplate(AppComp, `
+      const fixture = initWithTemplate(
-        <ng-template i18n tplRef>
+          AppComp, `
-          {count, select, 10 {ten} 20 {twenty} other {other}}
+        <ng-template i18n tplRef>` +
-        </ng-template>
+              `{count, select, 10 {ten} 20 {twenty} other {other}}` +
+              `</ng-template>
       `);
 
       const element = fixture.nativeElement;
@@ -931,8 +932,8 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
             select,
             A {A }
             B {B }
-            other {other - {{ typeC // i18n(ph="PH WITH SPACES") }}} 
+            other {other - {{ typeC // i18n(ph="PH WITH SPACES") }}}
-          }  
+          }
           </ng-template>
 
           <div *ngFor="let type of types">
@@ -1112,14 +1113,15 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
             'début {$interpolation_1} milieu {$interpolation} fin',
         '{VAR_PLURAL, plural, =0 {no {START_BOLD_TEXT}emails{CLOSE_BOLD_TEXT}!} =1 {one {START_ITALIC_TEXT}email{CLOSE_ITALIC_TEXT}} other {{INTERPOLATION} emails}}':
             '{VAR_PLURAL, plural, =0 {aucun {START_BOLD_TEXT}email{CLOSE_BOLD_TEXT}!} =1 {un {START_ITALIC_TEXT}email{CLOSE_ITALIC_TEXT}} other {{INTERPOLATION} emails}}',
-        ' trad: {$icu}': ' traduction: {$icu}'
+        ' trad: {$icu} ': ' traduction: {$icu} '
       }
     });
     const fixture = TestBed.createComponent(MyApp);
     fixture.detectChanges();
     expect(fixture.nativeElement.innerHTML)
         .toEqual(
-            `<div test="" title="début 2 milieu 1 fin" class="foo"> traduction: un <i>email</i><!--ICU 20--></div><div test="" class="foo"></div>`);
+            `<div test="" title="début 2 milieu 1 fin" class="foo"> traduction: un <i>email</i><!--ICU 20--> ` +
+            `</div><div test="" class="foo"></div>`);
 
     directiveInstances.forEach(instance => instance.klass = 'bar');
     fixture.componentRef.instance.exp1 = 2;
@@ -1127,7 +1129,8 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
     fixture.detectChanges();
     expect(fixture.nativeElement.innerHTML)
         .toEqual(
-            `<div test="" title="début 3 milieu 2 fin" class="bar"> traduction: 2 emails<!--ICU 20--></div><div test="" class="bar"></div>`);
+            `<div test="" title="début 3 milieu 2 fin" class="bar"> traduction: 2 emails<!--ICU 20--> ` +
+            `</div><div test="" class="bar"></div>`);
   });
 
   it('should handle i18n attribute with directive inputs', () => {