docs: add deprecation info about default currency code (#32584)

In v10 the default currency code will be taken from the
current locale, rather than simply defaulting to `USD`.

PR Close #32584

aio/content/guide/deprecations.md

@@ -36,6 +36,7 @@ v9 - v12
 | Area                          | API or Feature                                                                | May be removed in |
 | ----------------------------- | ---------------------------------------------------------------------------   | ----------------- |
 | `@angular/common`             | [`ReflectiveInjector`](#reflectiveinjector)                                   | <!--v8--> v10 |
+| `@angular/common`             | [`CurrencyPipe` - `DEFAULT_CURRENCY_CODE`](api/common/CurrencyPipe#currency-code-deprecation) | <!--v9--> v11 |
 | `@angular/core`               | [`CollectionChangeRecord`](#core)                                             | <!--v7--> v10 |
 | `@angular/core`               | [`DefaultIterableDiffer`](#core)                                              | <!--v7--> v10 |
 | `@angular/core`               | [`ReflectiveKey`](#core)                                                      | <!--v8--> v10 |
@@ -74,6 +75,14 @@ Tip: In the [API reference section](api) of this doc site, deprecated APIs are i
 
 </div>
 
+{@a common}
+### @angular/common
+
+| API                                                                                           | Replacement                                         | Deprecation announced | Notes |
+| --------------------------------------------------------------------------------------------- | --------------------------------------------------- | --------------------- | ----- |
+| [`CurrencyPipe` - `DEFAULT_CURRENCY_CODE`](api/common/CurrencyPipe#currency-code-deprecation) | `{provide: DEFAULT_CURRENCY_CODE, useValue: 'USD'}` | v9                    | From v11 the default code will be extracted from the locale data given by `LOCAL_ID`, rather than `USD`. |
+
+
 {@a core}
 ### @angular/core
 

aio/content/guide/updating-to-version-9.md

@@ -35,6 +35,7 @@ See our [template type-checking guide](guide/template-typecheck) for more inform
 | API                                                                     | Replacement                          | Notes |
 | ------------------------------------------------------------------------| ------------------------------------ | ----- |
 | [`entryComponents`](api/core/NgModule#entryComponents)                  | none                                 | See [`entryComponents`](guide/deprecations#entryComponents) |
+| [`CurrencyPipe` - `DEFAULT_CURRENCY_CODE`](api/common/CurrencyPipe#currency-code-deprecation)| `{provide: DEFAULT_CURRENCY_CODE, useValue: 'USD'}` | From v11 the default code will be extracted from the locale data given by `LOCAL_ID`, rather than `USD`. |
 | [`ANALYZE_FOR_ENTRY_COMPONENTS`](api/core/ANALYZE_FOR_ENTRY_COMPONENTS) | none                                 | See [`ANALYZE_FOR_ENTRY_COMPONENTS`](guide/deprecations#entryComponents) |
 | `ModuleWithProviders` without a generic                                 | `ModuleWithProviders` with a generic | See [`ModuleWithProviders` section](guide/deprecations#moduleWithProviders) |
 | Undecorated base classes that use Angular features                      | Base classes with `@Directive()` decorator that use Angular features | See [undecorated base classes section](guide/deprecations#undecorated-base-classes) |

packages/common/src/pipes/number_pipe.ts

@@ -123,9 +123,7 @@ export class PercentPipe implements PipeTransform {
    */
   transform(value: any, digitsInfo?: string, locale?: string): string|null {
     if (isEmpty(value)) return null;
-
     locale = locale || this._locale;
-
     try {
       const num = strToNumber(value);
       return formatPercent(num, locale, digitsInfo);
@@ -143,6 +141,26 @@ export class PercentPipe implements PipeTransform {
  * that determine group sizing and separator, decimal-point character,
  * and other locale-specific configurations.
  *
+ * {@a currency-code-deprecation}
+ * <div class="alert is-helpful">
+ *
+ * **Deprecation notice:**
+ *
+ * The default currency code is currently always `USD` but this is deprecated from v9.
+ *
+ * **In v11 the default currency code will be taken from the current locale identified by
+ * the `LOCAL_ID` token. See the [i18n guide](guide/i18n#setting-up-the-locale-of-your-app) for
+ * more information.**
+ *
+ * If you need the previous behavior then set it by creating a `DEFAULT_CURRENCY_CODE` provider in
+ * your application `NgModule`:
+ *
+ * ```ts
+ * {provide: DEFAULT_CURRENCY_CODE, useValue: 'USD'}
+ * ```
+ *
+ * </div>
+ *
  * @see `getCurrencySymbol()`
  * @see `formatCurrency()`
  *

packages/core/src/i18n/tokens.ts

@@ -39,6 +39,23 @@ export const LOCALE_ID = new InjectionToken<string>('LocaleId');
  *
  * See the [i18n guide](guide/i18n#setting-up-locale) for more information.
  *
+ * <div class="alert is-helpful">
+ *
+ * **Deprecation notice:**
+ *
+ * The default currency code is currently always `USD` but this is deprecated from v9.
+ *
+ * **In v10 the default currency code will be taken from the current locale.**
+ *
+ * If you need the previous behavior then set it by creating a `DEFAULT_CURRENCY_CODE` provider in
+ * your application `NgModule`:
+ *
+ * ```ts
+ * {provide: DEFAULT_CURRENCY_CODE, useValue: 'USD'}
+ * ```
+ *
+ * </div>
+ *
  * @usageNotes
  * ### Example
  *