diff --git a/goldens/public-api/compiler-cli/error_code.d.ts b/goldens/public-api/compiler-cli/error_code.d.ts
index 41ad716477..b9ed59e469 100644
--- a/goldens/public-api/compiler-cli/error_code.d.ts
+++ b/goldens/public-api/compiler-cli/error_code.d.ts
@@ -19,6 +19,7 @@ export declare enum ErrorCode {
     CONFIG_FLAT_MODULE_NO_INDEX = 4001,
     CONFIG_STRICT_TEMPLATES_IMPLIES_FULL_TEMPLATE_TYPECHECK = 4002,
     HOST_BINDING_PARSE_ERROR = 5001,
+    TEMPLATE_PARSE_ERROR = 5002,
     NGMODULE_INVALID_DECLARATION = 6001,
     NGMODULE_INVALID_IMPORT = 6002,
     NGMODULE_INVALID_EXPORT = 6003,
diff --git a/packages/compiler-cli/src/ngtsc/core/BUILD.bazel b/packages/compiler-cli/src/ngtsc/core/BUILD.bazel
index e6b2d8fe54..ce0cef9979 100644
--- a/packages/compiler-cli/src/ngtsc/core/BUILD.bazel
+++ b/packages/compiler-cli/src/ngtsc/core/BUILD.bazel
@@ -34,6 +34,7 @@ ts_library(
         "//packages/compiler-cli/src/ngtsc/transform",
         "//packages/compiler-cli/src/ngtsc/typecheck",
         "//packages/compiler-cli/src/ngtsc/typecheck/api",
+        "//packages/compiler-cli/src/ngtsc/typecheck/diagnostics",
         "//packages/compiler-cli/src/ngtsc/util",
         "@npm//typescript",
     ],
diff --git a/packages/compiler-cli/src/ngtsc/core/src/compiler.ts b/packages/compiler-cli/src/ngtsc/core/src/compiler.ts
index 2aed139c01..97b676c209 100644
--- a/packages/compiler-cli/src/ngtsc/core/src/compiler.ts
+++ b/packages/compiler-cli/src/ngtsc/core/src/compiler.ts
@@ -28,8 +28,9 @@ import {ComponentScopeReader, LocalModuleScopeRegistry, MetadataDtsModuleScopeRe
 import {generatedFactoryTransform} from '../../shims';
 import {ivySwitchTransform} from '../../switch';
 import {aliasTransformFactory, declarationTransformFactory, DecoratorHandler, DtsTransformRegistry, ivyTransformFactory, TraitCompiler} from '../../transform';
-import {isTemplateDiagnostic, TemplateTypeCheckerImpl} from '../../typecheck';
+import {TemplateTypeCheckerImpl} from '../../typecheck';
 import {OptimizeFor, TemplateTypeChecker, TypeCheckingConfig, TypeCheckingProgramStrategy} from '../../typecheck/api';
+import {isTemplateDiagnostic} from '../../typecheck/diagnostics';
 import {getSourceFileOrNull, isDtsPath, resolveModuleName} from '../../util/src/typescript';
 import {LazyRoute, NgCompilerAdapter, NgCompilerOptions} from '../api';
 
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/BUILD.bazel b/packages/compiler-cli/src/ngtsc/typecheck/BUILD.bazel
index 9676cb540f..b9c2e93c72 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/BUILD.bazel
+++ b/packages/compiler-cli/src/ngtsc/typecheck/BUILD.bazel
@@ -20,6 +20,7 @@ ts_library(
         "//packages/compiler-cli/src/ngtsc/shims:api",
         "//packages/compiler-cli/src/ngtsc/translator",
         "//packages/compiler-cli/src/ngtsc/typecheck/api",
+        "//packages/compiler-cli/src/ngtsc/typecheck/diagnostics",
         "//packages/compiler-cli/src/ngtsc/util",
         "@npm//@types/node",
         "@npm//typescript",
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/BUILD.bazel b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/BUILD.bazel
new file mode 100644
index 0000000000..e9c8b1e10b
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/BUILD.bazel
@@ -0,0 +1,15 @@
+load("//tools:defaults.bzl", "ts_library")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_library(
+    name = "diagnostics",
+    srcs = glob(["**/*.ts"]),
+    module_name = "@angular/compiler-cli/src/ngtsc/typecheck/diagnostics",
+    deps = [
+        "//packages:types",
+        "//packages/compiler",
+        "//packages/compiler-cli/src/ngtsc/typecheck/api",
+        "@npm//typescript",
+    ],
+)
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/index.ts b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/index.ts
new file mode 100644
index 0000000000..9d996df98f
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/index.ts
@@ -0,0 +1,10 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * 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
+ */
+
+export * from './src/diagnostic';
+export * from './src/id';
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/diagnostic.ts b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/diagnostic.ts
new file mode 100644
index 0000000000..4070a47a7a
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/diagnostic.ts
@@ -0,0 +1,128 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * 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 {ParseSourceSpan} from '@angular/compiler';
+import * as ts from 'typescript';
+
+import {ExternalTemplateSourceMapping, TemplateId, TemplateSourceMapping} from '../../api';
+
+/**
+ * A `ts.Diagnostic` with additional information about the diagnostic related to template
+ * type-checking.
+ */
+export interface TemplateDiagnostic extends ts.Diagnostic {
+  /**
+   * The component with the template that resulted in this diagnostic.
+   */
+  componentFile: ts.SourceFile;
+
+  /**
+   * The template id of the component that resulted in this diagnostic.
+   */
+  templateId: TemplateId;
+}
+
+/**
+ * Constructs a `ts.Diagnostic` for a given `ParseSourceSpan` within a template.
+ */
+export function makeTemplateDiagnostic(
+    templateId: TemplateId, mapping: TemplateSourceMapping, span: ParseSourceSpan,
+    category: ts.DiagnosticCategory, code: number, messageText: string|ts.DiagnosticMessageChain,
+    relatedMessage?: {
+      text: string,
+      span: ParseSourceSpan,
+    }): TemplateDiagnostic {
+  if (mapping.type === 'direct') {
+    let relatedInformation: ts.DiagnosticRelatedInformation[]|undefined = undefined;
+    if (relatedMessage !== undefined) {
+      relatedInformation = [{
+        category: ts.DiagnosticCategory.Message,
+        code: 0,
+        file: mapping.node.getSourceFile(),
+        start: relatedMessage.span.start.offset,
+        length: relatedMessage.span.end.offset - relatedMessage.span.start.offset,
+        messageText: relatedMessage.text,
+      }];
+    }
+    // For direct mappings, the error is shown inline as ngtsc was able to pinpoint a string
+    // constant within the `@Component` decorator for the template. This allows us to map the error
+    // directly into the bytes of the source file.
+    return {
+      source: 'ngtsc',
+      code,
+      category,
+      messageText,
+      file: mapping.node.getSourceFile(),
+      componentFile: mapping.node.getSourceFile(),
+      templateId,
+      start: span.start.offset,
+      length: span.end.offset - span.start.offset,
+      relatedInformation,
+    };
+  } else if (mapping.type === 'indirect' || mapping.type === 'external') {
+    // For indirect mappings (template was declared inline, but ngtsc couldn't map it directly
+    // to a string constant in the decorator), the component's file name is given with a suffix
+    // indicating it's not the TS file being displayed, but a template.
+    // For external temoplates, the HTML filename is used.
+    const componentSf = mapping.componentClass.getSourceFile();
+    const componentName = mapping.componentClass.name.text;
+    // TODO(alxhub): remove cast when TS in g3 supports this narrowing.
+    const fileName = mapping.type === 'indirect' ?
+        `${componentSf.fileName} (${componentName} template)` :
+        (mapping as ExternalTemplateSourceMapping).templateUrl;
+    // TODO(alxhub): investigate creating a fake `ts.SourceFile` here instead of invoking the TS
+    // parser against the template (HTML is just really syntactically invalid TypeScript code ;).
+    // Also investigate caching the file to avoid running the parser multiple times.
+    const sf = ts.createSourceFile(
+        fileName, mapping.template, ts.ScriptTarget.Latest, false, ts.ScriptKind.JSX);
+
+    let relatedInformation: ts.DiagnosticRelatedInformation[] = [];
+    if (relatedMessage !== undefined) {
+      relatedInformation.push({
+        category: ts.DiagnosticCategory.Message,
+        code: 0,
+        file: sf,
+        start: relatedMessage.span.start.offset,
+        length: relatedMessage.span.end.offset - relatedMessage.span.start.offset,
+        messageText: relatedMessage.text,
+      });
+    }
+
+    relatedInformation.push({
+      category: ts.DiagnosticCategory.Message,
+      code: 0,
+      file: componentSf,
+      // mapping.node represents either the 'template' or 'templateUrl' expression. getStart()
+      // and getEnd() are used because they don't include surrounding whitespace.
+      start: mapping.node.getStart(),
+      length: mapping.node.getEnd() - mapping.node.getStart(),
+      messageText: `Error occurs in the template of component ${componentName}.`,
+    });
+
+    return {
+      source: 'ngtsc',
+      category,
+      code,
+      messageText,
+      file: sf,
+      componentFile: componentSf,
+      templateId,
+      start: span.start.offset,
+      length: span.end.offset - span.start.offset,
+      // Show a secondary message indicating the component whose template contains the error.
+      relatedInformation,
+    };
+  } else {
+    throw new Error(`Unexpected source mapping type: ${(mapping as {type: string}).type}`);
+  }
+}
+
+export function isTemplateDiagnostic(diagnostic: ts.Diagnostic): diagnostic is TemplateDiagnostic {
+  return diagnostic.hasOwnProperty('componentFile') &&
+      ts.isSourceFile((diagnostic as any).componentFile);
+}
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/id.ts b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/id.ts
new file mode 100644
index 0000000000..b7ae05a833
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/typecheck/diagnostics/src/id.ts
@@ -0,0 +1,38 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import * as ts from 'typescript';
+
+import {TemplateId} from '../../api';
+
+
+const TEMPLATE_ID = Symbol('ngTemplateId');
+const NEXT_TEMPLATE_ID = Symbol('ngNextTemplateId');
+
+interface HasTemplateId {
+  [TEMPLATE_ID]: TemplateId;
+}
+
+interface HasNextTemplateId {
+  [NEXT_TEMPLATE_ID]: number;
+}
+
+export function getTemplateId(clazz: ts.Declaration): TemplateId {
+  const node = clazz as ts.Declaration & Partial<HasTemplateId>;
+  if (node[TEMPLATE_ID] === undefined) {
+    node[TEMPLATE_ID] = allocateTemplateId(node.getSourceFile());
+  }
+  return node[TEMPLATE_ID]!;
+}
+
+function allocateTemplateId(sf: ts.SourceFile&Partial<HasNextTemplateId>): TemplateId {
+  if (sf[NEXT_TEMPLATE_ID] === undefined) {
+    sf[NEXT_TEMPLATE_ID] = 1;
+  }
+  return (`tcb${sf[NEXT_TEMPLATE_ID]!++}`) as TemplateId;
+}
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/index.ts b/packages/compiler-cli/src/ngtsc/typecheck/index.ts
index 6c81aae866..aaa0b33c99 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/index.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/index.ts
@@ -9,7 +9,6 @@
 export {ReusedProgramStrategy} from './src/augmented_program';
 export {FileTypeCheckingData, TemplateTypeCheckerImpl} from './src/checker';
 export {TypeCheckContextImpl} from './src/context';
-export {isTemplateDiagnostic, TemplateDiagnostic} from './src/diagnostics';
 export {TypeCheckProgramHost} from './src/host';
 export {TypeCheckShimGenerator} from './src/shim';
 export {typeCheckFilePath} from './src/type_check_file';
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/checker.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/checker.ts
index b91825c55f..ac29846329 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/checker.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/checker.ts
@@ -16,9 +16,10 @@ import {ReflectionHost} from '../../reflection';
 import {isShim} from '../../shims';
 import {getSourceFileOrNull} from '../../util/src/typescript';
 import {OptimizeFor, ProgramTypeCheckAdapter, TemplateId, TemplateTypeChecker, TypeCheckingConfig, TypeCheckingProgramStrategy, UpdateMode} from '../api';
+import {TemplateDiagnostic} from '../diagnostics';
 
 import {InliningMode, ShimTypeCheckingData, TypeCheckContextImpl, TypeCheckingHost} from './context';
-import {findTypeCheckBlock, shouldReportDiagnostic, TemplateDiagnostic, TemplateSourceResolver, translateDiagnostic} from './diagnostics';
+import {findTypeCheckBlock, shouldReportDiagnostic, TemplateSourceResolver, translateDiagnostic} from './diagnostics';
 import {TemplateSourceManager} from './source';
 
 /**
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/context.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/context.ts
index fa80d5b0b3..fc37c26b78 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/context.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/context.ts
@@ -14,8 +14,8 @@ import {NoopImportRewriter, Reference, ReferenceEmitter} from '../../imports';
 import {ClassDeclaration, ReflectionHost} from '../../reflection';
 import {ImportManager} from '../../translator';
 import {ComponentToShimMappingStrategy, TemplateId, TemplateSourceMapping, TypeCheckableDirectiveMeta, TypeCheckBlockMetadata, TypeCheckContext, TypeCheckingConfig, TypeCtorMetadata} from '../api';
+import {TemplateDiagnostic} from '../diagnostics';
 
-import {TemplateDiagnostic} from './diagnostics';
 import {DomSchemaChecker, RegistryDomSchemaChecker} from './dom';
 import {Environment} from './environment';
 import {OutOfBandDiagnosticRecorder, OutOfBandDiagnosticRecorderImpl} from './oob';
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/diagnostics.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/diagnostics.ts
index 2b61b1bc39..99476d31e2 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/diagnostics.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/diagnostics.ts
@@ -10,23 +10,7 @@ import * as ts from 'typescript';
 
 import {getTokenAtPosition} from '../../util/src/typescript';
 import {ExternalTemplateSourceMapping, TemplateId, TemplateSourceMapping} from '../api';
-
-
-/**
- * A `ts.Diagnostic` with additional information about the diagnostic related to template
- * type-checking.
- */
-export interface TemplateDiagnostic extends ts.Diagnostic {
-  /**
-   * The component with the template that resulted in this diagnostic.
-   */
-  componentFile: ts.SourceFile;
-
-  /**
-   * The template id of the component that resulted in this diagnostic.
-   */
-  templateId: TemplateId;
-}
+import {makeTemplateDiagnostic, TemplateDiagnostic} from '../diagnostics';
 
 /**
  * Adapter interface which allows the template type-checking diagnostics code to interpret offsets
@@ -157,101 +141,6 @@ export function findTypeCheckBlock(file: ts.SourceFile, id: TemplateId): ts.Node
   return null;
 }
 
-/**
- * Constructs a `ts.Diagnostic` for a given `ParseSourceSpan` within a template.
- */
-export function makeTemplateDiagnostic(
-    templateId: TemplateId, mapping: TemplateSourceMapping, span: ParseSourceSpan,
-    category: ts.DiagnosticCategory, code: number, messageText: string|ts.DiagnosticMessageChain,
-    relatedMessage?: {
-      text: string,
-      span: ParseSourceSpan,
-    }): TemplateDiagnostic {
-  if (mapping.type === 'direct') {
-    let relatedInformation: ts.DiagnosticRelatedInformation[]|undefined = undefined;
-    if (relatedMessage !== undefined) {
-      relatedInformation = [{
-        category: ts.DiagnosticCategory.Message,
-        code: 0,
-        file: mapping.node.getSourceFile(),
-        start: relatedMessage.span.start.offset,
-        length: relatedMessage.span.end.offset - relatedMessage.span.start.offset,
-        messageText: relatedMessage.text,
-      }];
-    }
-    // For direct mappings, the error is shown inline as ngtsc was able to pinpoint a string
-    // constant within the `@Component` decorator for the template. This allows us to map the error
-    // directly into the bytes of the source file.
-    return {
-      source: 'ngtsc',
-      code,
-      category,
-      messageText,
-      file: mapping.node.getSourceFile(),
-      componentFile: mapping.node.getSourceFile(),
-      templateId,
-      start: span.start.offset,
-      length: span.end.offset - span.start.offset,
-      relatedInformation,
-    };
-  } else if (mapping.type === 'indirect' || mapping.type === 'external') {
-    // For indirect mappings (template was declared inline, but ngtsc couldn't map it directly
-    // to a string constant in the decorator), the component's file name is given with a suffix
-    // indicating it's not the TS file being displayed, but a template.
-    // For external temoplates, the HTML filename is used.
-    const componentSf = mapping.componentClass.getSourceFile();
-    const componentName = mapping.componentClass.name.text;
-    // TODO(alxhub): remove cast when TS in g3 supports this narrowing.
-    const fileName = mapping.type === 'indirect' ?
-        `${componentSf.fileName} (${componentName} template)` :
-        (mapping as ExternalTemplateSourceMapping).templateUrl;
-    // TODO(alxhub): investigate creating a fake `ts.SourceFile` here instead of invoking the TS
-    // parser against the template (HTML is just really syntactically invalid TypeScript code ;).
-    // Also investigate caching the file to avoid running the parser multiple times.
-    const sf = ts.createSourceFile(
-        fileName, mapping.template, ts.ScriptTarget.Latest, false, ts.ScriptKind.JSX);
-
-    let relatedInformation: ts.DiagnosticRelatedInformation[] = [];
-    if (relatedMessage !== undefined) {
-      relatedInformation.push({
-        category: ts.DiagnosticCategory.Message,
-        code: 0,
-        file: sf,
-        start: relatedMessage.span.start.offset,
-        length: relatedMessage.span.end.offset - relatedMessage.span.start.offset,
-        messageText: relatedMessage.text,
-      });
-    }
-
-    relatedInformation.push({
-      category: ts.DiagnosticCategory.Message,
-      code: 0,
-      file: componentSf,
-      // mapping.node represents either the 'template' or 'templateUrl' expression. getStart()
-      // and getEnd() are used because they don't include surrounding whitespace.
-      start: mapping.node.getStart(),
-      length: mapping.node.getEnd() - mapping.node.getStart(),
-      messageText: `Error occurs in the template of component ${componentName}.`,
-    });
-
-    return {
-      source: 'ngtsc',
-      category,
-      code,
-      messageText,
-      file: sf,
-      componentFile: componentSf,
-      templateId,
-      start: span.start.offset,
-      length: span.end.offset - span.start.offset,
-      // Show a secondary message indicating the component whose template contains the error.
-      relatedInformation,
-    };
-  } else {
-    throw new Error(`Unexpected source mapping type: ${(mapping as {type: string}).type}`);
-  }
-}
-
 interface SourceLocation {
   id: TemplateId;
   span: AbsoluteSourceSpan;
@@ -338,8 +227,3 @@ function hasIgnoreMarker(node: ts.Node, sourceFile: ts.SourceFile): boolean {
     return commentText === IGNORE_MARKER;
   }) === true;
 }
-
-export function isTemplateDiagnostic(diagnostic: ts.Diagnostic): diagnostic is TemplateDiagnostic {
-  return diagnostic.hasOwnProperty('componentFile') &&
-      ts.isSourceFile((diagnostic as any).componentFile);
-}
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/dom.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/dom.ts
index a946a2539d..4d22fd92fb 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/dom.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/dom.ts
@@ -11,8 +11,9 @@ import * as ts from 'typescript';
 
 import {ErrorCode, ngErrorCode} from '../../diagnostics';
 import {TemplateId} from '../api';
+import {makeTemplateDiagnostic, TemplateDiagnostic} from '../diagnostics';
 
-import {makeTemplateDiagnostic, TemplateDiagnostic, TemplateSourceResolver} from './diagnostics';
+import {TemplateSourceResolver} from './diagnostics';
 
 const REGISTRY = new DomElementSchemaRegistry();
 const REMOVE_XHTML_REGEX = /^:xhtml:/;
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/oob.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/oob.ts
index 0d9ab782a6..2b7cbd02e5 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/oob.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/oob.ts
@@ -12,8 +12,9 @@ import * as ts from 'typescript';
 import {ErrorCode, makeDiagnostic, makeRelatedInformation, ngErrorCode} from '../../diagnostics';
 import {ClassDeclaration} from '../../reflection';
 import {TemplateId} from '../api';
+import {makeTemplateDiagnostic, TemplateDiagnostic} from '../diagnostics';
 
-import {makeTemplateDiagnostic, TemplateDiagnostic, TemplateSourceResolver} from './diagnostics';
+import {TemplateSourceResolver} from './diagnostics';
 
 
 
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/src/source.ts b/packages/compiler-cli/src/ngtsc/typecheck/src/source.ts
index 2401cc8aae..6d0c7486fe 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/src/source.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/src/source.ts
@@ -8,7 +8,9 @@
 
 import {AbsoluteSourceSpan, ParseLocation, ParseSourceFile, ParseSourceSpan} from '@angular/compiler';
 import * as ts from 'typescript';
+
 import {TemplateId, TemplateSourceMapping} from '../api';
+import {getTemplateId} from '../diagnostics';
 
 import {TemplateSourceResolver} from './diagnostics';
 import {computeLineStartsMap, getLineAndCharacterFromPosition} from './line_mappings';
@@ -81,28 +83,3 @@ export class TemplateSourceManager implements TemplateSourceResolver {
     return templateSource.toParseSourceSpan(span.start, span.end);
   }
 }
-
-const TEMPLATE_ID = Symbol('ngTemplateId');
-const NEXT_TEMPLATE_ID = Symbol('ngNextTemplateId');
-
-interface HasTemplateId {
-  [TEMPLATE_ID]: TemplateId;
-}
-
-interface HasNextTemplateId {
-  [NEXT_TEMPLATE_ID]: number;
-}
-
-function getTemplateId(node: ts.ClassDeclaration&Partial<HasTemplateId>): TemplateId {
-  if (node[TEMPLATE_ID] === undefined) {
-    node[TEMPLATE_ID] = allocateTemplateId(node.getSourceFile());
-  }
-  return node[TEMPLATE_ID]!;
-}
-
-function allocateTemplateId(sf: ts.SourceFile&Partial<HasNextTemplateId>): TemplateId {
-  if (sf[NEXT_TEMPLATE_ID] === undefined) {
-    sf[NEXT_TEMPLATE_ID] = 1;
-  }
-  return (`tcb${sf[NEXT_TEMPLATE_ID]!++}`) as TemplateId;
-}
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/test/BUILD.bazel b/packages/compiler-cli/src/ngtsc/typecheck/test/BUILD.bazel
index cf18524f63..6e8e8b2f14 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/test/BUILD.bazel
+++ b/packages/compiler-cli/src/ngtsc/typecheck/test/BUILD.bazel
@@ -21,6 +21,7 @@ ts_library(
         "//packages/compiler-cli/src/ngtsc/testing",
         "//packages/compiler-cli/src/ngtsc/typecheck",
         "//packages/compiler-cli/src/ngtsc/typecheck/api",
+        "//packages/compiler-cli/src/ngtsc/typecheck/diagnostics",
         "//packages/compiler-cli/src/ngtsc/util",
         "@npm//typescript",
     ],
diff --git a/packages/compiler-cli/src/ngtsc/typecheck/test/test_utils.ts b/packages/compiler-cli/src/ngtsc/typecheck/test/test_utils.ts
index 37f66200f1..3c8a5c96b8 100644
--- a/packages/compiler-cli/src/ngtsc/typecheck/test/test_utils.ts
+++ b/packages/compiler-cli/src/ngtsc/typecheck/test/test_utils.ts
@@ -18,9 +18,9 @@ import {makeProgram} from '../../testing';
 import {getRootDirs} from '../../util/src/typescript';
 import {ProgramTypeCheckAdapter, TemplateTypeChecker, TypeCheckContext} from '../api';
 import {TemplateId, TemplateSourceMapping, TypeCheckableDirectiveMeta, TypeCheckBlockMetadata, TypeCheckingConfig, UpdateMode} from '../api/api';
+import {TemplateDiagnostic} from '../diagnostics';
 import {ReusedProgramStrategy} from '../src/augmented_program';
 import {TemplateTypeCheckerImpl} from '../src/checker';
-import {TemplateDiagnostic} from '../src/diagnostics';
 import {DomSchemaChecker} from '../src/dom';
 import {Environment} from '../src/environment';
 import {OutOfBandDiagnosticRecorder} from '../src/oob';