From ed81588c792c9c1c023bbd537b18b5a4d152e55d Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Tue, 29 Sep 2020 20:44:43 +0100
Subject: [PATCH] refactor(compiler-cli): move map creation to avoid
 unnecessary work (#38959)

If the `symbol` for the given `node` does not exist then there is no
point in creating the `map`.

PR Close #38959
---
 packages/compiler-cli/src/ngtsc/reflection/src/typescript.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/compiler-cli/src/ngtsc/reflection/src/typescript.ts b/packages/compiler-cli/src/ngtsc/reflection/src/typescript.ts
index 85be99477c..202a4c43b3 100644
--- a/packages/compiler-cli/src/ngtsc/reflection/src/typescript.ts
+++ b/packages/compiler-cli/src/ngtsc/reflection/src/typescript.ts
@@ -105,7 +105,6 @@ export class TypeScriptReflectionHost implements ReflectionHost {
     if (!ts.isSourceFile(node)) {
       throw new Error(`getExportsOfModule() called on non-SourceFile in TS code`);
     }
-    const map = new Map<string, Declaration>();
 
     // Reflect the module to a Symbol, and use getExportsOfModule() to get a list of exported
     // Symbols.
@@ -113,6 +112,8 @@ export class TypeScriptReflectionHost implements ReflectionHost {
     if (symbol === undefined) {
       return null;
     }
+
+    const map = new Map<string, Declaration>();
     this.checker.getExportsOfModule(symbol).forEach(exportSymbol => {
       // Map each exported Symbol to a Declaration and add it to the map.
       const decl = this.getDeclarationOfSymbol(exportSymbol, null);