From d0fd964b694997d7d67849f3ff822b599cd057ab Mon Sep 17 00:00:00 2001
From: Filipe Silva <filipematossilva@gmail.com>
Date: Fri, 22 Sep 2017 19:54:20 +0100
Subject: [PATCH] Fix getSourceFile return type (#18689)

---
 src/compiler/types.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 5347d7caaf..4e5ca9f07e 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -4095,8 +4095,8 @@ namespace ts {
     }
 
     export interface CompilerHost extends ModuleResolutionHost {
-        getSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void): SourceFile;
-        getSourceFileByPath?(fileName: string, path: Path, languageVersion: ScriptTarget, onError?: (message: string) => void): SourceFile;
+        getSourceFile(fileName: string, languageVersion: ScriptTarget, onError?: (message: string) => void): SourceFile | undefined;
+        getSourceFileByPath?(fileName: string, path: Path, languageVersion: ScriptTarget, onError?: (message: string) => void): SourceFile | undefined;
         getCancellationToken?(): CancellationToken;
         getDefaultLibFileName(options: CompilerOptions): string;
         getDefaultLibLocation?(): string;