From 7e482b27fbdb469654c87e11ba72a3986b22caf7 Mon Sep 17 00:00:00 2001
From: Alan Agius <alan.agius4@gmail.com>
Date: Mon, 2 Apr 2018 20:58:37 +0200
Subject: [PATCH] fix: `CompilerHost.getSourceFile` is being called for odd
 filenames besides the one being compiled

Ignore falsy file names from `getDefaultLibraryFileName`

Closes: #13629
---
 Jakefile.js                                   |  1 +
 src/compiler/program.ts                       |  7 ++--
 src/harness/tsconfig.json                     |  1 +
 .../unittests/programNoParseFalsyFileNames.ts | 37 +++++++++++++++++++
 4 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 src/harness/unittests/programNoParseFalsyFileNames.ts

diff --git a/Jakefile.js b/Jakefile.js
index f2821a01686..d570a7cfc3d 100644
--- a/Jakefile.js
+++ b/Jakefile.js
@@ -154,6 +154,7 @@ var harnessSources = harnessCoreSources.concat([
     "transform.ts",
     "customTransforms.ts",
     "programMissingFiles.ts",
+    "programNoParseFalsyFileNames.ts",
     "symbolWalker.ts",
     "languageService.ts",
     "publicApi.ts",
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 342b697b977..79baae92fa8 100755
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -611,8 +611,9 @@ namespace ts {
             if (!skipDefaultLib) {
                 // If '--lib' is not specified, include default library file according to '--target'
                 // otherwise, using options specified in '--lib' instead of '--target' default library file
-                if (!options.lib) {
-                    processRootFile(getDefaultLibraryFileName(), /*isDefaultLib*/ true);
+                const defaultLibraryFileName = getDefaultLibraryFileName();
+                if (!options.lib && defaultLibraryFileName) {
+                    processRootFile(defaultLibraryFileName, /*isDefaultLib*/ true);
                 }
                 else {
                     forEach(options.lib, libFileName => {
@@ -1117,7 +1118,7 @@ namespace ts {
             // otherwise, using options specified in '--lib' instead of '--target' default library file
             const equalityComparer = host.useCaseSensitiveFileNames() ? equateStringsCaseSensitive : equateStringsCaseInsensitive;
             if (!options.lib) {
-               return equalityComparer(file.fileName, getDefaultLibraryFileName());
+                return equalityComparer(file.fileName, getDefaultLibraryFileName());
             }
             else {
                 return forEach(options.lib, libFileName => equalityComparer(file.fileName, combinePaths(defaultLibraryPath, libFileName)));
diff --git a/src/harness/tsconfig.json b/src/harness/tsconfig.json
index 54766ed02ec..c9521979776 100644
--- a/src/harness/tsconfig.json
+++ b/src/harness/tsconfig.json
@@ -135,6 +135,7 @@
         "./unittests/telemetry.ts",
         "./unittests/languageService.ts",
         "./unittests/programMissingFiles.ts",
+        "./unittests/programNoParseFalsyFileNames.ts",
         "./unittests/publicApi.ts",
         "./unittests/hostNewLineSupport.ts"
     ]
diff --git a/src/harness/unittests/programNoParseFalsyFileNames.ts b/src/harness/unittests/programNoParseFalsyFileNames.ts
new file mode 100644
index 00000000000..3270f6b14be
--- /dev/null
+++ b/src/harness/unittests/programNoParseFalsyFileNames.ts
@@ -0,0 +1,37 @@
+/// <reference path="..\harness.ts" />
+namespace ts {
+    describe("programNoParseFalsyFileNames", () => {
+        let program: Program;
+
+        beforeEach(() => {
+            const testSource = `
+            class Foo extends HTMLElement {
+                bar: string = 'baz';
+            }`;
+
+            const host: CompilerHost = {
+                getSourceFile: (fileName: string, languageVersion: ScriptTarget, _onError?: (message: string) => void) => {
+                    return fileName === "test.ts" ? createSourceFile(fileName, testSource, languageVersion) : undefined;
+                },
+                getDefaultLibFileName: () => "",
+                writeFile: (_fileName, _content) => { throw new Error("unsupported"); },
+                getCurrentDirectory: () => sys.getCurrentDirectory(),
+                getCanonicalFileName: fileName => sys.useCaseSensitiveFileNames ? fileName : fileName.toLowerCase(),
+                getNewLine: () => sys.newLine,
+                useCaseSensitiveFileNames: () => sys.useCaseSensitiveFileNames,
+                fileExists: fileName => fileName === "test.ts",
+                readFile: fileName => fileName === "test.ts" ? testSource : undefined,
+                resolveModuleNames: (_moduleNames: string[], _containingFile: string) => { throw new Error("unsupported"); },
+                getDirectories: _path => { throw new Error("unsupported"); },
+            };
+
+            program = createProgram(["test.ts"], { module: ModuleKind.ES2015 }, host);
+        });
+
+        it("should not have missing file paths", () => {
+            assert(program.getSourceFiles().length === 1, "expected 'getSourceFiles' length to be 1");
+            assert(program.getMissingFilePaths().length === 0, "expected 'getMissingFilePaths' length to be 0");
+            assert(program.getFileProcessingDiagnostics().getDiagnostics().length === 0, "expected 'getFileProcessingDiagnostics' length to be 0");
+        });
+    });
+}
\ No newline at end of file