From c71e6cc9ef9f9b8ae0f2036336b0489cdc61318b Mon Sep 17 00:00:00 2001
From: Vladimir Matveev <vladima@microsoft.com>
Date: Tue, 13 Dec 2016 12:57:21 -0800
Subject: [PATCH] add a new line if after writing trailing comments (#12894)

---
 src/compiler/comments.ts                      |  3 +++
 src/compiler/transformers/module/system.ts    | 25 ++++++++++---------
 .../reference/systemModuleTrailingComments.js | 18 +++++++++++++
 .../systemModuleTrailingComments.symbols      |  5 ++++
 .../systemModuleTrailingComments.types        |  6 +++++
 .../compiler/systemModuleTrailingComments.ts  |  4 +++
 6 files changed, 49 insertions(+), 12 deletions(-)
 create mode 100644 tests/baselines/reference/systemModuleTrailingComments.js
 create mode 100644 tests/baselines/reference/systemModuleTrailingComments.symbols
 create mode 100644 tests/baselines/reference/systemModuleTrailingComments.types
 create mode 100644 tests/cases/compiler/systemModuleTrailingComments.ts

diff --git a/src/compiler/comments.ts b/src/compiler/comments.ts
index cd96981c093..bd9190dbec7 100644
--- a/src/compiler/comments.ts
+++ b/src/compiler/comments.ts
@@ -156,6 +156,9 @@ namespace ts {
 
             if (!skipTrailingComments) {
                 emitLeadingComments(detachedRange.end, /*isEmittedNode*/ true);
+                if (hasWrittenComment && !writer.isAtStartOfLine()) {
+                    writer.writeLine();
+                }
             }
 
             if (extendedDiagnostics) {
diff --git a/src/compiler/transformers/module/system.ts b/src/compiler/transformers/module/system.ts
index 91e29e09886..0e3a42da0d2 100644
--- a/src/compiler/transformers/module/system.ts
+++ b/src/compiler/transformers/module/system.ts
@@ -101,20 +101,21 @@ namespace ts {
             // So the helper will be emit at the correct position instead of at the top of the source-file
             const moduleName = tryGetModuleNameFromFile(node, host, compilerOptions);
             const dependencies = createArrayLiteral(map(dependencyGroups, dependencyGroup => dependencyGroup.name));
-            const updated = updateSourceFileNode(
-                node,
-                createNodeArray([
-                    createStatement(
-                        createCall(
-                            createPropertyAccess(createIdentifier("System"), "register"),
+            const updated = setEmitFlags(
+                updateSourceFileNode(
+                    node,
+                    createNodeArray([
+                        createStatement(
+                            createCall(
+                                createPropertyAccess(createIdentifier("System"), "register"),
                             /*typeArguments*/ undefined,
-                            moduleName
-                                ? [moduleName, dependencies, moduleBodyFunction]
-                                : [dependencies, moduleBodyFunction]
+                                moduleName
+                                    ? [moduleName, dependencies, moduleBodyFunction]
+                                    : [dependencies, moduleBodyFunction]
+                            )
                         )
-                    )
-                ], node.statements)
-            );
+                    ], node.statements)
+                ), EmitFlags.NoTrailingComments);
 
             if (!(compilerOptions.outFile || compilerOptions.out)) {
                 moveEmitHelpers(updated, moduleBodyBlock, helper => !helper.scoped);
diff --git a/tests/baselines/reference/systemModuleTrailingComments.js b/tests/baselines/reference/systemModuleTrailingComments.js
new file mode 100644
index 00000000000..41b0bd299a0
--- /dev/null
+++ b/tests/baselines/reference/systemModuleTrailingComments.js
@@ -0,0 +1,18 @@
+//// [systemModuleTrailingComments.ts]
+export const test = "TEST";
+
+//some comment
+
+//// [systemModuleTrailingComments.js]
+System.register([], function (exports_1, context_1) {
+    "use strict";
+    var __moduleName = context_1 && context_1.id;
+    var test;
+    return {
+        setters: [],
+        execute: function () {
+            exports_1("test", test = "TEST");
+            //some comment 
+        }
+    };
+});
diff --git a/tests/baselines/reference/systemModuleTrailingComments.symbols b/tests/baselines/reference/systemModuleTrailingComments.symbols
new file mode 100644
index 00000000000..4df59b45faa
--- /dev/null
+++ b/tests/baselines/reference/systemModuleTrailingComments.symbols
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/systemModuleTrailingComments.ts ===
+export const test = "TEST";
+>test : Symbol(test, Decl(systemModuleTrailingComments.ts, 0, 12))
+
+//some comment
diff --git a/tests/baselines/reference/systemModuleTrailingComments.types b/tests/baselines/reference/systemModuleTrailingComments.types
new file mode 100644
index 00000000000..235b46e6e8f
--- /dev/null
+++ b/tests/baselines/reference/systemModuleTrailingComments.types
@@ -0,0 +1,6 @@
+=== tests/cases/compiler/systemModuleTrailingComments.ts ===
+export const test = "TEST";
+>test : "TEST"
+>"TEST" : "TEST"
+
+//some comment
diff --git a/tests/cases/compiler/systemModuleTrailingComments.ts b/tests/cases/compiler/systemModuleTrailingComments.ts
new file mode 100644
index 00000000000..32c29617832
--- /dev/null
+++ b/tests/cases/compiler/systemModuleTrailingComments.ts
@@ -0,0 +1,4 @@
+// @module: system
+export const test = "TEST";
+
+//some comment
\ No newline at end of file