Merge pull request microsoft#3185 from Microsoft/variableStatementComments

Don't emit leading/trailing comments for omitted variable statements

Author: DanielRosenwasser

src/compiler/emitter.ts

@@ -2229,9 +2229,10 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
  emitEmbeddedStatement(node.statement);
  }
 
- /* Returns true if start of variable declaration list was emitted.
- * Return false if nothing was written - this can happen for source file level variable declarations
- * in system modules - such variable declarations are hoisted.
+ /**
+ * Returns true if start of variable declaration list was emitted.
+ * Returns false if nothing was written - this can happen for source file level variable declarations
+ * in system modules where such variable declarations are hoisted.
  */
  function tryEmitStartOfVariableDeclarationList(decl: VariableDeclarationList, startPos?: number): boolean {
  if (shouldHoistVariable(decl, /*checkIfSourceFileLevelDecl*/ true)) {
@@ -3060,6 +3061,7 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
 
  function emitVariableStatement(node: VariableStatement) {
  let startIsEmitted = false;
+
  if (node.flags & NodeFlags.Export) {
  if (isES6ExportedDeclaration(node)) {
  // Exported ES6 module member
@@ -3070,6 +3072,7 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
  else {
  startIsEmitted = tryEmitStartOfVariableDeclarationList(node.declarationList);
  }
+
  if (startIsEmitted) {
  emitCommaList(node.declarationList.declarations);
  write(";");
@@ -3085,6 +3088,28 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
  }
  }
 
+ function shouldEmitLeadingAndTrailingCommentsForVariableStatement(node: VariableStatement) {
+ // If we're not exporting the variables, there's nothing special here.
+ // Always emit comments for these nodes.
+ if (!(node.flags & NodeFlags.Export)) {
+ return true;
+ }
+
+ // If we are exporting, but it's a top-level ES6 module exports,
+ // we'll emit the declaration list verbatim, so emit comments too.
+ if (isES6ExportedDeclaration(node)) {
+ return true;
+ }
+
+ // Otherwise, only emit if we have at least one initializer present.
+ for (let declaration of node.declarationList.declarations) {
+ if (declaration.initializer) {
+ return true;
+ }
+ }
+ return false;
+ }
+
  function emitParameter(node: ParameterDeclaration) {
  if (languageVersion < ScriptTarget.ES6) {
  if (isBindingPattern(node.name)) {
@@ -5747,6 +5772,9 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
  case SyntaxKind.ExportAssignment:
  return false;
 
+ case SyntaxKind.VariableStatement:
+ return shouldEmitLeadingAndTrailingCommentsForVariableStatement(<VariableStatement>node);
+
  case SyntaxKind.ModuleDeclaration:
  // Only emit the leading/trailing comments for a module if we're actually
  // emitting the module as well.

tests/baselines/reference/commentsBeforeVariableStatement1.js

@@ -5,5 +5,4 @@ export var b: number;
 
 //// [commentsBeforeVariableStatement1.js]
 define(["require", "exports"], function (require, exports) {
- /** b's comment*/
 });

tests/baselines/reference/commentsExternalModules.js

@@ -66,7 +66,6 @@ define(["require", "exports"], function (require, exports) {
  /** Module comment*/
  var m1;
  (function (m1) {
- /** b's comment*/
  /** foo's comment*/
  function foo() {
  return m1.b;
@@ -96,7 +95,6 @@ define(["require", "exports"], function (require, exports) {
  /** Module comment */
  var m4;
  (function (m4) {
- /** b's comment */
  /** foo's comment
  */
  function foo() {

tests/baselines/reference/commentsExternalModules2.js

@@ -66,7 +66,6 @@ define(["require", "exports"], function (require, exports) {
  /** Module comment*/
  var m1;
  (function (m1) {
- /** b's comment*/
  /** foo's comment*/
  function foo() {
  return m1.b;
@@ -96,7 +95,6 @@ define(["require", "exports"], function (require, exports) {
  /** Module comment */
  var m4;
  (function (m4) {
- /** b's comment */
  /** foo's comment
  */
  function foo() {

tests/baselines/reference/commentsExternalModules3.js

@@ -65,7 +65,6 @@ export var newVar2 = new extMod.m4.m2.c();
 /** Module comment*/
 var m1;
 (function (m1) {
- /** b's comment*/
  /** foo's comment*/
  function foo() {
  return m1.b;
@@ -95,7 +94,6 @@ var myvar = new m1.m2.c();
 /** Module comment */
 var m4;
 (function (m4) {
- /** b's comment */
  /** foo's comment
  */
  function foo() {

tests/baselines/reference/commentsModules.js

@@ -101,7 +101,6 @@ new m7.m8.m9.c();
 /** Module comment*/
 var m1;
 (function (m1) {
- /** b's comment*/
  /** foo's comment*/
  function foo() {
  return m1.b;

tests/baselines/reference/declFileTypeAnnotationVisibilityErrorTypeAlias.js

@@ -52,7 +52,6 @@ var M;
  return Window;
  })();
  N.Window = Window;
- // Should report error that W is private
  })(N = M.N || (M.N = {}));
 })(M || (M = {}));
 var M1;
@@ -65,7 +64,6 @@ var M1;
  return Window;
  })();
  N.Window = Window;
- // No error
  })(N = M1.N || (M1.N = {}));
 })(M1 || (M1 = {}));
 var M2;

tests/baselines/reference/declFileTypeAnnotationVisibilityErrorTypeLiteral.js

@@ -59,8 +59,6 @@ var m;
  }
  };
  m.x3 = m.x;
- // Function type
  m.y2 = m.y;
- // constructor type
  m.z2 = m.z;
 })(m || (m = {}));

tests/baselines/reference/declarationEmit_nameConflicts3.js

@@ -74,7 +74,6 @@ var M;
  D[D["f"] = 0] = "f";
  })(P.D || (P.D = {}));
  var D = P.D;
- // ok
  P.w = M.D.f; // error, should be typeof M.D.f
  P.x = M.C.f; // error, should be typeof M.C.f
  P.x = M.E.f; // error, should be typeof M.E.f

tests/baselines/reference/declarationEmit_nameConflictsWithAlias.js

@@ -9,7 +9,6 @@ export module M {
 //// [declarationEmit_nameConflictsWithAlias.js]
 var M;
 (function (M) {
- // Gets emitted as C.I, which is the wrong interface
 })(M = exports.M || (exports.M = {}));