fix paren issues with tree shaking (#1101 #1128)

src/Module.js

@@ -18,7 +18,7 @@ function tryParse ( code, comments, acornOptions, id ) {
 			ecmaVersion: 7,
 			sourceType: 'module',
 			onComment: ( block, text, start, end ) => comments.push({ block, text, start, end }),
-			preserveParens: true
+			preserveParens: false
 		}, acornOptions ));
 	} catch ( err ) {
 		err.code = 'PARSE_ERROR';

src/ast/nodes/AssignmentExpression.js

@@ -5,8 +5,7 @@ import { NUMBER, STRING } from '../values.js';
 
 export default class AssignmentExpression extends Node {
 	bind ( scope ) {
-		let subject = this.left;
-		while ( this.left.type === 'ParenthesizedExpression' ) subject = subject.expression;
+		const subject = this.left;
 
 		this.subject = subject;
 		disallowIllegalReassignment( scope, subject );

src/ast/nodes/ExportDefaultDeclaration.js

@@ -49,11 +49,18 @@ export default class ExportDefaultDeclaration extends Node {
 		const treeshake = this.module.bundle.treeshake;
 		const name = this.getName( es );
 
+		// paren workaround: find first non-whitespace character position after `export default`
+		let declaration_start;
+		if ( this.declaration ) {
+			const statementStr = code.original.slice( this.start, this.end );
+			declaration_start = this.start + statementStr.match(/^export\s+default\s*/)[0].length;
+		}
+
 		if ( this.shouldInclude || this.declaration.activated ) {
 			if ( this.activated ) {
 				if ( functionOrClassDeclaration.test( this.declaration.type ) ) {
 					if ( this.declaration.id ) {
-						code.remove( this.start, this.declaration.start );
+						code.remove( this.start, declaration_start );
 					} else {
 						throw new Error( 'TODO anonymous class/function declaration' );
 					}
@@ -65,14 +72,14 @@ export default class ExportDefaultDeclaration extends Node {
 						code.remove( this.leadingCommentStart || this.start, this.next || this.end );
 						return; // don't render children. TODO this seems like a bit of a hack
 					} else {
-						code.overwrite( this.start, this.declaration.start, `${this.module.bundle.varOrConst} ${name} = ` );
+						code.overwrite( this.start, declaration_start, `${this.module.bundle.varOrConst} ${name} = ` );
 					}
 
 					this.insertSemicolon( code );
 				}
 			} else {
 				// remove `var foo` from `var foo = bar()`, if `foo` is unused
-				code.remove( this.start, this.declaration.start );
+				code.remove( this.start, declaration_start );
 			}
 
 			super.render( code, es );
@@ -82,10 +89,10 @@ export default class ExportDefaultDeclaration extends Node {
 					code.remove( this.leadingCommentStart || this.start, this.next || this.end );
 				} else {
 					const hasEffects = this.declaration.hasEffects( this.module.scope );
-					code.remove( this.start, hasEffects ? this.declaration.start : this.next || this.end );
+					code.remove( this.start, hasEffects ? declaration_start : this.next || this.end );
 				}
 			} else {
-				code.overwrite( this.start, this.declaration.start, `${this.module.bundle.varOrConst} ${name} = ` );
+				code.overwrite( this.start, declaration_start, `${this.module.bundle.varOrConst} ${name} = ` );
 			}
 			// code.remove( this.start, this.next || this.end );
 		}

src/ast/nodes/ParenthesizedExpression.js

@@ -1,11 +0,0 @@
-import Node from '../Node.js';
-
-export default class ParenthesizedExpression extends Node {
-	getPossibleValues ( values ) {
-		return this.expression.getPossibleValues( values );
-	}
-
-	getValue () {
-		return this.expression.getValue();
-	}
-}

src/ast/nodes/UpdateExpression.js

@@ -5,8 +5,7 @@ import { NUMBER } from '../values.js';
 
 export default class UpdateExpression extends Node {
 	bind ( scope ) {
-		let subject = this.argument;
-		while ( this.argument.type === 'ParenthesizedExpression' ) subject = subject.expression;
+		const subject = this.argument;
 
 		this.subject = subject;
 		disallowIllegalReassignment( scope, this.argument );

src/ast/nodes/index.js

@@ -24,7 +24,6 @@ import Literal from './Literal.js';
 import MemberExpression from './MemberExpression.js';
 import NewExpression from './NewExpression.js';
 import ObjectExpression from './ObjectExpression.js';
-import ParenthesizedExpression from './ParenthesizedExpression.js';
 import ReturnStatement from './ReturnStatement.js';
 import Statement from './shared/Statement.js';
 import TemplateLiteral from './TemplateLiteral.js';
@@ -63,7 +62,6 @@ export default {
 	MemberExpression,
 	NewExpression,
 	ObjectExpression,
-	ParenthesizedExpression,
 	ReturnStatement,
 	SwitchStatement: Statement,
 	TemplateLiteral,

src/ast/nodes/shared/assignTo.js

@@ -8,8 +8,6 @@ export default function assignToForLoopLeft ( node, scope, value ) {
 	}
 
 	else {
-		while ( node.type === 'ParenthesizedExpression' ) node = node.expression;
-
 		if ( node.type === 'MemberExpression' ) {
 			// apparently this is legal JavaScript? Though I don't know what
 			// kind of monster would write `for ( foo.bar of thing ) {...}`

src/ast/nodes/shared/isUsedByBundle.js

@@ -1,8 +1,6 @@
 import { UNKNOWN } from '../../values.js';
 
 export default function isUsedByBundle ( scope, node ) {
-	while ( node.type === 'ParenthesizedExpression' ) node = node.expression;
-
 	// const expression = node;
 	while ( node.type === 'MemberExpression' ) node = node.object;