Fix spurious duplicate variable definition errors for named functions.
## 5.0.2 (2017-03-30)
### Bug fixes
A binary operator after a parenthesized arrow expression is no longer incorrectly treated as an error.
## 5.0.0 (2017-03-28)
### Bug fixes
Raise an error for duplicated lexical bindings.
Fix spurious error when an assignement expression occurred after a spread expression.
Accept regular expressions after `of` (in `for`/`of`), `yield` (in a generator), and braced arrow functions.
Allow labels in front or `var` declarations, even in strict mode.
### Breaking changes
Parse declarations following `export default` as declaration nodes, not expressions. This means that class and function declarations nodes can now have `null` as their `id`.
## 4.0.11 (2017-02-07)
### Bug fixes
Allow all forms of member expressions to be parenthesized as lvalue.
## 4.0.10 (2017-02-07)
### Bug fixes
Don't expect semicolons after default-exported functions or classes,
even when they are expressions.
Check for use of `'use strict'` directives in non-simple parameter
functions, even when already in strict mode.
## 4.0.9 (2017-02-06)
### Bug fixes
Fix incorrect error raised for parenthesized simple assignment
targets, so that `(x) = 1` parses again.
## 4.0.8 (2017-02-03)
### Bug fixes
Solve spurious parenthesized pattern errors by temporarily erring on
the side of accepting programs that our delayed errors don't handle
correctly yet.
## 4.0.7 (2017-02-02)
### Bug fixes
Accept invalidly rejected code like `(x).y = 2` again.
Don't raise an error when a function _inside_ strict code has a
non-simple parameter list.
## 4.0.6 (2017-02-02)
### Bug fixes
Fix exponential behavior (manifesting itself as a complete hang for
even relatively small source files) introduced by the new 'use strict'
check.
## 4.0.5 (2017-02-02)
### Bug fixes
Disallow parenthesized pattern expressions.
Allow keywords as export names.
Don't allow the `async` keyword to be parenthesized.
Properly raise an error when a keyword contains a character escape.
Allow `"use strict"` to appear after other string literal expressions.
Disallow labeled declarations.
## 4.0.4 (2016-12-19)
### Bug fixes
Fix issue with loading acorn_loose.js with an AMD loader.
Fix crash when `export` was followed by a keyword that can't be
exported.
## 4.0.3 (2016-08-16)
### Bug fixes
Allow regular function declarations inside single-statement `if`
branches in loose mode. Forbid them entirely in strict mode.
Properly parse properties named `async` in ES2017 mode.
Fix bug where reserved words were broken in ES2017 mode.
## 4.0.2 (2016-08-11)
### Bug fixes
Don't ignore period or 'e' characters after octal numbers.
Fix broken parsing for call expressions in default parameter values
of arrow functions.
## 4.0.1 (2016-08-08)
### Bug fixes
Fix false positives in duplicated export name errors.
## 4.0.0 (2016-08-07)
### Breaking changes
The default `ecmaVersion` option value is now 7.
A number of internal method signatures changed, so plugins might need
to be updated.
### Bug fixes
The parser now raises errors on duplicated export names.
`arguments` and `eval` can now be used in shorthand properties.
Duplicate parameter names in non-simple argument lists now always
produce an error.
### New features
The `ecmaVersion` option now also accepts year-style version numbers
(2015, etc).
Support for `async`/`await` syntax when `ecmaVersion` is >= 8.
Support for trailing commas in call expressions when `ecmaVersion`
is >= 8.
## 3.3.0 (2016-07-25)
### Bug fixes
Fix bug in tokenizing of regexp operator after a function declaration.
Fix parser crash when parsing an array pattern with a hole.
### New features
Implement check against complex argument lists in functions that
enable strict mode in ES7.
## 3.2.0 (2016-06-07)
### Bug fixes
Improve handling of lack of unicode regexp support in host
environment.
Properly reject shorthand properties whose name is a keyword.
Don't crash when the loose parser is called without options object.
### New features
Visitors created with `visit.make` now have their base as _prototype_,
rather than copying properties into a fresh object.
Make it possible to use `visit.ancestor` with a walk state.
## 3.1.0 (2016-04-18)
### Bug fixes
Fix issue where the loose parser created invalid TemplateElement nodes
for unclosed template literals.
Properly tokenize the division operator directly after a function
expression.
Allow trailing comma in destructuring arrays.
### New features
The walker now allows defining handlers for `CatchClause` nodes.
## 3.0.4 (2016-02-25)
### Fixes
Allow update expressions as left-hand-side of the ES7 exponential
operator.
## 3.0.2 (2016-02-10)
### Fixes
Fix bug that accidentally made `undefined` a reserved word when
parsing ES7.
## 3.0.0 (2016-02-10)
### Breaking changes
The default value of the `ecmaVersion` option is now 6 (used to be 5).
Support for comprehension syntax (which was dropped from the draft
spec) has been removed.
### Fixes
`let` and `yield` are now “contextual keywords”, meaning you can
mostly use them as identifiers in ES5 non-strict code.
A parenthesized class or function expression after `export default` is
now parsed correctly.
### New features
When `ecmaVersion` is set to 7, Acorn will parse the exponentiation
operator (`**`).
The identifier character ranges are now based on Unicode 8.0.0.
Plugins can now override the `raiseRecoverable` method to override the
way non-critical errors are handled.
## 2.7.0 (2016-01-04)
### Fixes
Stop allowing rest parameters in setters.
Make sure the loose parser always attaches a `local` property to
`ImportNamespaceSpecifier` nodes.
Disallow `y` rexexp flag in ES5.
Disallow `\00` and `\000` escapes in strict mode.
Raise an error when an import name is a reserved word.
## 2.6.4 (2015-11-12)
### Fixes
Fix crash in loose parser when parsing invalid object pattern.
### New features
Support plugins in the loose parser.
## 2.6.2 (2015-11-10)
### Fixes
Don't crash when no options object is passed.
## 2.6.0 (2015-11-09)
### Fixes
Add `await` as a reserved word in module sources.
Disallow `yield` in a parameter default value for a generator.
Forbid using a comma after a rest pattern in an array destructuring.
### New features
Support parsing stdin in command-line tool.
## 2.5.2 (2015-10-27)
### Fixes
Fix bug where the walker walked an exported `let` statement as an
expression.
## 2.5.0 (2015-10-27)
### Fixes
Fix tokenizer support in the command-line tool.
In the loose parser, don't allow non-string-literals as import
sources.
Stop allowing `new.target` outside of functions.
Remove legacy `guard` and `guardedHandler` properties from try nodes.
Stop allowing multiple `__proto__` properties on an object literal in
strict mode.
Don't allow rest parameters to be non-identifier patterns.
Check for duplicate paramter names in arrow functions.