List of minor breaking changes from 1.0

[RyanCavanaugh]

For completeness's sake, this is a list of breaking changes from the 1.0 compiler that we believe very few users will encounter.

These are errors that should have been reported and represent very likely errors in user code:

• Comparison operators (<, >) more correctly check their operands for compatibility
• typeof undefined is now undefined, not any

These mainly cover how certain TypeScript language constructs are emitted in the presence of serious errors in the code:

• Classes with constructor overloads lacking an implementation, or with multiple implementations: emit has changed
• Duplicate export = assignments emit has changed
• Uses of this in fat arrow function expressions in static initializers no longer capture this
• Nonsense circular external module declarations are now an error
• Some constructs which are early errors in JavaScript are now considered as parse errors
• Invalid uses of super in fat arrow function expressions emit has changed

Emit in some cases has changed to semantically-equivalent, but better, code:

• Array copy code for unused rest parameters is no longer emitted
• Exact emit for certain boilerplate constructs (rest args, default parameter values) has changed

[basarat]

Nonsense circular external module declarations are now an error

are all circular external module declarations considered an error?

[johnnyreilly]

Array copy code for unused rest parameters is no longer emitted

👍 for this!

[RyanCavanaugh]

are all circular external module declarations considered an error?

No, only this exact pattern:

declare module 'foo' {
  import bar = require('foo');
}