angular/angular.js — pull request #3927 by vojtajina (2013-09-08 17:23:14+00:00)
Title: Fix $compile (remove templateUrl directive splitting)

How did compiling a templateUrl (async) directive with `replace:true` work before this commit?

1. apply all directives with higher priority than the templateUrl directive
2. partially apply the templateUrl directive (create `beforeTemplateNodeLinkFn`)
3. fetch the template
4. apply second part of the templateUrl directive on the fetched template
(`afterTemplateNodeLinkFn`)

That is, the templateUrl directive is basically split into two parts (two `nodeLinkFn` functions),
which has to be both applied.

Normally we compose linking functions (`nodeLinkFn`) using continuation - calling the linking
function of a parent element, passing the linking function of the child elements as an argument. The
parent linking function then does:

1. execute its pre-link functions
2. call the child elements linking function (traverse)
3. execute its post-link functions

Now, we have two linking functions for the same DOM element level (because the templateUrl directive
has been split).

There has been multiple issues because of the order of these two linking functions (creating
controller before setting up scope locals, running linking functions before instantiating
controller, etc.). It is easy to fix one use case, but it breaks some other use case. It is hard to
decide what is the "correct" order of these two linking functions as they are essentially on the
same level.

Running them side-by-side screws up pre/post linking functions for the high priority directives
(those executed before the templateUrl directive). It runs post-linking functions before traversing:
```js
beforeTemplateNodeLinkFn(null); // do not travers
afterTemplateNodeLinkFn(afterTemplateChildLinkFn);
```

Composing them (in any order) screws up the order of post-linking functions. We could fix this by
having post-linking functions to execute in reverse order (from the lowest priority to the highest)
which might actually make a sense.

**My solution is to remove this splitting.** This commit removes the `beforeTemplateNodeLinkFn`. The
first run (before we have the template) only schedules fetching the template. The rest (creating
scope locals, instantiating a controller, linking functions, etc) is done when processing the
directive again (in the context of the already fetched template; this is the cloned
`derivedSyncDirective`).

We still need to pass-through the linking functions of the higher priority directives (those
executed before the templateUrl directive), that's why I added `preLinkFns` and `postLinkFns`
arguments to `applyDirectivesToNode`.

This also changes the "$compile transclude should make the result of a transclusion available to the
parent directive in post- linking phase (templateUrl)" unit test. It was testing that a parent
directive can see the content of transclusion in its pre-link function. That is IMHO wrong (as the
`ngTransclude` directive inserts the translusion in its linking function). This test was only passing because of
c173ca412878d537b18df01f39e400ea48a4b398, which changed the behavior of the compiler to traverse
before executing the parent linking function. That was wrong and also caused the #3792 issue, which
this change fixes.

Closes #3792