[regression] packageMap doesn't work with modules built into dojo/dojo

[ben hockey]

consider this part 2 of #15535 - it used to work (1.7.2) but now it doesn't.

in trunk, modules built into dojo/dojo don't load properly when packageMap is in play.

the attached files are arranged similar to #15535 and the contents are only changed slightly:

rootDir/

pkg/

layer.js - some code with an i18n dependency

pkg.profile.js - build profile

plain.html - loads pkg/layer without using a packageMap config

packageMap.html - loads pkg/layer using a packageMap config

the key difference is that in the profile, "pkg/layer" is now included in "dojo/dojo"

        layers: {
                "dojo/dojo": {
                        include: [
                                "dojo/i18n",
                                "pkg/layer"
                        ],
                        boot: true,
                        customBase: true
                }
        },

[Rawld Gill]

This is a very interesting special case. Looking at the last few lines of the built dojo/dojo.js, you'll see this:

'*now':function(r){return;r(['dojo/i18n!*preload*dojo/nls/dojo*["ar","ca","cs","da","de","el","en-gb","en-us","es-es","fi-fi","fr-fr","he-il","hu","it-it","ja-jp","ko-kr","nl-nl","nb","pl","pt-br","pt-pt","ru","sk","sl","sv","th","tr","zh-tw","zh-cn","ROOT"]']);}
}});
(function(){
	// must use this.require to make this work in node.js
	var require = this.require;
	// consume the cached dojo layer
	require({cache:{}});
	!require.async && require(["dojo"]);
	require.boot && require.apply(null, require.boot);
})();

When the cache gets consumed, the *now function is executed, which effectively executes

require(['dojo/i18n!*preload*dojo/nls/data*["ar"/* etc. */]');

...which causes lots of dojo modules to be loaded. So, in spite of the line...

!require.async && require(["dojo"]);

the dependency tree for dojo/i18n! gets loaded...which is essentially dojo base.

The next interesting thing that happens consequent to the i18n preload is attempting to load the flattened dojo/nls/dojo bundle for the current locale. E.g., on a en-us machine this results in loading the module dojo/nls/dojo_en-us. But, looking at the configuration provided in packageMap.html, we see an explicit baseUrl ("release") and no package config for the dojo package. This results in resolving dojo/nls/dojo_en-us to the url "./release/nls/dojo_en-us.js" which is incorrect and a 404 error results.

There are several ways to make this work:

For my taste, the best solution is to simply eliminate the preload algorithm by adding the build switch

localeList: 0,

to the profile. Since preloads are not being used, those code paths can optionally be trimmed from the build output by adding the static has values:

staticHasFeatures:{
	'dojo-preload-i18n-Api':0,
	'dojo-v1x-i18n-Api':0
},

Building with no further changes results in a clean load. Notice the output of the network panel results in three requests:(1) packageMap.html, dojo/dojo.js, and dojo/cldr/nls/en/number.js. This is exactly as efficient as the preload algorithm....and a lot less complex.

In general, I do not believe the preload algorithm is valuable in the great majority of the cases. It was implemented in the 1.x branch because several customers were unable to change directions. I hope to remove it completely in 2.0.

The second way to fix the problem is to simply add a dojo config to packageMap.html like this:

{
	name: 'dojo',
	location: 'dojo'
},

With no other changes, the program loads, but at the expensive of loading the possibly-useless dojo base module tree.

The third way to fix the problem is to hack the built dojo/dojo.js to remove the preload at the bottom of the file.

[ben hockey]

this has regressed after r29249

[Rawld Gill]

This seems to work after [29257] so long as localeList:0 is added to the build profile and

{
  name:"dojo",
  location:"dojo"
}

is added to the package config.