cljs-load-order-repro

Minimal reproduction of a possible issue with the ClojureScript compiler.

The issue

The order that namespaces are loaded at runtime seems to be independent of the order that the namespaces are required in user code.

It looks like some work to ensure the ordering at compile time was done as part of CLJS-1453, but it seems that things can get out of order by the time cljs_deps.js is emitted.

This seems to affect all optimization levels.

Potential cause

It seems that the output in cljs_deps.js for a given ClojureScript file is ultimately determined by the output of cljs.compiler/emit-source.

The code there removes duplicate deps in the same way that the 'ns parse method in cljs.analyzer did prior to CLJS-1453.

The attached patch resolves the issue for my narrow use case, but I believe the underlying functions are passing the :uses and :requires around as maps, so more work may be needed for a full solution.

How to reproduce

Running this command:

clj --main cljs.main --compile-opts '{:target :nodejs :main a}' --compile a

will compile the a namespace defined in a.cljs. That namespace requires—via the :require form of the ns macro— namespaces b through g in alphabetical order.

After compiling, observe the following:

• The goog.addDependency call for a.js in the output out/cljs_deps.js file includes its dependencies in an arbitrary order. For example, one run on my machine resulted in:

goog.addDependency("../a.js", ['a'], ['cljs.core', 'e', 'c', 'g', 'b', 'd', 'f']);

• The console output given by running the compiled code with node out/main.js indicates that the runtime load order is identical to the ordering reflected in out/cljs_deps.js

body of e

body of c

body of g

body of b 

body of d

body of f