[Pkg-javascript-devel] pkg-js-tools, nodejs and modules build ordering

[Roland Mas]

Hi all,

I'm still working on packaging ipywidgets and jupyterlab, each with its 
share of Node modules. I'm in the process of replacing the imperative 
parts of debian/rules with declarative files used by the nodejs 
buildsystem for debhelper, and I'm encountering a strange behaviour. 
Since I'm rather new to node module packaging in general and 
pkg-js-tools in particular, I'd rather discuss it here before filing a bug.

In short: when I specify dependencies between modules, the build order 
does not necessarily take them into account.

For instance, my current debian/nodejs/component_links reads as follows:

packages/coreutils packages/ui-components
packages/ui-components packages/apputils
packages/apputils packages/outputarea
packages/rendermime-interfaces packages/mathjax2
packages/rendermime packages/outputarea

Yet the build log shows that dh_auto_build tries to build 
packages/apputils first, although it should at least be built later than 
packages/ui-components. My suspicion is that the cmp_ordered_list 
function in /usr/share/perl5/Debian/Debhelper/Buildsystem/nodejs.pm is a 
bit optimistic in that it hopes that every pair of packages will be 
compared during the sorting of the list, which means not all 
dependencies are taken into account. Instrumenting the sort {} seems to 
confirm this hypothesis, since the apputils and ui-components items are 
not compared. As a result, the build ordering is not necessarily 
compliant with the requirements. It's quite possible that this behaviour 
only pops up when the list is large enough that the comparisons are 
sparse; in the case of jupyterlab, there are 91 modules, which are 
sorted using only 160 comparisons.

For reference and reproducibility, see the 
python-team/packages/jupyterlab repo on salsa; commit 2d334d40d8 
exhibits the "bug" for me using gbp buildpackage.

Am I missing something? I'd love to use the declarative approach and let 
the tools do the actual ordering :-)

Roland.