See warnings in libs when building in watch mode

Ecosystem
1

Hi,

I created a project based on Spin CLI template, so I have a bin module depending on lib and
I noticed that when building in watch mode (dune build -p #{self.name} --watch), warnings from the lib module (where most of my code is) don’t get reported. They do get reported when simply building dune build -p #{self.name}.

Is there anything I can do to change this behavior?

Thanks

2

Do they get not reported at all? Currently Dune’s handling of warnings is not ideal; they are printed the first time they are encountered, but during subsequent incremental builds, they are not re-displayed. This is one of the reason a lot of warnings are treated as errors in development mode.

FTR, this is one aspect of Dune we’d like to improve for 3.0.

3

No they don’t even get reported the first time in watch mode. They do get reported every time when simply building. I wouldn’t mind having to treat warnings as errors if that would allow me to see the warnings in watch mode every time.

4

Hmm, that seems like a bug then. Hopefully that should be sorted for Dune 3.0, but feel free to open a ticket about it on the Dune github project.

If you want to treat more warnings as errors, you can do so by writing the following in your toplevel dune file:

(env
 (dev
  (flags :standard -w +A)))

+A will make all warnings be errors, and you can turn only a subset via the syntax described in the man page for ocamlc.

5

I updated dune from 2.8.2 to 2.8.4 and warnings do seem to get reported the first time now.

Thanks for your help!

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