Stack fails to build without Setup.hs

[eborden]

General summary/comments

cabal is able to build without a Setup.hs by defaulting to the most basic Setup.hs. stack should have feature parity in this respect.

Steps to reproduce

1. git clone git@github.com:haskell/network.git
2. cd network
3. stack init
4. stack build

Expected

stack should build with a default Setup.hs when no Setup.hs is present.

Actual

stack cannot build without a Setup.hs.

$ stack init
Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- ./

Selecting the best among 15 snapshots...

Downloaded lts-13.3 build plan.    
Didn't see cheapskate-0.1.1.1@sha256:f03d9784fd13cc970ecf5be8792f6c592e3127dce208efad07d614f86ec3c655,3114 in your package indices.
Updating and trying again.
Selected mirror https://s3.amazonaws.com/hackage.fpcomplete.com/                                 
Downloading timestamp                                                                            
Downloading snapshot                                                                             
Updating index                                                                                   
Updated package index downloaded                                                                 
Update complete                                                                                  
Populated index cache.    
* Matches lts-13.3

Selected resolver: lts-13.3
Initialising configuration using resolver: lts-13.3
Total number of user packages considered: 1
Writing configuration to file: stack.yaml
All done.

$ stack build
No Setup.hs or Setup.lhs file found in /home/eborden/code/network/

Stack version

$ stack --version
Version 1.9.3, Git revision 40cf7b37526b86d1676da82167ea8758a854953b (6211 commits) x86_64 hpack-0.31.1

Method of installation

• Official binary, downloaded from stackage.org or fpcomplete's package repository

[dbaynard]

Are you missing a cd network between your steps 1 and 2? With that, I can't reproduce (stack throws an error because there's an existing stack.yaml file in the network source tree).

[eborden]

master of network has changed since this was produced. 🤦‍♂️

You could do the following to repro:

1. git clone git@github.com:haskell/network.git
2. cd network
3. rm Setup.hs
4. stack build

[mihaimaruseac]

Just confirmed this. It even manifests when doing stack unpack network in step 1.

As expected, stack init works even if there's no Setup.hs but not the build.

This should be easy, I think: just beforeexecuting the build plan, we should output the basic Setup.hs if none is found and then proceed with the build as before. I marked it as an easy PR.

[dbaynard]

It's because network uses build-type: configure. Without the Setup.hs file it shouldn't build?

[mihaimaruseac]

You are right. It builds without the Setup.hs file for a package using build-type: Simple (I tested on io-manager).

Closing this as it is actually not a Stack bug.

[eborden]

Great catch! network recently moved away from a more complex Setup.hs to simple. I'll fix the cabal file.