cabal-store-check: error in windows setting the compiler with `-w ghc-${version}`

[jneira]

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Hi, first of all thanks for these useful tools. Trying to fix the cabal-helper build for ghc-8.4.4 (my default one is ghc-8.6.5) i've go this error:

PS D:\dev\ws\haskell\haskell-ide-engine> cabal-store-check --with-compiler ghc --repair      
[   0.00138] debug: runProcess cwd=C:\Users\atrey\AppData\Roaming\ghc ghc --info
[   4.94895] info: Reading global package db
[   5.63529] info: 32 packages in D:\bin\stack\x86_64-windows\ghc-8.6.5\lib\package.conf.d
[   5.63569] info: Reading store package db
[   7.44641] error: Exception SomeAsyncException
......
PS D:\dev\ws\haskell\haskell-ide-engine> ghc-8.4.4 --version
The Glorious Glasgow Haskell Compilation System, version 8.4.4
PS D:\dev\ws\haskell\haskell-ide-engine> cabal-store-check --with-compiler ghc-8.4.4 --repair
[   0.00153] debug: runProcess cwd=C:\Users\atrey\AppData\Roaming\ghc ghc-8.4.4 --info
[   0.00608] error: Exception IOException
ghc-8.4.4: createProcess: does not exist (No such file or directory)

I guess it should be relatd with windows

The full path works:

PS D:\dev\ws\haskell\haskell-ide-engine> cabal-store-check --with-compiler D:\bin\ghc-8.4.4\bin\ghc-8.4.4 --repair
[   0.00164] debug: runProcess cwd=C:\Users\atrey\AppData\Roaming\ghc D:\bin\stack\x86_64-windows\ghc-8.4.4\bin\ghc-8.4.4 --info
[   0.31953] info: Reading global package db
[   0.82194] info: 30 packages in D:\bin\stack\x86_64-windows\ghc-8.4.4\lib\package.conf.d
[   0.82245] info: Reading store package db
.....

[phadej]

Thanks for the report.

Unfortunately I'm not actively supporting these tools (as they work well enough for me). Especially, I won't investigate why something doesn't work. Windows is quite a mystery for me.

For that reason I'm not actively advertising their existence either.

[fendor]

Can not reproduce on win 10:

> cabal-store-check --with-compiler ghc --repair
[   0.00045] debug: runProcess cwd=C:\Users\Privat\AppData\Roaming\ghc ghc --info
[   0.05799] info: Reading global package db
[   0.08145] info: 32 packages in C:\ProgramData\chocolatey\lib\ghc\tools\ghc-8.6.5\lib\package.conf.d
[   0.08162] info: Reading store package db
[   0.32378] info: 314 packages in C:\Users\Privat\AppData\Roaming\cabal\store\ghc-8.6.5\package.db
[   0.71628] info: 0 directly broken library components
[   0.71635] info: 0 transitively broken libraries
[   0.71636] info: 0 broken executable components
[   0.71637] debug: runPeu completed successfully

Only happens when this cabal-helper bug occurs?

[jneira]

@fendor it works for ghc (see my first report) but no for ghc-${version}

[fendor]

Thanks, misread the issue! Can reproduce!

[fendor]

I think this is either a problem with file extensions in process itself or not even a bug at all but expected behaviour on windows. The following snippet, already errors:

let p = proc "ghc-8.6.5" ["--info"] 
readCreateProcess p ""

But this succeeds:

let p = proc "ghc-8.6.5.exe" ["--info"] 
readCreateProcess p ""

Also, the following calls succeeds:

cabal-store-check -w ghc-8.6.5.exe

@jneira Maybe this is expected behaviour on windows? IIRC, the extension is important to windows.

[jneira]

well cabal -w ghc-8.4.4 works for windows and the fix would be "simply" add .exe if it is not already as suffix. Note that -w D:\bin\ghc-8.4.4\bin\ghc-8.4.4 also works and it has not the extension, so there would be anoher factor involved.

[fendor]

We can easily introduce a work-around for it. I just think the behaviour is weird for process.

[jneira]

As stated in https://github.com/phadej/cabal-extras/pull/20#issuecomment-584068495, it seems the solution should be upstream (in the directory package). I will keep the branch with the windows hack in the meanwhile, just in case someone wants to use it.

[phadej]

After a little more thinking, I'd like to have shell like search available in the library. I.e.

On unix-like systems simulate:

% command -v ghc-8.6.5
/opt/ghc/bin/ghc-8.6.5

and on windows whatever PowerShell does in:

Get-Command ghc-8.6.5

(It might find .bat and .cmd stuff, but I think that's what you should support as well, I think https://github.com/PowerShell/PowerShell/blob/a34d0f3e808659b0c07b8fdac83aaae1dae43c21/src/System.Management.Automation/engine/CommandSearcher.cs is one source of insight what happens in PowerShell, but I'm not 100% sure, I cannot read C#).

Obviously not listing anything for aliases and functions (which both AFAIK handle). The use-case is to simulate how the shell finds the commands, as that what you kind of expect when you say cabal-store-check -w ghc-8.6.5.

I think that's reasonable feature to have in directory, one could even argue that is exactly what findExecutable should do (and not some other function).