stack exec should propagate +RTS-options better

[michaxm]

stack new example
cd example
stack build --profile --executable-profiling --library-profiling
stack exec  example +RTS  -p

... fails with: the flag -p requires the program to be built with -prof

.stack-work/install/.../example +RTS -p

works.

It would be nice to use exec for this use case as well, as it is time consuming to discover you can't. I would consider this a feature request, cabal-install seems to have the same issue: http://stackoverflow.com/questions/22942194/profiling-an-executable-with-cabal

Could not find a documented "won't work / won't fix" anywhere for stack, so a decision documentation here would be nice.

[mgsloan]

The issue is that +RTS -p is getting interpreted by the stack executable. Use a -- to separate out the inner invocation - stack exec -- example +RTS -p. See the docs on this

[michaxm]

A part of the instructions I have overlooked so far, thanks a lot.

[ndmitchell]

This issue still persists. In particular the +RTS -p option after -- doesn't get passed through on Windows. As a concrete example:

stack new example
cd example
stack build
stack exec  -- example-exe +RTS  -?

This does not print out the help for example-exe, and examining process explorer the +RTS -? argument is not passed onwards.

[mgsloan]

@ndmitchell Curious, that works just fine for me on linux.

This reminded me of this comment - #2022 (comment) . Perhaps stack exec --RTS -- example-exe +RTS -? will work? Or perhaps stack exec example-exe --RTS -- +RTS -??

[ndmitchell]

@mgsloan I confirm both those things work. Do you do anything special to get the other one working? Is this a GHC issue? Should there be a --rts=... flag to stack to make this easier and consistent?

[varosi]

Will "--RTS" be automatically included in stack?
Currently it's not logical stack invocation to not work without --RTS:

myapp +RTS -s
stack exec -- myapp +RTS -s

It's logical both to be identical, but they aren't even on the latest stack-1.3.2 on Windows.

[mgsloan]

I think it'd be reasonable to add a --rts flag as @ndmitchell suggests. Does someone want to write a patch for this?

It'd also be worthwhile to explore whether we can get stack exec -- myapp +RTS -s to just work. It may be rather tricky because the runtime system parses the arguments first.

[AndreasPK]

Can this be closed via #3012 ?

[ndmitchell]

This answers my need, and covers what was discussed, so closing.