Make cannot satisfy package messages more helpful

[DanielG]

We should be able to look for package-dbs that might contain packages that cannot be satisfied. Also this seems to be caused by GHC version conflicts.

[nrolland]

I have seen many many users having this message in different circumstances. but it seems that they just accept and give up.. so that would be a good idea.

a systematic collect of errors would be awesome to know what are the most pressing needs.
sometimes small things we might not think of are effectively posing the biggest pb

[nrolland]

with the ghc-mod for ghcjs, I have <command line>: cannot satisfy -package-id aeson-0.9.0.1-18aa0b80940b48ed7f17b22f32a24d4f (use -v for more information) and not a clue what's wrong...

[DanielG]

We just pass whatever -package flags Cabal comes up with to GHC so you'll want to start debugging by looking at dist/setup-config, cabal-helper-wrapper . dist print-lbi --human | head -n1 | ppsh is your friend. cabal-helper-wrapper is installed in $libexec, ppsh is part of the pretty-show package.

[nrolland]

so much info, will parse that later

for reference to stackers, the command was, in my ghcjs project
/Users/nrolland/Sync/clones/cabal-helper-0.6.1.0/.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/cabal-helper-wrapper/cabal-helper-wrapper . .stack-work/dist/x86_64-osx/Cabal-1.22.4.0 print-lbi --human | head -n1 | push

and for getting verbose information

ghc-mod -v7 --ghcOpt=-v7 check example/todo/TodoComponents.hs

resulting in my case in

$ /Users/nrolland/Sync/clones/ghc-mod/.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/ghc-mod/ghc-mod -v7 --ghcOpt=-v7 check example/todo/TodoComponents.hs                              not sandboxed
DEBUG: reading cache: /Users/nrolland/Sync/clones/react-flux/.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/setup-config.ghc-mod.cabal-components
DEBUG: resolveEntrypoint:
       ["-i","-i.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build","-isrc","-i.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen","-I.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen","-I.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build","-optP-include","-optP.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen/cabal_macros.h"]
DEBUG: resolveEntrypoint: []
DEBUG: making sure autogen files exist
DEBUG: reading cache: .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/setup-config.ghc-mod.resolved-components
DEBUG: Could not find a component assignment, falling back to picking library
       component in cabal file.
VOMIT: Initializing GHC session with following options: "-fbuilding-cabal-package" "-O" "-outputdir" ".stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-odir" ".stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-hidir" ".stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-stubdir" ".stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-i" "-i.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-isrc" "-i.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen" "-I.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen" "-I.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build" "-optP-include" "-optP.stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/autogen/cabal_macros.h" "-hide-all-packages" "-no-user-package-db" "-package-db" "/Users/nrolland/.stack/snapshots/x86_64-osx/ghcjs-0.2.0.20151029_ghc-7.10.2/ghcjs-0.2.0.20151029_ghc-7.10.2/pkgdb/" "-package-db" "/Users/nrolland/Sync/clones/react-flux/.stack-work/install/x86_64-osx/ghcjs-0.2.0.20151029_ghc-7.10.2/ghcjs-0.2.0.20151029_ghc-7.10.2/pkgdb/" "-package-id" "aeson-0.9.0.1-18aa0b80940b48ed7f17b22f32a24d4f" "-package-id" "base-4.8.0.0-a3a3ebe3085e9d11c37cceba58a4365f" "-package-id" "bytestring-0.10.6.0-5352fe91f9dde68208480250c39ad337" "-package-id" "deepseq-1.4.1.1-221104de3b70837212b17aeb24781f46" "-package-id" "ghcjs-base-0.2.0.0-63fbb2f6833ad403ae52802aa0f12155" "-package-id" "mtl-2.2.1-88e615093eb72b33e8e48eca9396796c" "-package-id" "template-haskell-2.10.0.0-4a14865506a288db83640d5902bbf74e" "-package-id" "text-1.2.1.1-143e2b21f3b7f11ce926e3b74b97d235" "-package-id" "time-1.5.0.1-c55ef234a11d3c02dd441bdf346a7342" "-package-id" "unordered-containers-0.2.5.1-7321e65d882cabe2643a15780b81da9a" "-XHaskell2010" "-XCPP" "-XEmptyDataDecls" "-XExistentialQuantification" "-XFlexibleContexts" "-XFlexibleInstances" "-XFunctionalDependencies" "-XGeneralizedNewtypeDeriving" "-XMultiParamTypeClasses" "-XDeriveGeneric" "-XOverloadedStrings" "-XScopedTypeVariables" "-XTypeFamilies" "-Wall" "-O0" "-v7"
DEBUG: initSession: Session not initialized, creating new one
wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-befc8fea2f3d1fbb5c8d9d76daa004f8
wired-in package integer-gmp mapped to integer-gmp-0.5.1.0-fe48735f5952c9cfd131a37f6b03b1f3
wired-in package base mapped to base-4.8.0.0-a3a3ebe3085e9d11c37cceba58a4365f
wired-in package rts mapped to builtin_rts
wired-in package template-haskell mapped to template-haskell-2.10.0.0-4a14865506a288db83640d5902bbf74e
wired-in package ghc not found.
wired-in package dph-seq not found.
wired-in package dph-par not found.
wired-in package ghc-prim mapped to ghc-prim-0.4.0.0-befc8fea2f3d1fbb5c8d9d76daa004f8
wired-in package integer-gmp mapped to integer-gmp-0.5.1.0-fe48735f5952c9cfd131a37f6b03b1f3
wired-in package base mapped to base-4.8.0.0-a3a3ebe3085e9d11c37cceba58a4365f
wired-in package rts mapped to builtin_rts
wired-in package template-haskell mapped to template-haskell-2.10.0.0-4a14865506a288db83640d5902bbf74e
wired-in package ghc not found.
wired-in package dph-seq not found.
wired-in package dph-par not found.
<command line>: cannot satisfy -package-id aeson-0.9.0.1-18aa0b80940b48ed7f17b22f32a24d4f    (use -v for more information)

[DanielG]

This should take care of the majority of cases: #687