can't upgrade to latest; lacking happy

[silky]

while upgrading (stack upgrade --git), i get the following error:

Warning: Ignoring unknown field "generated-other-modules" in executable section "stack"
No packages found in snapshot which provide a "happy" executable, which is a build-tool dependency of "haskell-src-exts"
unicode-transforms-0.3.3: configure
unicode-transforms-0.3.3: build
th-reify-many-0.1.8: configure
th-reify-many-0.1.8: build
haskell-src-exts-1.20.2: configure
Cabal-2.2.0.1: configure
th-reify-many-0.1.8: copy/register                                         
Cabal-2.2.0.1: build                                                       
unicode-transforms-0.3.3: copy/register               
Cabal-2.2.0.1: copy/register                          
Progress 4/33               
--  While building custom Setup.hs for package haskell-src-exts-1.20.2 using:
      /home/noon/.stack/setup-exe-cache/x86_64-linux/Cabal-simple_mPHDZzAJ_2.0.1.0_ghc-8.2.2 --builddir=.stack-work/dist/x86_64-linux/Cabal-2.0.1.0 configure --with-ghc=/home/noon/.stack/programs/x86_64-linux/ghc-8.2.2/bin/ghc --with-ghc-pkg=/home/noon/.stack/programs/x86_64-linux/ghc-8.2.2/bin/ghc-pkg --user --package-db=clear --package-db=global --package-db=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/pkgdb --libdir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/lib --bindir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/bin --datadir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/share --libexecdir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/libexec --sysconfdir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/etc --docdir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/doc/haskell-src-exts-1.20.2 --htmldir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/doc/haskell-src-exts-1.20.2 --haddockdir=/home/noon/.stack/snapshots/x86_64-linux/lts-11.2/8.2.2/doc/haskell-src-exts-1.20.2 --dependency=array=array-0.5.2.0 --dependency=base=base-4.10.1.0 --dependency=cpphs=cpphs-1.20.8-4qz4Ij8cgjBERS28MKeWJw --dependency=ghc-prim=ghc-prim-0.5.1.1 --dependency=pretty=pretty-1.1.3.3
    Process exited with code: ExitFailure 1
    Logs have been written to: /tmp/stack-upgrade25461/stack/.stack-work/logs/haskell-src-exts-1.20.2.log

    Configuring haskell-src-exts-1.20.2...
    Cabal-simple_mPHDZzAJ_2.0.1.0_ghc-8.2.2: The program 'happy' version >=1.19 is
    required but it could not be found.

command:

stack upgrade --git

stack version:

> stack --version
Version 1.7.0, Git revision 83e7eb08d709d129c128d7d762d4fbeae3666606 x86_64 hpack-0.21.2

[rszibele]

The build also fails on my pull request (#3952) due to missing happy: https://ci.appveyor.com/project/snoyberg/stack/build/1.0.4733#L853

[borsboom]

This is due to #3922, and the fact that stack.yaml upgraded to a newer Stackage LTS snapshot that has a version of persistent that (transitively) requires haskell-src-exts, which triggers this bug. I've committed a fix that downgrades persistent so that haskell-src-exts is no longer needed.

[silky]

thanks @borsboom !