.travis.yml: Also test with GHC 8.4.

Author: 23Skidoo

.travis.yml

@@ -43,6 +43,12 @@ matrix:
     - compiler: "ghc-8.2.2"
     # env: TEST=--disable-tests BENCH=--disable-benchmarks
       addons: {apt: {packages: [ghc-ppa-tools,cabal-install-head,ghc-8.2.2], sources: [hvr-ghc]}}
+    - compiler: "ghc-8.4.1"
+      env: GHCHEAD=true
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-head,ghc-8.4.1], sources: [hvr-ghc]}}
+
+  allow_failures:
+    - compiler: "ghc-8.4.1"
 
 before_install:
   - HC=${CC}
@@ -65,6 +71,21 @@ install:
   - travis_retry cabal update -v
   - "sed -i.bak 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config"
   - rm -fv cabal.project cabal.project.local
+  # Overlay Hackage Package Index for GHC HEAD: https://github.com/hvr/head.hackage
+  - |
+    if $GHCHEAD; then
+      sed -i.bak 's/-- allow-newer:.*/allow-newer: *:base, *:template-haskell, *:ghc, *:Cabal/' ${HOME}/.cabal/config
+
+      echo 'repository head.hackage'                                                        >> ${HOME}/.cabal/config
+      echo '   url: http://head.hackage.haskell.org/'                                       >> ${HOME}/.cabal/config
+      echo '   secure: True'                                                                >> ${HOME}/.cabal/config
+      echo '   root-keys: 07c59cb65787dedfaef5bd5f987ceb5f7e5ebf88b904bbd4c5cbdeb2ff71b740' >> ${HOME}/.cabal/config
+      echo '              2e8555dde16ebd8df076f1a8ef13b8f14c66bad8eafefd7d9e37d0ed711821fb' >> ${HOME}/.cabal/config
+      echo '              8f79fd2389ab2967354407ec852cbe73f2e8635793ac446d09461ffb99527f6e' >> ${HOME}/.cabal/config
+      echo '   key-threshold: 3'                                                            >> ${HOME}/.cabal.config
+
+      cabal new-update head.hackage -v
+    fi
   - grep -Ev -- '^\s*--' ${HOME}/.cabal/config | grep -Ev '^\s*$'
   - "printf 'packages: \".\"\\n' > cabal.project"
   - cat cabal.project

ekg-core.cabal

@@ -14,7 +14,8 @@ category:            System
 build-type:          Simple
 extra-source-files:  CHANGES.md
 cabal-version:       >=1.10
-tested-with:         GHC==8.2.2, GHC==8.0.2, GHC == 7.10.3, GHC == 7.8.4, GHC == 7.6.3
+tested-with:         GHC == 8.4.1, GHC == 8.2.2, GHC == 8.0.2, GHC == 7.10.3
+                   , GHC == 7.8.4, GHC == 7.6.3
 
 library
   exposed-modules: