Update the travis-complex example

* Comment out older GHC 7.6.3 and 7.8.4 (3 version policy)
* Add in cabal 8.2.2
* Switch from lts-8 to lts-9
* Add support for running stack solver as needed
* Add a comment about hpack support

Author: snoyberg

doc/travis-complex.yml

@@ -44,18 +44,21 @@ matrix:
   #- env: BUILD=cabal GHCVER=7.4.2 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
   #  compiler: ": #GHC 7.4.2"
   #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.4.2,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  - env: BUILD=cabal GHCVER=7.6.3 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
-    compiler: ": #GHC 7.6.3"
-    addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
-  - env: BUILD=cabal GHCVER=7.8.4 CABALVER=1.18 HAPPYVER=1.19.5 ALEXVER=3.1.7
-    compiler: ": #GHC 7.8.4"
-    addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
+  #- env: BUILD=cabal GHCVER=7.6.3 CABALVER=1.16 HAPPYVER=1.19.5 ALEXVER=3.1.7
+  #  compiler: ": #GHC 7.6.3"
+  #  addons: {apt: {packages: [cabal-install-1.16,ghc-7.6.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
+  #- env: BUILD=cabal GHCVER=7.8.4 CABALVER=1.18 HAPPYVER=1.19.5 ALEXVER=3.1.7
+  #  compiler: ": #GHC 7.8.4"
+  #  addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
   - env: BUILD=cabal GHCVER=7.10.3 CABALVER=1.22 HAPPYVER=1.19.5 ALEXVER=3.1.7
     compiler: ": #GHC 7.10.3"
     addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.3,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
   - env: BUILD=cabal GHCVER=8.0.2 CABALVER=1.24 HAPPYVER=1.19.5 ALEXVER=3.1.7
     compiler: ": #GHC 8.0.2"
     addons: {apt: {packages: [cabal-install-1.24,ghc-8.0.2,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
+  - env: BUILD=cabal GHCVER=8.2.2 CABALVER=2.0 HAPPYVER=1.19.5 ALEXVER=3.1.7
+    compiler: ": #GHC 8.2.2"
+    addons: {apt: {packages: [cabal-install-2.0,ghc-8.2.2,happy-1.19.5,alex-3.1.7], sources: [hvr-ghc]}}
 
   # Build with the newest GHC and cabal-install. This is an accepted failure,
   # see below.
@@ -85,7 +88,7 @@ matrix:
     compiler: ": #stack 8.0.1"
     addons: {apt: {packages: [libgmp-dev]}}
 
-  - env: BUILD=stack ARGS="--resolver lts-8"
+  - env: BUILD=stack ARGS="--resolver lts-9"
     compiler: ": #stack 8.0.2"
     addons: {apt: {packages: [libgmp-dev]}}
 
@@ -116,7 +119,7 @@ matrix:
     compiler: ": #stack 8.0.1 osx"
     os: osx
 
-  - env: BUILD=stack ARGS="--resolver lts-8"
+  - env: BUILD=stack ARGS="--resolver lts-9"
     compiler: ": #stack 8.0.2 osx"
     os: osx
 
@@ -164,13 +167,21 @@ install:
   set -ex
   case "$BUILD" in
     stack)
+      # Add in extra-deps for older snapshots, as necessary
+      stack --no-terminal --install-ghc $ARGS test --bench --dry-run || ( \
+        stack --no-terminal $ARGS build cabal-install && \
+        stack --no-terminal $ARGS solver --update-config)
+
+      # Build the dependencies
       stack --no-terminal --install-ghc $ARGS test --bench --only-dependencies
       ;;
     cabal)
       cabal --version
       travis_retry cabal update
 
-      # Get the list of packages from the stack.yaml file
+      # Get the list of packages from the stack.yaml file. Note that
+      # this will also implicitly run hpack as necessary to generate
+      # the .cabal files needed by cabal-install.
       PACKAGES=$(stack --install-ghc query locals | grep '^ *path' | sed 's@^ *path:@@')
 
       cabal install --only-dependencies --enable-tests --enable-benchmarks --force-reinstalls --ghc-options=-O0 --reorder-goals --max-backjumps=-1 $CABALARGS $PACKAGES