Fix hpc on cross builds

Author: rvl

lib/cover-project.nix

@@ -67,14 +67,16 @@ in pkgs.runCommand "project-coverage-report"
     LOCALE_ARCHIVE = "${pkgs.buildPackages.glibcLocales}/lib/locale/locale-archive";
   })
   ''
+    local hpc=${pkgs.targetPackages.haskellPackages.ghc}/bin/hpc
+
     function markup() {
       local -n srcDs=$1
       local -n mixDs=$2
       local -n includedModules=$3
       local destDir=$4
       local tixFile=$5
 
-      local hpcMarkupCmd=("hpc" "markup" "--destdir=$destDir")
+      local hpcMarkupCmd=("$hpc" "markup" "--destdir=$destDir")
       for srcDir in "''${srcDs[@]}"; do
         hpcMarkupCmd+=("--srcdir=$srcDir")
       done
@@ -130,7 +132,7 @@ in pkgs.runCommand "project-coverage-report"
     if [ ''${#tixFiles[@]} -ne 0 ]; then
       # Create tix file with test run information for all packages
       tixFile="$out/share/hpc/vanilla/tix/all/all.tix"
-      hpcSumCmd=("hpc" "sum" "--union" "--output=$tixFile")
+      hpcSumCmd=("$hpc" "sum" "--union" "--output=$tixFile")
       hpcSumCmd+=("''${tixFiles[@]}")
       echo "''${hpcSumCmd[@]}"
       eval "''${hpcSumCmd[@]}"

lib/cover.nix

@@ -11,8 +11,6 @@
 # argument. Use a larger list of libraries if you would like the tests
 # of one local package to generate coverage for another.
 , mixLibraries ? [library]
-# hack for project-less projects
-, ghc ? library.project.pkg-set.config.ghc.package
 }:
 
 let
@@ -24,8 +22,7 @@ let
   srcDirs = map (l: l.src.outPath) mixLibraries;
 
 in pkgs.runCommand (name + "-coverage-report")
-  ({ buildInputs = [ ghc ];
-    passthru = {
+  ({ passthru = {
       inherit name library checks;
     };
     # HPC will fail if the Haskell file contains non-ASCII characters,
@@ -39,14 +36,16 @@ in pkgs.runCommand (name + "-coverage-report")
     LOCALE_ARCHIVE = "${pkgs.buildPackages.glibcLocales}/lib/locale/locale-archive";
   })
   ''
+    local hpc=${pkgs.targetPackages.haskellPackages.ghc}/bin/hpc
+
     function markup() {
       local -n srcDs=$1
       local -n mixDs=$2
       local -n includedModules=$3
       local destDir=$4
       local tixFile=$5
 
-      local hpcMarkupCmd=("hpc" "markup" "--destdir=$destDir")
+      local hpcMarkupCmd=("$hpc" "markup" "--destdir=$destDir")
       for srcDir in "''${srcDs[@]}"; do
         hpcMarkupCmd+=("--srcdir=$srcDir")
       done
@@ -70,7 +69,7 @@ in pkgs.runCommand (name + "-coverage-report")
       local -n tixFs=$2
       local outFile="$3"
 
-      local hpcSumCmd=("hpc" "sum" "--union" "--output=$outFile")
+      local hpcSumCmd=("$hpc" "sum" "--union" "--output=$outFile")
 
       for module in "''${includedModules[@]}"; do
         hpcSumCmd+=("--include=$module")