haskell-generic-builder: fix bug when buildTarget does not depend on library

pkgs/development/haskell-modules/generic-builder.nix

@@ -345,8 +345,10 @@ let
       (enableFeature doCoverage "coverage")
       (enableFeature enableStaticLibraries "static")
       (enableFeature enableSharedExecutables "executable-dynamic")
-      (enableFeature doCheck "tests")
-      (enableFeature doBenchmark "benchmarks")
+      # "--enable-tests/--enable-benchmarks are incompatible with explicitly
+      # specifying a component to configure."
+      (enableFeature (doCheck && buildTarget == "") "tests")
+      (enableFeature (doBenchmark && buildTarget == "") "benchmarks")
       "--enable-library-vanilla" # TODO: Should this be configurable?
       (enableFeature enableLibraryForGhci "library-for-ghci")
       (enableFeature enableDeadCodeElimination "split-sections")
@@ -724,7 +726,7 @@ lib.fix (
         runHook preConfigure
 
         echo configureFlags: $configureFlags
-        ${setupCommand} configure $configureFlags 2>&1 | ${coreutils}/bin/tee "$NIX_BUILD_TOP/cabal-configure.log"
+        ${setupCommand} configure ${buildTarget} $configureFlags 2>&1 | ${coreutils}/bin/tee "$NIX_BUILD_TOP/cabal-configure.log"
         ${lib.optionalString (!allowInconsistentDependencies) ''
           if grep -E -q -z 'Warning:.*depends on multiple versions' "$NIX_BUILD_TOP/cabal-configure.log"; then
             echo >&2 "*** abort because of serious configure-time warning from Cabal"
@@ -807,7 +809,10 @@ lib.fix (
               mkdir -p "$packageConfDir"
               ${setupCommand} register --gen-pkg-config=$packageConfFile
               if [ -d "$packageConfFile" ]; then
-                mv "$packageConfFile/"* "$packageConfDir"
+                # Avoid 'mv "$dir"/*' failing due to unexpanded glob in empty directory.
+                if [ -n "$(find "$packageConfFile" -mindepth 1 -print -quit)" ]; then
+                  mv "$packageConfFile/"* "$packageConfDir"
+                fi
                 rmdir "$packageConfFile"
               fi
               for packageConfFile in "$packageConfDir/"*; do

pkgs/test/haskell/default.nix

@@ -4,7 +4,7 @@ lib.recurseIntoAttrs {
   shellFor = callPackage ./shellFor { };
   cabalSdist = callPackage ./cabalSdist { };
   documentationTarball = callPackage ./documentationTarball { };
-  setBuildTarget = callPackage ./setBuildTarget { };
+  setBuildTarget = lib.recurseIntoAttrs (callPackage ./setBuildTarget { });
   incremental = callPackage ./incremental { };
   upstreamStackHpackVersion = callPackage ./upstreamStackHpackVersion { };
 }

pkgs/test/haskell/setBuildTarget/default.nix

@@ -1,6 +1,13 @@
-{ pkgs, haskellPackages }:
+{
+  haskell,
+  haskellPackages,
+  pkgs,
+  testers,
+}:
 
 let
+  inherit (haskell.lib.compose) doCheck dontCheck setBuildTarget;
+
   # This can be regenerated by running `cabal2nix ./src` in the current directory.
   pkgDef =
     {
@@ -12,9 +19,11 @@ let
       pname = "haskell-setBuildTarget";
       version = "0.1.0.0";
       src = ./src;
-      isLibrary = false;
+      isLibrary = true;
       isExecutable = true;
+      libraryHaskellDepends = [ base ];
       executableHaskellDepends = [ base ];
+      testHaskellDepends = [ base ];
       license = "unknown";
     };
 
@@ -23,7 +32,7 @@ let
   test =
     target: excluded:
     let
-      only = pkgs.haskell.lib.compose.setBuildTarget target drv;
+      only = dontCheck (setBuildTarget target drv);
     in
     ''
       if [[ ! -f "${only}/bin/${target}" ]]; then
@@ -38,14 +47,25 @@ let
     '';
 
 in
-pkgs.runCommand "test haskell.lib.compose.setBuildTarget"
-  {
-    meta = {
-      inherit (drv.meta) platforms;
-    };
-  }
-  ''
-    ${test "foo" "bar"}
-    ${test "bar" "foo"}
-    touch "$out"
-  ''
+{
+  pass-setBuildTarget =
+    pkgs.runCommand "test haskell.lib.compose.setBuildTarget"
+      { meta = { inherit (drv.meta) platforms; }; }
+      ''
+        ${test "foo" "bar"}
+        ${test "bar" "foo"}
+        touch "$out"
+      '';
+
+  # Not building the test-suite (that is mentioned in the .cabal file) is a
+  # failure when doCheck=true.
+  fail-doCheck-setBuildTarget =
+    pkgs.runCommand "fail-doCheck-setBuildTarget"
+      { result = testers.testBuildFailure (doCheck (setBuildTarget "exe:foo" drv)); }
+      ''
+        echo -n 'Checking testBuildFailure.log: '
+        grep --quiet --fixed-strings 'Error: Setup: No test suites enabled.' $result/testBuildFailure.log
+        echo OK
+        touch "$out"
+      '';
+}

pkgs/test/haskell/setBuildTarget/src/SomeModule.hs

@@ -0,0 +1 @@
+module SomeModule where

pkgs/test/haskell/setBuildTarget/src/haskell-setBuildTarget.cabal

@@ -14,3 +14,15 @@ executable bar
   main-is:             Bar.hs
   build-depends:       base
   default-language:    Haskell2010
+
+-- A library that the executables don't depend on.
+library
+  exposed-modules:     SomeModule
+  build-depends:       base
+  default-language:    Haskell2010
+
+test-suite sometest
+  type:                exitcode-stdio-1.0
+  main-is:             sometest.hs
+  build-depends:       base
+  default-language:    Haskell2010

pkgs/test/haskell/setBuildTarget/src/sometest.hs

@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = return ()