Allow build-type Configure to work with Components

When components were introduced, cabal had support for
build-type: Configure, which allows to run a `configure`
script prior to building the package.  Upon the introduction
of components, it became obvious that we can't just
configure each and every component, as this easily runs
into the situation where the `configure` script is run
potentially concurrently for all components.

However, build-type is a global option for cabal files, and
is usually used to produce a <pkg>.buildinfo file.  This file
is then used to augment the Main Library only.

This change now tracks whether or not we are building a
component to the setup invocation, and if we do, ignores
a build-type: Configure built-type from the package
description.  For end users who want to depend on
package configured values, they will need to set their
sub libraries, executables, ... and other components to
depend on the main library, and import any configured
values from there.

For lib:Cabal, which doesn't know about components
when configure is invoked, we will continue to execute
configure, even though cabal will never use that info.

Author: angerman

cabal-install/src/Distribution/Client/Configure.hs

@@ -300,6 +300,7 @@ configureSetupScript
       , useDependenciesExclusive = not defaultSetupDeps && isJust explicitSetupDeps
       , useVersionMacros = not defaultSetupDeps && isJust explicitSetupDeps
       , isInteractive = False
+      , isComponent = False
       }
     where
       -- When we are compiling a legacy setup script without an explicit

cabal-install/src/Distribution/Client/ProjectPlanning.hs

@@ -1833,7 +1833,10 @@ elaborateInstallPlan
               -- Once you've implemented this, swap it for the code below.
               cuz_buildtype =
                 case bt of
-                  PD.Configure -> [CuzBuildType CuzConfigureBuildType]
+                  PD.Configure -> []
+                  -- Configure is supported, but we only support configuring the
+                  -- main library in cabal. Other components will need to depend
+                  -- on the main library for configured data.
                   PD.Custom -> [CuzBuildType CuzCustomBuildType]
                   PD.Hooks -> [CuzBuildType CuzHooksBuildType]
                   PD.Make -> [CuzBuildType CuzMakeBuildType]
@@ -4028,6 +4031,9 @@ setupHsScriptOptions
       , forceExternalSetupMethod = isParallelBuild
       , setupCacheLock = Just cacheLock
       , isInteractive = False
+      , isComponent = case elabPkgOrComp of
+          ElabPackage{} -> False
+          ElabComponent{} -> True
       }
 
 -- | To be used for the input for elaborateInstallPlan.

cabal-install/src/Distribution/Client/SetupWrapper.hs

@@ -314,6 +314,12 @@ data SetupScriptOptions = SetupScriptOptions
   -- ^ Is the task we are going to run an interactive foreground task,
   -- or an non-interactive background task? Based on this flag we
   -- decide whether or not to delegate ctrl+c to the spawned task
+  , isComponent :: Bool
+  -- ^ Let the setup script logic know if it is being run to build a component
+  -- or a package.  This is used to determine if we should use the configure
+  -- command, if the build-type is 'Configure'.  For configure, only the
+  -- main library has 'configure' support, and thus we can skip running
+  -- configure for components.
   }
 
 defaultSetupScriptOptions :: SetupScriptOptions
@@ -338,6 +344,7 @@ defaultSetupScriptOptions =
     , forceExternalSetupMethod = False
     , setupCacheLock = Nothing
     , isInteractive = False
+    , isComponent = False
     }
 
 workingDir :: SetupScriptOptions -> FilePath
@@ -374,7 +381,9 @@ getSetup verbosity options mpkg = do
                 (useCabalVersion options)
                 (orLaterVersion (mkVersion (cabalSpecMinimumLibraryVersion (specVersion pkg))))
           }
-      buildType' = buildType pkg
+      buildType' = case (buildType pkg, isComponent options) of
+        (Configure, True) -> Simple
+        (bt, _) -> bt
   (version, method, options'') <-
     getSetupMethod verbosity options' pkg buildType'
   return