One-component configure, fixes haskell#2802.

Described in: ghc-proposals/ghc-proposals#4

./Setup configure now takes an argument to specify a specific
component name that should solely be configured.

Most of the gyrations in Configure are all about making it so that
we can feed in internal dependencies via --dependency.  I dropped
the package name match sanity check to handle convenience library
package name munging.  I also had to make register/copy unconditionally
install internal libraries; otherwise you can't refer to them
from later builds.

Also a miscellaneous refactor: convenience libraries are printed with a
"header" stanza now (not really a stanza header).

Signed-off-by: Edward Z. Yang <[email protected]>

Cabal/Cabal.cabal

@@ -94,6 +94,17 @@ extra-source-files:
   tests/PackageTests/Configure/include/HsZlibConfig.h.in
   tests/PackageTests/Configure/zlib.buildinfo.in
   tests/PackageTests/Configure/zlib.cabal
+  tests/PackageTests/ConfigureComponent/Exe/Bad.hs
+  tests/PackageTests/ConfigureComponent/Exe/Exe.cabal
+  tests/PackageTests/ConfigureComponent/Exe/Good.hs
+  tests/PackageTests/ConfigureComponent/SubLib/Lib.cabal
+  tests/PackageTests/ConfigureComponent/SubLib/Lib.hs
+  tests/PackageTests/ConfigureComponent/SubLib/exe/Exe.hs
+  tests/PackageTests/ConfigureComponent/Test/Lib.hs
+  tests/PackageTests/ConfigureComponent/Test/Test.cabal
+  tests/PackageTests/ConfigureComponent/Test/testlib/TestLib.hs
+  tests/PackageTests/ConfigureComponent/Test/testlib/testlib.cabal
+  tests/PackageTests/ConfigureComponent/Test/tests/Test.hs
   tests/PackageTests/CopyAssumeDepsUpToDate/CopyAssumeDepsUpToDate.cabal
   tests/PackageTests/CopyAssumeDepsUpToDate/Main.hs
   tests/PackageTests/CopyAssumeDepsUpToDate/P.hs

Cabal/Distribution/PackageDescription/Configuration.hs

@@ -421,11 +421,14 @@ overallDependencies enabled (TargetSet targets) = mconcat depss
   where
     (depss, _) = unzip $ filter (removeDisabledSections . snd) targets
     removeDisabledSections :: PDTagged -> Bool
-    removeDisabledSections (Lib l)     = componentEnabled enabled (CLib l)
-    removeDisabledSections (SubLib _ l) = componentEnabled enabled (CLib l)
-    removeDisabledSections (Exe _ e)   = componentEnabled enabled (CExe e)
-    removeDisabledSections (Test _ t)  = componentEnabled enabled (CTest t)
-    removeDisabledSections (Bench _ b) = componentEnabled enabled (CBench b)
+    -- UGH. The embedded componentName in the 'Component's here is
+    -- BLANK.  I don't know whose fault this is but I'll use the tag
+    -- instead. -- ezyang
+    removeDisabledSections (Lib _)     = componentNameEnabled enabled CLibName
+    removeDisabledSections (SubLib t _) = componentNameEnabled enabled (CSubLibName t)
+    removeDisabledSections (Exe t _)   = componentNameEnabled enabled (CExeName t)
+    removeDisabledSections (Test t _)  = componentNameEnabled enabled (CTestName t)
+    removeDisabledSections (Bench t _) = componentNameEnabled enabled (CBenchName t)
     removeDisabledSections PDNull      = True
 
 -- Apply extra constraints to a dependency map.

Cabal/Distribution/PackageDescription/Parse.hs

@@ -30,6 +30,7 @@ module Distribution.PackageDescription.Parse (
 
         pkgDescrFieldDescrs,
         libFieldDescrs,
+        subLibFieldDescrs,
         executableFieldDescrs,
         binfoFieldDescrs,
         sourceRepoFieldDescrs,
@@ -161,6 +162,14 @@ storeXFieldsPD _ _ = Nothing
 -- ---------------------------------------------------------------------------
 -- The Library type
 
+subLibFieldDescrs :: [FieldDescr Library]
+subLibFieldDescrs =
+  [ simpleField "library"
+                        showToken             parseTokenQ
+                        (fromMaybe "subLibFieldDescrs" . libName)
+                        (\xs lib -> lib{libName=Just xs})
+  ] ++ libFieldDescrs
+
 libFieldDescrs :: [FieldDescr Library]
 libFieldDescrs =
   [ listFieldWithSep vcat "exposed-modules" disp parseModuleNameQ

Cabal/Distribution/PackageDescription/PrettyPrint.hs

@@ -285,11 +285,12 @@ showPackageDescription pkg = render $
   $$ (case library pkg of
         Nothing -> mempty
         Just lib -> ppLibrary' lib)
-  $$ vcat [ space $$ ppLibrary' lib | lib <- subLibraries pkg ]
+  $$ vcat [ space $$ ppSubLibrary lib | lib <- subLibraries pkg ]
   $$ vcat [ space $$ ppExecutable exe | exe <- executables pkg ]
   where
     ppPackage    = ppFields pkgDescrFieldDescrs
     ppLibrary'   = ppFields libFieldDescrs
+    ppSubLibrary = ppFields subLibFieldDescrs
     ppExecutable = ppFields executableFieldDescrs
 
 -- | @since 1.26.0.0@

Cabal/Distribution/Simple.hs

@@ -579,7 +579,6 @@ defaultUserHooks = autoconfUserHooks {
     -- https://github.com/haskell/cabal/issues/158
     where oldCompatPostConf args flags pkg_descr lbi
               = do let verbosity = fromFlag (configVerbosity flags)
-                   noExtraFlags args
                    confExists <- doesFileExist "configure"
                    when confExists $
                        runConfigureScript verbosity
@@ -610,7 +609,6 @@ autoconfUserHooks
     where defaultPostConf :: Args -> ConfigFlags -> PackageDescription -> LocalBuildInfo -> IO ()
           defaultPostConf args flags pkg_descr lbi
               = do let verbosity = fromFlag (configVerbosity flags)
-                   noExtraFlags args
                    confExists <- doesFileExist "configure"
                    if confExists
                      then runConfigureScript verbosity

Cabal/Distribution/Simple/BuildTarget.hs

@@ -12,6 +12,7 @@
 module Distribution.Simple.BuildTarget (
     -- * Main interface
     readTargetInfos,
+    readBuildTargets, -- in case you don't have LocalBuildInfo
 
     -- * Build targets
     BuildTarget(..),
@@ -998,3 +999,7 @@ checkBuildTargets verbosity pkg_descr lbi targets = do
     formatReason cn DisabledAllBenchmarks =
         "Cannot process the " ++ cn ++ " because benchmarks are not "
      ++ "enabled. Re-run configure with the flag --enable-benchmarks"
+    formatReason cn (DisabledAllButOne cn') =
+        "Cannot process the " ++ cn ++ " because this package was "
+     ++ "configured only to build " ++ cn' ++ ". Re-run configure "
+     ++ "with the argument " ++ cn