Cabal: Add flag to ignore build tool dependencies

Add a flag to disable the hard requirement on the build-tools-(depends) declared on the Cabal package. When this flag is enabled (--ignore-build-tools), a build-tool which can't be found does not block compilation. Fixes haskell#10061
alt-romes · Jun 20, 2024 · 58355cd · 58355cd
1 parent 1c00507
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Showing 10 changed files with 83 additions and 26 deletions.
diff --git a/Cabal/src/Distribution/Simple/Configure.hs b/Cabal/src/Distribution/Simple/Configure.hs
@@ -848,29 +848,33 @@ configurePackage cfg lbc0 pkg_descr00 flags enabled comp platform programDb0 pac
   -- right before calling configurePackage?
 
   -- Configure certain external build tools, see below for which ones.
-  let requiredBuildTools = do
-        bi <- enabledBuildInfos pkg_descr0 enabled
-        -- First, we collect any tool dep that we know is external. This is,
-        -- in practice:
-        --
-        -- 1. `build-tools` entries on the whitelist
-        --
-        -- 2. `build-tool-depends` that aren't from the current package.
-        let externBuildToolDeps =
-              [ LegacyExeDependency (unUnqualComponentName eName) versionRange
-              | buildTool@(ExeDependency _ eName versionRange) <-
-                  getAllToolDependencies pkg_descr0 bi
-              , not $ isInternal pkg_descr0 buildTool
-              ]
-        -- Second, we collect any build-tools entry we don't know how to
-        -- desugar. We'll never have any idea how to build them, so we just
-        -- hope they are already on the PATH.
-        let unknownBuildTools =
-              [ buildTool
-              | buildTool <- buildTools bi
-              , Nothing == desugarBuildTool pkg_descr0 buildTool
-              ]
-        externBuildToolDeps ++ unknownBuildTools
+  let requiredBuildTools
+        -- If --ignore-build-tools is set, no build tool is required:
+        | fromFlagOrDefault False $ configIgnoreBuildTools cfg =
+            []
+        | otherwise = do
+            bi <- enabledBuildInfos pkg_descr0 enabled
+            -- First, we collect any tool dep that we know is external. This is,
+            -- in practice:
+            --
+            -- 1. `build-tools` entries on the whitelist
+            --
+            -- 2. `build-tool-depends` that aren't from the current package.
+            let externBuildToolDeps =
+                  [ LegacyExeDependency (unUnqualComponentName eName) versionRange
+                  | buildTool@(ExeDependency _ eName versionRange) <-
+                      getAllToolDependencies pkg_descr0 bi
+                  , not $ isInternal pkg_descr0 buildTool
+                  ]
+            -- Second, we collect any build-tools entry we don't know how to
+            -- desugar. We'll never have any idea how to build them, so we just
+            -- hope they are already on the PATH.
+            let unknownBuildTools =
+                  [ buildTool
+                  | buildTool <- buildTools bi
+                  , Nothing == desugarBuildTool pkg_descr0 buildTool
+                  ]
+            externBuildToolDeps ++ unknownBuildTools
 
   programDb1 <-
     configureAllKnownPrograms (lessVerbose verbosity) programDb0

diff --git a/Cabal/src/Distribution/Simple/Setup/Config.hs b/Cabal/src/Distribution/Simple/Setup/Config.hs
@@ -228,6 +228,10 @@ data ConfigFlags = ConfigFlags
   -- testsuites run with @--enable-coverage@. Notably, this list must exclude
   -- indefinite libraries and instantiations because HPC does not support
   -- backpack (Nov. 2023).
+  , configIgnoreBuildTools :: Flag Bool
+  -- ^ When this flag is set, all tools declared in `build-tool`s and
+  -- `build-tool-depends` will be ignored. This allows a Cabal package with
+  -- build-tool-dependencies to be built even if the tool is not found.
   }
   deriving (Generic, Read, Show, Typeable)
 
@@ -319,7 +323,9 @@ instance Eq ConfigFlags where
       && equal configDebugInfo
       && equal configDumpBuildInfo
       && equal configUseResponseFiles
+      && equal configAllowDependingOnPrivateLibs
       && equal configCoverageFor
+      && equal configIgnoreBuildTools
     where
       equal f = on (==) f a b
 
@@ -856,6 +862,15 @@ configureOptions showOrParseArgs =
               (Flag . (: []) . fromString)
               (fmap prettyShow . fromFlagOrDefault [])
           )
+       , option
+          ""
+          ["ignore-build-tools"]
+          ( "Ignore build tool dependencies. "
+              ++ "If set, declared build tools needn't be found for compilation to proceed."
+          )
+          configIgnoreBuildTools
+          (\v flags -> flags{configIgnoreBuildTools = v})
+          trueArg
        ]
   where
     liftInstallDirs =

diff --git a/cabal-install/src/Distribution/Client/Config.hs b/cabal-install/src/Distribution/Client/Config.hs
@@ -545,6 +545,7 @@ instance Semigroup SavedConfig where
           , configAllowDependingOnPrivateLibs =
               combine configAllowDependingOnPrivateLibs
           , configCoverageFor = combine configCoverageFor
+          , configIgnoreBuildTools = combine configIgnoreBuildTools
           }
         where
           combine = combine' savedConfigureFlags

diff --git a/cabal-install/src/Distribution/Client/ProjectConfig/Legacy.hs b/cabal-install/src/Distribution/Client/ProjectConfig/Legacy.hs
@@ -1112,6 +1112,7 @@ convertToLegacyAllPackageConfig
           , configDumpBuildInfo = mempty
           , configAllowDependingOnPrivateLibs = mempty
           , configCoverageFor = mempty
+          , configIgnoreBuildTools = mempty
           }
 
       haddockFlags =
@@ -1188,6 +1189,7 @@ convertToLegacyPerPackageConfig PackageConfig{..} =
         , configDumpBuildInfo = packageConfigDumpBuildInfo
         , configAllowDependingOnPrivateLibs = mempty
         , configCoverageFor = mempty
+        , configIgnoreBuildTools = mempty
         }
 
     installFlags =

diff --git a/cabal-install/src/Distribution/Client/ProjectPlanning.hs b/cabal-install/src/Distribution/Client/ProjectPlanning.hs
@@ -3960,6 +3960,7 @@ setupHsConfigureFlags
       configPrograms_ = mempty -- never use, shouldn't exist
       configUseResponseFiles = mempty
       configAllowDependingOnPrivateLibs = Flag $ not $ libraryVisibilitySupported pkgConfigCompiler
+      configIgnoreBuildTools = mempty
 
       cidToGivenComponent :: ConfiguredId -> GivenComponent
       cidToGivenComponent (ConfiguredId srcid mb_cn cid) = GivenComponent (packageName srcid) ln cid

diff --git a/cabal-install/src/Distribution/Client/Setup.hs b/cabal-install/src/Distribution/Client/Setup.hs
@@ -679,7 +679,7 @@ filterConfigureFlags' :: ConfigFlags -> Version -> ConfigFlags
 filterConfigureFlags' flags cabalLibVersion
   -- NB: we expect the latest version to be the most common case,
   -- so test it first.
-  | cabalLibVersion >= mkVersion [3, 11, 0] = flags_latest
+  | cabalLibVersion >= mkVersion [3, 12, 0] = flags_latest
   -- The naming convention is that flags_version gives flags with
   -- all flags *introduced* in version eliminated.
   -- It is NOT the latest version of Cabal library that
@@ -701,15 +701,19 @@ filterConfigureFlags' flags cabalLibVersion
   | cabalLibVersion < mkVersion [2, 5, 0] = flags_2_5_0
   | cabalLibVersion < mkVersion [3, 7, 0] = flags_3_7_0
   | cabalLibVersion < mkVersion [3, 11, 0] = flags_3_11_0
+  | cabalLibVersion < mkVersion [3, 12, 0] = flags_3_12_0
   | otherwise = error "the impossible just happened" -- see first guard
   where
-    flags_latest =
-      flags
+    flags_latest = flags
+
+    flags_3_12_0 =
+      flags_latest
         { -- Cabal >= 1.19.1 uses '--dependency' and does not need '--constraint'.
           -- Note: this is not in the wrong place. configConstraints gets
           -- repopulated in flags_1_19_1 but it needs to be set to empty for
           -- newer versions first.
           configConstraints = []
+        , configIgnoreBuildTools = NoFlag
         }
 
     flags_3_11_0 =

diff --git a/cabal-testsuite/PackageTests/IgnoreBuildTools/Hello.hs b/cabal-testsuite/PackageTests/IgnoreBuildTools/Hello.hs
@@ -0,0 +1,7 @@
+module Main where
+
+a :: String
+a = "0000"
+
+main :: IO ()
+main = putStrLn a
diff --git a/cabal-testsuite/PackageTests/IgnoreBuildTools/client.cabal b/cabal-testsuite/PackageTests/IgnoreBuildTools/client.cabal
@@ -0,0 +1,13 @@
+cabal-version:       3.0
+name:                client
+version:             0.1.0.0
+license:             MIT
+category:            Testing
+build-type:          Simple
+
+executable             hello-world
+  main-is:             Hello.hs
+  build-depends:       base
+  build-tool-depends:  pre-proc:zero-to-one, another:non-existent
+  -- build-tools:          somethingnonexists
+  default-language:    Haskell2010
diff --git a/cabal-testsuite/PackageTests/IgnoreBuildTools/setup.out b/cabal-testsuite/PackageTests/IgnoreBuildTools/setup.out
@@ -0,0 +1,5 @@
+# Setup configure
+Configuring client-0.1.0.0...
+# Setup build
+Preprocessing executable 'hello-world' for client-0.1.0.0...
+Building executable 'hello-world' for client-0.1.0.0...
diff --git a/cabal-testsuite/PackageTests/IgnoreBuildTools/setup.test.hs b/cabal-testsuite/PackageTests/IgnoreBuildTools/setup.test.hs
@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+-- Test --ignore-build-tools ignores build-tools and build-tool-depends
+main = setupTest $ do
+    setup "configure" ["--ignore-build-tools"]
+    setup "build" []