Merge pull request #10128 from alt-romes/wip/romes/disable-build-tool…

…-depends

Cabal: Add flag to ignore build tool dependencies

Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs

@@ -41,7 +41,7 @@ md5CheckGenericPackageDescription proxy = md5Check proxy
 md5CheckLocalBuildInfo :: Proxy LocalBuildInfo -> Assertion
 md5CheckLocalBuildInfo proxy = md5Check proxy
 #if MIN_VERSION_base(4,19,0)
-    0x31b94dc3e61eb01fea1a1c3c73d984ee
+    0x6809d4d86ae1810f2a032bc90c952b76
 #else
-    0xdc2f5e7a9c696a4e0bd64f02a0140b74
+    0x9409dca80a2e1522b1c3a39356e9aaef
 #endif

Cabal/src/Distribution/Simple/Configure.hs

@@ -858,29 +858,33 @@ 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

Cabal/src/Distribution/Simple/Setup/Config.hs

@@ -230,6 +230,10 @@ 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)
 
@@ -322,7 +326,9 @@ instance Eq ConfigFlags where
       && equal configDebugInfo
       && equal configDumpBuildInfo
       && equal configUseResponseFiles
+      && equal configAllowDependingOnPrivateLibs
       && equal configCoverageFor
+      && equal configIgnoreBuildTools
     where
       equal f = on (==) f a b
 
@@ -866,6 +872,15 @@ 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 =

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

@@ -546,6 +546,7 @@ instance Semigroup SavedConfig where
           , configAllowDependingOnPrivateLibs =
               combine configAllowDependingOnPrivateLibs
           , configCoverageFor = combine configCoverageFor
+          , configIgnoreBuildTools = combine configIgnoreBuildTools
           }
         where
           combine = combine' savedConfigureFlags

cabal-install/src/Distribution/Client/ProjectConfig/Legacy.hs

@@ -1114,6 +1114,7 @@ convertToLegacyAllPackageConfig
           , configDumpBuildInfo = mempty
           , configAllowDependingOnPrivateLibs = mempty
           , configCoverageFor = mempty
+          , configIgnoreBuildTools = mempty
           }
 
       haddockFlags =
@@ -1191,6 +1192,7 @@ convertToLegacyPerPackageConfig PackageConfig{..} =
         , configDumpBuildInfo = packageConfigDumpBuildInfo
         , configAllowDependingOnPrivateLibs = mempty
         , configCoverageFor = mempty
+        , configIgnoreBuildTools = mempty
         }
 
     installFlags =

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

@@ -4047,6 +4047,7 @@ 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

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

@@ -718,6 +718,7 @@ filterConfigureFlags' flags cabalLibVersion
       flags_latest
         { -- Building profiled shared libraries
           configProfShared = NoFlag
+        , configIgnoreBuildTools = NoFlag
         }
 
     flags_3_11_0 =

cabal-testsuite/PackageTests/IgnoreBuildTools/Hello.hs

@@ -0,0 +1,7 @@
+module Main where
+
+a :: String
+a = "0000"
+
+main :: IO ()
+main = putStrLn a

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

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...

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" []

changelog.d/pr-10128

@@ -0,0 +1,12 @@
+synopsis: Add flag ignore-build-tools
+packages: Cabal
+prs: #10128
+
+description: {
+
+- Adds flag --ignore-build-tools which allows a user to ignore the tool
+  dependencies declared in build-tool-depends. For general use, this flag
+  should never be needed, but it may be useful for packagers.
+
+}
+