hadrian: Allow override of Cabal configuration in hadrian.settings

Fixes #17612 by adding a `cabal.configure.opts` key for
`hadrian.settings`.

2 files changed, 32 insertions, 20 deletions

diff --git a/hadrian/doc/user-settings.md b/hadrian/doc/user-settings.md
index 04a526605d..064918efe2 100644
--- a/hadrian/doc/user-settings.md
+++ b/hadrian/doc/user-settings.md
@@ -385,25 +385,27 @@ the right names for them:
   only when building the given package, or that the said options should be used
   when building all known packages, if the Hadrian command ever gets them to be
   built;
-- the third slot is the builder, `ghc` or `cc`, to refer to GHC commands or
-  C compiler commands;
-- the final slot is the builder mode, `{c, hs, link, deps, toolargs}`:
+- the remaining slots specify the builder and how it was invoked,
+  
+  * `ghc` refers to GHC commands; the final slot refers to how GHC is invoked:
 
-    * `c` for commands that build C files with GHC
-	* `hs` for commands that compile Haskell modules with GHC
-	* `link` for GHC linking command
-	* `deps` for commands that figure out dependencies between Haskell modules
-	  (with `ghc -M`)
-	* `toolargs` for GHC commands that are used to generate the right ghci
-	  argument for `hadrian/ghci.sh` to work
+    * `c.opts` for commands that build C files with GHC
+	  * `hs.opts` for commands that compile Haskell modules with GHC
+	  * `link.opts` for GHC linking command
+	  * `deps.opts` for commands that figure out dependencies between Haskell modules
+	    (with `ghc -M`)
+	  * `toolargs.opts` for GHC commands that are used to generate the right ghci
+	    argument for `hadrian/ghci.sh` to work
 
-  for GHC and `{c, deps}`:
+  * `cc` refers to C compiler commands
 
-    * `c` for commands that call the C compiler on some C files
-	* `deps` for commands that call the C compiler for figuring out
-	  dependencies between C files
+    * `c.opts` for commands that call the C compiler on some C files
+	  * `deps.opts` for commands that call the C compiler for figuring out
+	    dependencies between C files
+
+  * `cabal.configure.opts` refers to Cabal configure command line. Note that
+    package flags can be given by adding `--flags=...` arguments.
 
-  for the C compiler;
 - using a wildcard (`*`) ranges over all possible values for a given "slot";
 - `=` entirely overrides the arguments for a given builder in a given context,
   with the value specified on the right hand side of `=`, while `+=` merely
diff --git a/hadrian/src/Settings.hs b/hadrian/src/Settings.hs
index 068e7ba914..b57029a967 100755
--- a/hadrian/src/Settings.hs
+++ b/hadrian/src/Settings.hs
@@ -226,11 +226,18 @@ builderPredicate = builderSetting <&> (\(wstg, wpkg, builderMode) ->
   wildcard (pure True) stage wstg <&&>
   wildcard (pure True) package wpkg <&&>
   (case builderMode of
-     Left ghcMode -> wildcard (builder Ghc) (builder . Ghc) ghcMode
-     Right ccMode -> wildcard (builder Cc) (builder . Cc) ccMode))
+     BM_Ghc ghcMode -> wildcard (builder Ghc) (builder . Ghc) ghcMode
+     BM_Cc  ccMode  -> wildcard (builder Cc) (builder . Cc) ccMode
+     BM_CabalConfigure -> builder (Cabal Setup) )
+  )
 
   where (<&&>) = liftA2 (&&)
 
+-- | Which builder a setting should apply to
+data BuilderMode = BM_Ghc (Wildcard GhcMode)
+                 | BM_Cc  (Wildcard CcMode)
+                 | BM_CabalConfigure
+
 -- | Interpretation-agnostic description of the builder settings
 --   supported by Hadrian.
 --
@@ -238,6 +245,7 @@ builderPredicate = builderSetting <&> (\(wstg, wpkg, builderMode) ->
 --
 --   > (<stage> or *).(<package name> or *).ghc.(<ghc mode> or *).opts
 --   > (<stage> or *).(<package name> or *).cc.(<cc mode> or *).opts
+--   > (<stage> or *).(<package name> or *).cabal.configure.opts
 --
 --   where:
 --     - @<stage>@ is one of @stage0@, @stage1@, @stage2@ or @stage3@;
@@ -255,13 +263,15 @@ builderPredicate = builderSetting <&> (\(wstg, wpkg, builderMode) ->
 --       apply GHC or C compiler options uniformly over all stages, packages
 --       and compiler modes, if we so desire, by using a wildcard in the
 --       appropriate spot.
-builderSetting :: Match f => f (Wildcard Stage, Wildcard Package, Either (Wildcard GhcMode) (Wildcard CcMode))
+builderSetting :: Match f
+               => f (Wildcard Stage, Wildcard Package, BuilderMode)
 builderSetting = (,,)
              <$> wild stages
              <*> wild pkgs
              <*> matchOneOf
-                   [ str "ghc" *> fmap Left (wild ghcBuilder) <* str "opts"
-                   , str "cc" *> fmap Right (wild ccBuilder) <* str "opts"
+                   [ str "ghc" *> fmap BM_Ghc (wild ghcBuilder) <* str "opts"
+                   , str "cc" *> fmap BM_Cc (wild ccBuilder) <* str "opts"
+                   , BM_CabalConfigure <$ str "cabal" <* str "configure" <* str "opts"
                    ]
 
   where ghcBuilder =