Hadrian: Fix untracked dependencies

This is a preparation for #16295: https://ghc.haskell.org/trac/ghc/ticket/16295

This commit mostly focuses on getting rid of untracked dependencies,
which prevent Shake's new `--shared` feature from appropriately caching
build rules.

There are three different solutions to untracked dependencies:

* Track them! This is the obvious and the best approach, but in some
  situations we cannot use it, for example, because a build rule creates
  files whose names are not known statically and hence cannot be
  specified as the rule's outputs.

* Use Shake's `produces` to record outputs dynamically, within the rule.

* Use Shake's `historyDisable` to disable caching for a particular build
  rule. We currently use this approach only for `ghc-pkg` which mutates
  the package database and the file `package.cache`.

These two tickets are fixed as the result:

Ticket #16271: ​https://ghc.haskell.org/trac/ghc/ticket/16271

Ticket #16272: ​https://ghc.haskell.org/trac/ghc/ticket/16272 (this one
is fixed only partially: we correctly record the dependency, but we
still copy files into the RTS build tree).

1 files changed, 14 insertions, 8 deletions

diff --git a/hadrian/src/Base.hs b/hadrian/src/Base.hs
index 77eec0a48a..7949fcf4b2 100644
--- a/hadrian/src/Base.hs
+++ b/hadrian/src/Base.hs
@@ -24,7 +24,8 @@ module Base (
     -- * Paths
     hadrianPath, configPath, configFile, sourcePath, shakeFilesDir,
     generatedDir, generatedPath, stageBinPath, stageLibPath, templateHscPath,
-    ghcDeps, haddockDeps, relativePackageDbPath, packageDbPath, packageDbStamp,
+    ghcDeps, includesDependencies, haddockDeps, relativePackageDbPath,
+    packageDbPath, packageDbStamp,
     ghcSplitPath
     ) where
 
@@ -106,15 +107,20 @@ stageBinPath stage = buildRoot <&> (-/- stageString stage -/- "bin")
 stageLibPath :: Stage -> Action FilePath
 stageLibPath stage = buildRoot <&> (-/- stageString stage -/- "lib")
 
--- | Files the `ghc` binary depends on
+-- | Files the GHC binary depends on.
 ghcDeps :: Stage -> Action [FilePath]
 ghcDeps stage = mapM (\f -> stageLibPath stage <&> (-/- f))
-      [ "ghc-usage.txt"
-      , "ghci-usage.txt"
-      , "llvm-targets"
-      , "llvm-passes"
-      , "platformConstants"
-      , "settings" ]
+    [ "ghc-usage.txt"
+    , "ghci-usage.txt"
+    , "llvm-targets"
+    , "llvm-passes"
+    , "platformConstants"
+    , "settings" ]
+
+includesDependencies :: Action [FilePath]
+includesDependencies = do
+    path <- generatedPath
+    return $ (path -/-) <$> [ "ghcautoconf.h", "ghcplatform.h", "ghcversion.h" ]
 
 -- | Files the `haddock` binary depends on
 haddockDeps :: Stage -> Action [FilePath]