plan.json: Include store-dir and compiler-abi fields

The plan.json file was missing crucial information needed to locate
packages in the store directory structure. When cabal-install stores
packages, it uses a full compiler identifier including an ABI tag (e.g.,
"ghc-9.10.1-69c3") but plan.json only included the basic compiler ID
("ghc-9.10.1"). This made it impossible for external tools like
cabal-plan to correctly locate packages and their files in the store.

This commit adds:

1. A new "compiler-abi" field with the ABI tag string
2. A "store-dir" section containing:
   - The complete store directory path (with full compiler ID)
   - The store package database path
   - The store incoming directory path

These additions allow tools to accurately locate packages in the store
without having to guess or reconstruct the paths themselves. The
StoreDirLayout is now passed to the JSON encoder, making all
store-related paths available in plan.json.

The issue reported in the original ticket seems to be about the location
of LICENSE files, but the plan.json may still lack sufficient
information to locate all license files since the packages may not be
located in the store, but in different package databases given by
the --package-db flag.  This will do for now.

Fixes #10726

Author: mpickering

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

@@ -85,22 +85,24 @@ import Distribution.Simple.Program.GHC (packageDbArgsDb)
 -- This is for the benefit of debugging and external tools like editors.
 writePlanExternalRepresentation
   :: DistDirLayout
+  -> StoreDirLayout
   -> ElaboratedInstallPlan
   -> ElaboratedSharedConfig
   -> IO ()
 writePlanExternalRepresentation
   distDirLayout
+  storeDirLayout
   elaboratedInstallPlan
   elaboratedSharedConfig =
     writeFileAtomic (distProjectCacheFile distDirLayout "plan.json")
       $ BB.toLazyByteString
         . J.encodeToBuilder
-      $ encodePlanAsJson distDirLayout elaboratedInstallPlan elaboratedSharedConfig
+      $ encodePlanAsJson distDirLayout storeDirLayout elaboratedInstallPlan elaboratedSharedConfig
 
 -- | Renders a subset of the elaborated install plan in a semi-stable JSON
 -- format.
-encodePlanAsJson :: DistDirLayout -> ElaboratedInstallPlan -> ElaboratedSharedConfig -> J.Value
-encodePlanAsJson distDirLayout elaboratedInstallPlan elaboratedSharedConfig =
+encodePlanAsJson :: DistDirLayout -> StoreDirLayout -> ElaboratedInstallPlan -> ElaboratedSharedConfig -> J.Value
+encodePlanAsJson distDirLayout storeDirLayout elaboratedInstallPlan elaboratedSharedConfig =
   -- TODO: [nice to have] include all of the sharedPackageConfig and all of
   --      the parts of the elaboratedInstallPlan
   J.object
@@ -109,9 +111,11 @@ encodePlanAsJson distDirLayout elaboratedInstallPlan elaboratedSharedConfig =
     , "compiler-id"
         J..= (J.String . showCompilerId . pkgConfigCompiler)
           elaboratedSharedConfig
+    , "compiler-abi" J..= J.String (prettyShow (compilerAbiTag (pkgConfigCompiler elaboratedSharedConfig)))
     , "os" J..= jdisplay os
     , "arch" J..= jdisplay arch
     , "install-plan" J..= installPlanToJ elaboratedInstallPlan
+    , "store-dir" J..= storeDirToJ storeDirLayout
     ]
   where
     plat :: Platform
@@ -120,6 +124,14 @@ encodePlanAsJson distDirLayout elaboratedInstallPlan elaboratedSharedConfig =
     installPlanToJ :: ElaboratedInstallPlan -> [J.Value]
     installPlanToJ = map planPackageToJ . InstallPlan.toList
 
+    storeDirToJ :: StoreDirLayout -> J.Value
+    storeDirToJ storeLayout =
+      J.object
+        [ "store-dir" J..= J.String (storeDirectory storeLayout (pkgConfigCompiler elaboratedSharedConfig))
+        , "store-package-db" J..= J.String (storePackageDBPath storeLayout (pkgConfigCompiler elaboratedSharedConfig))
+        , "store-incoming-dir" J..= J.String (storeIncomingDirectory storeLayout (pkgConfigCompiler elaboratedSharedConfig))
+        ]
+
     planPackageToJ :: ElaboratedPlanPackage -> J.Value
     planPackageToJ pkg =
       case pkg of

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

@@ -908,6 +908,7 @@ rebuildInstallPlan
         debug verbosity "Updating plan.json"
         writePlanExternalRepresentation
           distDirLayout
+          cabalStoreDirLayout
           elaboratedPlan
           elaboratedShared