diff --git a/.github/mergify.yml b/.github/mergify.yml
index e8f8e0d43282befe147ef3113e7e926f317843f1..7969fe95c25c68ade0d1dbdd3fc2aafa0426cf5d 100644
--- a/.github/mergify.yml
+++ b/.github/mergify.yml
@@ -9,7 +9,9 @@ pull_request_rules:
     name: Wait for 2 days before validating merge
     conditions:
       - updated-at<2 days ago
-      - label=merge me
+      - or:
+        - label=merge me
+        - label=squash+merge me
       - '#approved-reviews-by>=2'
 
   # rebase+merge strategy
@@ -57,6 +59,15 @@ pull_request_rules:
       - body~=backport
       - '#approved-reviews-by>=1'
 
+  # backports should be labeled as such
+  - actions:
+      label:
+        add:
+          - backport
+    name: Label backports as such
+    conditions:
+      - body~=automatic backport
+
 queue_rules:
   - name: default
     conditions: []
diff --git a/.github/workflows/changelogs.yml b/.github/workflows/changelogs.yml
index 5d3053c0b75cf9c8278bbd5476b8a7210d1ed6d8..daf2c5c01525b41fb62a4080e85ddb33a0e85a60 100644
--- a/.github/workflows/changelogs.yml
+++ b/.github/workflows/changelogs.yml
@@ -1,4 +1,4 @@
-name: Changelogs
+name: Assorted
 
 on:
   push:
@@ -21,6 +21,7 @@ defaults:
 
 jobs:
   build:
+    name: Changelogs
     runs-on: ubuntu-latest
 
     steps:
@@ -35,8 +36,9 @@ jobs:
       - name: ghcup
         run: |
           ghcup config set cache true
-          ghcup install ghc recommended
-          ghcup set ghc recommended
+          ghcup install ghc 8.10.7
+          ghcup set ghc 8.10.7
+      # GHC 8.10.7 needed due to https://github.com/phadej/changelog-d/pull/2
       - name: Update Hackage index
         run: cabal v2-update
       # Cannot install it from tarball due to
diff --git a/.github/workflows/users-guide.yml b/.github/workflows/users-guide.yml
index 29483a564ed921dd3369fdbe205c041052be185c..2d16715b7d75f309cd7ca37635482235cb6ceadd 100644
--- a/.github/workflows/users-guide.yml
+++ b/.github/workflows/users-guide.yml
@@ -1,6 +1,6 @@
 # Adapted from agda/agda/.github/workflows/user-manual.yml by Andreas, 2021-09-11
 
-name: Users guide
+name: Assorted
 
 # See: https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#concurrency.
 concurrency:
@@ -42,6 +42,7 @@ defaults:
 
 jobs:
   build:
+    name: Users guide
     runs-on: ubuntu-latest
     strategy:
       matrix:
diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index 2a79790a7b6c6e1d39ec034564b034c736987bf9..65a676c528beaa19be11d37d606eb8926274fa12 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -74,6 +74,10 @@ jobs:
           key: ${{ runner.os }}-${{ matrix.ghc }}-20220419-${{ github.sha }}
           restore-keys: ${{ runner.os }}-${{ matrix.ghc }}-20220419-
 
+      - name: Work around git problem https://bugs.launchpad.net/ubuntu/+source/git/+bug/1993586 (cabal PR #8546)
+        run: |
+          git config --global protocol.file.allow always
+
       # The '+exe' constraint below is important, otherwise cabal-install
       # might decide to build the library but not the executable which is
       # what we need.
diff --git a/.github/workflows/whitespace.yml b/.github/workflows/whitespace.yml
index 1617d02d18b940e52874781b53d9090b23f6aadb..1c6d884e253d42bafae760f76f3ef30f4768786d 100644
--- a/.github/workflows/whitespace.yml
+++ b/.github/workflows/whitespace.yml
@@ -1,4 +1,4 @@
-name: Whitespace
+name: Assorted
 
 on:
   push:
@@ -10,6 +10,7 @@ on:
       - created
 jobs:
   check:
+    name: Whitespace
     runs-on: ubuntu-latest
 
     env:
diff --git a/Cabal-syntax/src/Distribution/PackageDescription/FieldGrammar.hs b/Cabal-syntax/src/Distribution/PackageDescription/FieldGrammar.hs
index 47eba1ebbe522415d928c194179119cb878caeed..471cf489791613f581bef883d1f960897f8dcd04 100644
--- a/Cabal-syntax/src/Distribution/PackageDescription/FieldGrammar.hs
+++ b/Cabal-syntax/src/Distribution/PackageDescription/FieldGrammar.hs
@@ -6,6 +6,8 @@
 module Distribution.PackageDescription.FieldGrammar (
     -- * Package description
     packageDescriptionFieldGrammar,
+    CompatFilePath(..),
+    CompatLicenseFile(..),
     -- * Library
     libraryFieldGrammar,
     -- * Foreign library
diff --git a/Cabal-syntax/src/Language/Haskell/Extension.hs b/Cabal-syntax/src/Language/Haskell/Extension.hs
index 0559e8479dbf622845aed92a7ec3986aa8f4194b..1365398cd1f508043c34c325031c726f8cf2beee 100644
--- a/Cabal-syntax/src/Language/Haskell/Extension.hs
+++ b/Cabal-syntax/src/Language/Haskell/Extension.hs
@@ -77,7 +77,7 @@ instance Pretty Language where
   pretty other                   = Disp.text (show other)
 
 instance Parsec Language where
-  parsec = classifyLanguage <$> P.some P.anyChar
+  parsec = classifyLanguage <$> P.munch1 isAlphaNum
 
 classifyLanguage :: String -> Language
 classifyLanguage = \str -> case lookup str langTable of
@@ -165,6 +165,11 @@ data KnownExtension =
   -- | Enable the dreaded monomorphism restriction.
   | MonomorphismRestriction
 
+  -- | Enable deep subsumption, relaxing the simple subsumption rules,
+  -- implicitly inserting eta-expansions when matching up function types
+  -- with different quantification structures.
+  | DeepSubsumption
+
   -- | Allow a specification attached to a multi-parameter type class
   -- which indicates that some parameters are entirely determined by
   -- others. The implementation will check that this property holds
@@ -499,6 +504,9 @@ data KnownExtension =
   -- | Enable datatype promotion.
   | DataKinds
 
+  -- | Enable @type data@ declarations, defining constructors at the type level.
+  | TypeData
+
   -- | Enable parallel arrays syntax (@[:@, @:]@) for /Data Parallel Haskell/.
   | ParallelArrays
 
@@ -655,6 +663,9 @@ data KnownExtension =
   -- | Enable linear types.
   | LinearTypes
 
+  -- | Allow the use of visible forall in types of terms.
+  | RequiredTypeArguments
+
   -- | Enable the generation of selector functions corresponding to record fields.
   | FieldSelectors
 
diff --git a/Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs b/Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs
index bbf5481da557bb50abd53ab35e32c6cf4f9edc88..2491b1b93c96c301354ff175eb0cd517123068e5 100644
--- a/Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs
+++ b/Cabal-tests/tests/UnitTests/Distribution/Utils/Structured.hs
@@ -27,9 +27,9 @@ tests = testGroup "Distribution.Utils.Structured"
     -- The difference is in encoding of newtypes
 #if MIN_VERSION_base(4,7,0)
     , testCase "GenericPackageDescription" $
-      md5Check (Proxy :: Proxy GenericPackageDescription) 0xaf3d4c667a8f019c98a45451419ad71c
+      md5Check (Proxy :: Proxy GenericPackageDescription) 0xa3e9433662ecf0c7a3c26f6d75a53ba1
     , testCase "LocalBuildInfo" $
-      md5Check (Proxy :: Proxy LocalBuildInfo) 0x8ef5a39cb640e4340cf5c43a8300ff94
+      md5Check (Proxy :: Proxy LocalBuildInfo) 0x05ef40b1f97c55be526f63ea4cdacae1
 #endif
     ]
 
diff --git a/Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs b/Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs
index 6488ea06101023dd9ca13b0ccdb8a939b0ff171a..9100dc629ec0c9ea62db546bd6805c12f911ff2e 100644
--- a/Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs
+++ b/Cabal/src/Distribution/Simple/Build/PathsModule/Z.hs
@@ -41,6 +41,14 @@ render z_root = execWriter $ do
     return ()
   else do
     return ()
+  if (zSupportsCpp z_root)
+  then do
+    tell "#if __GLASGOW_HASKELL__ >= 810\n"
+    tell "{-# OPTIONS_GHC -Wno-prepositive-qualified-module #-}\n"
+    tell "#endif\n"
+    return ()
+  else do
+    return ()
   tell "{-# OPTIONS_GHC -fno-warn-missing-import-lists #-}\n"
   tell "{-# OPTIONS_GHC -w #-}\n"
   tell "module Paths_"
diff --git a/cabal-install/src/Distribution/Client/CmdBuild.hs b/cabal-install/src/Distribution/Client/CmdBuild.hs
index 3f2c7589c9a12c60de18e857973c1189d2095d2e..9c8943d939e0cf7fd83556f240486f58c4203a2c 100644
--- a/cabal-install/src/Distribution/Client/CmdBuild.hs
+++ b/cabal-install/src/Distribution/Client/CmdBuild.hs
@@ -101,7 +101,7 @@ defaultBuildFlags = BuildFlags
 --
 buildAction :: NixStyleFlags BuildFlags -> [String] -> GlobalFlags -> IO ()
 buildAction flags@NixStyleFlags { extraFlags = buildFlags, ..} targetStrings globalFlags
-  = withContextAndSelectors RejectNoTargets Nothing flags targetStrings globalFlags $ \targetCtx ctx targetSelectors -> do
+  = withContextAndSelectors RejectNoTargets Nothing flags targetStrings globalFlags BuildCommand $ \targetCtx ctx targetSelectors -> do
     -- TODO: This flags defaults business is ugly
     let onlyConfigure = fromFlag (buildOnlyConfigure defaultBuildFlags
                                  <> buildOnlyConfigure buildFlags)
diff --git a/cabal-install/src/Distribution/Client/CmdHaddockProject.hs b/cabal-install/src/Distribution/Client/CmdHaddockProject.hs
index b4cd4fa272c437b02acb29666aee432c995d3407..c9e160ca52eaf9a91402bf28aa14cb4fb2361ff7 100644
--- a/cabal-install/src/Distribution/Client/CmdHaddockProject.hs
+++ b/cabal-install/src/Distribution/Client/CmdHaddockProject.hs
@@ -19,6 +19,7 @@ import qualified Distribution.Client.NixStyleOptions as NixStyleOptions
 import Distribution.Client.ProjectOrchestration
                                               (AvailableTarget(..)
                                               ,AvailableTargetStatus(..)
+                                              ,CurrentCommand(..)
                                               ,ProjectBaseContext(..)
                                               ,ProjectBuildContext(..)
                                               ,TargetSelector(..)
@@ -141,7 +142,7 @@ haddockProjectAction flags _extraArgs globalFlags = do
     -- we need.
     --
 
-    withContextAndSelectors RejectNoTargets Nothing nixFlags ["all"] globalFlags $ \targetCtx ctx targetSelectors -> do
+    withContextAndSelectors RejectNoTargets Nothing nixFlags ["all"] globalFlags HaddockCommand $ \targetCtx ctx targetSelectors -> do
       baseCtx <- case targetCtx of
         ProjectContext             -> return ctx
         GlobalContext              -> return ctx
diff --git a/cabal-install/src/Distribution/Client/CmdListBin.hs b/cabal-install/src/Distribution/Client/CmdListBin.hs
index accf241700aa6d8ee725f6a87ae638d21b1d716d..cde9c8605159a16324b5821cb36f597fcd8d06db 100644
--- a/cabal-install/src/Distribution/Client/CmdListBin.hs
+++ b/cabal-install/src/Distribution/Client/CmdListBin.hs
@@ -78,7 +78,7 @@ listbinAction flags@NixStyleFlags{..} args globalFlags = do
       _   -> die' verbosity "One target is required, given multiple"
 
   -- configure and elaborate target selectors
-  withContextAndSelectors RejectNoTargets (Just ExeKind) flags [target] globalFlags $ \targetCtx ctx targetSelectors -> do
+  withContextAndSelectors RejectNoTargets (Just ExeKind) flags [target] globalFlags OtherCommand $ \targetCtx ctx targetSelectors -> do
     baseCtx <- case targetCtx of
       ProjectContext             -> return ctx
       GlobalContext              -> return ctx
diff --git a/cabal-install/src/Distribution/Client/CmdRepl.hs b/cabal-install/src/Distribution/Client/CmdRepl.hs
index bf89e7b10ddadc6a5b7a329763f7abfb36d822fa..be129b042f423e990b39403c66b01cb107750d1c 100644
--- a/cabal-install/src/Distribution/Client/CmdRepl.hs
+++ b/cabal-install/src/Distribution/Client/CmdRepl.hs
@@ -187,7 +187,7 @@ replCommand = Client.installCommand {
 --
 replAction :: NixStyleFlags (ReplOptions, EnvFlags) -> [String] -> GlobalFlags -> IO ()
 replAction flags@NixStyleFlags { extraFlags = (replOpts, envFlags), ..} targetStrings globalFlags
-  = withContextAndSelectors AcceptNoTargets (Just LibKind) flags targetStrings globalFlags $ \targetCtx ctx targetSelectors -> do
+  = withContextAndSelectors AcceptNoTargets (Just LibKind) flags targetStrings globalFlags ReplCommand $ \targetCtx ctx targetSelectors -> do
     when (buildSettingOnlyDeps (buildSettings ctx)) $
       die' verbosity $ "The repl command does not support '--only-dependencies'. "
           ++ "You may wish to use 'build --only-dependencies' and then "
diff --git a/cabal-install/src/Distribution/Client/CmdRun.hs b/cabal-install/src/Distribution/Client/CmdRun.hs
index 9bb34b2bfd25511af9e4fa4d94d3269ca8722cd2..64241fd8bbc82a30478dba974382e7a7aff507d4 100644
--- a/cabal-install/src/Distribution/Client/CmdRun.hs
+++ b/cabal-install/src/Distribution/Client/CmdRun.hs
@@ -122,7 +122,7 @@ runCommand = CommandUI
 --
 runAction :: NixStyleFlags () -> [String] -> GlobalFlags -> IO ()
 runAction flags@NixStyleFlags {..} targetAndArgs globalFlags
-  = withContextAndSelectors RejectNoTargets (Just ExeKind) flags targetStr globalFlags $ \targetCtx ctx targetSelectors -> do
+  = withContextAndSelectors RejectNoTargets (Just ExeKind) flags targetStr globalFlags OtherCommand $ \targetCtx ctx targetSelectors -> do
     (baseCtx, defaultVerbosity) <- case targetCtx of
       ProjectContext             -> return (ctx, normal)
       GlobalContext              -> return (ctx, normal)
diff --git a/cabal-install/src/Distribution/Client/ProjectOrchestration.hs b/cabal-install/src/Distribution/Client/ProjectOrchestration.hs
index ccbd84d43c31c71aecc1e5166606350d51d960e9..3d93b0db1153c7bd1eff5b3c1f9a9b655dbc9ab0 100644
--- a/cabal-install/src/Distribution/Client/ProjectOrchestration.hs
+++ b/cabal-install/src/Distribution/Client/ProjectOrchestration.hs
@@ -186,7 +186,7 @@ import           System.Posix.Signals (sigKILL, sigSEGV)
 
 -- | Tracks what command is being executed, because we need to hide this somewhere
 -- for cases that need special handling (usually for error reporting).
-data CurrentCommand = InstallCommand | HaddockCommand | OtherCommand
+data CurrentCommand = InstallCommand | HaddockCommand | BuildCommand | ReplCommand | OtherCommand
                     deriving (Show, Eq)
 
 -- | This holds the context of a project prior to solving: the content of the
@@ -859,8 +859,10 @@ printPlan verbosity
           ProjectBaseContext {
             buildSettings = BuildTimeSettings{buildSettingDryRun},
             projectConfig = ProjectConfig {
+              projectConfigAllPackages =
+                  PackageConfig {packageConfigOptimization = globalOptimization},
               projectConfigLocalPackages =
-                  PackageConfig {packageConfigOptimization}
+                  PackageConfig {packageConfigOptimization = localOptimization}
             }
           }
           ProjectBuildContext {
@@ -994,7 +996,7 @@ printPlan verbosity
     showBuildProfile :: String
     showBuildProfile = "Build profile: " ++ unwords [
       "-w " ++ (showCompilerId . pkgConfigCompiler) elaboratedShared,
-      "-O" ++  (case packageConfigOptimization of
+      "-O" ++  (case globalOptimization <> localOptimization of -- if local is not set, read global
                 Setup.Flag NoOptimisation      -> "0"
                 Setup.Flag NormalOptimisation  -> "1"
                 Setup.Flag MaximumOptimisation -> "2"
@@ -1150,7 +1152,7 @@ dieOnBuildFailures verbosity currentCommand plan buildOutcomes
       , [pkg]              <- rootpkgs
       , installedUnitId pkg == pkgid
       , isFailureSelfExplanatory (buildFailureReason failure)
-      , currentCommand /= InstallCommand
+      , currentCommand `notElem` [InstallCommand, BuildCommand, ReplCommand]
       = True
       | otherwise
       = False
diff --git a/cabal-install/src/Distribution/Client/ScriptUtils.hs b/cabal-install/src/Distribution/Client/ScriptUtils.hs
index c8372aed263f46e79ae8da7bb2f17f3ce301e5ac..db377c8f10a649d9e0e9fe2f1a7e5bb3516982fc 100644
--- a/cabal-install/src/Distribution/Client/ScriptUtils.hs
+++ b/cabal-install/src/Distribution/Client/ScriptUtils.hs
@@ -171,10 +171,11 @@ withContextAndSelectors
   -> NixStyleFlags a     -- ^ Command line flags
   -> [String]            -- ^ Target strings or a script and args.
   -> GlobalFlags         -- ^ Global flags.
+  -> CurrentCommand      -- ^ Current Command (usually for error reporting).
   -> (TargetContext -> ProjectBaseContext -> [TargetSelector] -> IO b)
   -- ^ The body of your command action.
   -> IO b
-withContextAndSelectors noTargets kind flags@NixStyleFlags {..} targetStrings globalFlags act
+withContextAndSelectors noTargets kind flags@NixStyleFlags {..} targetStrings globalFlags cmd act
   = withTemporaryTempDirectory $ \mkTmpDir -> do
     (tc, ctx) <- withProjectOrGlobalConfig verbosity ignoreProject globalConfigFlag with (without mkTmpDir)
 
@@ -209,11 +210,11 @@ withContextAndSelectors noTargets kind flags@NixStyleFlags {..} targetStrings gl
     defaultTarget = [TargetPackage TargetExplicitNamed [fakePackageId] Nothing]
 
     with = do
-      ctx <- establishProjectBaseContext verbosity cliConfig OtherCommand
+      ctx <- establishProjectBaseContext verbosity cliConfig cmd
       return (ProjectContext, ctx)
     without mkDir globalConfig = do
       distDirLayout <- establishDummyDistDirLayout verbosity (globalConfig <> cliConfig) =<< mkDir
-      ctx <- establishDummyProjectBaseContext verbosity (globalConfig <> cliConfig) distDirLayout [] OtherCommand
+      ctx <- establishDummyProjectBaseContext verbosity (globalConfig <> cliConfig) distDirLayout [] cmd
       return (GlobalContext, ctx)
     scriptOrError script err = do
       exists <- doesFileExist script
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.out b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.out
new file mode 100644
index 0000000000000000000000000000000000000000..bbedd1662c888792db25b4ba773566c0bb36e9e9
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.out
@@ -0,0 +1,8 @@
+# cabal build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O2
+In order, the following will be built:
+ - test-0.1.0.0 (lib) (first run)
+Configuring library for test-0.1.0.0..
+Preprocessing library for test-0.1.0.0..
+Building library for test-0.1.0.0..
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.project b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.project
new file mode 100644
index 0000000000000000000000000000000000000000..e6fdbadb4398bc0e333947b5fb8021778310d943
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.project
@@ -0,0 +1 @@
+packages: .
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.test.hs b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.test.hs
new file mode 100644
index 0000000000000000000000000000000000000000..010c47ea4b4734b7c9d0e2632ec0261f9b78bec2
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/cabal.test.hs
@@ -0,0 +1,7 @@
+-- 2022-09-20, issue #8487
+--
+
+import Test.Cabal.Prelude
+
+main = cabalTest $ do
+  cabalG [ "--config-file", "config.file" ] "build" [ "test" ]
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/config.file b/cabal-testsuite/PackageTests/ConfigFile/T8487/config.file
new file mode 100644
index 0000000000000000000000000000000000000000..9f3421cdcb2d94ad33db5d9222918f1faace3ee0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/config.file
@@ -0,0 +1 @@
+optimization: 2
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/src/MyLib.hs b/cabal-testsuite/PackageTests/ConfigFile/T8487/src/MyLib.hs
new file mode 100644
index 0000000000000000000000000000000000000000..e657c4403f66f966da13d2027bf595d9673387f6
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/src/MyLib.hs
@@ -0,0 +1,4 @@
+module MyLib (someFunc) where
+
+someFunc :: IO ()
+someFunc = putStrLn "someFunc"
diff --git a/cabal-testsuite/PackageTests/ConfigFile/T8487/test.cabal b/cabal-testsuite/PackageTests/ConfigFile/T8487/test.cabal
new file mode 100644
index 0000000000000000000000000000000000000000..f48ee85d0084f95759d9742f3ff91622831ce968
--- /dev/null
+++ b/cabal-testsuite/PackageTests/ConfigFile/T8487/test.cabal
@@ -0,0 +1,13 @@
+cabal-version:   3.0
+name:            test
+version:         0.1.0.0
+license:         NONE
+author:          a.pelenitsyn@gmail.com
+maintainer:      Artem Pelenitsyn
+build-type:      Simple
+
+library
+    exposed-modules:  MyLib
+    build-depends:    base
+    hs-source-dirs:   src
+    default-language: Haskell2010
diff --git a/cabal-testsuite/PackageTests/CustomWithoutCabal/cabal.out b/cabal-testsuite/PackageTests/CustomWithoutCabal/cabal.out
index 84f0d9bf31150852a813c08f7da71a4590a5de05..76b53a860518e0045a019d8ce33771cc9411d0ba 100644
--- a/cabal-testsuite/PackageTests/CustomWithoutCabal/cabal.out
+++ b/cabal-testsuite/PackageTests/CustomWithoutCabal/cabal.out
@@ -3,3 +3,4 @@ Resolving dependencies...
 Build profile: -w ghc-<GHCVER> -O1
 In order, the following will be built:
  - custom-setup-without-cabal-1.0 (lib:custom-setup-without-cabal) (first run)
+Error: cabal: Failed to build custom-setup-without-cabal-1.0-inplace. The failure occurred during the configure step.
diff --git a/cabal-testsuite/PackageTests/CustomWithoutCabalDefaultMain/cabal.out b/cabal-testsuite/PackageTests/CustomWithoutCabalDefaultMain/cabal.out
index da780d20081348adbd3cda5cff9e2491964eabac..047919ab3c0f3145142da356ac9dfe2bb397bf40 100644
--- a/cabal-testsuite/PackageTests/CustomWithoutCabalDefaultMain/cabal.out
+++ b/cabal-testsuite/PackageTests/CustomWithoutCabalDefaultMain/cabal.out
@@ -3,3 +3,4 @@ Resolving dependencies...
 Build profile: -w ghc-<GHCVER> -O1
 In order, the following will be built:
  - custom-setup-without-cabal-defaultMain-1.0 (lib:custom-setup-without-cabal-defaultMain) (first run)
+Error: cabal: Failed to build custom-setup-without-cabal-defaultMain-1.0-inplace. The failure occurred during the configure step.
diff --git a/cabal-testsuite/PackageTests/NewBuild/MonitorCabalFiles/cabal.out b/cabal-testsuite/PackageTests/NewBuild/MonitorCabalFiles/cabal.out
index 8822537f7929b53ba97389e49bf8c16cd2acac24..9ca34b2924c730caa9b1e9e01622727e6653ec75 100644
--- a/cabal-testsuite/PackageTests/NewBuild/MonitorCabalFiles/cabal.out
+++ b/cabal-testsuite/PackageTests/NewBuild/MonitorCabalFiles/cabal.out
@@ -6,6 +6,7 @@ In order, the following will be built:
 Configuring executable 'q' for q-0.1.0.0..
 Preprocessing executable 'q' for q-0.1.0.0..
 Building executable 'q' for q-0.1.0.0..
+Error: cabal: Failed to build q-0.1.0.0-inplace-q.
 # cabal v2-build
 Resolving dependencies...
 Build profile: -w ghc-<GHCVER> -O1
diff --git a/cabal-testsuite/PackageTests/NewHaddock/Fails/cabal.out b/cabal-testsuite/PackageTests/NewHaddock/Fails/cabal.out
index 306afff155be08f0876a0476af34a606b35a5a73..e02fc11e31642437a04c01c5f681ed898ba470f4 100644
--- a/cabal-testsuite/PackageTests/NewHaddock/Fails/cabal.out
+++ b/cabal-testsuite/PackageTests/NewHaddock/Fails/cabal.out
@@ -6,6 +6,7 @@ In order, the following will be built:
 Configuring library for example-1.0..
 Preprocessing library for example-1.0..
 Building library for example-1.0..
+Error: cabal: Failed to build example-1.0-inplace.
 # cabal v2-haddock
 Build profile: -w ghc-<GHCVER> -O1
 In order, the following will be built:
diff --git a/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/Main.hs b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/Main.hs
new file mode 100644
index 0000000000000000000000000000000000000000..d82a4bd93b7e75a6ff9845150450ae0709b93086
--- /dev/null
+++ b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/Main.hs
@@ -0,0 +1,4 @@
+module Main where
+
+main :: IO ()
+main = return ()
diff --git a/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/my.cabal b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/my.cabal
new file mode 100644
index 0000000000000000000000000000000000000000..8ad771ececd78b10ff4819ac1b9f9772b18f4607
--- /dev/null
+++ b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/my.cabal
@@ -0,0 +1,17 @@
+name: PathsModule
+version: 0.1
+license: BSD3
+author: Martijn Bastiaan
+category: PackageTests
+build-type: Simple
+Cabal-version: >= 1.2
+
+description:
+    Check that the generated paths module compiles.
+
+Executable TestPathsModule
+    main-is: Main.hs
+    if impl(ghc >= 8.10.0)
+        ghc-options: -Werror -fwarn-prepositive-qualified-module
+    other-modules: Paths_PathsModule
+    build-depends: base
diff --git a/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.cabal.out b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.cabal.out
new file mode 100644
index 0000000000000000000000000000000000000000..bead24d62fd344f6bd773e048d3aa2f7334755f2
--- /dev/null
+++ b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.cabal.out
@@ -0,0 +1,5 @@
+# Setup configure
+Configuring PathsModule-0.1...
+# Setup build
+Preprocessing executable 'TestPathsModule' for PathsModule-0.1..
+Building executable 'TestPathsModule' for PathsModule-0.1..
diff --git a/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.out b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.out
new file mode 100644
index 0000000000000000000000000000000000000000..bead24d62fd344f6bd773e048d3aa2f7334755f2
--- /dev/null
+++ b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.out
@@ -0,0 +1,5 @@
+# Setup configure
+Configuring PathsModule-0.1...
+# Setup build
+Preprocessing executable 'TestPathsModule' for PathsModule-0.1..
+Building executable 'TestPathsModule' for PathsModule-0.1..
diff --git a/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.test.hs b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.test.hs
new file mode 100644
index 0000000000000000000000000000000000000000..ac477fa75675666b1cfe51c46c4fde7659fc5bef
--- /dev/null
+++ b/cabal-testsuite/PackageTests/PathsModule/ImportQualifiedPost/setup.test.hs
@@ -0,0 +1,4 @@
+import Test.Cabal.Prelude
+-- Test that Paths module is generated and available for executables.
+main = setupAndCabalTest $ setup_build []
+
diff --git a/cabal-testsuite/PackageTests/Regression/T8507/Foo.hs b/cabal-testsuite/PackageTests/Regression/T8507/Foo.hs
new file mode 100644
index 0000000000000000000000000000000000000000..614d2790c839bf2e048440d634069791ebcb123c
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T8507/Foo.hs
@@ -0,0 +1,4 @@
+module Foo where
+
+foo :: a
+foo = undefined
diff --git a/cabal-testsuite/PackageTests/Regression/T8507/cabal.out b/cabal-testsuite/PackageTests/Regression/T8507/cabal.out
new file mode 100644
index 0000000000000000000000000000000000000000..0c53c8b3d30b8188da375d2b6ee5f0bde0d1f510
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T8507/cabal.out
@@ -0,0 +1,8 @@
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following will be built:
+ - pkg-0 (lib) (first run)
+Configuring library for pkg-0..
+Preprocessing library for pkg-0..
+Building library for pkg-0..
diff --git a/cabal-testsuite/PackageTests/Regression/T8507/cabal.project b/cabal-testsuite/PackageTests/Regression/T8507/cabal.project
new file mode 100644
index 0000000000000000000000000000000000000000..8834d04402a2a77a2fa0c4f718102dc0b450cbce
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T8507/cabal.project
@@ -0,0 +1,2 @@
+packages:
+  ./
diff --git a/cabal-testsuite/PackageTests/Regression/T8507/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T8507/cabal.test.hs
new file mode 100644
index 0000000000000000000000000000000000000000..58266256b471e7e002bdec13430571828cadf2cd
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T8507/cabal.test.hs
@@ -0,0 +1,6 @@
+import Test.Cabal.Prelude
+
+-- Issue #8507: trailing space in `default-language` should not make
+-- `cabal build` complain.
+main = cabalTest $ cabal "v2-build" ["all"]
+
diff --git a/cabal-testsuite/PackageTests/Regression/T8507/pkg.cabal b/cabal-testsuite/PackageTests/Regression/T8507/pkg.cabal
new file mode 100644
index 0000000000000000000000000000000000000000..80fb8e284aee035fffe207e6cb6ac69a3b7f6628
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T8507/pkg.cabal
@@ -0,0 +1,14 @@
+cabal-version: 3.0
+name: pkg
+synopsis: synopsis
+description: description
+version: 0
+category: example
+maintainer: none@example.com
+license: GPL-3.0-or-later
+
+library
+  exposed-modules: Foo,
+  build-depends: base == 4.*
+  default-language: Haskell2010    
+    -- Note whitespace after “Haskell 2010”.
diff --git a/cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.out b/cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.out
index 444a64e19568cd3d01d1ad3380b845b25c4b146e..4c07cde5ed0fce6f6d86cd37aebc3924021831f8 100644
--- a/cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.out
+++ b/cabal-testsuite/PackageTests/ShowBuildInfo/CompileFail/compile-fail.out
@@ -10,6 +10,7 @@ Building library for CompileFail-0.1.0.0..
 Configuring test suite 'CompileFail-test' for CompileFail-0.1.0.0..
 Preprocessing test suite 'CompileFail-test' for CompileFail-0.1.0.0..
 Building test suite 'CompileFail-test' for CompileFail-0.1.0.0..
+Error: cabal: Failed to build CompileFail-0.1.0.0-inplace-CompileFail-test.
 # cabal build
 Build profile: -w ghc-<GHCVER> -O1
 In order, the following will be built:
diff --git a/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.negative.project b/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.negative.project
index 0100cb0075b08027fbb8fa00a9885e8263af1b56..dfdcf6d3c5b00785f52a38276f324a1649fa094d 100644
--- a/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.negative.project
+++ b/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.negative.project
@@ -3,6 +3,7 @@ packages: .
 source-repository-package
     type: git
 -- A Sample repo to test post-checkout-command
-    location: https://github.com/haskell/bytestring 
+    location: https://github.com/haskell/bytestring
     post-checkout-command: false
+    tag: 0.10.9.0
 -- https://en.wikipedia.org/wiki/True_and_false_(commands)
diff --git a/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.positive.project b/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.positive.project
index a4f1e08217fd6bd0aab3c0888ad9a871c902e622..3ed5801628cdc78831963e5875eca1845a851df0 100644
--- a/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.positive.project
+++ b/cabal-testsuite/PackageTests/postCheckoutCommand/cabal.positive.project
@@ -5,4 +5,5 @@ source-repository-package
 -- A Sample repo to test post-checkout-command
     location: https://github.com/haskell/bytestring
     post-checkout-command: true
+    tag: 0.10.9.0
 -- https://en.wikipedia.org/wiki/True_and_false_(commands)
diff --git a/cabal.project b/cabal.project
index aea54a32efea73d76f5840259114c47b9ae35d65..5f0af8dfa4cc69481f3f655eeab421cabc027d26 100644
--- a/cabal.project
+++ b/cabal.project
@@ -25,32 +25,5 @@ constraints: these -assoc
 constraints: text >= 2.0
 constraints: time >= 1.12
 
--- So us hackers get all the assertion failures early:
---
--- NOTE: currently commented out, see
--- https://github.com/haskell/cabal/issues/3911
--- as a workaround we specify it for each package individually:
---
--- program-options
---   ghc-options: -fno-ignore-asserts
---
-package Cabal
-  ghc-options: -fno-ignore-asserts
-
-package cabal-testsuite
-  ghc-options: -fno-ignore-asserts
-
-package Cabal-QuickCheck
-  ghc-options: -fno-ignore-asserts
-
-package Cabal-tree-diff
-  ghc-options: -fno-ignore-asserts
-
-package Cabal-described
-  ghc-options: -fno-ignore-asserts
-
-package cabal-install-solver
-  ghc-options: -fno-ignore-asserts
-
-package cabal-install
+program-options
   ghc-options: -fno-ignore-asserts
diff --git a/cabal.project.coverage b/cabal.project.coverage
index 7c39810b88f8a6c178bbe0b319ccbfb8d7df3115..2afe3d10df7eafd8c5aefe5724992e8ad5590033 100644
--- a/cabal.project.coverage
+++ b/cabal.project.coverage
@@ -28,6 +28,9 @@ allow-newer: windns-0.1.0.1:base
 constraints: rere -rere-cfg
 constraints: these
 
+program-options
+  ghc-options: -fno-ignore-asserts
+
 -- NOTE: for library coverage in multi-project builds,
 -- see:
 --
@@ -39,41 +42,33 @@ constraints: these
 -- the `cabal-install` library
 --
 package Cabal-syntax
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package Cabal
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package cabal-testsuite
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package Cabal-QuickCheck
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package Cabal-tree-diff
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package Cabal-described
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package cabal-install-solver
-  ghc-options: -fno-ignore-asserts
   coverage: False
   library-coverage: False
 
 package cabal-install
-  ghc-options: -fno-ignore-asserts
   coverage: True
   library-coverage: True
diff --git a/cabal.project.libonly b/cabal.project.libonly
index e11d81f5d771411559cce345a35f4c7267f0d0fd..59873fd4ad1026b77e116f29d6a64d60c59f3255 100644
--- a/cabal.project.libonly
+++ b/cabal.project.libonly
@@ -11,17 +11,4 @@ tests: True
 --optional-packages: */
 
 program-options
-  -- So us hackers get all the assertion failures early:
-  --
-  -- NOTE: currently commented out, see
-  -- https://github.com/haskell/cabal/issues/3911
-  --
-  -- ghc-options: -fno-ignore-asserts
-  --
-  -- as a workaround we specify it for each package individually:
-package Cabal-syntax
-  ghc-options: -fno-ignore-asserts
-package Cabal
-  ghc-options: -fno-ignore-asserts
-package cabal-testsuite
   ghc-options: -fno-ignore-asserts
diff --git a/cabal.project.validate b/cabal.project.validate
index 6f9dc0b45d3cf5d7081711ea0e2ed17c049c29dc..66e823f62b172a6a88a8dc0aaba4b36834c2335b 100644
--- a/cabal.project.validate
+++ b/cabal.project.validate
@@ -19,11 +19,14 @@ constraints: these -assoc
 
 write-ghc-environment-files: never
 
+program-options
+  ghc-options: -fno-ignore-asserts
+
 package Cabal-syntax
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 package Cabal
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 package cabal-testsuite
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 package cabal-install
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
diff --git a/cabal.project.validate.libonly b/cabal.project.validate.libonly
index 2566a5cc8d2589c275a6515548839448b24e67a0..3baafa1661aaa8372f44bf2465e5e2eb67531336 100644
--- a/cabal.project.validate.libonly
+++ b/cabal.project.validate.libonly
@@ -14,12 +14,15 @@ write-ghc-environment-files: never
 constraints: rere -rere-cfg
 constraints: these -assoc
 
+program-options
+  ghc-options: -fno-ignore-asserts
+
 package Cabal-syntax
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 package Cabal
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 package cabal-testsuite
-  ghc-options: -Werror -fno-ignore-asserts
+  ghc-options: -Werror
 
 -- https://github.com/haskell-hvr/cryptohash-sha256/issues/12
 allow-newer: cryptohash-sha256:base
diff --git a/changelog.d/issue-8487 b/changelog.d/issue-8487
new file mode 100644
index 0000000000000000000000000000000000000000..432c74d81d6df74b283fcf174cc9d9134f4c66a2
--- /dev/null
+++ b/changelog.d/issue-8487
@@ -0,0 +1,12 @@
+synopsis: "Build profile" message now reflects optimization level set in global config
+packages: cabal-install
+prs: #8488
+issues: #8487
+
+description: {
+
+Imagine you have `optimization: 2` in your `~/.cabal/config`, and you call `cabal build`
+in a project that doesn't have optimization level explicitly set in its project file.
+You will still see 'Build profile: -w ghc-<VER> -O1'. This is incorrect and was fixed
+in this patch: now you'll see '-O2'.
+}
diff --git a/changelog.d/pr-8493 b/changelog.d/pr-8493
new file mode 100644
index 0000000000000000000000000000000000000000..27344116e271ba68b5de8119701d7fb462a1e678
--- /dev/null
+++ b/changelog.d/pr-8493
@@ -0,0 +1,11 @@
+synopsis: Add language extensions DeepSubsumption and TypeData
+packages: Cabal-syntax
+prs: #8493
+significance: significant
+
+description: {
+
+- adds support for the DeepSubsumption language extension (GHC proposal #511)
+- adds support for the TypeData language extension (GHC proposal #106)
+
+}
diff --git a/doc/cabal-project.rst b/doc/cabal-project.rst
index 4ba2c26f87f90487bd2618f3a9c7f4d95920689d..863ad1bf3cb926fdbd14b5cda53237d3e4b7202f 100644
--- a/doc/cabal-project.rst
+++ b/doc/cabal-project.rst
@@ -127,8 +127,10 @@ project are:
 .. cfg-field:: extra-packages: package list with version bounds (comma separated)
     :synopsis: Adds external packages as local
 
-    :strike:`Specifies a list of external packages from Hackage which
-    should be considered local packages.` (Not implemented)
+    Specifies a list of external packages from Hackage, which
+    should be considered local packages. The motivation for
+    :cfg-field:`extra-packages` is making libraries that are not
+    dependencies of any package in the project available for use in ghci.
 
     There is no command line variant of this field.
 
diff --git a/doc/nix-local-build.rst b/doc/nix-local-build.rst
index 19cca22c9f3cae3be9515517cfa91b06b8298e86..3186be8bbf2165b8fa406022ebb9b911c28d6a19 100644
--- a/doc/nix-local-build.rst
+++ b/doc/nix-local-build.rst
@@ -146,11 +146,10 @@ must be built per-project, versus external packages, which can be cached
 across projects. To be more precise:
 
 1. A **local package** is one that is listed explicitly in the
-   ``packages``, ``optional-packages`` or ``extra-packages`` field of a
-   project. Usually, these refer to packages whose source code lives
-   directly in a folder in your project. But you can list an
-   arbitrary Hackage package in :cfg-field:`packages`
-   to force it to be treated as local.
+   ``packages``, ``optional-packages`` or ``extra-packages`` fields of a
+   project. Packages in the former two fields will usually have their
+   source code stored in a folder in your project, while ``extra-packages`` lists
+   packages residing on Hackage that are treated as being local anyway.
 
 Local packages, as well as the external packages (below) which depend on
 them, are built **inplace**, meaning that they are always built
@@ -159,8 +158,8 @@ packages are not cached and not given unique hashes, which makes them
 suitable for packages which you want to edit and recompile.
 
 2. An **external package** is any package which is not listed in the
-   ``packages`` field. The source code for external packages is usually
-   retrieved from Hackage.
+   ``packages``, ``optional-packages`` and ``extra-packages`` fields.
+   The source code for external packages is usually retrieved from Hackage.
 
 When an external package does not depend on an inplace package, it can
 be built and installed to a **global** store, which can be shared across
diff --git a/editors/vim/syntax/cabal.vim b/editors/vim/syntax/cabal.vim
index 6a6929abe46ecba11533de949589e3ae53c16234..1fc84f4d8af285d21c8e1ae16a9ae19b5c04860e 100644
--- a/editors/vim/syntax/cabal.vim
+++ b/editors/vim/syntax/cabal.vim
@@ -160,6 +160,7 @@ syn keyword cabalExtension contained
   \ DataKinds
   \ DatatypeContexts
   \ DefaultSignatures
+  \ DeepSubsumption
   \ DeriveAnyClass
   \ DeriveDataTypeable
   \ DeriveFoldable
@@ -207,6 +208,7 @@ syn keyword cabalExtension contained
   \ LexicalNegation
   \ LiberalTypeSynonyms
   \ LinearTypes
+  \ RequiredTypeArguments
   \ MagicHash
   \ MonadComprehensions
   \ MonadFailDesugaring
@@ -266,6 +268,7 @@ syn keyword cabalExtension contained
   \ TransformListComp
   \ TupleSections
   \ TypeApplications
+  \ TypeData
   \ TypeFamilies
   \ TypeFamilyDependencies
   \ TypeInType
@@ -343,6 +346,7 @@ syn keyword cabalExtension contained
   \ NoLexicalNegation
   \ NoLiberalTypeSynonyms
   \ NoLinearTypes
+  \ NoRequiredTypeArguments
   \ NoMagicHash
   \ NoMonadComprehensions
   \ NoMonadFailDesugaring
diff --git a/fix-whitespace.yaml b/fix-whitespace.yaml
index bbec61f156f21812ed0c1d292c2b9d1e72350b82..d96e84188b16535ada900573e6602f638daecec4 100644
--- a/fix-whitespace.yaml
+++ b/fix-whitespace.yaml
@@ -92,6 +92,7 @@ excluded-files:
   - Cabal-syntax/src/Distribution/Fields/Lexer.hs
   - Cabal-tests/tests/ParserTests/warnings/tab.cabal
   - Cabal-tests/tests/ParserTests/warnings/utf8.cabal
+  - cabal-testsuite/PackageTests/Regression/T8507/pkg.cabal
 
   # These also contain tabs that affect the golden value:
   # Could be removed from exceptions, but then the tab warning
diff --git a/templates/Paths_pkg.template.hs b/templates/Paths_pkg.template.hs
index 6bc6b7875e6d37ad464cc53a2e6021c2d69084bb..8e1e03d27e425cb0a0114ad6186162dc3da7d69a 100644
--- a/templates/Paths_pkg.template.hs
+++ b/templates/Paths_pkg.template.hs
@@ -7,6 +7,11 @@
 {% if not absolute %}
 {-# LANGUAGE ForeignFunctionInterface #-}
 {% endif %}
+{% if supportsCpp %}
+#if __GLASGOW_HASKELL__ >= 810
+{-# OPTIONS_GHC -Wno-prepositive-qualified-module #-}
+#endif
+{% endif %}
 {-# OPTIONS_GHC -fno-warn-missing-import-lists #-}
 {-# OPTIONS_GHC -w #-}
 module Paths_{{ manglePkgName packageName }} (