From 223f737ee047e0847f4a8029747a3134fd9ddb03 Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Mon, 3 Apr 2023 19:08:53 +0200
Subject: [PATCH 1/8] Abstract `isDistError`

There are two places in cabal codebase where `isDistError` is defined
(would Hackage refuse the package based on this error?), plus another
one in hackage-server (src/Distribution/Server/Packages/Unpack.hs).

This commit refactors the definitions into a singel `isHackageDistError`
(in Distribution.Client.Check) so everything is in sync. The function
is exported, for the benefit of third-party tools.
---
 Cabal/src/Distribution/PackageDescription/Check.hs | 7 +++++++
 Cabal/src/Distribution/Simple/SrcDist.hs           | 5 +----
 cabal-install/src/Distribution/Client/Check.hs     | 7 ++-----
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/Cabal/src/Distribution/PackageDescription/Check.hs b/Cabal/src/Distribution/PackageDescription/Check.hs
index 5d11072b354..22102253c7f 100644
--- a/Cabal/src/Distribution/PackageDescription/Check.hs
+++ b/Cabal/src/Distribution/PackageDescription/Check.hs
@@ -28,6 +28,7 @@ module Distribution.PackageDescription.Check (
         checkConfiguredPackage,
         wrapParseWarning,
         ppPackageCheck,
+        isHackageDistError,
 
         -- ** Checking package contents
         checkPackageFiles,
@@ -846,6 +847,12 @@ data PackageCheck =
      | PackageDistInexcusable { explanation :: CheckExplanation }
   deriving (Eq, Ord)
 
+-- | Would Hackage refuse a package because of this error?
+isHackageDistError :: PackageCheck -> Bool
+isHackageDistError (PackageDistSuspicious {}) = False
+isHackageDistError (PackageDistSuspiciousWarn {}) = False
+isHackageDistError _ = True
+
 -- | Pretty printing 'PackageCheck'.
 --
 ppPackageCheck :: PackageCheck -> String
diff --git a/Cabal/src/Distribution/Simple/SrcDist.hs b/Cabal/src/Distribution/Simple/SrcDist.hs
index 99f1bb8166c..e3bf177ac24 100644
--- a/Cabal/src/Distribution/Simple/SrcDist.hs
+++ b/Cabal/src/Distribution/Simple/SrcDist.hs
@@ -501,10 +501,7 @@ printPackageProblems :: Verbosity -> PackageDescription -> IO ()
 printPackageProblems verbosity pkg_descr = do
   ioChecks      <- checkPackageFiles verbosity pkg_descr "."
   let pureChecks = checkConfiguredPackage pkg_descr
-      isDistError (PackageDistSuspicious     _) = False
-      isDistError (PackageDistSuspiciousWarn _) = False
-      isDistError _                             = True
-      (errors, warnings) = partition isDistError (pureChecks ++ ioChecks)
+      (errors, warnings) = partition isHackageDistError (pureChecks ++ ioChecks)
   unless (null errors) $
       notice verbosity $ "Distribution quality errors:\n"
                       ++ unlines (map ppPackageCheck errors)
diff --git a/cabal-install/src/Distribution/Client/Check.hs b/cabal-install/src/Distribution/Client/Check.hs
index b08fa164e5d..1724624aeef 100644
--- a/cabal-install/src/Distribution/Client/Check.hs
+++ b/cabal-install/src/Distribution/Client/Check.hs
@@ -94,12 +94,9 @@ check verbosity = do
         warn verbosity "The following errors will cause portability problems on other environments:"
         printCheckMessages distInexusable
 
-    let isDistError (PackageDistSuspicious     {}) = False
-        isDistError (PackageDistSuspiciousWarn {}) = False
-        isDistError _                              = True
-        isCheckError (PackageDistSuspiciousWarn {}) = False
+    let isCheckError (PackageDistSuspiciousWarn {}) = False
         isCheckError _                              = True
-        errors = filter isDistError packageChecks
+        errors = filter isHackageDistError packageChecks
 
     unless (null errors) $
         warn verbosity "Hackage would reject this package."

From f7080a38e45bd857aebd605ab1a9357ad2b89b7a Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Mon, 3 Apr 2023 19:19:13 +0200
Subject: [PATCH 2/8] Make `check` comply with Hackage requirements
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

`cabal check` exits with 0 or 1. As now the `1` exit is slightly
stricter than “Hackage would reject this”, as even PackageDistSuspicious
errors will trigger a `1` exit.

This patch rectifies this and also specifies the behaviour in the
documentation. Notice the usage of “should” and “will”: we cannot
be sure Hackage will accept a package (e.g.: maybe there are name
clashes) but there are no type I errors: if it fails `cabal check`,
Hackage will refuse it.
---
 cabal-install/src/Distribution/Client/Check.hs | 10 +++++-----
 cabal-install/src/Distribution/Client/Setup.hs |  4 ++--
 doc/cabal-commands.rst                         |  3 ++-
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/cabal-install/src/Distribution/Client/Check.hs b/cabal-install/src/Distribution/Client/Check.hs
index 1724624aeef..f032b148555 100644
--- a/cabal-install/src/Distribution/Client/Check.hs
+++ b/cabal-install/src/Distribution/Client/Check.hs
@@ -48,7 +48,9 @@ readGenericPackageDescriptionCheck verbosity fpath = do
             die' verbosity "parse error"
         Right x  -> return (warnings, x)
 
--- | Note: must be called with the CWD set to the directory containing
+-- | Checks a packge for common errors. Returns @True@ if the package
+-- is fit to upload to Hackage, @False@ otherwise.
+-- Note: must be called with the CWD set to the directory containing
 -- the '.cabal' file.
 check :: Verbosity -> IO Bool
 check verbosity = do
@@ -94,9 +96,7 @@ check verbosity = do
         warn verbosity "The following errors will cause portability problems on other environments:"
         printCheckMessages distInexusable
 
-    let isCheckError (PackageDistSuspiciousWarn {}) = False
-        isCheckError _                              = True
-        errors = filter isHackageDistError packageChecks
+    let errors = filter isHackageDistError packageChecks
 
     unless (null errors) $
         warn verbosity "Hackage would reject this package."
@@ -104,7 +104,7 @@ check verbosity = do
     when (null packageChecks) $
         notice verbosity "No errors or warnings could be found in the package."
 
-    return (not . any isCheckError $ packageChecks)
+    return (null errors)
 
   where
     printCheckMessages :: [PackageCheck] -> IO ()
diff --git a/cabal-install/src/Distribution/Client/Setup.hs b/cabal-install/src/Distribution/Client/Setup.hs
index 6db91d9cf98..2e890a70ce1 100644
--- a/cabal-install/src/Distribution/Client/Setup.hs
+++ b/cabal-install/src/Distribution/Client/Setup.hs
@@ -1201,8 +1201,8 @@ checkCommand = CommandUI {
          "Expects a .cabal package file in the current directory.\n"
       ++ "\n"
       ++ "The checks correspond to the requirements to packages on Hackage. "
-      ++ "If no errors and warnings are reported, Hackage will accept this "
-      ++ "package.\n",
+      ++ "If no errors and warnings are reported, Hackage should accept the "
+      ++ "package. If 1 is returned, Hackage will refuse it.\n",
     commandNotes        = Nothing,
     commandUsage        = usageFlags "check",
     commandDefaultFlags = toFlag normal,
diff --git a/doc/cabal-commands.rst b/doc/cabal-commands.rst
index 0ea968b0f5d..d40a6083c7b 100644
--- a/doc/cabal-commands.rst
+++ b/doc/cabal-commands.rst
@@ -977,7 +977,8 @@ Run ``cabal check`` in the folder where your ``.cabal`` package file is.
     Set verbosity level (0–3, default is 1).
 
 ``cabal check`` mimics Hackage's requirements: if no error or warning
-is reported, Hackage should accept your package.
+is reported, Hackage should accept your package. If ``cabal check`` exits
+with ``1``, Hackage will refuse it.
 
 cabal sdist
 ^^^^^^^^^^^

From 0cc8cd76a815844dee03fa6f39e5b15b8b495397 Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Tue, 4 Apr 2023 08:15:15 +0200
Subject: [PATCH 3/8] Make testsuite pass

All the modified tests returned 1 on exit, now they return 0.
---
 .../Check/ConfiguredPackage/COptions/CxxOs/cabal.test.hs        | 2 +-
 .../CabalVersion/DefaultExtension/cabal.test.hs                 | 2 +-
 .../CabalVersion/DefaultLanguage/cabal.test.hs                  | 2 +-
 .../CabalVersion/ExtraDynamicLibraryFlavour/cabal.test.hs       | 2 +-
 .../Check/ConfiguredPackage/CabalVersion/Mixins/cabal.test.hs   | 2 +-
 .../Check/ConfiguredPackage/CabalVersion/Sources/cabal.test.hs  | 2 +-
 .../ConfiguredPackage/CabalVersion/VirtualModules/cabal.test.hs | 2 +-
 .../ConfiguredPackage/Fields/DeprecatedExtension/cabal.test.hs  | 2 +-
 .../Check/ConfiguredPackage/Fields/NoCategory/cabal.test.hs     | 2 +-
 .../Check/ConfiguredPackage/Fields/NoDescription/cabal.test.hs  | 2 +-
 .../Check/ConfiguredPackage/Fields/NoMaintainer/cabal.test.hs   | 2 +-
 .../Check/ConfiguredPackage/Fields/NoSynopsis/cabal.test.hs     | 2 +-
 .../ConfiguredPackage/Fields/ShortDescription/cabal.test.hs     | 2 +-
 .../ConfiguredPackage/GHCOptions/GHCSharedOptions/cabal.test.hs | 2 +-
 .../ConfiguredPackage/License/NoFileSpecified/cabal.test.hs     | 2 +-
 .../ConfiguredPackage/License/SuspiciousLicense/cabal.test.hs   | 2 +-
 .../ConfiguredPackage/License/SuspiciousVersion/cabal.test.hs   | 2 +-
 .../License/WarnAllRightsReserved/cabal.test.hs                 | 2 +-
 .../ConfiguredPackage/Sanity/VersionSignatures/cabal.test.hs    | 2 +-
 .../Check/NonConfCheck/DevOnlyFlags/Profiling/cabal.test.hs     | 2 +-
 .../PackageTests/Check/NonConfCheck/UnusedFlags/cabal.test.hs   | 2 +-
 .../PackageTests/Check/PackageFiles/VCSInfo/cabal.test.hs       | 2 +-
 22 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/COptions/CxxOs/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/COptions/CxxOs/cabal.test.hs
index 9706be30598..af9d416967c 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/COptions/CxxOs/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/COptions/CxxOs/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `cxx-options`, do not use `-O1`.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultExtension/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultExtension/cabal.test.hs
index 558722a1e75..ed1e8720e0c 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultExtension/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultExtension/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `default-extensions` need ≥1.10.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultLanguage/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultLanguage/cabal.test.hs
index 9b2fb76f2fe..aefcb6e899e 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultLanguage/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/DefaultLanguage/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `default-language` need ≥1.10.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/ExtraDynamicLibraryFlavour/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/ExtraDynamicLibraryFlavour/cabal.test.hs
index d6de120a48b..ea93456bba3 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/ExtraDynamicLibraryFlavour/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/ExtraDynamicLibraryFlavour/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `extra-dynamic-library-flavour` need ≥3.0.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Mixins/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Mixins/cabal.test.hs
index 59b761f8008..b1d092438d8 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Mixins/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Mixins/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `mixins` need ≥2.0.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Sources/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Sources/cabal.test.hs
index 4b34bdad916..5b8c31c0b66 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Sources/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/Sources/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `cmm-sources` and friends need ≥3.0.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/VirtualModules/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/VirtualModules/cabal.test.hs
index 4672147a484..7a92518d401 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/VirtualModules/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/CabalVersion/VirtualModules/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `virtual-modules` need ≥2.2.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/DeprecatedExtension/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/DeprecatedExtension/cabal.test.hs
index 1d31f4c583e..73f0a75bdee 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/DeprecatedExtension/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/DeprecatedExtension/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Deprecated extension.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoCategory/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoCategory/cabal.test.hs
index 484b17857ac..50fb012514d 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoCategory/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoCategory/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- No category.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoDescription/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoDescription/cabal.test.hs
index 388d77437df..ee2c3ac0018 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoDescription/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoDescription/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- No description.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoMaintainer/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoMaintainer/cabal.test.hs
index 6a615a7ee67..832b74a21a3 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoMaintainer/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoMaintainer/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- No maintainer.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoSynopsis/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoSynopsis/cabal.test.hs
index ea88909bb5d..f2ee05944ac 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoSynopsis/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/NoSynopsis/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- No synopsis.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/ShortDescription/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/ShortDescription/cabal.test.hs
index 9974626c7a6..723a2dca2dc 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/ShortDescription/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Fields/ShortDescription/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Description should be longer than synopsis.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/GHCOptions/GHCSharedOptions/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/GHCOptions/GHCSharedOptions/cabal.test.hs
index 8974491ac0d..672a005ed41 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/GHCOptions/GHCSharedOptions/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/GHCOptions/GHCSharedOptions/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Tricky option in `ghc-shared-options`.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/NoFileSpecified/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/NoFileSpecified/cabal.test.hs
index 65cef73d457..7a81a247159 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/NoFileSpecified/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/NoFileSpecified/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `licence-file` missing.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousLicense/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousLicense/cabal.test.hs
index 086abf34304..37ee44418e0 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousLicense/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousLicense/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Suspicious license BSD4.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousVersion/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousVersion/cabal.test.hs
index ae6610af429..9ba2f98306d 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousVersion/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/SuspiciousVersion/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Suspicious license version.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/WarnAllRightsReserved/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/WarnAllRightsReserved/cabal.test.hs
index f618ac6fb3d..7719c9ffd9e 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/WarnAllRightsReserved/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/License/WarnAllRightsReserved/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Dubious AllRightsReserved.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/VersionSignatures/cabal.test.hs b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/VersionSignatures/cabal.test.hs
index 2ef34c34581..da01864a554 100644
--- a/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/VersionSignatures/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/VersionSignatures/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- `signatures` field used with cabal-version < 2.0
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/NonConfCheck/DevOnlyFlags/Profiling/cabal.test.hs b/cabal-testsuite/PackageTests/Check/NonConfCheck/DevOnlyFlags/Profiling/cabal.test.hs
index ad9c8f4bb76..ac7dc0a3ef8 100644
--- a/cabal-testsuite/PackageTests/Check/NonConfCheck/DevOnlyFlags/Profiling/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/NonConfCheck/DevOnlyFlags/Profiling/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Profiling flags unsuited for distribution.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/NonConfCheck/UnusedFlags/cabal.test.hs b/cabal-testsuite/PackageTests/Check/NonConfCheck/UnusedFlags/cabal.test.hs
index 7bbbaf8e4ce..15c29338ada 100644
--- a/cabal-testsuite/PackageTests/Check/NonConfCheck/UnusedFlags/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/NonConfCheck/UnusedFlags/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Unused flag.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []
diff --git a/cabal-testsuite/PackageTests/Check/PackageFiles/VCSInfo/cabal.test.hs b/cabal-testsuite/PackageTests/Check/PackageFiles/VCSInfo/cabal.test.hs
index 0d6ac3d42f4..a2321d77b22 100644
--- a/cabal-testsuite/PackageTests/Check/PackageFiles/VCSInfo/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Check/PackageFiles/VCSInfo/cabal.test.hs
@@ -2,4 +2,4 @@ import Test.Cabal.Prelude
 
 -- Missing VCS info.
 main = cabalTest $
-  fails $ cabal "check" []
+  cabal "check" []

From 83345968566ec554d70b6e59b58a5c88918d91da Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Tue, 4 Apr 2023 17:55:53 +0200
Subject: [PATCH 4/8] Add changelog for #8897

---
 changelog.d/pr-8897 | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 changelog.d/pr-8897

diff --git a/changelog.d/pr-8897 b/changelog.d/pr-8897
new file mode 100644
index 00000000000..a89023dc416
--- /dev/null
+++ b/changelog.d/pr-8897
@@ -0,0 +1,14 @@
+synopsis: Make check comply with Hackage requirements
+packages: Cabal cabal-install
+prs: #8897
+
+description: {
+
+- `cabal check` will only return exitcode 1 when the package is not fit
+  for Hackage. E.g. it will not error anymore when your `synopsis:` is
+  larger than `description:`, just emit a warning.
+- Cabal: Distribution.Client.Check now exports `isHackageDistError`, for
+  third-party tools to know if a specific error will preclude a package
+  from being uploaded to Hacakge.
+
+}

From a341f74fd6a0ca981f5b9514fbb917bf7deaf1aa Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Thu, 6 Apr 2023 20:06:40 +0200
Subject: [PATCH 5/8] Expand catchall into constructors
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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(Andreas’ review) For `isHackageDistError`, so that in the future, when
constructors are added, the compiler will warn about missing them missing and
a thoughtful choice will be made.
---
 Cabal/src/Distribution/PackageDescription/Check.hs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Cabal/src/Distribution/PackageDescription/Check.hs b/Cabal/src/Distribution/PackageDescription/Check.hs
index 22102253c7f..4064e0db3c1 100644
--- a/Cabal/src/Distribution/PackageDescription/Check.hs
+++ b/Cabal/src/Distribution/PackageDescription/Check.hs
@@ -849,9 +849,11 @@ data PackageCheck =
 
 -- | Would Hackage refuse a package because of this error?
 isHackageDistError :: PackageCheck -> Bool
+isHackageDistError (PackageBuildImpossible {}) = True
+isHackageDistError (PackageBuildWarning {}) = True
+isHackageDistError (PackageDistInexcusable {}) = True
 isHackageDistError (PackageDistSuspicious {}) = False
 isHackageDistError (PackageDistSuspiciousWarn {}) = False
-isHackageDistError _ = True
 
 -- | Pretty printing 'PackageCheck'.
 --

From 8fffe3217c16acd5eee2919e95449046ea94ea68 Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Sat, 15 Apr 2023 16:55:51 +0200
Subject: [PATCH 6/8] Use LambdaCase
MIME-Version: 1.0
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(Artem’s review) Saves typing `isHackageDistError` four times more.
---
 Cabal/src/Distribution/PackageDescription/Check.hs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/Cabal/src/Distribution/PackageDescription/Check.hs b/Cabal/src/Distribution/PackageDescription/Check.hs
index 4064e0db3c1..e602a9a6ee3 100644
--- a/Cabal/src/Distribution/PackageDescription/Check.hs
+++ b/Cabal/src/Distribution/PackageDescription/Check.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE LambdaCase #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Distribution.PackageDescription.Check
@@ -849,11 +851,12 @@ data PackageCheck =
 
 -- | Would Hackage refuse a package because of this error?
 isHackageDistError :: PackageCheck -> Bool
-isHackageDistError (PackageBuildImpossible {}) = True
-isHackageDistError (PackageBuildWarning {}) = True
-isHackageDistError (PackageDistInexcusable {}) = True
-isHackageDistError (PackageDistSuspicious {}) = False
-isHackageDistError (PackageDistSuspiciousWarn {}) = False
+isHackageDistError = \case
+    (PackageBuildImpossible {}) -> True
+    (PackageBuildWarning {}) -> True
+    (PackageDistInexcusable {}) -> True
+    (PackageDistSuspicious {}) -> False
+    (PackageDistSuspiciousWarn {}) -> False
 
 -- | Pretty printing 'PackageCheck'.
 --

From d2a830dba59c6f19301396d7ee0ac3511682abd6 Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Sat, 15 Apr 2023 17:12:07 +0200
Subject: [PATCH 7/8] Reword help strings
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

(Artem’s review) Make clear that errors will make `check` return 1.
---
 cabal-install/src/Distribution/Client/Setup.hs | 3 ++-
 doc/cabal-commands.rst                         | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/cabal-install/src/Distribution/Client/Setup.hs b/cabal-install/src/Distribution/Client/Setup.hs
index 2e890a70ce1..10244ea97c2 100644
--- a/cabal-install/src/Distribution/Client/Setup.hs
+++ b/cabal-install/src/Distribution/Client/Setup.hs
@@ -1202,7 +1202,8 @@ checkCommand = CommandUI {
       ++ "\n"
       ++ "The checks correspond to the requirements to packages on Hackage. "
       ++ "If no errors and warnings are reported, Hackage should accept the "
-      ++ "package. If 1 is returned, Hackage will refuse it.\n",
+      ++ "package. If errors are present, `check` exits with 1 and Hackage "
+      ++ "will refuse the package.\n",
     commandNotes        = Nothing,
     commandUsage        = usageFlags "check",
     commandDefaultFlags = toFlag normal,
diff --git a/doc/cabal-commands.rst b/doc/cabal-commands.rst
index d40a6083c7b..a4f793c6799 100644
--- a/doc/cabal-commands.rst
+++ b/doc/cabal-commands.rst
@@ -977,8 +977,8 @@ Run ``cabal check`` in the folder where your ``.cabal`` package file is.
     Set verbosity level (0–3, default is 1).
 
 ``cabal check`` mimics Hackage's requirements: if no error or warning
-is reported, Hackage should accept your package. If ``cabal check`` exits
-with ``1``, Hackage will refuse it.
+is reported, Hackage should accept your package. If errors are present
+``cabal check`` exits with ``1`` and Hackage will will refuse the package.
 
 cabal sdist
 ^^^^^^^^^^^

From 5c3b107580db35ae7906824de24456a653d1324d Mon Sep 17 00:00:00 2001
From: Francesco Ariis <fa-ml@ariis.it>
Date: Sat, 15 Apr 2023 18:20:48 +0200
Subject: [PATCH 8/8] Fix typo

---
 doc/cabal-commands.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/cabal-commands.rst b/doc/cabal-commands.rst
index a4f793c6799..3ce853429ce 100644
--- a/doc/cabal-commands.rst
+++ b/doc/cabal-commands.rst
@@ -978,7 +978,7 @@ Run ``cabal check`` in the folder where your ``.cabal`` package file is.
 
 ``cabal check`` mimics Hackage's requirements: if no error or warning
 is reported, Hackage should accept your package. If errors are present
-``cabal check`` exits with ``1`` and Hackage will will refuse the package.
+``cabal check`` exits with ``1`` and Hackage will refuse the package.
 
 cabal sdist
 ^^^^^^^^^^^