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Matthew Pickering pushed to branch wip/with-hs-doc-identifiers-determ at Glasgow Haskell Compiler / GHC

Commits:

fa45b63d

by Matthew Pickering at 2026-02-04T14:28:34+00:00

determinism: Use a stable sort in WithHsDocIdentifiers binary instance

`WithHsDocIdentifiers` is defined as

```
 71 data WithHsDocIdentifiers a pass = WithHsDocIdentifiers
 72   { hsDocString      :: !a
 73   , hsDocIdentifiers :: ![Located (IdP pass)]
 74   }
```

This list of names is populated from `rnHsDocIdentifiers`, which calls
`lookupGRE`, which calls `lookupOccEnv_AllNameSpaces`, which calls
`nonDetEltsUFM` and returns the results in an order depending on
uniques.

Sorting the list with a stable sort before returning the interface makes
the output deterministic and follows the approach taken by other fields
in `Docs`.

Fixes #26858

4 changed files:

compiler/GHC/Hs/Doc.hs
testsuite/tests/showIface/DocsInHiFile1.stdout
testsuite/tests/showIface/HaddockSpanIssueT24378.stdout
testsuite/tests/showIface/MagicHashInHaddocks.stdout

Changes:

compiler/GHC/Hs/Doc.hs

@@ -45,6 +45,7 @@ import qualified GHC.Utils.Outputable as O
  import GHC.Hs.Extension
  import GHC.Types.Unique.Map
  import Data.List (sortBy)
 +import Data.Function
  import GHC.Hs.DocString
@@ -83,7 +84,7 @@ instance Outputable a => Outputable (WithHsDocIdentifiers a pass) where
  instance Binary a => Binary (WithHsDocIdentifiers a GhcRn) where
    put_ bh (WithHsDocIdentifiers s ids) = do
      put_ bh s
 -    put_ bh $ BinLocated <$> ids
 +    put_ bh $ BinLocated <$> (sortBy  (stableNameCmp `on` getName) ids)
    get bh =
      liftA2 WithHsDocIdentifiers (get bh) (fmap unBinLocated <$> get bh)

testsuite/tests/showIface/DocsInHiFile1.stdout

@@ -6,14 +6,14 @@ docs:
  '<>', ':=:', 'Bool'
  -}
                identifiers:
 +                {DocsInHiFile.hs:4:2-3}
 +                GHC.Internal.Base.<>
                  {DocsInHiFile.hs:2:6-9}
                  GHC.Internal.Data.Foldable.elem
 -                {DocsInHiFile.hs:2:6-9}
 -                elem
                  {DocsInHiFile.hs:2:14-18}
                  GHC.Internal.System.IO.print
 -                {DocsInHiFile.hs:4:2-3}
 -                GHC.Internal.Base.<>
 +                {DocsInHiFile.hs:2:6-9}
 +                elem
                  {DocsInHiFile.hs:4:15-18}
                  GHC.Internal.Types.Bool
         export docs:

testsuite/tests/showIface/HaddockSpanIssueT24378.stdout

@@ -6,14 +6,14 @@ docs:
  '<>', ':=:', 'Bool'
  -}
                identifiers:
 +                {HaddockSpanIssueT24378.hs:3:2-3}
 +                GHC.Internal.Base.<>
                  {HaddockSpanIssueT24378.hs:1:6-9}
                  GHC.Internal.Data.Foldable.elem
 -                {HaddockSpanIssueT24378.hs:1:6-9}
 -                elem
                  {HaddockSpanIssueT24378.hs:1:14-18}
                  GHC.Internal.System.IO.print
 -                {HaddockSpanIssueT24378.hs:3:2-3}
 -                GHC.Internal.Base.<>
 +                {HaddockSpanIssueT24378.hs:1:6-9}
 +                elem
                  {HaddockSpanIssueT24378.hs:3:15-18}
                  GHC.Internal.Types.Bool
         export docs:

testsuite/tests/showIface/MagicHashInHaddocks.stdout

@@ -3,10 +3,10 @@ docs:
           Just text:
                  -- | 'foo#' `Bar##` `*##`
                identifiers:
 -                {MagicHashInHaddocks.hs:3:7-10}
 -                foo#
                  {MagicHashInHaddocks.hs:3:14-18}
                  Bar##
 +                {MagicHashInHaddocks.hs:3:7-10}
 +                foo#
         export docs:
           []
         declaration docs: