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Magnus pushed to branch wip/mangoiv/bp-16719 at Glasgow Haskell Compiler / GHC

Commits:

45a3ea31

by Phil Hazelden at 2026-10-26T16:52:30+01:00

Fix build with werror on glibc 2.43.

We've been defining `_XOPEN_SOURCE` and `_POSIX_C_SOURCE` to the same
values as defined in glibc prior to 2.43. But in 2.43, glibc changes
them to new values, which means we get a warning when redefining them.
By `#undef`ing them first, we no longer get a warning.

Closes #27076.

(cherry picked from commit 7b9a75f09a0a8d11d843f43e8e938b6608fb5166)

8c1d9459
by mangoiv at 2026-10-28T17:24:07+01:00
```
fixup! Fix a few tag inference bugs.
```

6a4afcb2

by Zubin Duggal at 2026-10-28T17:24:36+01:00

DmdAnal: Make AbsDmd neutral in maxDmd

fixes #27845

(cherry picked from commit f76464cff4a9b55bb01e612bffe0dd866a9982e3)

15 changed files:

+ changelog.d/27845
compiler/GHC/Types/Demand.hs
rts/include/rts/PosixSource.h
testsuite/tests/bytecode/T27001.stdout
testsuite/tests/bytecode/T27842.stdout
testsuite/tests/bytecode/all.T
+ testsuite/tests/dmdanal/should_run/T27845.hs
+ testsuite/tests/dmdanal/should_run/T27845.stdout
+ testsuite/tests/dmdanal/should_run/T27845_Lib.hs
+ testsuite/tests/dmdanal/should_run/T27845b.hs
+ testsuite/tests/dmdanal/should_run/T27845b.stdout
+ testsuite/tests/dmdanal/should_run/T27845b_Lib.hs
testsuite/tests/dmdanal/should_run/all.T
testsuite/tests/simplStg/should_run/T22042.stdout
testsuite/tests/simplStg/should_run/all.T

Changes:

changelog.d/27845

 +section: compiler
 +synopsis: Fix a bug where an argument used lazily only by a function's stable
 +  unfolding could be treated as strict in its fields.
 +mrs: !16746
 +issues: #27845

compiler/GHC/Types/Demand.hs

@@ -927,6 +927,8 @@ maxCard (Card a) (Card b) = Card ((a .&. b .&. 0b001) .|. ((a .|. b) .&. 0b110))
  maxDmd :: Demand -> Demand -> Demand
  maxDmd BotDmd      dmd2        = dmd2
  maxDmd dmd1        BotDmd      = dmd1
 +maxDmd AbsDmd      dmd2        = dmd2
 +maxDmd dmd1        AbsDmd      = dmd1
  maxDmd (n1 :* sd1) (n2 :* sd2) =
    maxCard n1 n2 :* maxSubDmd sd1 sd2

rts/include/rts/PosixSource.h

@@ -29,6 +29,8 @@
     Oracle's Solaris 11 supports only up to XPG6, hence the ifdef.
    */
 +#undef _POSIX_C_SOURCE
 +#undef _XOPEN_SOURCE
  #if defined(solaris2_HOST_OS)
  #define _POSIX_C_SOURCE 200112L
  #define _XOPEN_SOURCE   600

testsuite/tests/bytecode/T27001.stdout

 -(0.40 secs,)
 +(0.19 secs,)
  it :: ()
 .0
 -(0.19 secs, 51,566,088 bytes)
 +(0.12 secs, 51,566,088 bytes)

testsuite/tests/bytecode/T27842.stdout

	1	+(0.28 secs,)
	2	+it :: ()
1	3	42
2	4	42
3	5	3
	6	+(0.08 secs, 142,200 bytes)

testsuite/tests/bytecode/all.T

@@ -21,5 +21,5 @@ test('T27001', [extra_files(['T27001.hs']), req_interp],
  test('T27842', [extra_files(['T27842A.hs', 'T27842N.hs']), req_interp],
       run_command,
       ['{compiler} -e main -O -fno-unoptimized-core-for-interpreter '
 -      '-fobject-code -fbyte-code-and-object-code -fwrite-byte-code -fprefer-byte-code '
 +      '-fobject-code -fbyte-code-and-object-code -fprefer-byte-code '
        'T27842.hs'])

testsuite/tests/dmdanal/should_run/T27845.hs

 +module Main where
 +import T27845_Lib (f)
 +import System.Environment (getArgs)
++
 +{-# NOINLINE mkArg #-}
 +mkArg :: Int -> Int
 +mkArg n | n < 0     = n
 +        | otherwise = error ("boom " ++ show n)
++
 +main :: IO ()
 +main = do
 +  n <- length <$> getArgs
 +  let x = mkArg n
 +  print (length (f (x, x) n))

testsuite/tests/dmdanal/should_run/T27845.stdout

+0

testsuite/tests/dmdanal/should_run/T27845_Lib.hs

 +module T27845_Lib where
++
 +{-# INLINABLE [2] f #-}
 +f :: a -> Int -> [a]
 +f p x = lazyUse p x ++ lazyUse p (x + 1) ++ lazyUse p (x + 2)
++
 +{-# NOINLINE lazyUse #-}
 +lazyUse :: a -> Int -> [a]
 +lazyUse p x = p `seq` replicate x p
++
 +{-# RULES "lazyUse" [1] forall p x. lazyUse p x = [] #-}

testsuite/tests/dmdanal/should_run/T27845b.hs

 +module Main where
 +import T27845b_Lib (outer)
 +import System.Environment (getArgs)
++
 +{-# NOINLINE mkArg #-}
 +mkArg :: Int -> Int
 +mkArg n | n < 0     = n
 +        | otherwise = error ("boom " ++ show n)
++
 +main :: IO ()
 +main = do
 +  n <- length <$> getArgs
 +  let x = mkArg n
 +  print (length (outer (x, x) n))

testsuite/tests/dmdanal/should_run/T27845b.stdout

+0

testsuite/tests/dmdanal/should_run/T27845b_Lib.hs

 +module T27845b_Lib where
++
 +outer :: a -> Int -> [a]
 +outer a n =
 +  let {-# INLINABLE [2] g #-}
 +      g x = lazyUse a (x + 0) ++ lazyUse a (x + 1) ++ lazyUse a (x + 2)
 +  in g n ++ g (n + 1) ++ g (n + 2)
 +{-# NOINLINE outer #-}
++
 +{-# NOINLINE lazyUse #-}
 +lazyUse :: a -> Int -> [a]
 +lazyUse p x = p `seq` replicate x p
++
 +{-# RULES "lazyUse" [1] forall p x. lazyUse p x = [] #-}

testsuite/tests/dmdanal/should_run/all.T

@@ -36,3 +36,5 @@ test('T23208', exit_code(1), multimod_compile_and_run, ['T23208_Lib', 'T23208'])
  test('T25439', normal, compile_and_run, [''])
  test('T26416', [extra_files(['M1.hs'])], multimod_compile_and_run, ['T26416','M1.hs'])
  test('T27626', [extra_files(['M2.hs'])], multimod_compile_and_run, ['T27626','M2.hs'])
 +test('T27845', [extra_files(['T27845_Lib.hs'])], multimod_compile_and_run, ['T27845','T27845_Lib.hs'])
 +test('T27845b', [extra_files(['T27845b_Lib.hs'])], multimod_compile_and_run, ['T27845b','T27845b_Lib.hs'])

testsuite/tests/simplStg/should_run/T22042.stdout

 -(0.30 secs,)
 +(0.11 secs,)
  it :: ()
  ABC
 -(0.14 secs, 223,768 bytes)
 +(0.06 secs, 223,768 bytes)

testsuite/tests/simplStg/should_run/all.T

@@ -26,9 +26,6 @@ test('T22042', [extra_files(['T22042a.hs']),only_ways('normal'),unless(have_dyna
  # Depends on tag inference being similarly effective for bytecode which it is not yet.
  test('T23783', omit_ghci, multimod_compile_and_run, ['T23783', '-O -v0'])
 -# Requires UNPACK which needs -O
 -test('unpack_enum', omit_ways(['ghci']), compile_and_run, [''])
+-
  # Tests that tag inference optimizes well, which is not the case for bytecode or
  # when we insert profiling ticks.
  test('T27005a', omit_ways(ghci_ways + prof_ways), compile_and_run, [''])