diff --git a/Data/Foldable1.hs b/Data/Foldable1.hs
--- a/Data/Foldable1.hs
+++ b/Data/Foldable1.hs
@@ -2,6 +2,9 @@
 -- Copyright: Edward Kmett, Oleg Grenrus
 -- License: BSD-3-Clause
 --
+-- A class of non-empty data structures that can be folded to a summary value.
+--
+-- @since 4.18.0.0
 
 {-# LANGUAGE FlexibleInstances          #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
@@ -12,7 +15,6 @@
 {-# LANGUAGE Trustworthy                #-}
 {-# LANGUAGE TypeOperators              #-}
 
--- | A class of non-empty data structures that can be folded to a summary value.
 module Data.Foldable1 (
     Foldable1(..),
     foldr1, foldr1',
@@ -65,6 +67,8 @@
 -------------------------------------------------------------------------------
 
 -- | Non-empty data structures that can be folded.
+--
+-- @since 4.18.0.0
 class Foldable t => Foldable1 t where
     {-# MINIMAL foldMap1 | foldrMap1 #-}
 
@@ -83,6 +87,7 @@
     --     foldrMap1 f g = foldrMap1 f g . toNonEmpty
 
     -- | Combine the elements of a structure using a semigroup.
+    -- @since 4.18.0.0
     fold1 :: Semigroup m => t m -> m
     fold1 = foldMap1 id
 
@@ -92,6 +97,7 @@
     -- >>> foldMap1 Sum (1 :| [2, 3, 4])
     -- Sum {getSum = 10}
     --
+    -- @since 4.18.0.0
     foldMap1 :: Semigroup m => (a -> m) -> t a -> m
     foldMap1 f = foldrMap1 f (\a m -> f a <> m)
 
@@ -100,6 +106,7 @@
     -- >>> foldMap1' Sum (1 :| [2, 3, 4])
     -- Sum {getSum = 10}
     --
+    -- @since 4.18.0.0
     foldMap1' :: Semigroup m => (a -> m) -> t a -> m
     foldMap1' f = foldlMap1' f (\m a -> m <> f a)
 
@@ -108,6 +115,7 @@
     -- >>> toNonEmpty (Identity 2)
     -- 2 :| []
     --
+    -- @since 4.18.0.0
     toNonEmpty :: t a -> NonEmpty a
     toNonEmpty = runNonEmptyDList . foldMap1 singleton
 
@@ -116,6 +124,7 @@
     -- >>> maximum (32 :| [64, 8, 128, 16])
     -- 128
     --
+    -- @since 4.18.0.0
     maximum :: Ord a => t a -> a
     maximum = getMax #. foldMap1' Max
 
@@ -124,6 +133,7 @@
     -- >>> minimum (32 :| [64, 8, 128, 16])
     -- 8
     --
+    -- @since 4.18.0.0
     minimum :: Ord a => t a -> a
     minimum = getMin #. foldMap1' Min
 
@@ -132,6 +142,7 @@
     -- >>> head (1 :| [2, 3, 4])
     -- 1
     --
+    -- @since 4.18.0.0
     head :: t a -> a
     head = getFirst #. foldMap1 First
 
@@ -140,10 +151,12 @@
     -- >>> last (1 :| [2, 3, 4])
     -- 4
     --
+    -- @since 4.18.0.0
     last :: t a -> a
     last = getLast #. foldMap1 Last
 
     -- | Generalized 'foldr1'.
+    -- @since 4.18.0.0
     foldrMap1 :: (a -> b) -> (a -> b -> b) -> t a -> b
     foldrMap1 f g xs =
         appFromMaybe (foldMap1 (FromMaybe #. h) xs) Nothing
@@ -152,6 +165,7 @@
         h a (Just b) = g a b
 
     -- | Generalized 'foldl1''.
+    -- @since 4.18.0.0
     foldlMap1' :: (a -> b) -> (b -> a -> b) -> t a -> b
     foldlMap1' f g xs =
         foldrMap1 f' g' xs SNothing
@@ -165,6 +179,7 @@
         g' a x (SJust b) = x $! SJust (g b a)
 
     -- | Generalized 'foldl1'.
+    -- @since 4.18.0.0
     foldlMap1 :: (a -> b) -> (b -> a -> b) -> t a -> b
     foldlMap1 f g xs =
         appFromMaybe (getDual (foldMap1 ((Dual . FromMaybe) #. h) xs)) Nothing
@@ -173,6 +188,7 @@
         h a (Just b) = g b a
 
     -- | Generalized 'foldr1''.
+    -- @since 4.18.0.0
     foldrMap1' :: (a -> b) -> (a -> b -> b) -> t a -> b
     foldrMap1' f g xs =
         foldlMap1 f' g' xs SNothing
@@ -204,6 +220,7 @@
 --
 -- @foldr1 f = foldr1 f . 'toNonEmpty'@
 --
+-- @since 4.18.0.0
 foldr1 :: Foldable1 t => (a -> a -> a) -> t a -> a
 foldr1 = foldrMap1 id
 {-# INLINE foldr1 #-}
@@ -211,6 +228,7 @@
 -- | Right-associative fold of a structure, but with strict application of
 -- the operator.
 --
+-- @since 4.18.0.0
 foldr1' :: Foldable1 t => (a -> a -> a) -> t a -> a
 foldr1' = foldrMap1' id
 {-# INLINE foldr1' #-}
@@ -239,6 +257,7 @@
 --
 -- @foldl1 f z = foldl1 f . 'toNonEmpty'@
 --
+-- @since 4.18.0.0
 foldl1 :: Foldable1 t => (a -> a -> a) -> t a -> a
 foldl1 = foldlMap1 id
 {-# INLINE foldl1 #-}
@@ -256,6 +275,7 @@
 --
 -- @foldl1' f z = foldl1 f . 'toNonEmpty'@
 --
+-- @since 4.18.0.0
 foldl1' :: Foldable1 t => (a -> a -> a) -> t a -> a
 foldl1' = foldlMap1' id
 {-# INLINE foldl1' #-}
@@ -271,6 +291,7 @@
 -- >>> intercalate1 mempty $ "I" :| ["Am", "Fine", "You?"]
 -- "IAmFineYou?"
 --
+-- @since 4.18.0.0
 intercalate1 :: (Foldable1 t, Semigroup m) => m -> t m -> m
 intercalate1 = flip intercalateMap1 id
 
@@ -279,10 +300,14 @@
 
 -- | Monadic fold over the elements of a non-empty structure,
 -- associating to the right, i.e. from right to left.
+--
+-- @since 4.18.0.0
 foldrM1 :: (Foldable1 t, Monad m) => (a -> a -> m a) -> t a -> m a
 foldrM1 = foldrMapM1 return
 
 -- | Map variant of 'foldrM1'.
+--
+-- @since 4.18.0.0
 foldrMapM1 :: (Foldable1 t, Monad m) => (a -> m b) -> (a -> b -> m b) -> t a -> m b
 foldrMapM1 g f = go . toNonEmpty
   where
@@ -293,16 +318,22 @@
 
 -- | Monadic fold over the elements of a non-empty structure,
 -- associating to the left, i.e. from left to right.
+--
+-- @since 4.18.0.0
 foldlM1 :: (Foldable1 t, Monad m) => (a -> a -> m a) -> t a -> m a
 foldlM1 = foldlMapM1 return
 
 -- | Map variant of 'foldlM1'.
+--
+-- @since 4.18.0.0
 foldlMapM1 :: (Foldable1 t, Monad m) => (a -> m b) -> (b -> a -> m b) -> t a -> m b
 foldlMapM1 g f t = g x >>= \y -> foldlM f y xs
   where x:|xs = toNonEmpty t
 
 -- | The largest element of a non-empty structure with respect to the
 -- given comparison function.
+--
+-- @since 4.18.0.0
 maximumBy :: Foldable1 t => (a -> a -> Ordering) -> t a -> a
 maximumBy cmp = foldl1' max'
   where max' x y = case cmp x y of
@@ -311,6 +342,8 @@
 
 -- | The least element of a non-empty structure with respect to the
 -- given comparison function.
+--
+-- @since 4.18.0.0
 minimumBy :: Foldable1 t => (a -> a -> Ordering) -> t a -> a
 minimumBy cmp = foldl1' min'
   where min' x y = case cmp x y of
@@ -356,6 +389,7 @@
 -- Instances for misc base types
 -------------------------------------------------------------------------------
 
+-- | @since 4.18.0.0
 instance Foldable1 NonEmpty where
     foldMap1 f (x :| xs) = go (f x) xs where
         go y [] = y
@@ -375,9 +409,11 @@
     head = NE.head
     last = NE.last
 
+-- | @since 4.18.0.0
 instance Foldable1 Down where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Complex where
     foldMap1 f (x :+ y) = f x <> f y
 
@@ -389,6 +425,7 @@
 
 -- 3+ tuples are not Foldable/Traversable
 
+-- | @since 4.18.0.0
 instance Foldable1 Solo where
     foldMap1 f (MkSolo y) = f y
     toNonEmpty (MkSolo x) = x :| []
@@ -397,6 +434,7 @@
     head (MkSolo x) = x
     last (MkSolo x) = x
 
+-- | @since 4.18.0.0
 instance Foldable1 ((,) a) where
     foldMap1 f (_, y) = f y
     toNonEmpty (_, x) = x :| []
@@ -409,52 +447,68 @@
 -- Monoid / Semigroup instances
 -------------------------------------------------------------------------------
 
+-- | @since 4.18.0.0
 instance Foldable1 Dual where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Sum where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Product where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Min where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Max where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 First where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 instance Foldable1 Last where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 deriving instance (Foldable1 f) => Foldable1 (Mon.Alt f)
 
+-- | @since 4.18.0.0
 deriving instance (Foldable1 f) => Foldable1 (Mon.Ap f)
 
 -------------------------------------------------------------------------------
 -- GHC.Generics instances
 -------------------------------------------------------------------------------
 
+-- | @since 4.18.0.0
 instance Foldable1 V1 where
     foldMap1 _ x = x `seq` error "foldMap1 @V1"
 
+-- | @since 4.18.0.0
 instance Foldable1 Par1 where
     foldMap1 = coerce
 
+-- | @since 4.18.0.0
 deriving instance Foldable1 f => Foldable1 (Rec1 f)
 
+-- | @since 4.18.0.0
 deriving instance Foldable1 f => Foldable1 (M1 i c f)
 
+-- | @since 4.18.0.0
 instance (Foldable1 f, Foldable1 g) => Foldable1 (f :+: g) where
     foldMap1 f (L1 x) = foldMap1 f x
     foldMap1 f (R1 y) = foldMap1 f y
 
+-- | @since 4.18.0.0
 instance (Foldable1 f, Foldable1 g) => Foldable1 (f :*: g) where
     foldMap1 f (x :*: y) = foldMap1 f x <> foldMap1 f y
 
+-- | @since 4.18.0.0
 instance (Foldable1 f, Foldable1 g) => Foldable1 (f :.: g) where
     foldMap1 f = foldMap1 (foldMap1 f) . unComp1
 
@@ -462,6 +516,7 @@
 -- Extra instances
 -------------------------------------------------------------------------------
 
+-- | @since 4.18.0.0
 instance Foldable1 Identity where
     foldMap1      = coerce
 
@@ -486,6 +541,7 @@
     head (Functor.Pair x _) = head x
     last (Functor.Pair _ y) = last y
 
+-- | @since 4.18.0.0
 instance (Foldable1 f, Foldable1 g) => Foldable1 (Functor.Sum f g) where
     foldMap1 f (Functor.InL x) = foldMap1 f x
     foldMap1 f (Functor.InR y) = foldMap1 f y
@@ -506,6 +562,7 @@
     maximum (Functor.InL x) = maximum x
     maximum (Functor.InR y) = maximum y
 
+-- | @since 4.18.0.0
 instance (Foldable1 f, Foldable1 g) => Foldable1 (Compose f g) where
     foldMap1 f = foldMap1 (foldMap1 f) . getCompose
 
diff --git a/Debug/Trace.hs b/Debug/Trace.hs
--- a/Debug/Trace.hs
+++ b/Debug/Trace.hs
@@ -173,7 +173,7 @@
 hello
 ("hello","world")
 
-@since 4.17.0.0
+@since 4.18.0.0
 -}
 traceWith :: (a -> String) -> a -> a
 traceWith f a = trace (f a) a
@@ -186,7 +186,7 @@
 3
 [1,2,3]
 
-@since 4.17.0.0
+@since 4.18.0.0
 -}
 traceShowWith :: Show b => (a -> b) -> a -> a
 traceShowWith f = traceWith (show . f)
@@ -303,7 +303,7 @@
 -- | Like 'traceEvent', but emits the result of calling a function on its
 -- argument.
 --
--- @since 4.17.0.0
+-- @since 4.18.0.0
 traceEventWith :: (a -> String) -> a -> a
 traceEventWith f a = traceEvent (f a) a
 
diff --git a/GHC/Float.hs b/GHC/Float.hs
--- a/GHC/Float.hs
+++ b/GHC/Float.hs
@@ -1640,3 +1640,22 @@
 
 "Word# -> Natural -> Double#"
   forall x. naturalToDouble# (NS x) = word2Double# x #-}
+
+-- We don't have word64ToFloat/word64ToDouble primops (#23908), only
+-- word2Float/word2Double, so we can only perform these transformations when
+-- word-size is 64-bit.
+#if WORD_SIZE_IN_BITS == 64
+{-# RULES
+
+"Int64# -> Integer -> Float#"
+  forall x. integerToFloat# (integerFromInt64# x) = int2Float# (int64ToInt# x)
+
+"Int64# -> Integer -> Double#"
+  forall x. integerToDouble# (integerFromInt64# x) = int2Double# (int64ToInt# x)
+
+"Word64# -> Integer -> Float#"
+  forall x. integerToFloat# (integerFromWord64# x) = word2Float# (word64ToWord# x)
+
+"Word64# -> Integer -> Double#"
+  forall x. integerToDouble# (integerFromWord64# x) = word2Double# (word64ToWord# x) #-}
+#endif
diff --git a/Numeric.hs b/Numeric.hs
--- a/Numeric.hs
+++ b/Numeric.hs
@@ -117,6 +117,14 @@
 
 -- | Reads an /unsigned/ 'RealFrac' value,
 -- expressed in decimal scientific notation.
+--
+-- Note that this function takes time linear in the magnitude of its input
+-- which can scale exponentially with input size (e.g. @"1e100000000"@ is a
+-- very large number while having a very small textual form).
+-- For this reason, users should take care to avoid using this function on
+-- untrusted input. Users needing to parse floating point values
+-- (e.g. 'Float') are encouraged to instead use 'read', which does
+-- not suffer from this issue.
 readFloat :: RealFrac a => ReadS a
 readFloat = readP_to_S readFloatP
 
diff --git a/System/Posix/Internals.hs b/System/Posix/Internals.hs
--- a/System/Posix/Internals.hs
+++ b/System/Posix/Internals.hs
@@ -499,7 +499,7 @@
    c_ftruncate :: CInt -> FileOffset -> IO CInt
 foreign import javascript interruptible "(($1_1,$1_2,$c) => { return h$base_unlink($1_1,$1_2,$c); })"
    c_unlink :: CString -> IO CInt
-foreign import javascript unsafe "(() => { return h$base_getpid; })"
+foreign import javascript unsafe "h$base_getpid"
    c_getpid :: IO CPid
 -- foreign import ccall unsafe "HsBase.h fork"
 --   c_fork :: IO CPid
diff --git a/base.cabal b/base.cabal
--- a/base.cabal
+++ b/base.cabal
@@ -1,6 +1,6 @@
 cabal-version:  3.0
 name:           base
-version:        4.18.0.0
+version:        4.18.1.0
 -- NOTE: Don't forget to update ./changelog.md
 
 license:        BSD-3-Clause
@@ -397,6 +397,7 @@
     if os(windows)
         -- Windows requires some extra libraries for linking because the RTS
         -- is no longer re-exporting them.
+        -- mingwex: provides GNU POSIX extensions that aren't provided by ucrt.
         -- mingw32: Unfortunately required because of a resource leak between
         --          mingwex and mingw32. the __math_err symbol is defined in
         --          mingw32 which is required by mingwex.
@@ -409,7 +410,7 @@
         -- advapi32: provides advanced kernel functions
         extra-libraries:
             wsock32, user32, shell32, mingw32, kernel32, advapi32,
-            ws2_32, shlwapi, ole32, rpcrt4, ntdll
+            mingwex, ws2_32, shlwapi, ole32, rpcrt4, ntdll
         -- Minimum supported Windows version.
         -- These numbers can be found at:
         --  https://msdn.microsoft.com/en-us/library/windows/desktop/aa383745(v=vs.85).aspx
diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,7 +1,15 @@
 # Changelog for [`base` package](http://hackage.haskell.org/package/base)
 
-## 4.18.0.0 *TBA*
+## 4.18.1.0 *September 2023*
 
+   * Add missing int64/word64-to-double/float rules ([CLC Proposal #203](https://github.com/haskell/core-libraries-committee/issues/203))
+
+   * Restore `mingwex` dependency on Windows (#23309).
+
+   * Fix an incorrect CPP guard on `darwin_HOST_OS`.
+
+## 4.18.0.0 *March 2023*
+
   * Add `INLINABLE` pragmas to `generic*` functions in Data.OldList ([CLC proposal #129](https://github.com/haskell/core-libraries-committee/issues/130))
   * `Foreign.C.ConstPtr.ConstrPtr` was added to encode `const`-qualified
     pointer types in foreign declarations when using `CApiFFI` extension. ([CLC proposal #117](https://github.com/haskell/core-libraries-committee/issues/117))
@@ -71,6 +79,9 @@
     * `InfoProv` now has additional `ipSrcFile` and `ipSrcSpan` fields. `ipLoc`
       is now a function computed from these fields.
     * The `whereFrom` function has been moved
+  * Add functions `traceWith`, `traceShowWith`, `traceEventWith` to
+    `Debug.Trace`, per
+    [CLC proposal #36](https://github.com/haskell/core-libraries-committee/issues/36).
   * Refactor `generalCategory` to stop very large literal string being inlined to call-sites.
       ([CLC proposal #130](https://github.com/haskell/core-libraries-committee/issues/130))
   * Add INLINABLE pragmas to `generic*` functions in Data.OldList ([CLC proposal #129](https://github.com/haskell/core-libraries-committee/issues/130))
diff --git a/include/HsBase.h b/include/HsBase.h
--- a/include/HsBase.h
+++ b/include/HsBase.h
@@ -540,7 +540,7 @@
 }
 #endif
 
-#if darwin_HOST_OS
+#if defined(darwin_HOST_OS)
 // You should not access _environ directly on Darwin in a bundle/shared library.
 // See #2458 and http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man7/environ.7.html
 #include <crt_externs.h>