Windows: Remove mingwex dependency

The clang based toolchain uses ucrt as its math library
and so mingwex is no longer needed.  In fact using mingwex
will cause incompatibilities as the default routines in both
have differing ULPs and string formatting modifiers.

```
$ LIBRARY_PATH=/mingw64/lib ghc/_build/stage1/bin/ghc Bug.hs -fforce-recomp && ./Bug.exe
[1 of 2] Compiling Main             ( Bug.hs, Bug.o )
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `__imp___p__environ'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `__hscore_get_errno'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_ForeignziCziError_errnoToIOError_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziWindows_failIf2_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziIOziEncodingziCodePageziAPI_mkCodePageEncoding_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziIOziEncodingziCodePage_currentCodePage_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziIOziEncoding_getForeignEncoding_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_ForeignziCziString_withCStringLen1_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziIOziHandleziInternals_zdwflushCharReadBuffer_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziIOziHandleziText_hGetBuf1_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziFingerprint_fingerprintString_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_DataziTypeableziInternal_mkTrCon_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziException_errorCallWithCallStackException_closure'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\base-4.17.0.0\libHSbase-4.17.0.0.a: unknown symbol `base_GHCziErr_error_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\template-haskell-2.19.0.0\libHStemplate-haskell-2.19.0.0.a: unknown symbol `base_DataziMaybe_fromJust1_info'
ghc.exe:  | C:\Users\winferno\Software\ghc\_build\stage1\lib\x86_64-windows-ghc-9.5.20220908\template-haskell-2.19.0.0\libHStemplate-haskell-2.19.0.0.a: unknown symbol `templatezmhaskell_LanguageziHaskellziTHziSyntax_IntPrimL_con_info'
ghc.exe: ^^ Could not load 'templatezmhaskell_LanguageziHaskellziTHziLibziInternal_stringL_closure', dependency unresolved. See top entry above.

<no location info>: error:

GHC.ByteCode.Linker.lookupCE
During interactive linking, GHCi couldn't find the following symbol:
  templatezmhaskell_LanguageziHaskellziTHziLibziInternal_stringL_closure
This may be due to you not asking GHCi to load extra object files,
archives or DLLs needed by your current session.  Restart GHCi, specifying
the missing library using the -L/path/to/object/dir and -lmissinglibname
flags, or simply by naming the relevant files on the GHCi command line.
Alternatively, this link failure might indicate a bug in GHCi.
If you suspect the latter, please report this as a GHC bug:
  https://www.haskell.org/ghc/reportabug
```

14 files changed, 95 insertions, 260 deletions

diff --git a/configure.ac b/configure.ac
index dbd91685b0..6d04d6f207 100644
--- a/configure.ac
+++ b/configure.ac
@@ -934,17 +934,6 @@ AC_CHECK_DECLS([program_invocation_short_name], , ,
 [#define _GNU_SOURCE 1
 #include <errno.h>])
 
-dnl ** check for mingwex library
-AC_CHECK_LIB(
-  [mingwex],
-  [closedir],
-  [AC_SUBST([HaveLibMingwEx],[YES])] [AC_SUBST([CabalMingwex],[True])],
-  [AC_SUBST([HaveLibMingwEx],[NO])] [AC_SUBST([CabalMingwex],[False])])
-
-if test $HaveLibMingwEx = YES ; then
-  AC_DEFINE([HAVE_MINGWEX], [1], [Define to 1 if you have the mingwex library.])
-fi
-
 dnl ** check for math library
 dnl    Keep that check as early as possible.
 dnl    as we need to know whether we need libm
diff --git a/hadrian/cfg/system.config.in b/hadrian/cfg/system.config.in
index 8cefe803ac..6a891b4363 100644
--- a/hadrian/cfg/system.config.in
+++ b/hadrian/cfg/system.config.in
@@ -205,7 +205,6 @@ libnuma-lib-dir       = @LibNumaLibDir@
 
 use-lib-dw        = @UseLibdw@
 use-lib-numa      = @UseLibNuma@
-use-lib-mingw-ex  = @HaveLibMingwEx@
 use-lib-m         = @UseLibm@
 use-lib-rt        = @UseLibrt@
 use-lib-dl        = @UseLibdl@
diff --git a/hadrian/src/Oracles/Flag.hs b/hadrian/src/Oracles/Flag.hs
index 1f585595c5..d3baec4932 100644
--- a/hadrian/src/Oracles/Flag.hs
+++ b/hadrian/src/Oracles/Flag.hs
@@ -35,7 +35,6 @@ data Flag = ArSupportsAtFile
           | UseLibffiForAdjustors
           | UseLibdw
           | UseLibnuma
-          | UseLibmingwex
           | UseLibm
           | UseLibrt
           | UseLibdl
@@ -66,7 +65,6 @@ flag f = do
             UseLibffiForAdjustors -> "use-libffi-for-adjustors"
             UseLibdw             -> "use-lib-dw"
             UseLibnuma           -> "use-lib-numa"
-            UseLibmingwex        -> "use-lib-mingw-ex"
             UseLibm              -> "use-lib-m"
             UseLibrt             -> "use-lib-rt"
             UseLibdl             -> "use-lib-dl"
diff --git a/hadrian/src/Rules/Generate.hs b/hadrian/src/Rules/Generate.hs
index a37d69d7d1..e6e5ecd96b 100644
--- a/hadrian/src/Rules/Generate.hs
+++ b/hadrian/src/Rules/Generate.hs
@@ -284,8 +284,7 @@ projectVersion = mconcat
 
 rtsCabalFlags :: Interpolations
 rtsCabalFlags = mconcat
-    [ flag "CabalMingwex" UseLibmingwex
-    , flag "CabalHaveLibdw" UseLibdw
+    [ flag "CabalHaveLibdw" UseLibdw
     , flag "CabalHaveLibm" UseLibm
     , flag "CabalHaveLibrt" UseLibrt
     , flag "CabalHaveLibdl" UseLibdl
diff --git a/hadrian/src/Settings/Packages.hs b/hadrian/src/Settings/Packages.hs
index 901ff10a09..c441ca6cb3 100644
--- a/hadrian/src/Settings/Packages.hs
+++ b/hadrian/src/Settings/Packages.hs
@@ -404,7 +404,6 @@ rtsPackageArgs = package rts ? do
           [ "-DTOP="             ++ show top ]
 
         , builder HsCpp ? flag UseLibdw ? arg "-DUSE_LIBDW"
-        , builder HsCpp ? flag UseLibmingwex ? arg "-DHAVE_LIBMINGWEX" ]
 
 -- Compile various performance-critical pieces *without* -fPIC -dynamic
 -- even when building a shared library.  If we don't do this, then the
diff --git a/libraries/base/System/Posix/Internals.hs b/libraries/base/System/Posix/Internals.hs
index 44065be7c4..6aae25ab5e 100644
--- a/libraries/base/System/Posix/Internals.hs
+++ b/libraries/base/System/Posix/Internals.hs
@@ -452,7 +452,6 @@ foreign import ccall unsafe "HsBase.h __hscore_fstat"
 
 foreign import ccall unsafe "HsBase.h __hscore_lstat"
    lstat :: CFilePath -> Ptr CStat -> IO CInt
-
 #endif
 
 #if defined(js_HOST_ARCH)
@@ -592,109 +591,95 @@ foreign import javascript unsafe "(($1,$2,$3_1,$3_2) => { return h$base_c_fcntl_
 
 #else
 
-{- Note: Win32 POSIX functions
-Functions that are not part of the POSIX standards were
-at some point deprecated by Microsoft. This deprecation
-was performed by renaming the functions according to the
-C++ ABI Section 17.6.4.3.2b. This was done to free up the
-namespace of normal Windows programs since Windows isn't
-POSIX compliant anyway.
+#if defined(mingw32_HOST_OS)
+-- See Note [Windows types]
+foreign import capi unsafe "HsBase.h _read"
+   c_read :: CInt -> Ptr Word8 -> CUInt -> IO CInt
 
-These were working before since the RTS was re-exporting
-these symbols under the undeprecated names. This is no longer
-being done. See #11223
+-- See Note [Windows types]
+foreign import capi safe "HsBase.h _read"
+   c_safe_read :: CInt -> Ptr Word8 -> CUInt -> IO CInt
 
-See https://msdn.microsoft.com/en-us/library/ms235384.aspx
-for more.
+foreign import ccall unsafe "HsBase.h _umask"
+   c_umask :: CMode -> IO CMode
 
-However since we can't hope to get people to support Windows
-packages we should support the deprecated names. See #12497
--}
-foreign import capi unsafe "unistd.h lseek"
-   c_lseek :: CInt -> COff -> CInt -> IO COff
+-- See Note [Windows types]
+foreign import capi unsafe "HsBase.h _write"
+   c_write :: CInt -> Ptr Word8 -> CUInt -> IO CInt
 
-foreign import ccall unsafe "HsBase.h access"
+-- See Note [Windows types]
+foreign import capi safe "HsBase.h _write"
+   c_safe_write :: CInt -> Ptr Word8 -> CUInt -> IO CInt
+
+foreign import ccall unsafe "HsBase.h _pipe"
+   c_pipe :: Ptr CInt -> IO CInt
+
+foreign import capi unsafe "HsBase.h _lseeki64"
+   c_lseek :: CInt -> Int64 -> CInt -> IO Int64
+
+foreign import capi unsafe "HsBase.h _access"
    c_access :: CString -> CInt -> IO CInt
 
 #if !defined(HAVE_CHMOD)
 c_chmod :: CString -> CMode -> IO CInt
-c_chmod _ _ = ioError (ioeSetLocation unsupportedOperation "chmod")
+c_chmod _ _ = ioError (ioeSetLocation unsupportedOperation "_chmod")
 #else
-foreign import ccall unsafe "HsBase.h chmod"
+foreign import ccall unsafe "HsBase.h _chmod"
    c_chmod :: CString -> CMode -> IO CInt
 #endif
 
-foreign import ccall unsafe "HsBase.h close"
+foreign import capi unsafe "HsBase.h _close"
    c_close :: CInt -> IO CInt
 
-foreign import ccall unsafe "HsBase.h creat"
+foreign import capi unsafe "HsBase.h _creat"
    c_creat :: CString -> CMode -> IO CInt
 
 #if !defined(HAVE_DUP)
 c_dup :: CInt -> IO CInt
-c_dup _ = ioError (ioeSetLocation unsupportedOperation "dup")
+c_dup _ = ioError (ioeSetLocation unsupportedOperation "_dup")
 
 c_dup2 :: CInt -> CInt -> IO CInt
-c_dup2 _ _ = ioError (ioeSetLocation unsupportedOperation "dup2")
+c_dup2 _ _ = ioError (ioeSetLocation unsupportedOperation "_dup2")
 #else
-foreign import ccall unsafe "HsBase.h dup"
+foreign import ccall unsafe "HsBase.h _dup"
    c_dup :: CInt -> IO CInt
 
-foreign import ccall unsafe "HsBase.h dup2"
+foreign import ccall unsafe "HsBase.h _dup2"
    c_dup2 :: CInt -> CInt -> IO CInt
 #endif
 
-foreign import ccall unsafe "HsBase.h isatty"
+foreign import capi unsafe "HsBase.h _isatty"
    c_isatty :: CInt -> IO CInt
 
-#if defined(mingw32_HOST_OS)
--- See Note: Windows types
-foreign import capi unsafe "HsBase.h _read"
-   c_read :: CInt -> Ptr Word8 -> CUInt -> IO CInt
-
--- See Note: Windows types
-foreign import capi safe "HsBase.h _read"
-   c_safe_read :: CInt -> Ptr Word8 -> CUInt -> IO CInt
-
-foreign import ccall unsafe "HsBase.h _umask"
-   c_umask :: CMode -> IO CMode
-
--- See Note: Windows types
-foreign import capi unsafe "HsBase.h _write"
-   c_write :: CInt -> Ptr Word8 -> CUInt -> IO CInt
+foreign import capi unsafe "HsBase.h _unlink"
+   c_unlink :: CString -> IO CInt
 
--- See Note: Windows types
-foreign import capi safe "HsBase.h _write"
-   c_safe_write :: CInt -> Ptr Word8 -> CUInt -> IO CInt
+foreign import capi unsafe "HsBase.h _utime"
+   c_utime :: CString -> Ptr CUtimbuf -> IO CInt
 
-foreign import ccall unsafe "HsBase.h _pipe"
-   c_pipe :: Ptr CInt -> IO CInt
+foreign import capi unsafe "HsBase.h _getpid"
+   c_getpid :: IO CPid
 #else
 -- We use CAPI as on some OSs (eg. Linux) this is wrapped by a macro
 -- which redirects to the 64-bit-off_t versions when large file
 -- support is enabled.
 
--- See Note: Windows types
+-- See Note [Windows types]
 foreign import capi unsafe "HsBase.h read"
    c_read :: CInt -> Ptr Word8 -> CSize -> IO CSsize
 
--- See Note: Windows types
+-- See Note [Windows types]
 foreign import capi safe "HsBase.h read"
    c_safe_read :: CInt -> Ptr Word8 -> CSize -> IO CSsize
 
-#if defined(HAVE_UMASK)
 foreign import ccall unsafe "HsBase.h umask"
    c_umask :: CMode -> IO CMode
-#else
-c_umask :: CMode -> IO CMode
-c_umask _ = ioError (ioeSetLocation unsupportedOperation "umask")
-#endif
 
--- See Note: Windows types
+-- See Note [Windows types]
 foreign import capi unsafe "HsBase.h write"
    c_write :: CInt -> Ptr Word8 -> CSize -> IO CSsize
 
--- See Note: Windows types
+-- See Note [Windows types]
 foreign import capi safe "HsBase.h write"
    c_safe_write :: CInt -> Ptr Word8 -> CSize -> IO CSsize
 
@@ -705,8 +690,44 @@ c_pipe _ = ioError (ioeSetLocation unsupportedOperation "pipe")
 foreign import ccall unsafe "HsBase.h pipe"
    c_pipe :: Ptr CInt -> IO CInt
 #endif
+
+foreign import capi unsafe "unistd.h lseek"
+   c_lseek :: CInt -> COff -> CInt -> IO COff
+
+foreign import ccall unsafe "HsBase.h access"
+   c_access :: CString -> CInt -> IO CInt
+
+#if !defined(HAVE_CHMOD)
+c_chmod :: CString -> CMode -> IO CInt
+c_chmod _ _ = ioError (ioeSetLocation unsupportedOperation "chmod")
+#else
+foreign import ccall unsafe "HsBase.h chmod"
+   c_chmod :: CString -> CMode -> IO CInt
+#endif
+
+foreign import ccall unsafe "HsBase.h close"
+   c_close :: CInt -> IO CInt
+
+foreign import ccall unsafe "HsBase.h creat"
+   c_creat :: CString -> CMode -> IO CInt
+
+#if !defined(HAVE_DUP)
+c_dup :: CInt -> IO CInt
+c_dup _ = ioError (ioeSetLocation unsupportedOperation "dup")
+
+c_dup2 :: CInt -> CInt -> IO CInt
+c_dup2 _ _ = ioError (ioeSetLocation unsupportedOperation "dup2")
+#else
+foreign import ccall unsafe "HsBase.h dup"
+   c_dup :: CInt -> IO CInt
+
+foreign import ccall unsafe "HsBase.h dup2"
+   c_dup2 :: CInt -> CInt -> IO CInt
 #endif
 
+foreign import ccall unsafe "HsBase.h isatty"
+   c_isatty :: CInt -> IO CInt
+
 foreign import ccall unsafe "HsBase.h unlink"
    c_unlink :: CString -> IO CInt
 
@@ -720,6 +741,7 @@ c_getpid = pure 1
 foreign import ccall unsafe "HsBase.h getpid"
    c_getpid :: IO CPid
 #endif
+#endif
 
 #if !defined(js_HOST_ARCH)
 foreign import ccall unsafe "HsBase.h __hscore_stat"
@@ -881,7 +903,7 @@ foreign import capi  unsafe "stdio.h value SEEK_END" sEEK_END :: CInt
 #endif
 
 {-
-Note: Windows types
+Note [Windows types]
 
 Windows' _read and _write have types that differ from POSIX. They take an
 unsigned int for length and return a signed int where POSIX uses size_t and
diff --git a/libraries/base/base.cabal b/libraries/base/base.cabal
index d615108c58..5e7fdc17c6 100644
--- a/libraries/base/base.cabal
+++ b/libraries/base/base.cabal
@@ -397,7 +397,6 @@ Library
     if os(windows)
         -- Windows requires some extra libraries for linking because the RTS
         -- is no longer re-exporting them.
-        -- mingwex: provides C99 compatibility. libm is a stub on MingW.
         -- 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.
@@ -410,7 +409,7 @@ Library
         -- advapi32: provides advanced kernel functions
         extra-libraries:
             wsock32, user32, shell32, mingw32, kernel32, advapi32,
-            mingwex, ws2_32, shlwapi, ole32, rpcrt4, ntdll
+            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/libraries/base/configure.ac b/libraries/base/configure.ac
index a1c68577aa..cea01384aa 100644
--- a/libraries/base/configure.ac
+++ b/libraries/base/configure.ac
@@ -39,7 +39,7 @@ AC_CHECK_LIB([rt], [clock_gettime])
 AC_CHECK_FUNCS([clock_gettime])
 AC_CHECK_DECLS([CLOCK_PROCESS_CPUTIME_ID], [], [], [[#include <time.h>]])
 AC_CHECK_FUNCS([getclock getrusage times])
-AC_CHECK_FUNCS([_chsize ftruncate])
+AC_CHECK_FUNCS([_chsize_s ftruncate])
 
 # event-related fun
 # The line below already defines HAVE_KQUEUE and HAVE_POLL, so technically some of the
diff --git a/libraries/base/include/HsBase.h b/libraries/base/include/HsBase.h
index 12edce964d..d841141be2 100644
--- a/libraries/base/include/HsBase.h
+++ b/libraries/base/include/HsBase.h
@@ -280,15 +280,12 @@ __hscore_o_nonblock( void )
 INLINE int
 __hscore_ftruncate( int fd, off_t where )
 {
-#if defined(HAVE_FTRUNCATE)
+#if defined(HAVE__CHSIZE_S)
+  return _chsize_s(fd,where);
+#elif defined(HAVE_FTRUNCATE)
   return ftruncate(fd,where);
-#elif defined(HAVE__CHSIZE)
-  return _chsize(fd,where);
 #else
-// ToDo: we should use _chsize_s() on Windows which allows a 64-bit
-// offset, but it doesn't seem to be available from mingw at this time
-// --SDM (01/2008)
-#error at least ftruncate or _chsize functions are required to build
+#error at least _chsize_s or ftruncate functions are required to build
 #endif
 }
 
diff --git a/libraries/ghc-prim/ghc-prim.cabal b/libraries/ghc-prim/ghc-prim.cabal
index dbe1e32545..5393363505 100644
--- a/libraries/ghc-prim/ghc-prim.cabal
+++ b/libraries/ghc-prim/ghc-prim.cabal
@@ -66,15 +66,14 @@ Library
     if os(windows)
         -- Windows requires some extra libraries for linking because the RTS
         -- is no longer re-exporting them (see #11223)
-        -- msvcrt: standard C library. The RTS will automatically include this,
-        --         but is added for completeness.
-        -- mingwex: provides C99 compatibility. libm is a stub on MingW.
+        -- ucrt: standard C library. The RTS will automatically include this,
+        --       but is added for completeness.
         -- 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.
         -- user32: provides access to apis to modify user components (UI etc)
         --         on Windows. Required because of mingw32.
-        extra-libraries: user32, mingw32, mingwex, ucrt
+        extra-libraries: user32, mingw32, ucrt
 
     if os(linux)
         -- we need libm, but for musl and other's we might need libc, as libm
diff --git a/rts/Linker.c b/rts/Linker.c
index 6300240c48..af91a098be 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -135,7 +135,8 @@ extern void iconv();
    This is to enable lazy loading of symbols. Eager loading is problematic
    as it means that all symbols must be available, even those which we will
    never use. This is especially painful on Windows, where the number of
-   libraries required to link things like mingwex grows to be quite high.
+   libraries required to link things like mingwex (TODO: We no longer depend
+   on mingwex, so think of a different example here) grows to be quite high.
 
    We proceed through these stages as follows,
 
@@ -193,7 +194,8 @@ extern void iconv();
 
    1) Dependency chains, if A.o required a .o in libB but A.o isn't required to link
       then we don't need to load libB. This means the dependency chain for libraries
-      such as mingw32 and mingwex can be broken down.
+      such as mingw32 and mingwex (TODO: We no longer depend on mingwex, so think of
+      a different example here) can be broken down.
 
    2) The number of duplicate symbols, since now only symbols that are
       true duplicates will display the error.
diff --git a/rts/RtsSymbols.c b/rts/RtsSymbols.c
index 357ea4ddce..a95a1b1231 100644
--- a/rts/RtsSymbols.c
+++ b/rts/RtsSymbols.c
@@ -113,26 +113,6 @@ extern char **environ;
  * by the RtsSymbols entry. To avoid this we introduce a horrible special case
  * in `ghciInsertSymbolTable`, ensure that `atexit` is never overridden.
  */
-/*
- * Note [Symbols for MinGW's printf]
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- * The printf offered by Microsoft's libc implementation, msvcrt, is quite
- * incomplete, lacking support for even %ull. Consequently mingw-w64 offers its
- * own implementation which we enable. However, to be thread-safe the
- * implementation uses _lock_file. This would be fine except msvcrt.dll doesn't
- * export _lock_file, only numbered versions do (e.g. msvcrt90.dll).
- *
- * To work around this mingw-w64 packages a static archive of msvcrt which
- * includes their own implementation of _lock_file. However, this means that
- * the archive contains things which the dynamic library does not; consequently
- * we need to ensure that the runtime linker provides this symbol.
- *
- * It's all just so terrible.
- *
- * See also:
- * https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/
- * https://sourceforge.net/p/mingw-w64/discussion/723797/thread/55520785/
- */
 /* Note [_iob_func symbol]
  * ~~~~~~~~~~~~~~~~~~~~~~~
  * Microsoft in VS2013 to VS2015 transition made a backwards incompatible change
@@ -170,10 +150,6 @@ extern char **environ;
       SymI_NeedsProto(__mingw_module_is_dll)             \
       RTS_WIN32_ONLY(SymI_NeedsProto(___chkstk_ms))      \
       RTS_WIN64_ONLY(SymI_NeedsProto(___chkstk_ms))      \
-      RTS_WIN64_ONLY(SymI_HasProto(_errno))  \
-      /* see Note [Symbols for MinGW's printf] */        \
-      SymI_HasProto(_lock_file)                          \
-      SymI_HasProto(_unlock_file)                        \
       SymI_HasProto(__mingw_vsnwprintf)                  \
       /* ^^ Need to figure out why this is needed.  */   \
       /* See Note [_iob_func symbol] */                  \
@@ -185,120 +161,8 @@ extern char **environ;
       /* ^^ Need to figure out why this is needed.  */   \
       SymI_HasProto(__mingw_vfprintf)                    \
       /* ^^ Need to figure out why this is needed.  */
-
-#define RTS_MINGW_COMPAT_SYMBOLS                         \
-      SymI_HasProto_deprecated(access)                   \
-      SymI_HasProto_deprecated(cabs)                     \
-      SymI_HasProto_deprecated(cgets)                    \
-      SymI_HasProto_deprecated(chdir)                    \
-      SymI_HasProto_deprecated(chmod)                    \
-      SymI_HasProto_deprecated(chsize)                   \
-      SymI_HasProto_deprecated(close)                    \
-      SymI_HasProto_deprecated(cprintf)                  \
-      SymI_HasProto_deprecated(cputs)                    \
-      SymI_HasProto_deprecated(creat)                    \
-      SymI_HasProto_deprecated(cscanf)                   \
-      SymI_HasProto_deprecated(cwait)                    \
-      SymI_HasProto_deprecated(dup)                      \
-      SymI_HasProto_deprecated(dup2)                     \
-      SymI_HasProto_deprecated(ecvt)                     \
-      SymI_HasProto_deprecated(eof)                      \
-      SymI_HasProto_deprecated(execl)                    \
-      SymI_HasProto_deprecated(execle)                   \
-      SymI_HasProto_deprecated(execlp)                   \
-      SymI_HasProto_deprecated(execlpe)                  \
-      SymI_HasProto_deprecated(execv)                    \
-      SymI_HasProto_deprecated(execve)                   \
-      SymI_HasProto_deprecated(execvp)                   \
-      SymI_HasProto_deprecated(execvpe)                  \
-      SymI_HasProto_deprecated(fcloseall)                \
-      SymI_HasProto_deprecated(fcvt)                     \
-      SymI_HasProto_deprecated(fdopen)                   \
-      SymI_HasProto_deprecated(fgetchar)                 \
-      SymI_HasProto_deprecated(filelength)               \
-      SymI_HasProto_deprecated(fileno)                   \
-      SymI_HasProto_deprecated(flushall)                 \
-      SymI_HasProto_deprecated(fputchar)                 \
-      SymI_HasProto_deprecated(gcvt)                     \
-      SymI_HasProto_deprecated(getch)                    \
-      SymI_HasProto_deprecated(getche)                   \
-      SymI_HasProto_deprecated(getcwd)                   \
-      SymI_HasProto_deprecated(getpid)                   \
-      SymI_HasProto_deprecated(getw)                     \
-      SymI_HasProto_deprecated(hypot)                    \
-      SymI_HasProto_deprecated(inp)                      \
-      SymI_HasProto_deprecated(inpw)                     \
-      SymI_HasProto_deprecated(isascii)                  \
-      SymI_HasProto_deprecated(isatty)                   \
-      SymI_HasProto_deprecated(iscsym)                   \
-      SymI_HasProto_deprecated(iscsymf)                  \
-      SymI_HasProto_deprecated(itoa)                     \
-      SymI_HasProto_deprecated(j0)                       \
-      SymI_HasProto_deprecated(j1)                       \
-      SymI_HasProto_deprecated(jn)                       \
-      SymI_HasProto_deprecated(kbhit)                    \
-      SymI_HasProto_deprecated(lfind)                    \
-      SymI_HasProto_deprecated(locking)                  \
-      SymI_HasProto_deprecated(lsearch)                  \
-      SymI_HasProto_deprecated(lseek)                    \
-      SymI_HasProto_deprecated(ltoa)                     \
-      SymI_HasProto_deprecated(memccpy)                  \
-      SymI_HasProto_deprecated(memicmp)                  \
-      SymI_HasProto_deprecated(mkdir)                    \
-      SymI_HasProto_deprecated(mktemp)                   \
-      SymI_HasProto_deprecated(open)                     \
-      SymI_HasProto_deprecated(outp)                     \
-      SymI_HasProto_deprecated(outpw)                    \
-      SymI_HasProto_deprecated(putch)                    \
-      SymI_HasProto_deprecated(putenv)                   \
-      SymI_HasProto_deprecated(putw)                     \
-      SymI_HasProto_deprecated(read)                     \
-      SymI_HasProto_deprecated(rmdir)                    \
-      SymI_HasProto_deprecated(rmtmp)                    \
-      SymI_HasProto_deprecated(setmode)                  \
-      SymI_HasProto_deprecated(sopen)                    \
-      SymI_HasProto_deprecated(spawnl)                   \
-      SymI_HasProto_deprecated(spawnle)                  \
-      SymI_HasProto_deprecated(spawnlp)                  \
-      SymI_HasProto_deprecated(spawnlpe)                 \
-      SymI_HasProto_deprecated(spawnv)                   \
-      SymI_HasProto_deprecated(spawnve)                  \
-      SymI_HasProto_deprecated(spawnvp)                  \
-      SymI_HasProto_deprecated(spawnvpe)                 \
-      SymI_HasProto_deprecated(strcmpi)                  \
-      SymI_HasProto_deprecated(strdup)                   \
-      SymI_HasProto_deprecated(stricmp)                  \
-      SymI_HasProto_deprecated(strlwr)                   \
-      SymI_HasProto_deprecated(strnicmp)                 \
-      SymI_HasProto_deprecated(strnset)                  \
-      SymI_HasProto_deprecated(strrev)                   \
-      SymI_HasProto_deprecated(strset)                   \
-      SymI_HasProto_deprecated(strupr)                   \
-      SymI_HasProto_deprecated(swab)                     \
-      SymI_HasProto_deprecated(tell)                     \
-      SymI_HasProto_deprecated(tempnam)                  \
-      SymI_HasProto_deprecated(toascii)                  \
-      SymI_HasProto_deprecated(tzset)                    \
-      SymI_HasProto_deprecated(ultoa)                    \
-      SymI_HasProto_deprecated(umask)                    \
-      SymI_HasProto_deprecated(ungetch)                  \
-      SymI_HasProto_deprecated(unlink)                   \
-      SymI_HasProto_deprecated(wcsdup)                   \
-      SymI_HasProto_deprecated(wcsicmp)                  \
-      SymI_HasProto_deprecated(wcsicoll)                 \
-      SymI_HasProto_deprecated(wcslwr)                   \
-      SymI_HasProto_deprecated(wcsnicmp)                 \
-      SymI_HasProto_deprecated(wcsnset)                  \
-      SymI_HasProto_deprecated(wcsrev)                   \
-      SymI_HasProto_deprecated(wcsset)                   \
-      SymI_HasProto_deprecated(wcsupr)                   \
-      SymI_HasProto_deprecated(write)                    \
-      SymI_HasProto_deprecated(y0)                       \
-      SymI_HasProto_deprecated(y1)                       \
-      SymI_HasProto_deprecated(yn)
 #else
 #define RTS_MINGW_ONLY_SYMBOLS /**/
-#define RTS_MINGW_COMPAT_SYMBOLS /**/
 #endif
 
 
@@ -1121,7 +985,6 @@ extern char **environ;
 #define SymI_HasProto(vvv) /**/
 #define SymI_HasDataProto(vvv) /**/
 #define SymI_HasProto_redirect(vvv,xxx,strength,ty) /**/
-#define SymI_HasProto_deprecated(vvv) /**/
 
 RTS_SYMBOLS
 RTS_RET_SYMBOLS
@@ -1139,7 +1002,6 @@ RTS_LIBFFI_SYMBOLS
 #undef SymI_HasProto
 #undef SymI_HasDataProto
 #undef SymI_HasProto_redirect
-#undef SymI_HasProto_deprecated
 #undef SymE_HasProto
 #undef SymE_HasDataProto
 #undef SymE_NeedsProto
@@ -1165,22 +1027,11 @@ RTS_LIBFFI_SYMBOLS
     { MAYBE_LEADING_UNDERSCORE_STR(#vvv),    \
       (void*)(&(xxx)), strength, ty },
 
-// SymI_HasProto_deprecated allows us to redirect references from their deprecated
-// names to the undeprecated ones. e.g. access -> _access.
-// We use the hexspeak for unallocated memory 0xBAADF00D to signal the RTS
-// that this needs to be loaded from somewhere else.
-// These are inserted as weak symbols to prevent us overriding packages that do
-// define them, since on Windows these functions shouldn't be in the top level
-// namespace, but we have them for POSIX compatibility.
-#define SymI_HasProto_deprecated(vvv)   \
-   { #vvv, (void*)0xBAADF00D, STRENGTH_WEAK, SYM_TYPE_CODE },
-
 RtsSymbolVal rtsSyms[] = {
       RTS_SYMBOLS
       RTS_RET_SYMBOLS
       RTS_POSIX_ONLY_SYMBOLS
       RTS_MINGW_ONLY_SYMBOLS
-      RTS_MINGW_COMPAT_SYMBOLS
       RTS_DARWIN_ONLY_SYMBOLS
       RTS_OPENBSD_ONLY_SYMBOLS
       RTS_LIBGCC_SYMBOLS
diff --git a/rts/linker/PEi386.c b/rts/linker/PEi386.c
index 8e2ce984ca..8d5238f792 100644
--- a/rts/linker/PEi386.c
+++ b/rts/linker/PEi386.c
@@ -2171,21 +2171,7 @@ SymbolAddr *lookupSymbol_PEi386(SymbolName *lbl, ObjectCode *dependent, SymType
     } else {
         if (type) *type = pinfo->type;
 
-        // If Windows, perform initialization of uninitialized
-        // Symbols from the C runtime which was loaded above.
-        // We do this on lookup to prevent the hit when
-        // The symbol isn't being used.
-        if (pinfo->value == (void*)0xBAADF00D)
-        {
-            char symBuffer[50];
-            const char *crt_impl = "ucrtbase";
-            sprintf(symBuffer, "_%s", lbl);
-            static HMODULE crt = NULL;
-            if (!crt) crt = GetModuleHandle(crt_impl);
-            pinfo->value = GetProcAddress(crt, symBuffer);
-            return pinfo->value;
-        }
-        else if (pinfo && pinfo->owner && isSymbolImport (pinfo->owner, lbl))
+        if (pinfo && pinfo->owner && isSymbolImport (pinfo->owner, lbl))
         {
             /* See Note [BFD import library].  */
             HINSTANCE dllInstance = (HINSTANCE)lookupDependentSymbol(pinfo->value, dependent, type);
diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in
index be54a086e9..00d720d4ff 100644
--- a/rts/rts.cabal.in
+++ b/rts/rts.cabal.in
@@ -39,8 +39,6 @@ flag need-pthread
   default: @CabalNeedLibpthread@
 flag libbfd
   default: @CabalHaveLibbfd@
-flag mingwex
-  default: @CabalMingwex@
 flag need-atomic
   default: @CabalNeedLibatomic@
 flag libdw
@@ -83,7 +81,6 @@ library
 
     exposed: True
     exposed-modules:
-
     if os(ghcjs)
 
       include-dirs: include
@@ -209,8 +206,6 @@ library
       if flag(libbfd)
          -- for debugging
          extra-libraries: bfd iberty
-      if flag(mingwex)
-         extra-libraries: mingwex
       if flag(libdw)
          -- for backtraces
          extra-libraries: elf dw