From 38ebb8ff828d29252379cd62ede753d8a5edfa4e Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Sun, 27 Oct 2019 20:05:48 -0400
Subject: [PATCH 01/10] fetchurl: Eliminate pointless cross differences

---
 pkgs/build-support/fetchurl/default.nix | 4 ++--
 pkgs/top-level/all-packages.nix         | 6 ++++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index 6300587a7d1..7d23a3a7f8f 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenvNoCC, curl }: # Note that `curl' may be `null', in case of the native stdenvNoCC.
+{ lib, buildPackages ? { inherit stdenvNoCC; }, stdenvNoCC, curl }: # Note that `curl' may be `null', in case of the native stdenvNoCC.
 
 let
 
@@ -10,7 +10,7 @@ let
   # resulting store derivations (.drv files) much smaller, which in
   # turn makes nix-env/nix-instantiate faster.
   mirrorsFile =
-    stdenvNoCC.mkDerivation ({
+    buildPackages.stdenvNoCC.mkDerivation ({
       name = "mirrors-list";
       builder = ./write-mirror-list.sh;
       preferLocalBuild = true;
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index a4ae7430e0f..5a1b9cfab69 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -283,8 +283,10 @@ in
   fetchhg = callPackage ../build-support/fetchhg { };
 
   # `fetchurl' downloads a file from the network.
-  fetchurl = makeOverridable (import ../build-support/fetchurl) {
-    inherit lib stdenvNoCC;
+  fetchurl = if stdenv.buildPlatform != stdenv.hostPlatform
+   then buildPackages.fetchurl # No need to do special overrides twice,
+   else makeOverridable (import ../build-support/fetchurl) {
+    inherit lib stdenvNoCC buildPackages;
     curl = buildPackages.curl.override (old: rec {
       # break dependency cycles
       fetchurl = stdenv.fetchurlBoot;

From 91718534f1f476a727b51a256c93885e57cf602d Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Sun, 10 Nov 2019 20:02:44 -0500
Subject: [PATCH 02/10] lib: Switch to w64 vendor for MinGW

It is needed for the `-municode` flag, supposedly.
---
 lib/systems/examples.nix | 4 ++--
 lib/systems/parse.nix    | 3 +++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/systems/examples.nix b/lib/systems/examples.nix
index 511ae197948..585156c2475 100644
--- a/lib/systems/examples.nix
+++ b/lib/systems/examples.nix
@@ -207,7 +207,7 @@ rec {
 
   # 32 bit mingw-w64
   mingw32 = {
-    config = "i686-pc-mingw32";
+    config = "i686-w64-mingw32";
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
     platform = {};
   };
@@ -215,7 +215,7 @@ rec {
   # 64 bit mingw-w64
   mingwW64 = {
     # That's the triplet they use in the mingw-w64 docs.
-    config = "x86_64-pc-mingw32";
+    config = "x86_64-w64-mingw32";
     libc = "msvcrt"; # This distinguishes the mingw (non posix) toolchain
     platform = {};
   };
diff --git a/lib/systems/parse.nix b/lib/systems/parse.nix
index 5e12df32ffd..5a3805cf997 100644
--- a/lib/systems/parse.nix
+++ b/lib/systems/parse.nix
@@ -208,6 +208,9 @@ rec {
   vendors = setTypes types.openVendor {
     apple = {};
     pc = {};
+    # Actually matters, unlocking some MinGW-w64-specific options in GCC. See
+    # bottom of https://sourceforge.net/p/mingw-w64/wiki2/Unicode%20apps/
+    w64 = {};
 
     none = {};
     unknown = {};

From 0a63190c3115126e6a571b6ca555fa684b8bf4ed Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Sun, 10 Nov 2019 22:32:31 -0500
Subject: [PATCH 03/10] windows top-level: Clean up with makeScope

---
 pkgs/os-specific/windows/default.nix | 42 +++++++++++++---------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/pkgs/os-specific/windows/default.nix b/pkgs/os-specific/windows/default.nix
index 4621c2da10f..8c2f3ca5498 100644
--- a/pkgs/os-specific/windows/default.nix
+++ b/pkgs/os-specific/windows/default.nix
@@ -1,29 +1,27 @@
-{ newScope, crossLibcStdenv }: let
+{ stdenv, newScope, crossLibcStdenv }:
 
-  callPackage = newScope self;
+stdenv.lib.makeScope newScope (self: with self; {
 
-  self = {
-    cygwinSetup = callPackage ./cygwin-setup { };
+  cygwinSetup = callPackage ./cygwin-setup { };
 
-    jom = callPackage ./jom { };
+  jom = callPackage ./jom { };
 
-    w32api = callPackage ./w32api { };
+  w32api = callPackage ./w32api { };
 
-    mingwrt = callPackage ./mingwrt { };
-    mingw_runtime = self.mingwrt;
+  mingwrt = callPackage ./mingwrt { };
+  mingw_runtime = mingwrt;
 
-    mingw_w64 = callPackage ./mingw-w64 {
-      stdenv = crossLibcStdenv;
-    };
-
-    mingw_w64_headers = callPackage ./mingw-w64/headers.nix { };
-
-    mingw_w64_pthreads = callPackage ./mingw-w64/pthreads.nix { };
-
-    pthreads = callPackage ./pthread-w32 { };
-
-    wxMSW = callPackage ./wxMSW-2.8 { };
-
-    libgnurx = callPackage ./libgnurx { };
+  mingw_w64 = callPackage ./mingw-w64 {
+    stdenv = crossLibcStdenv;
   };
-in self
+
+  mingw_w64_headers = callPackage ./mingw-w64/headers.nix { };
+
+  mingw_w64_pthreads = callPackage ./mingw-w64/pthreads.nix { };
+
+  pthreads = callPackage ./pthread-w32 { };
+
+  wxMSW = callPackage ./wxMSW-2.8 { };
+
+  libgnurx = callPackage ./libgnurx { };
+})

From 06c5e811e6e0244a8e5a9645fd8347c719aab228 Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Sun, 10 Nov 2019 22:35:59 -0500
Subject: [PATCH 04/10] mcfgthreads: Init from git

---
 pkgs/os-specific/windows/default.nix          | 22 +++++++++++++++++--
 .../windows/mcfgthreads/default.nix           | 19 ++++++++++++++++
 pkgs/top-level/all-packages.nix               |  2 +-
 3 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 pkgs/os-specific/windows/mcfgthreads/default.nix

diff --git a/pkgs/os-specific/windows/default.nix b/pkgs/os-specific/windows/default.nix
index 8c2f3ca5498..7f1634d5c0b 100644
--- a/pkgs/os-specific/windows/default.nix
+++ b/pkgs/os-specific/windows/default.nix
@@ -1,4 +1,6 @@
-{ stdenv, newScope, crossLibcStdenv }:
+{ stdenv, buildPackages
+, newScope, overrideCC, crossLibcStdenv, libcCross
+}:
 
 stdenv.lib.makeScope newScope (self: with self; {
 
@@ -15,9 +17,25 @@ stdenv.lib.makeScope newScope (self: with self; {
     stdenv = crossLibcStdenv;
   };
 
+  crossThreadsStdenv = overrideCC crossLibcStdenv
+    (if stdenv.hostPlatform.useLLVM or false
+     then buildPackages.llvmPackages_8.lldClangNoLibcxx
+     else buildPackages.gccCrossStageStatic.override (old: {
+       bintools = old.bintools.override {
+         libc = libcCross;
+       };
+       libc = libcCross;
+     }));
+
   mingw_w64_headers = callPackage ./mingw-w64/headers.nix { };
 
-  mingw_w64_pthreads = callPackage ./mingw-w64/pthreads.nix { };
+  mingw_w64_pthreads = callPackage ./mingw-w64/pthreads.nix {
+    stdenv = crossThreadsStdenv;
+  };
+
+  mcfgthreads = callPackage ./mcfgthreads {
+    stdenv = crossThreadsStdenv;
+  };
 
   pthreads = callPackage ./pthread-w32 { };
 
diff --git a/pkgs/os-specific/windows/mcfgthreads/default.nix b/pkgs/os-specific/windows/mcfgthreads/default.nix
new file mode 100644
index 00000000000..468e92a1e9d
--- /dev/null
+++ b/pkgs/os-specific/windows/mcfgthreads/default.nix
@@ -0,0 +1,19 @@
+{ stdenv, fetchFromGitHub, autoreconfHook }:
+
+stdenv.mkDerivation {
+  pname = "mcfgthreads";
+  version = "git";
+  src = fetchFromGitHub {
+    owner = "lhmouse";
+    repo = "mcfgthread";
+    rev = "9570e5ca7b98002d707c502c919d951bf256b9c6";
+    sha256 = "10y2x3x601a7c1hkd6zlr3xpfsnlr05xl28v23clf619756a5755";
+  };
+  # Don't want prebuilt binaries sneaking in.
+  postUnpack = ''
+    rm -r "$sourceRoot/debug" "$sourceRoot/release"
+  '';
+  nativeBuildInputs = [
+    autoreconfHook
+  ];
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 5a1b9cfab69..4ca16cc81e6 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -7577,7 +7577,7 @@ in
     ../development/compilers/gcc/libstdc++-hook.sh;
 
   crossLibcStdenv = overrideCC stdenv
-    (if stdenv.targetPlatform.useLLVM or false
+    (if stdenv.hostPlatform.useLLVM or false
      then buildPackages.llvmPackages_8.lldClangNoLibc
      else buildPackages.gccCrossStageStatic);
 

From 999ef20129cf0c4809a3d654f2378192f6b32ef1 Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 00:08:45 -0500
Subject: [PATCH 05/10] mingw-w64 libc: Multiple outputs and parallel builds

Also deduplicate more of the GCC derivations.
---
 .../development/compilers/gcc/4.8/default.nix | 25 +++++------------
 .../development/compilers/gcc/4.9/default.nix | 25 +++++------------
 pkgs/development/compilers/gcc/5/default.nix  | 25 +++++------------
 pkgs/development/compilers/gcc/6/default.nix  | 25 +++++------------
 pkgs/development/compilers/gcc/7/default.nix  | 25 +++++------------
 pkgs/development/compilers/gcc/8/default.nix  | 25 +++++------------
 pkgs/development/compilers/gcc/9/default.nix  | 25 +++++------------
 .../compilers/gcc/common/configure-flags.nix  |  2 +-
 .../gcc/common/extra-target-flags.nix         | 28 +++++++++++++++++++
 .../compilers/gcc/snapshot/default.nix        | 25 +++++------------
 .../os-specific/windows/mingw-w64/default.nix |  4 +++
 11 files changed, 89 insertions(+), 145 deletions(-)
 create mode 100644 pkgs/development/compilers/gcc/common/extra-target-flags.nix

diff --git a/pkgs/development/compilers/gcc/4.8/default.nix b/pkgs/development/compilers/gcc/4.8/default.nix
index 324599e4982..e8892e17b71 100644
--- a/pkgs/development/compilers/gcc/4.8/default.nix
+++ b/pkgs/development/compilers/gcc/4.8/default.nix
@@ -251,24 +251,13 @@ stdenv.mkDerivation ({
     ++ optionals javaAwtGtk [ gmp mpfr ]
   ));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/4.9/default.nix b/pkgs/development/compilers/gcc/4.9/default.nix
index 9d4d8a9b6ac..4f6d32b3317 100644
--- a/pkgs/development/compilers/gcc/4.9/default.nix
+++ b/pkgs/development/compilers/gcc/4.9/default.nix
@@ -257,24 +257,13 @@ stdenv.mkDerivation ({
     ++ optionals javaAwtGtk [ gmp mpfr ]
   ));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/5/default.nix b/pkgs/development/compilers/gcc/5/default.nix
index d809c6c4e36..3c8cdde8103 100644
--- a/pkgs/development/compilers/gcc/5/default.nix
+++ b/pkgs/development/compilers/gcc/5/default.nix
@@ -264,24 +264,13 @@ stdenv.mkDerivation ({
     ++ optionals javaAwtGtk [ gmp mpfr ]
   ));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/6/default.nix b/pkgs/development/compilers/gcc/6/default.nix
index 1eec43cb320..82cec33756d 100644
--- a/pkgs/development/compilers/gcc/6/default.nix
+++ b/pkgs/development/compilers/gcc/6/default.nix
@@ -266,24 +266,13 @@ stdenv.mkDerivation ({
     ++ optionals javaAwtGtk [ gmp mpfr ]
   ));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/7/default.nix b/pkgs/development/compilers/gcc/7/default.nix
index 7a4b0ed3222..c500bb477a2 100644
--- a/pkgs/development/compilers/gcc/7/default.nix
+++ b/pkgs/development/compilers/gcc/7/default.nix
@@ -230,24 +230,13 @@ stdenv.mkDerivation ({
 
   LIBRARY_PATH = optionals (targetPlatform == hostPlatform) (makeLibraryPath (optional (zlib != null) zlib));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/8/default.nix b/pkgs/development/compilers/gcc/8/default.nix
index c0df37bd5f8..6ce10a78427 100644
--- a/pkgs/development/compilers/gcc/8/default.nix
+++ b/pkgs/development/compilers/gcc/8/default.nix
@@ -212,24 +212,13 @@ stdenv.mkDerivation ({
 
   LIBRARY_PATH = optionals (targetPlatform == hostPlatform) (makeLibraryPath (optional (zlib != null) zlib));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/9/default.nix b/pkgs/development/compilers/gcc/9/default.nix
index 23a5eeafb8b..0e78cffdef2 100644
--- a/pkgs/development/compilers/gcc/9/default.nix
+++ b/pkgs/development/compilers/gcc/9/default.nix
@@ -211,24 +211,13 @@ stdenv.mkDerivation ({
 
   LIBRARY_PATH = optionals (targetPlatform == hostPlatform) (makeLibraryPath (optional (zlib != null) zlib));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/development/compilers/gcc/common/configure-flags.nix b/pkgs/development/compilers/gcc/common/configure-flags.nix
index 0707e087178..a0c9941e3c6 100644
--- a/pkgs/development/compilers/gcc/common/configure-flags.nix
+++ b/pkgs/development/compilers/gcc/common/configure-flags.nix
@@ -49,7 +49,7 @@ let
       "--disable-decimal-float" # requires libc
       "--disable-libmpx" # requires libc
     ] ++ lib.optionals crossMingw [
-      "--with-headers=${libcCross}/include"
+      "--with-headers=${lib.getDev libcCross}/include"
       "--with-gcc"
       "--with-gnu-as"
       "--with-gnu-ld"
diff --git a/pkgs/development/compilers/gcc/common/extra-target-flags.nix b/pkgs/development/compilers/gcc/common/extra-target-flags.nix
new file mode 100644
index 00000000000..1c2fad8fbc5
--- /dev/null
+++ b/pkgs/development/compilers/gcc/common/extra-target-flags.nix
@@ -0,0 +1,28 @@
+{ stdenv, crossStageStatic, libcCross }:
+
+let
+  inherit (stdenv) lib hostPlatform targetPlatform;
+in
+
+{
+  EXTRA_TARGET_FLAGS = let
+      mkFlags = dep: lib.optionals (targetPlatform != hostPlatform && dep != null) ([
+        "-idirafter ${lib.getDev dep}${dep.incdir or "/include"}"
+      ] ++ stdenv.lib.optionals (! crossStageStatic) [
+        "-B${lib.getLib dep}${dep.libdir or "/lib"}"
+      ]);
+    in mkFlags libcCross
+    ;
+
+  EXTRA_TARGET_LDFLAGS = let
+      mkFlags = dep: lib.optionals (targetPlatform != hostPlatform && dep != null) ([
+        "-Wl,-L${lib.getLib dep}${dep.libdir or "/lib"}"
+      ] ++ (if crossStageStatic then [
+          "-B${lib.getLib dep}${dep.libdir or "/lib"}"
+        ] else [
+          "-Wl,-rpath,${lib.getLib dep}${dep.libdir or "/lib"}"
+          "-Wl,-rpath-link,${lib.getLib dep}${dep.libdir or "/lib"}"
+      ]));
+    in mkFlags libcCross
+    ;
+}
diff --git a/pkgs/development/compilers/gcc/snapshot/default.nix b/pkgs/development/compilers/gcc/snapshot/default.nix
index d073edfb09c..f431df03549 100644
--- a/pkgs/development/compilers/gcc/snapshot/default.nix
+++ b/pkgs/development/compilers/gcc/snapshot/default.nix
@@ -184,24 +184,13 @@ stdenv.mkDerivation ({
 
   LIBRARY_PATH = optionals (targetPlatform == hostPlatform) (makeLibraryPath (optional (zlib != null) zlib));
 
-  EXTRA_TARGET_FLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-idirafter ${getDev libcCross}${libcCross.incdir or "/include"}"
-    ] ++ optionals (! crossStageStatic) [
-      "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]);
-
-  EXTRA_TARGET_LDFLAGS = optionals
-    (targetPlatform != hostPlatform && libcCross != null)
-    ([
-      "-Wl,-L${libcCross.out}${libcCross.libdir or "/lib"}"
-    ] ++ (if crossStageStatic then [
-        "-B${libcCross.out}${libcCross.libdir or "/lib"}"
-      ] else [
-        "-Wl,-rpath,${libcCross.out}${libcCross.libdir or "/lib"}"
-        "-Wl,-rpath-link,${libcCross.out}${libcCross.libdir or "/lib"}"
-    ]));
+  inherit
+    (import ../common/extra-target-flags.nix {
+      inherit stdenv crossStageStatic libcCross;
+    })
+    EXTRA_TARGET_FLAGS
+    EXTRA_TARGET_LDFLAGS
+    ;
 
   passthru = {
     inherit langC langCC langObjC langObjCpp langFortran langGo version;
diff --git a/pkgs/os-specific/windows/mingw-w64/default.nix b/pkgs/os-specific/windows/mingw-w64/default.nix
index 022aaffe596..7efc2e21313 100644
--- a/pkgs/os-specific/windows/mingw-w64/default.nix
+++ b/pkgs/os-specific/windows/mingw-w64/default.nix
@@ -11,11 +11,15 @@ in stdenv.mkDerivation {
     sha256 = "00zq3z1hbzd5yzmskskjg79xrzwsqx7ihyprfaxy4hb897vf29sm";
   };
 
+  outputs = [ "out" "dev" ];
+
   configureFlags = [
     "--enable-idl"
     "--enable-secure-api"
   ];
 
+  enableParallelBuilding = true;
+
   buildInputs = [ windows.mingw_w64_headers ];
   dontStrip = true;
   hardeningDisable = [ "stackprotector" "fortify" ];

From 04cb05d20c780f0cbe76eca6dfc2f08e741a1660 Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 00:23:32 -0500
Subject: [PATCH 06/10] gcc: Build MinGW stage two with threading library

Currently this is set up to be mcfgthreads, but it could be something
else instead.
---
 .../development/compilers/gcc/4.8/default.nix | 11 +++++++++--
 .../development/compilers/gcc/4.9/default.nix | 11 +++++++++--
 pkgs/development/compilers/gcc/5/default.nix  | 15 +++++++++++++--
 pkgs/development/compilers/gcc/6/default.nix  | 18 ++++++++++++++----
 pkgs/development/compilers/gcc/7/default.nix  | 17 ++++++++++++++---
 pkgs/development/compilers/gcc/8/default.nix  | 19 +++++++++++++++----
 pkgs/development/compilers/gcc/9/default.nix  | 19 +++++++++++++++----
 .../compilers/gcc/common/configure-flags.nix  |  2 +-
 .../gcc/common/extra-target-flags.nix         |  4 +++-
 .../gcc/common/mfcgthreads-patches-repo.nix   |  1 +
 .../compilers/gcc/snapshot/default.nix        | 19 +++++++++++++++----
 .../windows/mcfgthreads/default.nix           |  5 +++++
 pkgs/top-level/all-packages.nix               | 17 ++++++++++++++++-
 13 files changed, 130 insertions(+), 28 deletions(-)
 create mode 100644 pkgs/development/compilers/gcc/common/mfcgthreads-patches-repo.nix

diff --git a/pkgs/development/compilers/gcc/4.8/default.nix b/pkgs/development/compilers/gcc/4.8/default.nix
index e8892e17b71..eee2c1a97a8 100644
--- a/pkgs/development/compilers/gcc/4.8/default.nix
+++ b/pkgs/development/compilers/gcc/4.8/default.nix
@@ -23,6 +23,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -47,10 +48,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "4.8.5";
+let majorVersion = "4";
+    version = "${majorVersion}.8.5";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -171,6 +176,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   preConfigure = import ../common/pre-configure.nix {
     inherit (stdenv) lib;
     inherit version hostPlatform langJava langGo;
@@ -253,7 +260,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/4.9/default.nix b/pkgs/development/compilers/gcc/4.9/default.nix
index 4f6d32b3317..b4ac68be1a3 100644
--- a/pkgs/development/compilers/gcc/4.9/default.nix
+++ b/pkgs/development/compilers/gcc/4.9/default.nix
@@ -23,6 +23,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -47,10 +48,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "4.9.4";
+let majorVersion = "4";
+    version = "${majorVersion}.9.4";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -177,6 +182,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   preConfigure = import ../common/pre-configure.nix {
     inherit (stdenv) lib;
     inherit version hostPlatform langJava langGo;
@@ -259,7 +266,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/5/default.nix b/pkgs/development/compilers/gcc/5/default.nix
index 3c8cdde8103..cb327864f6e 100644
--- a/pkgs/development/compilers/gcc/5/default.nix
+++ b/pkgs/development/compilers/gcc/5/default.nix
@@ -23,6 +23,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -45,10 +46,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "5.5.0";
+let majorVersion = "5";
+    version = "${majorVersion}.5.0";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -61,6 +66,10 @@ let version = "5.5.0";
       ++ optional stdenv.hostPlatform.isMusl (fetchpatch {
         url = https://raw.githubusercontent.com/richfelker/musl-cross-make/e84b1bd1fc12a3def33111ca6df522cd6e5ec361/patches/gcc-5.3.0/0001-musl.diff;
         sha256 = "0pppbf8myi2kjhm3z3479ihn1cm60kycfv60gj8yy1bs0pl1qcfm";
+      })
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "074bl5n27d1ksa31pvzj4vd8xd46r118k0w94gdv3s1vydg7mah0";
       });
 
     javaEcj = fetchurl {
@@ -183,6 +192,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
   preConfigure = import ../common/pre-configure.nix {
@@ -266,7 +277,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/6/default.nix b/pkgs/development/compilers/gcc/6/default.nix
index 82cec33756d..2cecc5bbaa0 100644
--- a/pkgs/development/compilers/gcc/6/default.nix
+++ b/pkgs/development/compilers/gcc/6/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, targetPackages, fetchurl, noSysDirs
+{ stdenv, targetPackages, fetchurl, fetchpatch, noSysDirs
 , langC ? true, langCC ? true, langFortran ? false
 , langObjC ? stdenv.targetPlatform.isDarwin
 , langObjCpp ? stdenv.targetPlatform.isDarwin
@@ -23,6 +23,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -45,10 +46,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "6.5.0";
+let majorVersion = "6";
+    version = "${majorVersion}.5.0";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -58,7 +63,10 @@ let version = "6.5.0";
       ++ optional noSysDirs ../no-sys-dirs.patch
       ++ optional langFortran ../gfortran-driving.patch
       ++ optional (targetPlatform.libc == "musl") ../libgomp-dont-force-initial-exec.patch
-      ;
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "1c449jgm1vx9g4kv82bxmvlgrwb8f6kwkl0gqmjlmhf7f4hjy2nr";
+      });
 
     javaEcj = fetchurl {
       # The `$(top_srcdir)/ecj.jar' file is automatically picked up at
@@ -185,6 +193,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
   preConfigure = import ../common/pre-configure.nix {
@@ -268,7 +278,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/7/default.nix b/pkgs/development/compilers/gcc/7/default.nix
index c500bb477a2..c1592dbcb9b 100644
--- a/pkgs/development/compilers/gcc/7/default.nix
+++ b/pkgs/development/compilers/gcc/7/default.nix
@@ -16,6 +16,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -34,10 +35,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "7.4.0";
+let majorVersion = "7";
+    version = "${majorVersion}.4.0";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -58,7 +63,11 @@ let version = "7.4.0";
       })
       ++ optional langFortran ../gfortran-driving.patch
       ++ optional (targetPlatform.libc == "musl" && targetPlatform.isPower) ../ppc-musl.patch
-      ++ optional (targetPlatform.libc == "musl") ../libgomp-dont-force-initial-exec.patch;
+      ++ optional (targetPlatform.libc == "musl") ../libgomp-dont-force-initial-exec.patch
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "1nyjnshpq5gbcbbpfv27hy4ajvycmgkpiabkjlxnnrnq1d99k1ay";
+      });
 
     /* Cross-gcc settings (build == host != target) */
     crossMingw = targetPlatform != hostPlatform && targetPlatform.libc == "msvcrt";
@@ -160,6 +169,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_CFLAGS_COMPILE = stdenv.lib.optionalString (stdenv.cc.isClang && langFortran) "-Wno-unused-command-line-argument";
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
@@ -232,7 +243,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/8/default.nix b/pkgs/development/compilers/gcc/8/default.nix
index 6ce10a78427..2f222a8bc94 100644
--- a/pkgs/development/compilers/gcc/8/default.nix
+++ b/pkgs/development/compilers/gcc/8/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, targetPackages, fetchurl, noSysDirs
+{ stdenv, targetPackages, fetchurl, fetchpatch, noSysDirs
 , langC ? true, langCC ? true, langFortran ? false
 , langObjC ? stdenv.targetPlatform.isDarwin
 , langObjCpp ? stdenv.targetPlatform.isDarwin
@@ -16,6 +16,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -34,10 +35,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "8.3.0";
+let majorVersion = "8";
+    version = "${majorVersion}.3.0";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -50,7 +55,11 @@ let version = "8.3.0";
       }) */
       ++ optional langFortran ../gfortran-driving.patch
       ++ optional (targetPlatform.libc == "musl" && targetPlatform.isPower) ../ppc-musl.patch
-      ++ optional (targetPlatform.libc == "musl") ../libgomp-dont-force-initial-exec.patch;
+      ++ optional (targetPlatform.libc == "musl") ../libgomp-dont-force-initial-exec.patch
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "1in5kvcknlpi9z1vvjw6jfmwy8k12zvbqlqfnq84qpm99r0rh00a";
+      });
 
     /* Cross-gcc settings (build == host != target) */
     crossMingw = targetPlatform != hostPlatform && targetPlatform.libc == "msvcrt";
@@ -147,6 +156,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
   preConfigure = import ../common/pre-configure.nix {
@@ -214,7 +225,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/9/default.nix b/pkgs/development/compilers/gcc/9/default.nix
index 0e78cffdef2..1fdba1baa29 100644
--- a/pkgs/development/compilers/gcc/9/default.nix
+++ b/pkgs/development/compilers/gcc/9/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, targetPackages, fetchurl, noSysDirs
+{ stdenv, targetPackages, fetchurl, fetchpatch, noSysDirs
 , langC ? true, langCC ? true, langFortran ? false
 , langObjC ? stdenv.targetPlatform.isDarwin
 , langObjCpp ? stdenv.targetPlatform.isDarwin
@@ -16,6 +16,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -34,10 +35,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "9.2.0";
+let majorVersion = "9";
+    version = "${majorVersion}.2.0";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -49,7 +54,11 @@ let version = "9.2.0";
         sha256 = ""; # TODO: uncomment and check hash when available.
       }) */
       ++ optional langFortran ../gfortran-driving.patch
-      ++ optional (targetPlatform.libc == "musl" && targetPlatform.isPower) ../ppc-musl.patch;
+      ++ optional (targetPlatform.libc == "musl" && targetPlatform.isPower) ../ppc-musl.patch
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "1in5kvcknlpi9z1vvjw6jfmwy8k12zvbqlqfnq84qpm99r0rh00a";
+      });
 
     /* Cross-gcc settings (build == host != target) */
     crossMingw = targetPlatform != hostPlatform && targetPlatform.libc == "msvcrt";
@@ -146,6 +155,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
   preConfigure = import ../common/pre-configure.nix {
@@ -213,7 +224,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/development/compilers/gcc/common/configure-flags.nix b/pkgs/development/compilers/gcc/common/configure-flags.nix
index a0c9941e3c6..96026a2d932 100644
--- a/pkgs/development/compilers/gcc/common/configure-flags.nix
+++ b/pkgs/development/compilers/gcc/common/configure-flags.nix
@@ -62,7 +62,7 @@ let
       "--enable-__cxa_atexit"
       "--enable-long-long"
       "--enable-threads=${if targetPlatform.isUnix then "posix"
-                          else if targetPlatform.isWindows then "win32"
+                          else if targetPlatform.isWindows then "mcf"
                           else "single"}"
       "--enable-nls"
       "--disable-decimal-float" # No final libdecnumber (it may work only in 386)
diff --git a/pkgs/development/compilers/gcc/common/extra-target-flags.nix b/pkgs/development/compilers/gcc/common/extra-target-flags.nix
index 1c2fad8fbc5..bce9a8d4738 100644
--- a/pkgs/development/compilers/gcc/common/extra-target-flags.nix
+++ b/pkgs/development/compilers/gcc/common/extra-target-flags.nix
@@ -1,4 +1,4 @@
-{ stdenv, crossStageStatic, libcCross }:
+{ stdenv, crossStageStatic, libcCross, threadsCross }:
 
 let
   inherit (stdenv) lib hostPlatform targetPlatform;
@@ -12,6 +12,7 @@ in
         "-B${lib.getLib dep}${dep.libdir or "/lib"}"
       ]);
     in mkFlags libcCross
+    ++ lib.optionals (!crossStageStatic) (mkFlags threadsCross)
     ;
 
   EXTRA_TARGET_LDFLAGS = let
@@ -24,5 +25,6 @@ in
           "-Wl,-rpath-link,${lib.getLib dep}${dep.libdir or "/lib"}"
       ]));
     in mkFlags libcCross
+    ++ lib.optionals (!crossStageStatic) (mkFlags threadsCross)
     ;
 }
diff --git a/pkgs/development/compilers/gcc/common/mfcgthreads-patches-repo.nix b/pkgs/development/compilers/gcc/common/mfcgthreads-patches-repo.nix
new file mode 100644
index 00000000000..f8822c6dba0
--- /dev/null
+++ b/pkgs/development/compilers/gcc/common/mfcgthreads-patches-repo.nix
@@ -0,0 +1 @@
+"740f233da00c4fb5bcc225b2e29768824bcecc58"
diff --git a/pkgs/development/compilers/gcc/snapshot/default.nix b/pkgs/development/compilers/gcc/snapshot/default.nix
index f431df03549..0519f04629e 100644
--- a/pkgs/development/compilers/gcc/snapshot/default.nix
+++ b/pkgs/development/compilers/gcc/snapshot/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, targetPackages, fetchurl, noSysDirs
+{ stdenv, targetPackages, fetchurl, fetchpatch, noSysDirs
 , langC ? true, langCC ? true, langFortran ? false
 , langObjC ? stdenv.targetPlatform.isDarwin
 , langObjCpp ? stdenv.targetPlatform.isDarwin
@@ -16,6 +16,7 @@
 , enablePlugin ? stdenv.hostPlatform == stdenv.buildPlatform # Whether to support user-supplied plug-ins
 , name ? "gcc"
 , libcCross ? null
+, threadsCross ? null # for MinGW
 , crossStageStatic ? false
 , # Strip kills static libs of other archs (hence no cross)
   stripped ? stdenv.hostPlatform == stdenv.buildPlatform
@@ -35,10 +36,14 @@ assert stdenv.hostPlatform.isDarwin -> gnused != null;
 # The go frontend is written in c++
 assert langGo -> langCC;
 
+# threadsCross is just for MinGW
+assert threadsCross != null -> stdenv.targetPlatform.isWindows;
+
 with stdenv.lib;
 with builtins;
 
-let version = "7-20170409";
+let majorVersion = "7";
+    version = "${majorVersion}-20170409";
 
     inherit (stdenv) buildPlatform hostPlatform targetPlatform;
 
@@ -46,7 +51,11 @@ let version = "7-20170409";
       [ ]
       ++ optional (targetPlatform != hostPlatform) ../libstdc++-target.patch
       ++ optional noSysDirs ../no-sys-dirs.patch
-      ++ optional langFortran ../gfortran-driving.patch;
+      ++ optional langFortran ../gfortran-driving.patch
+      ++ optional (!crossStageStatic && targetPlatform.isMinGW) (fetchpatch {
+        url = "https://raw.githubusercontent.com/lhmouse/MINGW-packages/${import ../common/mfcgthreads-patches-repo.nix}/mingw-w64-gcc-git/9000-gcc-${majorVersion}-branch-Added-mcf-thread-model-support-from-mcfgthread.patch";
+        sha256 = "1nyjnshpq5gbcbbpfv27hy4ajvycmgkpiabkjlxnnrnq1d99k1ay";
+      });
 
     /* Cross-gcc settings (build == host != target) */
     crossMingw = targetPlatform != hostPlatform && targetPlatform.libc == "msvcrt";
@@ -118,6 +127,8 @@ stdenv.mkDerivation ({
     ++ (optional hostPlatform.isDarwin gnused)
     ;
 
+  depsTargetTarget = optional (!crossStageStatic && threadsCross != null) threadsCross;
+
   NIX_LDFLAGS = stdenv.lib.optionalString  hostPlatform.isSunOS "-lm -ldl";
 
   preConfigure = import ../common/pre-configure.nix {
@@ -186,7 +197,7 @@ stdenv.mkDerivation ({
 
   inherit
     (import ../common/extra-target-flags.nix {
-      inherit stdenv crossStageStatic libcCross;
+      inherit stdenv crossStageStatic libcCross threadsCross;
     })
     EXTRA_TARGET_FLAGS
     EXTRA_TARGET_LDFLAGS
diff --git a/pkgs/os-specific/windows/mcfgthreads/default.nix b/pkgs/os-specific/windows/mcfgthreads/default.nix
index 468e92a1e9d..6c4cd171025 100644
--- a/pkgs/os-specific/windows/mcfgthreads/default.nix
+++ b/pkgs/os-specific/windows/mcfgthreads/default.nix
@@ -3,16 +3,21 @@
 stdenv.mkDerivation {
   pname = "mcfgthreads";
   version = "git";
+
   src = fetchFromGitHub {
     owner = "lhmouse";
     repo = "mcfgthread";
     rev = "9570e5ca7b98002d707c502c919d951bf256b9c6";
     sha256 = "10y2x3x601a7c1hkd6zlr3xpfsnlr05xl28v23clf619756a5755";
   };
+
+  outputs = [ "out" "dev" ];
+
   # Don't want prebuilt binaries sneaking in.
   postUnpack = ''
     rm -r "$sourceRoot/debug" "$sourceRoot/release"
   '';
+
   nativeBuildInputs = [
     autoreconfHook
   ];
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 4ca16cc81e6..c524add8b05 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -7610,6 +7610,7 @@ in
       };
       bintools = binutils1;
       libc = libcCross1;
+      extraPackages = [];
   };
 
   gcc48 = lowPrio (wrapCC (callPackage ../development/compilers/gcc/4.8 {
@@ -7619,6 +7620,7 @@ in
     profiledCompiler = with stdenv; (!isSunOS && !isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_14 else null;
     cloog = if !stdenv.isDarwin then cloog else null;
@@ -7632,6 +7634,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_11 else null;
 
@@ -7645,6 +7648,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_14 else null;
   }));
@@ -7656,6 +7660,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_14 else null;
   }));
@@ -7667,6 +7672,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_17 else null;
   }));
@@ -7678,6 +7684,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_17 else null;
   }));
@@ -7689,6 +7696,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = if !stdenv.isDarwin then isl_0_17 else null;
   }));
@@ -7700,6 +7708,7 @@ in
     profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
 
     libcCross = if stdenv.targetPlatform != stdenv.buildPlatform then libcCross else null;
+    threadsCross = if stdenv.targetPlatform != stdenv.buildPlatform then threadsCross else null;
 
     isl = isl_0_17;
   }));
@@ -8497,6 +8506,7 @@ in
       # provide the default choice, avoiding infinite recursion.
       bintools ? if stdenv.targetPlatform.isDarwin then darwin.binutils else binutils
     , libc ? bintools.libc
+    , extraPackages ? stdenv.lib.optional (cc.isGNU or false && stdenv.targetPlatform.isMinGW) threadsCross
     , ...
     } @ extraArgs:
       callPackage ../build-support/cc-wrapper (let self = {
@@ -8508,7 +8518,7 @@ in
     isGNU = cc.isGNU or false;
     isClang = cc.isClang or false;
 
-    inherit cc bintools libc;
+    inherit cc bintools libc extraPackages;
   } // extraArgs; in self);
 
   wrapCC = cc: wrapCCWith {
@@ -10973,6 +10983,11 @@ in
 
   libcCross = assert stdenv.targetPlatform != stdenv.buildPlatform; libcCrossChooser stdenv.targetPlatform.libc;
 
+  threadsCross =
+    if stdenv.targetPlatform.isMinGW && !(stdenv.targetPlatform.useLLVM or false)
+    then targetPackages.windows.mcfgthreads or windows.mcfgthreads
+    else null;
+
   wasilibc = callPackage ../development/libraries/wasilibc {
     stdenv = crossLibcStdenv;
   };

From 89ec69e25eec35b64e8fd384e3ff0ef53a419cbb Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 00:26:23 -0500
Subject: [PATCH 07/10] pcre: Skip winpthread dep

Seems to build just fine without it, maybe it was just using C++ threads
which mcfgthread provides?
---
 pkgs/development/libraries/pcre/default.nix | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pkgs/development/libraries/pcre/default.nix b/pkgs/development/libraries/pcre/default.nix
index 2e111240758..cf08f989369 100644
--- a/pkgs/development/libraries/pcre/default.nix
+++ b/pkgs/development/libraries/pcre/default.nix
@@ -29,8 +29,6 @@ in stdenv.mkDerivation {
   ]
     ++ optional (variant != null) "--enable-${variant}";
 
-  buildInputs = optional (stdenv.hostPlatform.libc == "msvcrt") windows.mingw_w64_pthreads;
-
   # https://bugs.exim.org/show_bug.cgi?id=2173
   patches = [ ./stacksize-detection.patch ];
 

From e00237e79086b6187c019a4d88f1eec2014972b4 Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 13:53:02 -0500
Subject: [PATCH 08/10] boehm-gc: Fix build on MinGW with mcfgthreads

CC @lhmouse
---
 pkgs/development/libraries/boehm-gc/default.nix      |  8 +++++++-
 pkgs/development/libraries/boehm-gc/mcfgthread.patch | 11 +++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 pkgs/development/libraries/boehm-gc/mcfgthread.patch

diff --git a/pkgs/development/libraries/boehm-gc/default.nix b/pkgs/development/libraries/boehm-gc/default.nix
index cf76d9e7d24..f03a1385cf3 100644
--- a/pkgs/development/libraries/boehm-gc/default.nix
+++ b/pkgs/development/libraries/boehm-gc/default.nix
@@ -1,4 +1,5 @@
 { lib, stdenv, fetchurl
+, autoreconfHook
 , enableLargeConfig ? false # doc: https://github.com/ivmai/bdwgc/blob/v7.6.6/doc/README.macros#L179
 }:
 
@@ -23,13 +24,18 @@ stdenv.mkDerivation rec {
 
   patches =
     # https://github.com/ivmai/bdwgc/pull/208
-    lib.optional stdenv.hostPlatform.isRiscV ./riscv.patch;
+    lib.optional stdenv.hostPlatform.isRiscV ./riscv.patch
+    # boehm-gc whitelists GCC threading models
+    ++ lib.optional stdenv.hostPlatform.isMinGW ./mcfgthread.patch;
 
   configureFlags =
     [ "--enable-cplusplus" "--with-libatomic-ops=none" ]
     ++ lib.optional enableLargeConfig "--enable-large-config"
     ++ lib.optional (stdenv.hostPlatform.libc == "musl") "--disable-static";
 
+  nativeBuildInputs =
+    lib.optional stdenv.hostPlatform.isMinGW autoreconfHook;
+
   doCheck = true; # not cross;
 
   enableParallelBuilding = true;
diff --git a/pkgs/development/libraries/boehm-gc/mcfgthread.patch b/pkgs/development/libraries/boehm-gc/mcfgthread.patch
new file mode 100644
index 00000000000..c4aa996aebd
--- /dev/null
+++ b/pkgs/development/libraries/boehm-gc/mcfgthread.patch
@@ -0,0 +1,11 @@
+--- a/configure.ac
++++ b/configure.ac
+@@ -277,7 +277,7 @@ case "$THREADS" in
+         ;;
+     esac
+     ;;
+- win32)
++ win32 | mcf)
+     AC_DEFINE(GC_THREADS)
+     use_parallel_mark=$enable_parallel_mark
+     if test "${enable_parallel_mark}" != no \

From dec8d2c5daa9988b1679811a35bf8a385bf8a37f Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 13:56:14 -0500
Subject: [PATCH 09/10] openssl: Switch deafult for MinGW

Working around broken build for now.
---
 pkgs/top-level/all-packages.nix | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index c524add8b05..9fe66cd96b3 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -12954,7 +12954,10 @@ in
 
   wolfssl = callPackage ../development/libraries/wolfssl { };
 
-  openssl = openssl_1_1;
+  openssl =
+    if stdenv.hostPlatform.isMinGW # Work around broken cross build
+    then openssl_1_0_2
+    else openssl_1_1;
 
   inherit (callPackages ../development/libraries/openssl { })
     openssl_1_0_2

From 63eac673199d78b2dcd061904811445addad3822 Mon Sep 17 00:00:00 2001
From: John Ericson <git@JohnEricson.me>
Date: Mon, 11 Nov 2019 14:07:37 -0500
Subject: [PATCH 10/10] nghttp2: Fix MinGW build by skipping some optional deps

I think those deps could be made to build, but I didn't want to get
bogged down investigating further. "Use flags" are always a good thing,
so this is fine for now.
---
 pkgs/development/libraries/nghttp2/default.nix | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/libraries/nghttp2/default.nix b/pkgs/development/libraries/nghttp2/default.nix
index d02247196b1..04018f0e80b 100644
--- a/pkgs/development/libraries/nghttp2/default.nix
+++ b/pkgs/development/libraries/nghttp2/default.nix
@@ -1,7 +1,9 @@
 { stdenv, fetchurl, pkgconfig
 
 # Optional Dependencies
-, openssl ? null, libev ? null, zlib ? null, c-ares ? null
+, openssl ? null, zlib ? null
+, enableLibEv ? !stdenv.hostPlatform.isWindows, libev ? null
+, enableCAres ? !stdenv.hostPlatform.isWindows, c-ares ? null
 , enableHpack ? false, jansson ? null
 , enableAsioLib ? false, boost ? null
 , enableGetAssets ? false, libxml2 ? null
@@ -28,7 +30,10 @@ stdenv.mkDerivation rec {
   outputs = [ "bin" "out" "dev" "lib" ];
 
   nativeBuildInputs = [ pkgconfig ];
-  buildInputs = [ openssl libev zlib c-ares ]
+  buildInputs = [ openssl ]
+    ++ optional enableLibEv libev
+    ++ [ zlib ]
+    ++ optional enableCAres c-ares
     ++ optional enableHpack jansson
     ++ optional enableAsioLib boost
     ++ optional enableGetAssets libxml2