wasm: init cross target

Adds pkgsCross.wasm32 and pkgsCross.wasm64. Use it to build Nixpkgs
with a WebAssembly toolchain.

stdenv/cross: use static overlay on isWasm

isWasm doesn’t make sense dynamically linked.

lib/systems/default.nix

@@ -30,6 +30,7 @@ rec {
       libc =
         /**/ if final.isDarwin              then "libSystem"
         else if final.isMinGW               then "msvcrt"
+        else if final.isWasi                then "wasilibc"
         else if final.isMusl                then "musl"
         else if final.isUClibc              then "uclibc"
         else if final.isAndroid             then "bionic"
@@ -62,7 +63,7 @@ rec {
           "netbsd" = "NetBSD";
           "freebsd" = "FreeBSD";
           "openbsd" = "OpenBSD";
-          "wasm" = "Wasm";
+          "wasi" = "Wasi";
         }.${final.parsed.kernel.name} or null;
 
          # uname -p

lib/systems/doubles.nix

@@ -17,6 +17,8 @@ let
     "x86_64-netbsd" "x86_64-openbsd" "x86_64-solaris"
 
     "x86_64-windows" "i686-windows"
+
+    "wasm64-wasi" "wasm32-wasi"
   ];
 
   allParsed = map parse.mkSystemFromString all;
@@ -45,6 +47,7 @@ in rec {
   netbsd  = filterDoubles predicates.isNetBSD;
   openbsd = filterDoubles predicates.isOpenBSD;
   unix    = filterDoubles predicates.isUnix;
+  wasi    = filterDoubles predicates.isWasi;
   windows = filterDoubles predicates.isWindows;
 
   mesaPlatforms = ["i686-linux" "x86_64-linux" "x86_64-darwin" "armv5tel-linux" "armv6l-linux" "armv7l-linux" "armv7a-linux" "aarch64-linux" "powerpc64le-linux"];

lib/systems/examples.nix

@@ -211,4 +211,14 @@ rec {
     config = "x86_64-unknown-netbsd";
     libc = "nblibc";
   };
+
+  #
+  # WASM
+  #
+
+  wasi32 = {
+    config = "wasm32-unknown-wasi";
+    useLLVM = true;
+  };
+
 }

lib/systems/for-meta.nix

@@ -32,6 +32,7 @@ in rec {
   openbsd = [ patterns.isOpenBSD ];
   unix    = patterns.isUnix; # Actually a list
   windows = [ patterns.isWindows ];
+  wasi    = [ patterns.isWasi ];
 
   inherit (lib.systems.doubles) mesaPlatforms;
 }

lib/systems/inspect.nix

@@ -43,9 +43,10 @@ rec {
     isWindows      = { kernel = kernels.windows; };
     isCygwin       = { kernel = kernels.windows; abi = abis.cygnus; };
     isMinGW        = { kernel = kernels.windows; abi = abis.gnu; };
+    isWasi         = { kernel = kernels.wasi; };
 
     isAndroid      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
-    isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
+    isMusl         = (with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ]) ++ [{ kernel = kernels.wasi; }];
     isUClibc       = with abis; map (a: { abi = a; }) [ uclibc uclibceabi uclibceabihf ];
 
     isEfi          = map (family: { cpu.family = family; })

lib/systems/parse.nix

@@ -226,6 +226,7 @@ rec {
     elf = {};
     macho = {};
     pe = {};
+    wasm = {};
 
     unknown = {};
   };
@@ -268,6 +269,7 @@ rec {
     none    = { execFormat = unknown; families = { }; };
     openbsd = { execFormat = elf;     families = { inherit bsd; }; };
     solaris = { execFormat = elf;     families = { }; };
+    wasi    = { execFormat = wasm;    families = { }; };
     windows = { execFormat = pe;      families = { }; };
   } // { # aliases
     # 'darwin' is the kernel for all of them. We choose macOS by default.
@@ -376,6 +378,8 @@ rec {
         then { cpu = elemAt l 0;                      kernel = elemAt l 1; abi = elemAt l 2; }
       else if (elemAt l 2 == "mingw32") # autotools breaks on -gnu for window
         then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "windows";                    }
+      else if (elemAt l 2 == "wasi")
+        then { cpu = elemAt l 0; vendor = elemAt l 1; kernel = "wasi";                       }
       else if hasPrefix "netbsd" (elemAt l 2)
         then { cpu = elemAt l 0; vendor = elemAt l 1;    kernel = elemAt l 2;                }
       else if (elem (elemAt l 2) ["eabi" "eabihf" "elf"])

pkgs/build-support/bintools-wrapper/default.nix

@@ -191,7 +191,8 @@ stdenv.mkDerivation {
       else if targetPlatform.isAvr then "avr"
       else if targetPlatform.isAlpha then "alpha"
       else throw "unknown emulation for platform: ${targetPlatform.config}";
-    in targetPlatform.platform.bfdEmulation or (fmt + sep + arch);
+    in if targetPlatform.useLLVM or false then ""
+       else targetPlatform.platform.bfdEmulation or (fmt + sep + arch);
 
   strictDeps = true;
   depsTargetTargetPropagated = extraPackages;

pkgs/build-support/cc-wrapper/default.nix

@@ -299,6 +299,12 @@ stdenv.mkDerivation {
       hardening_unsupported_flags+=" stackprotector fortify pie pic"
     ''
 
+    + optionalString targetPlatform.isWasm ''
+      hardening_unsupported_flags+=" stackprotector fortify pie pic"
+    '' + optionalString (targetPlatform.isWasm && libc != null) ''
+      echo "--allow-undefined-file=${libc}/share/wasm32-wasi/undefined-symbols.txt" >> $out/nix-support/cc-ldflags
+    ''
+
     + optionalString (libc != null && targetPlatform.isAvr) ''
       for isa in avr5 avr3 avr4 avr6 avr25 avr31 avr35 avr51 avrxmega2 avrxmega4 avrxmega5 avrxmega6 avrxmega7 tiny-stack; do
         echo "-B${getLib libc}/avr/lib/$isa" >> $out/nix-support/libc-cflags

pkgs/development/compilers/llvm/8/compiler-rt.nix

@@ -60,7 +60,11 @@ stdenv.mkDerivation rec {
     ln -s $out/lib/*/clang_rt.crtend-*.o $out/lib/crtend.o
     ln -s $out/lib/*/clang_rt.crtbegin_shared-*.o $out/lib/crtbeginS.o
     ln -s $out/lib/*/clang_rt.crtend_shared-*.o $out/lib/crtendS.o
+  '' + stdenv.lib.optionalString stdenv.hostPlatform.isWasm ''
+    ln -s $out/lib/*/* $out/lib
   '';
 
+  NIX_LDFLAGS = stdenv.lib.optionalString stdenv.hostPlatform.isWasm "--allow-undefined --no-entry";
+
   enableParallelBuilding = true;
 }

pkgs/development/compilers/llvm/8/default.nix

@@ -97,12 +97,14 @@ let
         targetLlvmLibraries.libcxx
         targetLlvmLibraries.libcxxabi
         targetLlvmLibraries.compiler-rt
+      ] ++ stdenv.lib.optionals (!stdenv.targetPlatform.isWasm) [
         targetLlvmLibraries.libunwind
       ];
       extraBuildCommands = ''
         echo "-target ${stdenv.targetPlatform.config}" >> $out/nix-support/cc-cflags
         echo "-rtlib=compiler-rt -Wno-unused-command-line-argument" >> $out/nix-support/cc-cflags
         echo "-B${targetLlvmLibraries.compiler-rt}/lib" >> $out/nix-support/cc-cflags
+      '' + stdenv.lib.optionalString (!stdenv.targetPlatform.isWasm) ''
         echo "--unwindlib=libunwind" >> $out/nix-support/cc-cflags
       '' + mkExtraBuildCommands cc;
     };

pkgs/development/compilers/llvm/8/libc++/default.nix

@@ -1,4 +1,5 @@
-{ lib, stdenv, fetch, cmake, python, libcxxabi, fixDarwinDylibNames, version }:
+{ lib, stdenv, fetch, cmake, python, libcxxabi, fixDarwinDylibNames, version
+, enableShared ? true }:
 
 stdenv.mkDerivation rec {
   name = "libc++-${version}";
@@ -31,7 +32,11 @@ stdenv.mkDerivation rec {
     "-DLIBCXX_LIBCPPABI_VERSION=2"
     "-DLIBCXX_CXX_ABI=libcxxabi"
   ] ++ stdenv.lib.optional stdenv.hostPlatform.isMusl "-DLIBCXX_HAS_MUSL_LIBC=1"
-    ++ stdenv.lib.optional (stdenv.hostPlatform.useLLVM or false) "-DLIBCXX_USE_COMPILER_RT=ON";
+    ++ stdenv.lib.optional (stdenv.hostPlatform.useLLVM or false) "-DLIBCXX_USE_COMPILER_RT=ON"
+    ++ stdenv.lib.optional stdenv.hostPlatform.isWasm [
+      "-DLIBCXX_ENABLE_THREADS=OFF"
+      "-DLIBCXX_ENABLE_FILESYSTEM=OFF"
+    ] ++ stdenv.lib.optional (!enableShared) "-DLIBCXX_ENABLE_SHARED=OFF";
 
   enableParallelBuilding = true;
 
@@ -46,6 +51,6 @@ stdenv.mkDerivation rec {
     homepage = http://libcxx.llvm.org/;
     description = "A new implementation of the C++ standard library, targeting C++11";
     license = with stdenv.lib.licenses; [ ncsa mit ];
-    platforms = stdenv.lib.platforms.unix;
+    platforms = stdenv.lib.platforms.all;
   };
 }

pkgs/development/compilers/llvm/8/libc++abi.nix

@@ -1,4 +1,5 @@
-{ stdenv, cmake, fetch, libcxx, libunwind, llvm, version }:
+{ stdenv, cmake, fetch, libcxx, libunwind, llvm, version
+, enableShared ? true }:
 
 stdenv.mkDerivation {
   name = "libc++abi-${version}";
@@ -6,13 +7,20 @@ stdenv.mkDerivation {
   src = fetch "libcxxabi" "1k875f977ybdkpdnr9105wa6hccy9qvpd9xd42n75h7p56bdxmn2";
 
   nativeBuildInputs = [ cmake ];
-  buildInputs = stdenv.lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD) libunwind;
+  buildInputs = stdenv.lib.optional (!stdenv.isDarwin && !stdenv.isFreeBSD && !stdenv.hostPlatform.isWasm) libunwind;
 
   cmakeFlags = stdenv.lib.optionals (stdenv.hostPlatform.useLLVM or false) [
     "-DLLVM_ENABLE_LIBCXX=ON"
     "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
+  ] ++ stdenv.lib.optionals stdenv.hostPlatform.isWasm [
+    "-DUNIX=ON"
+    "-DLIBCXXABI_ENABLE_THREADS=OFF"
+  ] ++ stdenv.lib.optionals (!enableShared) [
+    "-DLIBCXXABI_ENABLE_SHARED=OFF"
   ];
 
+  patches = [ ./libcxxabi-no-threads.patch ];
+
   postUnpack = ''
     unpackFile ${libcxx.src}
     unpackFile ${llvm.src}
@@ -39,8 +47,9 @@ stdenv.mkDerivation {
     else ''
       install -d -m 755 $out/include $out/lib
       install -m 644 lib/libc++abi.a $out/lib
-      install -m 644 lib/libc++abi.so.1.0 $out/lib
       install -m 644 ../include/cxxabi.h $out/include
+    '' + stdenv.lib.optionalString enableShared ''
+      install -m 644 lib/libc++abi.so.1.0 $out/lib
       ln -s libc++abi.so.1.0 $out/lib/libc++abi.so
       ln -s libc++abi.so.1.0 $out/lib/libc++abi.so.1
     '';
@@ -50,6 +59,6 @@ stdenv.mkDerivation {
     description = "A new implementation of low level support for a standard C++ library";
     license = with stdenv.lib.licenses; [ ncsa mit ];
     maintainers = with stdenv.lib.maintainers; [ vlstill ];
-    platforms = stdenv.lib.platforms.unix;
+    platforms = stdenv.lib.platforms.all;
   };
 }

pkgs/development/compilers/llvm/8/libcxxabi-no-threads.patch

@@ -0,0 +1,12 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 4138acf..41b4763 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -362,6 +362,7 @@ if (NOT LIBCXXABI_ENABLE_THREADS)
+                         " is also set to ON.")
+   endif()
+   add_definitions(-D_LIBCXXABI_HAS_NO_THREADS)
++  add_definitions(-D_LIBCPP_HAS_NO_THREADS)
+ endif()
+ 
+ if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)

pkgs/development/libraries/wasilibc/default.nix

@@ -0,0 +1,28 @@
+{ stdenv, fetchFromGitHub, lib }:
+
+stdenv.mkDerivation {
+  name = "wasilibc-20190413";
+  src = fetchFromGitHub {
+    owner = "CraneStation";
+    repo = "wasi-sysroot";
+    rev = "079d7bda78bc0ad8f69c1594444b54786545ce57";
+    sha256 = "09s906bc9485wzkgibnpfh0mii7jkldzr1a6g8k7ch0si8rshi5r";
+  };
+  makeFlags = [
+    "WASM_CC=${stdenv.cc.targetPrefix}cc"
+    "WASM_NM=${stdenv.cc.targetPrefix}nm"
+    "WASM_AR=${stdenv.cc.targetPrefix}ar"
+    "INSTALL_DIR=${placeholder "out"}"
+  ];
+
+  postInstall = ''
+    mv $out/lib/*/* $out/lib
+  '';
+
+  meta = {
+    description = "WASI libc implementation for WebAssembly";
+    homepage    = "https://wasi.dev";
+    platforms   = lib.platforms.wasi;
+    maintainers = [ lib.maintainers.matthewbauer ];
+  };
+}

pkgs/stdenv/cross/default.nix

@@ -37,7 +37,8 @@ in lib.init bootStages ++ [
   # Run Packages
   (buildPackages: {
     inherit config;
-    overlays = overlays ++ crossOverlays;
+    overlays = overlays ++ crossOverlays
+      ++ (if crossSystem.isWasm then [(import ../../top-level/static.nix)] else []);
     selfBuild = false;
     stdenv = buildPackages.stdenv.override (old: rec {
       buildPlatform = localSystem;

pkgs/stdenv/generic/default.nix

@@ -91,6 +91,9 @@ let
       '' + lib.optionalString hostPlatform.isDarwin ''
         export NIX_DONT_SET_RPATH=1
         export NIX_NO_SELF_RPATH=1
+      '' + lib.optionalString (hostPlatform.parsed.kernel.execFormat != lib.systems.parse.execFormats.elf && hostPlatform.parsed.kernel.execFormat != lib.systems.parse.execFormats.macho) ''
+        export NIX_DONT_SET_RPATH=1
+        export NIX_NO_SELF_RPATH=1
       ''
       # TODO this should be uncommented, but it causes stupid mass rebuilds. I
       # think the best solution would just be to fixup linux RPATHs so we don't

pkgs/test/cross/default.nix

@@ -93,8 +93,7 @@ let
 
   };
 
-in (lib.mapAttrs (_: mapMultiPlatformTest builtins.id) tests)
-// (lib.mapAttrs' (name: test: {
-    name = "${name}-llvm";
-    value = mapMultiPlatformTest (system: system // {useLLVM = true;}) test;
-  }) tests)
+in {
+  gcc = (lib.mapAttrs (_: mapMultiPlatformTest (system: system // {useLLVM = false;})) tests);
+  llvm = (lib.mapAttrs (_: mapMultiPlatformTest (system: system // {useLLVM = true;})) tests);
+}

pkgs/top-level/all-packages.nix

@@ -10311,10 +10311,15 @@ in
     else if stdenv.targetPlatform.useiOSPrebuilt then targetPackages.darwin.iosSdkPkgs.libraries or darwin.iosSdkPkgs.libraries
     else if name == "libSystem" then targetPackages.darwin.xcode
     else if name == "nblibc" then targetPackages.netbsdCross.libc
-    else throw "Unknown libc";
+    else if name == "wasilibc" then targetPackages.wasilibc
+    else throw "Unknown libc ${name}";
 
   libcCross = assert stdenv.targetPlatform != stdenv.buildPlatform; libcCrossChooser stdenv.targetPlatform.libc;
 
+  wasilibc = callPackages ../development/libraries/wasilibc {
+    stdenv = crossLibcStdenv;
+  };
+
   # Only supported on Linux, using glibc
   glibcLocales = if stdenv.hostPlatform.libc == "glibc" then callPackage ../development/libraries/glibc/locales.nix { } else null;
 

pkgs/top-level/static.nix

@@ -148,4 +148,16 @@ in {
     };
   };
 
+  llvmPackages_8 = super.llvmPackages_8 // {
+    libraries = super.llvmPackages_8.libraries // rec {
+      libcxxabi = super.llvmPackages_8.libraries.libcxxabi.override {
+        enableShared = false;
+      };
+      libcxx = super.llvmPackages_8.libraries.libcxx.override {
+        enableShared = false;
+        inherit libcxxabi;
+      };
+    };
+  };
+
 }