wasm: don’t assume musl

lib/systems/inspect.nix

@@ -46,7 +46,7 @@ rec {
     isWasi         = { kernel = kernels.wasi; };
 
     isAndroid      = [ { abi = abis.android; } { abi = abis.androideabi; } ];
-    isMusl         = (with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ]) ++ [{ kernel = kernels.wasi; }];
+    isMusl         = with abis; map (a: { abi = a; }) [ musl musleabi musleabihf ];
     isUClibc       = with abis; map (a: { abi = a; }) [ uclibc uclibceabi uclibceabihf ];
 
     isEfi          = map (family: { cpu.family = family; })

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

@@ -23,7 +23,8 @@ stdenv.mkDerivation rec {
   '' + lib.optionalString stdenv.hostPlatform.isMusl ''
     patchShebangs utils/cat_files.py
   '';
-  nativeBuildInputs = [ cmake ] ++ stdenv.lib.optional stdenv.hostPlatform.isMusl python;
+  nativeBuildInputs = [ cmake ]
+    ++ stdenv.lib.optional (stdenv.hostPlatform.isMusl || stdenv.hostPlatform.isWasi) python;
 
   buildInputs = [ libcxxabi ] ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
 
@@ -31,11 +32,12 @@ stdenv.mkDerivation rec {
     "-DLIBCXX_LIBCXXABI_LIB_PATH=${libcxxabi}/lib"
     "-DLIBCXX_LIBCPPABI_VERSION=2"
     "-DLIBCXX_CXX_ABI=libcxxabi"
-  ] ++ stdenv.lib.optional stdenv.hostPlatform.isMusl "-DLIBCXX_HAS_MUSL_LIBC=1"
+  ] ++ stdenv.lib.optional (stdenv.hostPlatform.isMusl || stdenv.hostPlatform.isWasi) "-DLIBCXX_HAS_MUSL_LIBC=1"
     ++ 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"
+      "-DLIBCXX_ENABLE_EXCEPTIONS=OFF"
     ] ++ stdenv.lib.optional (!enableShared) "-DLIBCXX_ENABLE_SHARED=OFF";
 
   enableParallelBuilding = true;

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

@@ -15,6 +15,7 @@ stdenv.mkDerivation {
   ] ++ stdenv.lib.optionals stdenv.hostPlatform.isWasm [
     "-DUNIX=ON"
     "-DLIBCXXABI_ENABLE_THREADS=OFF"
+    "-DLIBCXXABI_ENABLE_EXCEPTIONS=OFF"
   ] ++ stdenv.lib.optionals (!enableShared) [
     "-DLIBCXXABI_ENABLE_SHARED=OFF"
   ];