qtwebengine: fix build for darwin

pkgs/development/libraries/qt-5/modules/qtwebengine.nix

@@ -13,7 +13,7 @@
 , systemd
 , enableProprietaryCodecs ? true
 , gn
-, cups, darwin, openbsm, runCommand, xcbuild
+, cups, darwin, openbsm, runCommand, xcbuild, writeScriptBin
 , ffmpeg_3 ? null
 , lib, stdenv
 }:
@@ -51,6 +51,13 @@ qtModule {
       substituteInPlace ./src/3rdparty/chromium/v8/gypfiles/standalone.gypi \
         --replace /bin/echo ${coreutils}/bin/echo
     ''
+    # Prevent Chromium build script from making the path to `clang` relative to
+    # the build directory.  `clang_base_path` is the value of `QMAKE_CLANG_DIR`
+    # from `src/core/config/mac_osx.pri`.
+    + optionalString stdenv.isDarwin ''
+      substituteInPlace ./src/3rdparty/chromium/build/toolchain/mac/BUILD.gn \
+        --replace 'prefix = rebase_path("$clang_base_path/bin/", root_build_dir)' 'prefix = "$clang_base_path/bin/"'
+    ''
     # Patch library paths in Qt sources
     + ''
       sed -i \
@@ -69,32 +76,15 @@ qtModule {
     ''
     + optionalString stdenv.isDarwin (''
       substituteInPlace src/core/config/mac_osx.pri \
-        --replace /usr ${stdenv.cc}
+        --replace 'QMAKE_CLANG_DIR = "/usr"' 'QMAKE_CLANG_DIR = "${stdenv.cc}"'
     ''
+     # Following is required to prevent a build error:
+     # ninja: error: '/nix/store/z8z04p0ph48w22rqzx7ql67gy8cyvidi-SDKs/MacOSX10.12.sdk/usr/include/mach/exc.defs', needed by 'gen/third_party/crashpad/crashpad/util/mach/excUser.c', missing and no known rule to make it
     + (optionalString (lib.versionAtLeast qtCompatVersion "5.11") ''
       substituteInPlace src/3rdparty/chromium/third_party/crashpad/crashpad/util/BUILD.gn \
         --replace '$sysroot/usr' "${darwin.xnu}"
     '')
     + ''
-
-    cat <<EOF > src/3rdparty/chromium/build/mac/find_sdk.py
-#!/usr/bin/env python
-print("${darwin.apple_sdk.sdk}")
-print("10.12.0")
-EOF
-
-    cat <<EOF > src/3rdparty/chromium/build/config/mac/sdk_info.py
-#!/usr/bin/env python
-print('xcode_version="0910"')
-print('xcode_version_int=910')
-print('xcode_build="9B55"')
-print('machine_os_build="17E199"')
-print('sdk_path=""')
-print('sdk_version="10.10"')
-print('sdk_platform_path=""')
-print('sdk_build="17B41"')
-EOF
-
     # Apple has some secret stuff they don't share with OpenBSM
     substituteInPlace src/3rdparty/chromium/base/mac/mach_port_broker.mm \
       --replace "audit_token_to_pid(msg.trailer.msgh_audit)" "msg.trailer.msgh_audit.val[5]"
@@ -111,8 +101,8 @@ EOF
     # TODO: investigate and fix properly
     "-march=westmere"
   ] ++ lib.optionals stdenv.isDarwin [
-    "-DMAC_OS_X_VERSION_MAX_ALLOWED=MAC_OS_X_VERSION_10_10"
-    "-DMAC_OS_X_VERSION_MIN_REQUIRED=MAC_OS_X_VERSION_10_10"
+    "-DMAC_OS_X_VERSION_MAX_ALLOWED=MAC_OS_X_VERSION_10_12"
+    "-DMAC_OS_X_VERSION_MIN_REQUIRED=MAC_OS_X_VERSION_10_12"
 
     #
     # Prevent errors like
@@ -189,6 +179,7 @@ EOF
     CoreWLAN
     Quartz
     Cocoa
+    LocalAuthentication
 
     openbsm
     libunwind
@@ -197,6 +188,21 @@ EOF
   buildInputs = optionals stdenv.isDarwin (with darwin; [
     cups
 
+    # `sw_vers` is used by `src/3rdparty/chromium/build/config/mac/sdk_info.py`
+    # to get some information about the host platform.
+    (writeScriptBin "sw_vers" ''
+      #!${stdenv.shell}
+
+      while [ $# -gt 0 ]; do
+        case "$1" in
+          -buildVersion) echo "17E199";;
+        *) break ;;
+
+        esac
+        shift
+      done
+    '')
+
     # For sandbox.h include
     (runCommand "MacOS_SDK_sandbox.h" {} ''
       install -Dm444 "${lib.getDev darwin.apple_sdk.sdk}"/include/sandbox.h "$out"/include/sandbox.h