Fixed isysroot settings on MacOS

src/compile_commands.cpp

@@ -126,8 +126,16 @@ std::vector<std::string> CompileCommands::get_arguments(const boost::filesystem:
 #ifdef __APPLE__
   // Add -isysroot argument if it is missing on MacOS, which is needed by newer libclang
   if(std::none_of(arguments.begin(), arguments.end(), [](const std::string &argument) { return argument == "-isysroot"; })) {
-    arguments.emplace_back("-isysroot");
-    arguments.emplace_back("/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk");
+    auto sysroots = {"/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk",
+                     "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk"};
+    boost::system::error_code ec;
+    for(auto &sysroot : sysroots) {
+      if(boost::filesystem::exists(sysroot, ec)) {
+        arguments.emplace_back("-isysroot");
+        arguments.emplace_back(sysroot);
+        break;
+      }
+    }
   }
 #endif