Apple LLVM 9.0 Error, Unable to execute command: Killed:9

I'm working on a game in Unity with Easy AR, OneSignal, Firebase, local android notifications in the project. I've had no issues building for Android, neither for iOS till Xcode 8. As soon as I upgraded to Xcode 9.4, I could no longer build for iOS, I get this error

clang: error: unable to execute command: Killed: 9 clang: error: clang frontend command failed due to signal (use -v to see invocation) Apple LLVM version 9.1.0 (clang-902.0.39.2) Target: arm-apple-darwin17.6.0

Thread model: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin clang: note: diagnostic msg: PLEASE submit a bug report to http://developer.apple.com/bugreporter/ and include the crash backtrace, preprocessed source, and associated run script. clang: note: diagnostic msg:

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT: Preprocessed source(s) and associated run script(s) are located at: clang: note: diagnostic msg: /var/folders/1z/x7jst_x1nlcs9hrw97dtydr0000gn/T/Bulk_Assembly-CSharp_8-709ede.cpp clang: note: diagnostic msg: /var/folders/1z/x7jstx1nlcs9hrw97dtydr0000gn/T/Bulk_Assembly-CSharp_8-709ede.sh clang: note: diagnostic msg: Crash backtrace is located in clang: note: diagnostic msg: /Users/rajivsethi/Library/Logs/DiagnosticReports/clang_.crash clang: note: diagnostic msg: (choose the .crash file that corresponds to your crash) clang: note: diagnostic msg:

I'm using cocoapods with firebase and am using the workspace rather the xcodeproject, I find this very strange that I can easily build for Xcode 8 with no problems whatsoever but when I try to build for Xcode 9 I get this error.

Unity version: 2018.1 xcode: 9.4

Been stuck for quite some time, any help would be greatly appreciated.