Use Swift-style args for Driver

Author: jslegendre

include/swift/Option/Options.td

@@ -550,10 +550,10 @@ def lto : Joined<["-"], "lto=">,
   Flags<[FrontendOption, NoInteractiveOption]>,
   HelpText<"Specify the LTO type to either 'llvm-thin' or 'llvm-full'">;
 
-def lto_library : Separate<["-"], "lto_library">,
+def lto_library : Separate<["-"], "lto-library">,
   Flags<[FrontendOption, ArgumentIsPath, SwiftAPIExtractOption, SwiftSymbolGraphExtractOption,
          SwiftAPIDigesterOption]>,
-  HelpText<"Perform LTO with <lto_library>">, MetaVarName<"<lto_library>">;
+  HelpText<"Perform LTO with <lto-library>">, MetaVarName<"<lto-library>">;
 
 def access_notes_path : Separate<["-"], "access-notes-path">,
   Flags<[FrontendOption, ArgumentIsPath]>,

test/Driver/link-time-opt-darwin-ld-lib.swift

@@ -28,12 +28,12 @@
 
 // Check that driver does not see libLTO.dylib as an input
 
-// RUN: %swiftc_driver -driver-print-jobs %S/../Inputs/empty.swift -lto=llvm-full -lto_library /foo/libLTO.dylib -target x86_64-apple-macosx10.9     | %FileCheck %s --check-prefix=CHECK-SIMPLE-LTO-LIB --check-prefix=CHECK-SIMPLE-LTO-LIB-macosx
+// RUN: %swiftc_driver -driver-print-jobs %S/../Inputs/empty.swift -lto=llvm-full -lto-library /foo/libLTO.dylib -target x86_64-apple-macosx10.9     | %FileCheck %s --check-prefix=CHECK-SIMPLE-LTO-LIB --check-prefix=CHECK-SIMPLE-LTO-LIB-macosx
 
 // CHECK-SIMPLE-LTO-LIB: swift
 // CHECK-SIMPLE-LTO-LIB-DAG: -emit-bc
 // CHECK-SIMPLE-LTO-LIB-DAG: -lto=llvm-full
-// CHECK-SIMPLE-LTO-LIB-NOT: -lto_library /foo/libLTO.dylib
+// CHECK-SIMPLE-LTO-LIB-NOT: -lto-library /foo/libLTO.dylib
 // CHECK-SIMPLE-LTO-LIB-DAG: -o [[OBJECTFILE:.*\.bc]]
 
 // CHECK-SIMPLE-LTO-LIB-macosx: ld