Convert GN single-item list concat to use lists.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/sysroot.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 
@@ skipping 35 matching lines @@
       "-fvisibility=hidden",
     ]
     cflags_cc += [
       "-fno-exceptions",
       "-fno-threadsafe-statics",
       "-fvisibility-inlines-hidden",
     ]
 
     # Stack protection.
     if (is_mac) {
-      cflags += "-fstack-protector-all"
+      cflags += [ "-fstack-protector-all" ]
     } else if (is_linux) {
       cflags += [ "-fstack-protector", "--param=ssp-buffer-size=4" ]
     }
   }
 
   # Mac-specific compiler flags setup.
   # ----------------------------------
   if (is_mac) {
     # These flags are shared between the C compiler and linker.
     common_mac_flags = [
       "-isysroot", sysroot,
       "-mmacosx-version-min=10.6",
     ]
 
     # CPU architecture.
     if (cpu_arch == "x64") {
-      common_mac_flags += "-arch x86_64"
+      common_mac_flags += [ "-arch x86_64" ]
     } else if (cpu_arch == "x86") {
-      common_mac_flags += "-arch i386"
+      common_mac_flags += [ "-arch i386" ]
     }
 
     cflags += common_mac_flags + [
       # Without this, the constructors and destructors of a C++ object inside
       # an Objective C struct won't be called, which is very bad.
       "-fobjc-call-cxx-cdtors",
     ]
 
     cflags_c += [ "-std=c99" ]
     cflags_cc += [ "-std=gnu++11" ]
 
     ldflags += common_mac_flags + [
       "-L.",
 
       # TODO(brettW) I don't understand these options.
       "-Wl,-rpath,@loader_path/.",
       "-Wl,-rpath,@loader_path/../../..",
     ]
   } else if (is_posix) {
     # Non-Mac Posix compiler flags setup.
     # -----------------------------------
 
     # CPU architecture. We may or may not be doing a cross compile now, so for
     # simplicity we always explicitly set the architecture.
     if (cpu_arch == "x64") {
-      cflags += "-m64"
-      ldflags += "-m64"
+      cflags += [ "-m64" ]
+      ldflags += [ "-m64" ]
     } else if (cpu_arch == "x86") {
-      cflags += "-m32"
-      ldflags += "-m32"
+      cflags += [ "-m32" ]
+      ldflags += [ "-m32" ]
     } else if (cpu_arch == "arm") {
       # Don't set the compiler flags for the WebView build. These will come
       # from the Android build system.
       if (!is_android_webview_build) {
         cflags += [
           "-march=$arm_arch",
           "-mfpu=$arm_fpu",
           "-mfloat-abi=$arm_float_abi",
         ]
         if (arm_tune != "") {
-          cflags += "-mtune=$arm_tune"
+          cflags += [ "-mtune=$arm_tune" ]
         }
         if (arm_use_thumb) {
           cflags += [ "-mthumb" ]
           if (is_android && !is_clang) {  # Clang doesn't support this option.
             cflags += [ "-mthumb-interwork" ]
           }
         }
       }
     }
 
@@ skipping 40 matching lines @@
         # saved ~20% of link time.
         # https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
         # Only apply this to the target linker, since the host
         # linker might not be gold, but isn't used much anyway.
         "-Wl,--threads",
         "-Wl,--thread-count=4",
       ]
     }
 
     if (sysroot != "") {
-      cflags += "--sysroot=" + sysroot
-      ldflags += "--sysroot=" + sysroot
+      cflags += [ "--sysroot=" + sysroot ]
+      ldflags += [ "--sysroot=" + sysroot ]
 
       # Need to get some linker flags out of the sysroot.
-      ldflags += exec_script("../linux/sysroot_ld_path.py",
+      ldflags += [ exec_script("../linux/sysroot_ld_path.py",
           [rebase_path("../../linux/sysroot_ld_path.sh", ".", root_build_dir),
            sysroot],
-          "value")
+          "value") ]
     }
 
     ldflags += [
       "-fPIC",
       "-pthread",
       "-Wl,-z,noexecstack",
       "-Wl,-z,now",
       "-Wl,-z,relro",
     ]
   }
@@ skipping 484 matching lines @@
     cflags = [ "-g1" ]
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }