Move clang_version setting back into declare_args

build/toolchain/toolchain.gni

Index: build/toolchain/toolchain.gni
diff --git a/build/toolchain/toolchain.gni b/build/toolchain/toolchain.gni
index f389eec29e41bf0d97c8a8ade6b867d497fe386b..0b25d5eb940db4d5e3ded6fc74234cf4f5d40cab 100644
--- a/build/toolchain/toolchain.gni
+++ b/build/toolchain/toolchain.gni
@@ -34,16 +34,16 @@ declare_args() {
   # with the build. Used on iOS to ship official builds (as they are built
   # with the version of clang shipped with Xcode).
   use_xcode_clang = is_ios && is_official_build
-}
 
-if (is_clang) {
-  # Clang compiler version. Clang files are placed at version-dependent paths.
-  clang_version = "3.9.0"
+  if (is_clang) {
+    # Clang compiler version. Clang files are placed at version-dependent paths.
+    clang_version = "3.9.0"
 
-  if (llvm_force_head_revision) {
-    # TODO(hans): Remove after next Clang roll.
-    # ToT Clang has a higher version number.
-    clang_version = "4.0.0"
+    if (llvm_force_head_revision) {
+      # TODO(hans): Remove after next Clang roll.
+      # ToT Clang has a higher version number.
+      clang_version = "4.0.0"
+    }

[Dirk Pranke, 2016/08/02 23:58:59]

Can you move this all into a separate declare_args() block? I'm not sure if
this'll actually work correctly as written, because I think the
llvm_force_head_revision=true in your args.gn won't take effect until the end of
the first declare_args() block.

[Reid Kleckner, 2016/08/03 00:03:30]

Thanks! We probably wouldn't have caught that until it hit the clang TOT
waterfall if that's really how it works.

   }
 }