[gn] port bf17016 (-gen-clang-diags-enums)

Author: nico

llvm/utils/gn/secondary/clang/include/clang/Basic/BUILD.gn

@@ -40,14 +40,25 @@ foreach(diag_group, diag_groups) {
     ]
     td_file = "Diagnostic.td"
   }
+
+  clang_tablegen("Diagnostic${diag_group}Enums") {
+    args = [
+      "-gen-clang-diags-enums",
+      "-clang-component=${diag_group}",
+    ]
+    td_file = "Diagnostic.td"
+  }
 }
 group("diags_tablegen") {
   # DiagnosticGroups and DiagnosticIndexName are intentionally not part of this
   # group.  Much of clang depends on the DiagKinds.inc files transitively,
   # but almost nothing needs DiagnosticGroups.inc or DiagnosticIndexName.inc.
   public_deps = []
   foreach(diag_group, diag_groups) {
-    public_deps += [ ":Diagnostic${diag_group}Kinds" ]
+    public_deps += [
+        ":Diagnostic${diag_group}Kinds",
+        ":Diagnostic${diag_group}Enums",
+    ]
   }
 }