🚙 GN: Add write_runtime_deps variable

tools/gn/target.cc

Index: tools/gn/target.cc
diff --git a/tools/gn/target.cc b/tools/gn/target.cc
index 714fd911f9657c038dda56c1b096ded0365d759c..17e308c81a86ac2e9e18244a047998bf9d8d0923 100644
--- a/tools/gn/target.cc
+++ b/tools/gn/target.cc
@@ -83,6 +83,7 @@ bool EnsureFileIsGeneratedByDependency(const Target* target,
                                        const OutputFile& file,
                                        bool check_private_deps,
                                        bool consider_object_files,
+                                       bool check_data_deps,
                                        std::set<const Target*>* seen_targets) {
   if (seen_targets->find(target) != seen_targets->end())
     return false;  // Already checked this one and it's not found.
@@ -96,6 +97,10 @@ bool EnsureFileIsGeneratedByDependency(const Target* target,
       return true;
   }
 
+  if (file == target->write_runtime_deps_output()) {
+    return true;
+  }
+
   // Check binary target intermediate files if requested.
   if (consider_object_files && target->IsBinary()) {
     std::vector<OutputFile> source_outputs;
@@ -109,11 +114,22 @@ bool EnsureFileIsGeneratedByDependency(const Target* target,
     }
   }
 
+  if (check_data_deps) {
+    check_data_deps = false;  // Consider only direct data_deps.
+    for (const auto& pair : target->data_deps()) {
+      if (EnsureFileIsGeneratedByDependency(pair.ptr, file, false,
+                                            consider_object_files,
+                                            check_data_deps, seen_targets))
+        return true;  // Found a path.
+    }
+  }
+
   // Check all public dependencies (don't do data ones since those are
   // runtime-only).
   for (const auto& pair : target->public_deps()) {
     if (EnsureFileIsGeneratedByDependency(pair.ptr, file, false,
-                                          consider_object_files, seen_targets))
+                                          consider_object_files,
+                                          check_data_deps, seen_targets))
       return true;  // Found a path.
   }
 
@@ -122,7 +138,7 @@ bool EnsureFileIsGeneratedByDependency(const Target* target,
     for (const auto& pair : target->private_deps()) {
       if (EnsureFileIsGeneratedByDependency(pair.ptr, file, false,
                                             consider_object_files,
-                                            seen_targets))
+                                            check_data_deps, seen_targets))
         return true;  // Found a path.
     }
   }
@@ -761,13 +777,20 @@ void Target::CheckSourceGenerated(const SourceFile& source) const {
   // can be filtered out of this list.
   OutputFile out_file(settings()->build_settings(), source);
   std::set<const Target*> seen_targets;
-  if (!EnsureFileIsGeneratedByDependency(this, out_file, true, false,
+  bool check_data_deps = false;
+  bool consider_object_files = false;
+  if (!EnsureFileIsGeneratedByDependency(this, out_file, true,
+                                         consider_object_files, check_data_deps,
                                          &seen_targets)) {
+    seen_targets.clear();
+    // Allow dependency to be through data_deps for files generated by gn.
+    check_data_deps = g_scheduler->IsFileGeneratedByWriteRuntimeDeps(out_file);
     // Check object files (much slower and very rare) only if the "normal"
     // output check failed.
-    seen_targets.clear();
-    if (!EnsureFileIsGeneratedByDependency(this, out_file, true, true,
-                                           &seen_targets))
+    consider_object_files = !check_data_deps;
+    if (!EnsureFileIsGeneratedByDependency(this, out_file, true,
+                                           consider_object_files,
+                                           check_data_deps, &seen_targets))
       g_scheduler->AddUnknownGeneratedInput(this, source);
   }
 }