From 496ba37128bd8861e09223679e3df8e00078c052 Mon Sep 17 00:00:00 2001
From: JohnnyMorganz <johnnymorganz@outlook.com>
Date: Thu, 20 Oct 2022 16:56:05 +0100
Subject: [PATCH] Add FFlag

---
 Analysis/src/Frontend.cpp | 24 +++++++++++++++++++-----
 tests/Frontend.test.cpp   |  4 ++++
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/Analysis/src/Frontend.cpp b/Analysis/src/Frontend.cpp
index cca058c9..cfe710d9 100644
--- a/Analysis/src/Frontend.cpp
+++ b/Analysis/src/Frontend.cpp
@@ -30,6 +30,7 @@ LUAU_FASTFLAGVARIABLE(LuauAutocompleteDynamicLimits, false)
 LUAU_FASTINTVARIABLE(LuauAutocompleteCheckTimeoutMs, 100)
 LUAU_FASTFLAGVARIABLE(DebugLuauDeferredConstraintResolution, false)
 LUAU_FASTFLAG(DebugLuauLogSolverToJson);
+LUAU_FASTFLAGVARIABLE(LuauFixMarkDirtyReverseDeps, false)
 
 namespace Luau
 {
@@ -807,13 +808,26 @@ void Frontend::markDirty(const ModuleName& name, std::vector<ModuleName>* marked
         sourceNode.dirtyModule = true;
         sourceNode.dirtyModuleForAutocomplete = true;
 
-        if (0 == reverseDeps.count(next))
-            continue;
+        if (FFlag::LuauFixMarkDirtyReverseDeps)
+        {
+            if (0 == reverseDeps.count(next))
+                continue;
 
-        sourceModules.erase(next);
+            sourceModules.erase(next);
 
-        const std::vector<ModuleName>& dependents = reverseDeps[next];
-        queue.insert(queue.end(), dependents.begin(), dependents.end());
+            const std::vector<ModuleName>& dependents = reverseDeps[next];
+            queue.insert(queue.end(), dependents.begin(), dependents.end());
+        }
+        else
+        {
+            if (0 == reverseDeps.count(name))
+                continue;
+
+            sourceModules.erase(name);
+
+            const std::vector<ModuleName>& dependents = reverseDeps[name];
+            queue.insert(queue.end(), dependents.begin(), dependents.end());
+        }
     }
 }
 
diff --git a/tests/Frontend.test.cpp b/tests/Frontend.test.cpp
index 2012a9a8..df0abdc9 100644
--- a/tests/Frontend.test.cpp
+++ b/tests/Frontend.test.cpp
@@ -519,6 +519,10 @@ TEST_CASE_FIXTURE(FrontendFixture, "recheck_if_dependent_script_is_dirty")
 
 TEST_CASE_FIXTURE(FrontendFixture, "mark_non_immediate_reverse_deps_as_dirty")
 {
+    ScopedFastFlag sff[] = {
+        {"LuauFixMarkDirtyReverseDeps", true},
+    };
+
     fileResolver.source["game/Gui/Modules/A"] = "return {hello=5, world=true}";
     fileResolver.source["game/Gui/Modules/B"] = R"(
         return require(game:GetService('Gui').Modules.A)