From 298ae5574ddd926e67c14f1384fbf523f2f3c7a8 Mon Sep 17 00:00:00 2001
From: Ben Barham <ben_barham@apple.com>
Date: Wed, 11 Dec 2024 10:11:30 -0800
Subject: [PATCH] Revert "[Modules] Process include files changes (#90319)"

This reverts commit 9a9cff15a15b103ae1dc1efa98b53901cdda78f1, which
combined with CAS (where every file has a 0 mtime), causes content
validation to run on every input file.

(cherry picked from commit ffe014a999bc5aff09310e7e4dd6bc42d5476e27)
---
 clang/lib/Serialization/ASTReader.cpp         |  8 -----
 .../Modules/implicit-module-no-timestamp.cpp  | 33 -------------------
 2 files changed, 41 deletions(-)
 delete mode 100644 clang/test/Modules/implicit-module-no-timestamp.cpp

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index eba83f20befc7..d68cef0f7e5bb 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2671,14 +2671,6 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
       F.StandardCXXModule && FileChange.Kind == Change::None)
     FileChange = HasInputContentChanged(FileChange);
 
-  // When we have StoredTime equal to zero and ValidateASTInputFilesContent,
-  // it is better to check the content of the input files because we cannot rely
-  // on the file modification time, which will be the same (zero) for these
-  // files.
-  if (!StoredTime && ValidateASTInputFilesContent &&
-      FileChange.Kind == Change::None)
-    FileChange = HasInputContentChanged(FileChange);
-
   // For an overridden file, there is nothing to validate.
   if (!Overridden && FileChange.Kind != Change::None) {
     if (Complain && !Diags.isDiagnosticInFlight()) {
diff --git a/clang/test/Modules/implicit-module-no-timestamp.cpp b/clang/test/Modules/implicit-module-no-timestamp.cpp
deleted file mode 100644
index 50767b4a11468..0000000000000
--- a/clang/test/Modules/implicit-module-no-timestamp.cpp
+++ /dev/null
@@ -1,33 +0,0 @@
-// RUN: rm -rf %t
-// RUN: split-file %s %t
-// RUN: cd %t
-//
-// RUN: cp a1.h a.h
-// RUN: %clang_cc1 -fmodules -fvalidate-ast-input-files-content -fno-pch-timestamp -fmodule-map-file=module.modulemap -fmodules-cache-path=%t test1.cpp
-// RUN: cp a2.h a.h
-// RUN: %clang_cc1 -fmodules -fvalidate-ast-input-files-content -fno-pch-timestamp -fmodule-map-file=module.modulemap -fmodules-cache-path=%t test2.cpp
-
-//--- a1.h
-#define FOO
-
-//--- a2.h
-#define BAR
-
-//--- module.modulemap
-module a {
-  header "a.h"
-}
-
-//--- test1.cpp
-#include "a.h"
-
-#ifndef FOO
-#error foo
-#endif
-
-//--- test2.cpp
-#include "a.h"
-
-#ifndef BAR
-#error bar
-#endif