[clang][Modules] Clarify error message when size check fails in lookupModuleFile

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index 61c4e9e..d466ea0 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -110,7 +110,9 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type,
   // Look for the file entry. This only fails if the expected size or
   // modification time differ.
   OptionalFileEntryRef Entry;
-  if (Type == MK_ExplicitModule || Type == MK_PrebuiltModule) {
+  const bool IgnoreModTime =
+      (Type == MK_ExplicitModule || Type == MK_PrebuiltModule);
+  if (IgnoreModTime) {
     // If we're not expecting to pull this file out of the module cache, it
     // might have a different mtime due to being moved across filesystems in
     // a distributed build. The size must still match, though. (As must the
@@ -120,7 +122,9 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type,
   // Note: ExpectedSize and ExpectedModTime will be 0 for MK_ImplicitModule
   // when using an ASTFileSignature.
   if (lookupModuleFile(FileName, ExpectedSize, ExpectedModTime, Entry)) {
-    ErrorStr = "module file has a different size or mtime than expected";
+    ErrorStr = IgnoreModTime
+                   ? "module file has a different size than expected"
+                   : "module file has a different size or mtime than expected";
     return OutOfDate;
   }