[modules] If we're given a module file, via -fmodule-file=, for a module, but

we can't load that file due to a configuration mismatch, and implicit module
building is disabled, and the user turns off the error-by-default warning for
that situation, then fall back to textual inclusion for the module rather than
giving an error if any of its headers are included.

llvm-svn: 252114

1 files changed, 12 insertions, 6 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index b7b56f68b81..32656037921 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -2151,6 +2151,7 @@ ASTReader::ReadControlBlock(ModuleFile &F,
                             const ModuleFile *ImportedBy,
                             unsigned ClientLoadCapabilities) {
   BitstreamCursor &Stream = F.Stream;
+  ASTReadResult Result = Success;
 
   if (Stream.EnterSubBlock(CONTROL_BLOCK_ID)) {
     Error("malformed block record in AST file");
@@ -2211,7 +2212,7 @@ ASTReader::ReadControlBlock(ModuleFile &F,
         }
       }
 
-      return Success;
+      return Result;
     }
 
     case llvm::BitstreamEntry::SubBlock:
@@ -2239,16 +2240,21 @@ ASTReader::ReadControlBlock(ModuleFile &F,
           bool AllowCompatibleConfigurationMismatch =
               F.Kind == MK_ExplicitModule;
 
-          auto Result = ReadOptionsBlock(Stream, ClientLoadCapabilities,
-                                         AllowCompatibleConfigurationMismatch,
-                                         *Listener, SuggestedPredefines);
+          Result = ReadOptionsBlock(Stream, ClientLoadCapabilities,
+                                    AllowCompatibleConfigurationMismatch,
+                                    *Listener, SuggestedPredefines);
           if (Result == Failure) {
             Error("malformed block record in AST file");
             return Result;
           }
 
-          if (!DisableValidation && Result != Success &&
-              (Result != ConfigurationMismatch || !AllowConfigurationMismatch))
+          if (DisableValidation ||
+              (AllowConfigurationMismatch && Result == ConfigurationMismatch))
+            Result = Success;
+
+          // If we've diagnosed a problem, we're done.
+          if (Result != Success &&
+              isDiagnosedResult(Result, ClientLoadCapabilities))
             return Result;
         } else if (Stream.SkipBlock()) {
           Error("malformed block record in AST file");