[clang] Load AST files as binary on z/OS (PR #191840)

[Sean Perry via cfe-commits]

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@@ -2873,7 +2873,9 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
     Overridden = false;
   }
 
-  auto File = FileMgr.getOptionalFileRef(*Filename, /*OpenFile=*/false);
+  auto File = FileMgr.getOptionalFileRef(*Filename, /*OpenFile=*/false,
+                                         /*CacheFailure=*/true,
+                                         /*IsText=*/false);
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perry-ca wrote:

I looked at these again and you're correct.  This call should still be opening the file as text.  In the unit test the header is created with ascii encoding which is why opening it as binary still worked.  I've updated the change.

https://github.com/llvm/llvm-project/pull/191840