[clang] [SystemZ][z/OS] Implement #pragma export (PR #141671)

[Sean Perry via cfe-commits]

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@@ -568,6 +574,11 @@ void Parser::initializePragmaHandlers() {
   MaxTokensTotalPragmaHandler = std::make_unique<PragmaMaxTokensTotalHandler>();
   PP.AddPragmaHandler("clang", MaxTokensTotalPragmaHandler.get());
 
+  if (getLangOpts().ZOSExt) {
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perry-ca wrote:

This pragma duplicates on a limited scope the functionality of the visibility attribute.  We're adding the pragma for compatibility with the z/OS XL C/C++ compiler.  I'm more that happy to make it available everywhere.  I just didn't want to cause confusion by providing yet another mechanism for specifying visibility especially since it is limited to which C++ declarations it can be applied too.

https://github.com/llvm/llvm-project/pull/141671