[clang] [SystemZ][z/OS] Add visibility features for z/OS (eg. _Export, pragma export) (PR #111035)

[Sean Perry via cfe-commits]

================
@@ -4504,6 +4504,11 @@ void Parser::ParseDeclarationSpecifiers(
       isInvalid = DS.setFunctionSpecNoreturn(Loc, PrevSpec, DiagID);
       break;
 
+    case tok::kw__Export:
+      // We're done with the declaration-specifiers.
+      goto DoneWithDeclSpec;
----------------
perry-ca wrote:

The test case above is valid and exports x.
```
@x = global ptr null, align 8
```
I'll add a test case to cover this.

You are correct.  This keyword is expected to appear right before the identifier of the symbol being exported.

https://github.com/llvm/llvm-project/pull/111035