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

[Sean Perry via cfe-commits]

================
@@ -1400,6 +1416,171 @@ bool Parser::HandlePragmaMSAllocText(StringRef PragmaName,
   return true;
 }
 
+NestedNameSpecifier *
+Parser::zOSParseIdentifier(StringRef PragmaName,
+                           const IdentifierInfo *IdentName) {
+  NestedNameSpecifier *NestedId = nullptr;
----------------
perry-ca wrote:

The grammar for the pragma is:
```
'#pragma' 'map' '(' name  ',' string-literal ')'
```
or
```
'#pragma' 'map' '(' qualified-name '(' argument-list ')' cv-qualifiers ',' string-literal ')'
```
The first syntax is straight forward.  The name matches functions declared as extern "C" in C++.  The second syntax provides matching for functions with C++ linkage.  The qualified name here isn't an expression.  It is like the declarator-id and will match a future declaration.  I haven't seen anything that does what this code does.

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