[clang] [MS] Add /Zc:tlsGuards option to control tls guard emission (PR #113830)

[Eli Friedman via cfe-commits]

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@@ -186,6 +186,7 @@ COMPATIBLE_LANGOPT(RecoveryAST, 1, 1, "Preserve expressions in AST when encounte
 COMPATIBLE_LANGOPT(RecoveryASTType, 1, 1, "Preserve the type in recovery expressions")
 
 BENIGN_LANGOPT(ThreadsafeStatics , 1, 1, "thread-safe static initializers")
+BENIGN_LANGOPT(TlsGuards , 1, 1, "on-demand TLS initialization")
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efriedma-quic wrote:

Should this be a CODEGENOPT instead of a LANGOPT?  I guess it's not a big difference either way.  (ThreadsafeStatics is a LANGOPT because it also controls a preprocessor define.)

https://github.com/llvm/llvm-project/pull/113830