[clang] [clang] Accept lambdas in C++03 as an extensions (PR #73376)

[via cfe-commits]

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@@ -1030,6 +1030,7 @@ def err_capture_default_first : Error<
 def ext_decl_attrs_on_lambda : ExtWarn<
   "%select{an attribute specifier sequence|%0}1 in this position "
   "is a C++23 extension">, InGroup<CXX23>;
+def ext_lambda : ExtWarn<"lambdas are a C++11 extension">, InGroup<CXX11>;
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cor3ntin wrote:

This is not tested.  Also you probably want to move that next to warn_cxx98_compat_lambda

https://github.com/llvm/llvm-project/pull/73376