[clang] [clang][Basic] Add helper APIs to get language version codes from LangOptions (PR #163348)

[Aaron Ballman via cfe-commits]

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@@ -184,6 +184,28 @@ class LangOptionsBase {
     HLSL_202y = 2029,
   };
 
+  /// C language version codes as defined by the standard.
+  enum CLangStd : uint32_t {
+    // FIXME: Use correct value for C2y.
+    C_2y = 202400,
+    C_23 = 202311,
+    C_17 = 201710,
+    C_11 = 201112,
+    C_99 = 199901,
+  };
+
+  /// C++ language version codes as defined by the standard.
+  enum CPlusPlusLangStd : uint32_t {
+    // FIXME: Use correct value for C++26.
+    CPP_26 = 202400,
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AaronBallman wrote:

`Cpp26` or `Cxx26` instead of the underscore?

https://github.com/llvm/llvm-project/pull/163348