[clang] clang_EvalResult_getAsCXString impl (PR #134551)

[Aaron Ballman via cfe-commits]

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@@ -52,6 +54,7 @@ typedef struct {
  * to `std::string::c_str()`.
  */
 CINDEX_LINKAGE const char *clang_getCString(CXString string);
+CINDEX_LINKAGE const char *clang_getCString2(CXString string, size_t *length);
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AaronBallman wrote:

We should document that `length` cannot be null.

https://github.com/llvm/llvm-project/pull/134551