[clang] clang_EvalResult_getAsCXString impl (PR #134551)

[via cfe-commits]

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@@ -25,14 +25,19 @@ enum CXStringFlag {
   /// CXString contains a 'const char *' that it doesn't own.
   CXS_Unmanaged,
 
-  /// CXString contains a 'const char *' that it allocated with malloc().
-  CXS_Malloc,
+  /// CXString contains a 'CStringImpl' that it allocated with malloc().
+  CXS_MallocWithSize,
 
   /// CXString contains a CXStringBuf that needs to be returned to the
   /// CXStringPool.
   CXS_StringBuf
 };
 
+struct CStringImpl {
+  size_t length;
+  char buffer[sizeof(length)];
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dingxiangfei2009 wrote:

@xTachyon Thank you for checking it out! I personally still prefer the general direction that this patch is heading.

I have to admit that bringing back the `CXSMalloc` is still a thorny business... I am thinking about just move those constructor into an `internal.h` headers. They will be just `static inline`s and will only ever be used by `c-index-test` and will never be installed. So a question to @AaronBallman, do you find this idea of deploying an internal only header file acceptable? If so, I will make one more commit for this clean-up I will post another patch to @xTachyon.

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