[clang] [Clang][Sema] Avoid pack expansion for expanded empty PackIndexingExprs (PR #92385)

[Younan Zhang via cfe-commits]

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@@ -4377,15 +4377,20 @@ class PackIndexingExpr final
   // The pack being indexed, followed by the index
   Stmt *SubExprs[2];
 
-  size_t TransformedExpressions;
+  // The size of the trailing expressions.
+  unsigned TransformedExpressions : 31;
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zyn0217 wrote:

Aside: I'm not spelling it as `: sizeof(unsigned) - 1` because we seem to write down the number 31 directly elsewhere. So I think i'd better respect the convention.

https://github.com/llvm/llvm-project/pull/92385