[clang] [Clang] Fix dependency computation for pack indexing expression (PR #91933)

[via cfe-commits]

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@@ -377,7 +377,7 @@ ExprDependence clang::computeDependence(PackExpansionExpr *E) {
 ExprDependence clang::computeDependence(PackIndexingExpr *E) {
   ExprDependence D = E->getIndexExpr()->getDependence();
   if (D & ExprDependence::Value)
-    D |= ExprDependence::TypeInstantiation;
+    D |= E->getPackIdExpression()->getDependence() & ExprDependence::Type;
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RungeCC wrote:

> In that case (no selected expression) the pack is always type dependent.

I don't get it, could you explain the reason? FWIW, new test failed in CI so we may need to reconsider this.

https://github.com/llvm/llvm-project/pull/91933