[clang] [Clang] Reapply CWG2369 "Ordering between constraints and substitution" (PR #122423)

[Younan Zhang via cfe-commits]

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@@ -8058,6 +8059,54 @@ bool Sema::CheckNonDependentConversions(
     }
   }
 
+  // A heuristic & speculative workaround for bug
+  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99599 that manifests after
+  // CWG2369.
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zyn0217 wrote:

Yes, I'll look into that; this is just rebasing from my old attempt

https://github.com/llvm/llvm-project/pull/122423