[clang] [Concepts] Add Decls from the outer scope of the current lambda for conversion function constraints (PR #83420)

[Younan Zhang via cfe-commits]

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@@ -7976,7 +7976,8 @@ void Sema::AddConversionCandidate(
 
   if (Conversion->getTrailingRequiresClause()) {
     ConstraintSatisfaction Satisfaction;
-    if (CheckFunctionConstraints(Conversion, Satisfaction) ||
+    if (CheckFunctionConstraints(Conversion, Satisfaction, /*UsageLoc=*/{},
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zyn0217 wrote:

Hmm... Yes, the flag would tell the LSI to look into its parents as well, although we don't have any coverage test cases for it yet. Maybe I think we can narrow it down to the inside of CheckFunctionConstraints.

https://github.com/llvm/llvm-project/pull/83420