[clang] [Clang] Fix the lambda context for constraint evaluation (PR #184319)

[Corentin Jabot via cfe-commits]

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@@ -705,6 +708,21 @@ ExprResult ConstraintSatisfactionChecker::EvaluateSlow(
     return ExprEmpty();
   }
 
+  // This is dumb: generic lambdas inside requires body require a lambda context
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cor3ntin wrote:

```suggestion
  // FIXME: generic lambdas inside requires body require a lambda context
```

https://github.com/llvm/llvm-project/pull/184319