[clang] [clang-tools-extra] [llvm] [clang] WIP: Improved Context Declaration tracking (PR #107942)

[Matheus Izvekov via cfe-commits]

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@@ -961,6 +961,7 @@ static const Expr *SubstituteConstraintExpressionWithoutSatisfaction(
 
   if (MLTAL.getNumSubstitutedLevels() == 0)
     return ConstrExpr;
+  MLTAL.setKind(TemplateSubstitutionKind::Rewrite);
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mizvekov wrote:

The new difference introduced in this patch is that a Rewrite is depth preserving, while a specialization is not.

In this case, we want to rewrite a requires clause from another potential redeclaration to see if it matches, and confirm it really is a redeclaration.

If we don't preserve the depth here, this would trip a new assert, where we would be instantiating a requires clause at template depth 0, but then parenting it to a declaration at depth 1, which is incorrect.

https://github.com/llvm/llvm-project/pull/107942