[clang] [lldb] [clang] implement CWG1980 and CWG2064: instantiation-dependency improvements (PR #190495)

[Corentin Jabot via cfe-commits]

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@@ -89,23 +89,20 @@ static bool SubstQualifier(Sema &SemaRef, const DeclT *OldDecl, DeclT *NewDecl,
     NestedNameSpecifierLoc NewQualifierLoc =
         SemaRef.SubstNestedNameSpecifierLoc(OldDecl->getQualifierLoc(),
                                             TemplateArgs);
-
-    if (!NewQualifierLoc)
-      return true;
-
+    assert(NewQualifierLoc &&
+           "substitution for the declaration qualifiers should never fail");
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cor3ntin wrote:

How? The thing you can have in a NNS is fairly arbitrary

https://github.com/llvm/llvm-project/pull/190495