[clang] [clang-tools-extra] [clang] improve class type sugar preservation in pointers to members (PR #130537)

[Erich Keane via cfe-commits]

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@@ -13461,13 +13486,112 @@ static ElaboratedTypeKeyword getCommonTypeKeyword(const T *X, const T *Y) {
                                             : ElaboratedTypeKeyword::None;
 }
 
+static NestedNameSpecifier *getCommonNNS(ASTContext &Ctx,
+                                         NestedNameSpecifier *X,
+                                         NestedNameSpecifier *Y, bool Sugar) {
+  if (X == Y)
+    return X;
+
+  NestedNameSpecifier *Canon = Ctx.getCanonicalNestedNameSpecifier(X);
+  if (Canon != Ctx.getCanonicalNestedNameSpecifier(Y)) {
+    if (Sugar)
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erichkeane wrote:

`assert(Sugar && "Should be the same NestedNameSpecifier")` instead of the unreachable.

https://github.com/llvm/llvm-project/pull/130537