[lldb] [clang-tools-extra] [clang] [c++20] P1907R1: Support for generalized non-type template arguments of scalar type. (PR #78041)

[Aaron Ballman via cfe-commits]

================
@@ -6472,7 +6494,20 @@ void CXXNameMangler::mangleValueInTemplateArg(QualType T, const APValue &V,
       Out << "plcvPcad";
       Kind = Offset;
     } else {
-      if (!V.getLValuePath().empty() || V.isLValueOnePastTheEnd()) {
+      // Clang 11 and before mangled an array subject to array-to-pointer decay
+      // as if it were the declaration itself.
+      bool IsArrayToPointerDecayMangledAsDecl = false;
+      if (TopLevel && Ctx.getLangOpts().getClangABICompat() <=
+                          LangOptions::ClangABI::Ver11) {
+        QualType BType = B.getType();
+        IsArrayToPointerDecayMangledAsDecl =
+            BType->isArrayType() && V.getLValuePath().size() == 1 &&
+            V.getLValuePath()[0].getAsArrayIndex() == 0 &&
+            Ctx.hasSimilarType(T, Ctx.getDecayedType(BType));
+      }
+
----------------
AaronBallman wrote:

Thank you for the details!

https://github.com/llvm/llvm-project/pull/78041