[clang] [Clang] Fix template elision to preserve qualifiers in diagnostics (PR #180175)

[Corentin Jabot via cfe-commits]

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@@ -1205,8 +1205,15 @@ class TemplateDiff {
              "Both template specializations need to be valid.");
       Qualifiers FromQual = FromType.getQualifiers(),
                  ToQual = ToType.getQualifiers();
-      FromQual -= QualType(FromArgTST, 0).getQualifiers();
-      ToQual -= QualType(ToArgTST, 0).getQualifiers();
+      // FromQual -= QualType(FromArgTST, 0).getQualifiers();
+      // ToQual -= QualType(ToArgTST, 0).getQualifiers();
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cor3ntin wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/180175