[cling] Use SuppressUnwrittenScope to strip anonymous namespace names

Since LLVM12, suppressing inline and anonymous namespaces were separated
into distinct flags:
- SuppressUnwrittenScope: suppresses anonymous namespaces
- SuppressInlineNamespace: suppresses redundant inline namespaces

See: llvm/llvm-project@5f12f4ff

Add `SuppressUnwrittenScope = true` to strip anonymous namespace prefixes
Without this, types in anonymous namespaces are printed as
'::(anonymous namespace)::EvNavHandler' which is invalid C++ and causes
compilation failures in rootcling-generated dictionary code as seen when
building dd4hep against ROOT LLVM22.

We were relying on `SuppressScope` which was removed in LLVM22.

Also update the Transform.C test to reflect the corrected output

Author: devajithvs

core/clingutils/src/TClingUtils.cxx

@@ -660,8 +660,10 @@ bool TClingLookupHelper::GetPartiallyDesugaredNameWithScopeHandling(const std::s
          policy.SuppressTagKeyword = true; // Never get the class or struct keyword
          policy.SuppressTagKeywordInAnonNames = true; // Skip printing tags for anonymous entities
          // The scope suppression is required for getting rid of the anonymous part of the name of a class defined in an anonymous namespace.
-         // This gives us more control vs not using the clang::ElaboratedType and relying on the Policy.SuppressUnwrittenScope which would
-         // strip both the anonymous and the inline namespace names (and we probably do not want the later to be suppressed).
+         // In LLVM22 (and before), SuppressUnwrittenScope suppresses anonymous namespaces. Inline namespace suppression is separately
+         // controlled by SuppressInlineNamespace, which we probably don't want to be suppressed.
+         policy.SuppressUnwrittenScope = true; // Strip anonymous namespace names
+
          // getAsStringInternal() appends.
          result.clear();
          dest.getAsStringInternal(result, policy);
@@ -4231,8 +4233,9 @@ void ROOT::TMetaUtils::GetNormalizedName(std::string &norm_name, const clang::Qu
    policy.SuppressTagKeywordInAnonNames = true; // Skip printing tags for anonymous entities
    policy.AnonymousTagLocations = false; // Do not extract file name + line number for anonymous types.
    // The scope suppression is required for getting rid of the anonymous part of the name of a class defined in an anonymous namespace.
-   // This gives us more control vs not using the clang::ElaboratedType and relying on the Policy.SuppressUnwrittenScope which would
-   // strip both the anonymous and the inline namespace names (and we probably do not want the later to be suppressed).
+   // In LLVM22 (and before), SuppressUnwrittenScope suppresses anonymous namespaces. Inline namespace suppression is separately
+   // controlled by SuppressInlineNamespace, which we probably don't want to be suppressed.
+   policy.SuppressUnwrittenScope = true; // Strip anonymous namespace names
 
    std::string normalizedNameStep1;
 

interpreter/cling/test/Utils/Transform.C

@@ -231,16 +231,17 @@ Transform::GetPartiallyDesugaredType(Ctx, QT, transConfig).getAsString().c_str()
 // The above result is not quite want we want, so the client must using
 // the following:
 // The scope suppression is required for getting rid of the anonymous part of the name of a class defined in an anonymous namespace.
-// This gives us more control vs not using the clang::ElaboratedType and relying on the Policy.SuppressUnwrittenScope which would
-// strip both the anonymous and the inline namespace names (and we probably do not want the later to be suppressed).
+// In LLVM22 (and before), SuppressUnwrittenScope suppresses anonymous namespaces. Inline namespace suppression is separately
+// controlled by SuppressInlineNamespace, which we probably don't want to be suppressed.
+Policy.SuppressUnwrittenScope = true; // Strip anonymous namespace names
 clang::PrintingPolicy Policy(Ctx.getPrintingPolicy());
 Policy.SuppressTagKeyword = true; // Never get the class or struct keyword
 Policy.SuppressTagKeywordInAnonNames = true; // Skip printing tags for anonymous entities
 Policy.SplitTemplateClosers = true; // Print a<b<c> >' rather than 'a<b<c>>'.
 std::string name;
 Transform::GetPartiallyDesugaredType(Ctx, QT, transConfig).getAsStringInternal(name,Policy);
 name.c_str()
-// CHECK: ({{[^)]+}}) "(anonymous namespace)::InsideAnonymous"
+// CHECK: ({{[^)]+}}) "InsideAnonymous"
 
 // Test desugaring pointers types:
 QT = lookup.findType("Int_t*", diags);