[clang-tools-extra] [clang-tidy] modernize-use-nullptr matches "NULL" in templates (PR #109169)

[Thomas Köppe via cfe-commits]

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@@ -38,7 +38,9 @@ AST_MATCHER(Type, sugaredNullptrType) {
 StatementMatcher makeCastSequenceMatcher(llvm::ArrayRef<StringRef> NameList) {
   auto ImplicitCastToNull = implicitCastExpr(
       anyOf(hasCastKind(CK_NullToPointer), hasCastKind(CK_NullToMemberPointer)),
-      unless(hasImplicitDestinationType(qualType(substTemplateTypeParmType()))),
+      anyOf(hasSourceExpression(gnuNullExpr()),
----------------
tkoeppe wrote:

How about:

```
/// TODO/NOTE: The second "anyOf" below discards matches on a substituted type,
/// since we don't know if that would _always_ be a pointer type for all other
/// specializations, unless the expression was "__null", in which case we assume
/// that all specializations are expected to be for pointer types. Ideally this
/// would check for the NULL macro instead, but that'd be harder to express. In
/// practice, NULL is often defined as __null, and this is a useful condition.
```

?

https://github.com/llvm/llvm-project/pull/109169