================
@@ -3343,6 +3343,120 @@ class TemplateParamObjectDecl : public ValueDecl,
static bool classofKind(Kind K) { return K == TemplateParamObject; }
};
+/// Represents a C++26 expansion statement declaration.
+///
+/// This is a bit of a hack, since expansion statements shouldn't really be
+/// 'declarations' per se (they don't declare anything). Nevertheless, we *do*
+/// need them to be declaration *contexts*, because the DeclContext is used to
+/// compute the 'template depth' of entities enclosed therein. In particular,
+/// the 'template depth' is used to find instantiations of parameter variables,
+/// and a lambda enclosed within an expansion statement cannot compute its
+/// template depth without a pointer to the enclosing expansion statement.
+///
+/// For the remainder of this comment, let 'expanding' an expansion statement
+/// refer to the process of performing template substitution on its body N
+/// times, where N is the expansion size (how this size is determined depends
on
+/// the kind of expansion statement); by contrast we may sometimes
'instantiate'
+/// an expansion statement (because it happens to be in a template). This is
+/// just regular template instantiation.
+///
+/// Apart from a template parameter list that contains a template parameter
used
----------------
erichkeane wrote:
What else does the list contain? And why a list instead of a single template
parameter if that is the only thing in the list?
https://github.com/llvm/llvm-project/pull/169680
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