c++: Perform the iterating expansion stmt N evaluation in immediate context [PR123611]

For the N evaluation for iterating expansion stmts where the standard says
to evaluate:
[] consteval {
  std::ptrdiff_t result = 0;
  for (auto i = begin; i != end; ++i) ++result;
  return result;                                // distance from begin to end
}()
right now (subject to further changes in CWG3140) I wanted to save compile
time/memory and effort to actually construct the lambda and it is evaluated
just using TARGET_EXPRs.  On the following testcase it makes a difference,
when the lambda is consteval, the expressions inside of it are evaluated
in immediate context and so the testcase should be accepted, but we
currently reject it when i has consteval-only type and expansion stmt
doesn't appear in an immediate or immediate-escalating function.

The following patch fixes this by forcing in_immediate_context () to be true
around the evaluation.

2026-02-04  Jakub Jelinek  <jakub@redhat.com>

	PR c++/123611
	* pt.cc (finish_expansion_stmt): Temporarily enable
	in_immediate_context () for the iterating expansion stmt N
	computation.

	* g++.dg/reflect/expansion-stmt1.C: New test.

0 files changed, 0 insertions, 0 deletions