c++: fix ICE with sizeof in a template [PR112869]

This test shows that we cannot clear *walk_subtrees in
cp_fold_immediate_r when we're in_immediate_context, because that
checks even e.g. sk_template_parms, and, as the comment says, affects
cp_fold_r as well.  Here we had an expression with

  min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr
    (int) <<< error >>> >>>)

as its sub-expression, and we never evaluated that into

  min ((long int) bytecount, 4)

so the SIZEOF_EXPR leaked into the middle end.  We need to make sure
we are calling cp_fold on the SIZEOF_EXPR.

	PR c++/112869

gcc/cp/ChangeLog:

	* cp-gimplify.cc (cp_fold_immediate_r): Check cp_unevaluated_operand
	and DECL_IMMEDIATE_FUNCTION_P rather than in_immediate_context.

gcc/testsuite/ChangeLog:

	* g++.dg/template/sizeof18.C: New test.

0 files changed, 0 insertions, 0 deletions