On 4/4/25 4:35 PM, Patrick Palka wrote:
On Fri, 4 Apr 2025, Jason Merrill wrote:
Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
Since r10-7441 we set processing_template_decl in a requires-expression so
that we can use tsubst_expr to evaluate the requirements, but that confuses
lambdas terribly; begin_lambda_type silently returns error_mark_node and we
continue into other failures. This patch clears processing_template_decl
again while we're defining the closure and op() function, so it only remains
set while parsing the introducer (i.e. any init-captures) and building the
resulting object. This properly avoids trying to create another lambda in
tsubst_lambda_expr.
I wonder if we couldn't just set current_template_parms to a dummy
template parameter list if it's empty when parsing a requires-expr?
I don't see the benefit of making a requires-expr even more
template-like; IIUC the change to set processing_template_decl was
largely for convenience because the implementation expects template
trees, I don't think it corresponds to anything in the language.
https://eel.is/c++draft/expr#prim.req.general-note-1
Jason
