On Thu, Oct 20, 2022 at 10:19:59AM -0400, Jason Merrill wrote: > I think in a template we want the same early-return behavior as in the > processing_template_decl block farther down in the function: specifically, > we want to return a CONSTRUCTOR (for which COMPOUND_LITERAL_P is true), so > it mangles as void{} rather than void().
So like this then? 2022-10-20 Jakub Jelinek <ja...@redhat.com> PR c++/106863 * semantics.cc (finish_compound_literal): For void{}, if processing_template_decl return a COMPOUND_LITERAL_P CONSTRUCTOR rather than void_node. * g++.dg/cpp0x/dr2351-2.C: New test. --- gcc/cp/semantics.cc.jj 2022-10-19 01:14:58.343483355 +0200 +++ gcc/cp/semantics.cc 2022-10-20 16:32:30.605571968 +0200 @@ -3164,7 +3164,16 @@ finish_compound_literal (tree type, tree { /* DR2351 */ if (VOID_TYPE_P (type) && CONSTRUCTOR_NELTS (compound_literal) == 0) - return void_node; + { + if (!processing_template_decl) + return void_node; + TREE_TYPE (compound_literal) = type; + TREE_HAS_CONSTRUCTOR (compound_literal) = 1; + CONSTRUCTOR_IS_DEPENDENT (compound_literal) = 0; + if (fcl_context == fcl_c99) + CONSTRUCTOR_C99_COMPOUND_LITERAL (compound_literal) = 1; + return compound_literal; + } else if (VOID_TYPE_P (type) && processing_template_decl && maybe_zero_constructor_nelts (compound_literal)) --- gcc/testsuite/g++.dg/cpp0x/dr2351-2.C.jj 2022-10-20 16:27:19.645821706 +0200 +++ gcc/testsuite/g++.dg/cpp0x/dr2351-2.C 2022-10-20 16:27:19.645821706 +0200 @@ -0,0 +1,16 @@ +// DR2351 +// { dg-do compile { target c++11 } } + +void bar (int); + +template <typename T> +auto foo (T t) -> decltype (bar (t), void{}) +{ + return bar (t); +} + +int +main () +{ + foo (0); +} Jakub