https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100079
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jason Merrill <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:89c863488bc8c7315596bcb753173aa2fd8be727 commit r11-8207-g89c863488bc8c7315596bcb753173aa2fd8be727 Author: Jason Merrill <ja...@redhat.com> Date: Wed Apr 14 17:27:19 2021 -0400 c++: C++20 class NTTP trailing zero-init [PR100079] The new testcase was breaking because constexpr evaluation was simplifying Bar{Baz<42>{}} to Bar{empty}, but then we weren't treating them as equivalent. Poking at this revealed that the code for eliding trailing zero-initialization in class non-type template argument mangling was pretty broken, including the test, mangle71. I dealt with the FIXME to support RANGE_EXPR, and fixed the confusion between a list-initialized temporary mangled as written (i.e. in the signature of a function template) and a template parameter object mangled as the value representation of the object. I'm distinguishing between these using COMPOUND_LITERAL_P. A later patch will adjust the use of COMPOUND_LITERAL_P to be more useful for this distinction, but it works now for distinguishing these cases in mangling. gcc/cp/ChangeLog: PR c++/100079 * cp-tree.h (first_field): Declare. * mangle.c (range_expr_nelts): New. (write_expression): Improve class NTTP mangling. * pt.c (get_template_parm_object): Clear TREE_HAS_CONSTRUCTOR. * tree.c (zero_init_expr_p): Improve class NTTP handling. * decl.c: Adjust comment. gcc/testsuite/ChangeLog: PR c++/100079 * g++.dg/abi/mangle71.C: Fix expected mangling. * g++.dg/abi/mangle77.C: New test. * g++.dg/cpp2a/nontype-class-union1.C: Likewise. * g++.dg/cpp2a/nontype-class-equiv1.C: Removed. * g++.dg/cpp2a/nontype-class44.C: New test.
