https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99331
--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:b281edd801018ed703ce7bb0d49fef59ff8cef8b commit r10-9688-gb281edd801018ed703ce7bb0d49fef59ff8cef8b Author: Marek Polacek <pola...@redhat.com> Date: Thu Mar 4 20:20:40 2021 -0500 c++: -Wconversion vs value-dependent expressions [PR99331] This PR complains that we issue a -Wconversion warning in template <int N> struct X {}; template <class T> X<sizeof(T)> foo(); saying "conversion from 'long unsigned int' to 'int' may change value". While it's not technically wrong, I suspect -Wconversion warnings aren't all that useful for value-dependent expressions. So this patch disables them. This is a regression that started with r241425: @@ -7278,7 +7306,7 @@ convert_template_argument (tree parm, val = error_mark_node; } } - else if (!dependent_template_arg_p (orig_arg) + else if (!type_dependent_expression_p (orig_arg) && !uses_template_parms (t)) /* We used to call digest_init here. However, digest_init will report errors, which we don't want when complain Here orig_arg is SIZEOF_EXPR<T>; dependent_template_arg_p (orig_arg) was true, but type_dependent_expression_p (orig_arg) is false so we warn in convert_nontype_argument. gcc/cp/ChangeLog: PR c++/99331 * call.c (build_converted_constant_expr_internal): Don't emit -Wconversion warnings. gcc/testsuite/ChangeLog: PR c++/99331 * g++.dg/warn/Wconversion5.C: New test. (cherry picked from commit 9efd72d28956eb79c7fca38e3c959733a3bb25bb)
