macro_rules!foo{($x:pat|$y:pat)=>{}}//~ ERROR the meaning of the `pat` fragment specifier is changing in Rust 2021, which may affect this macro
macro_rules!bar{($($x:pat)+|$($y:pat)+)=>{}}//~ ERROR the meaning of the `pat` fragment specifier is changing in Rust 2021, which may affect this macro
($expr:expr,$($($pat:pat)|+=>$expr_arm:expr),+)=>{//~ ERROR the meaning of the `pat` fragment specifier is changing in Rust 2021, which may affect this macro