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|
#![feature(macro_metavar_expr)]
macro_rules! a {
( $( { $( [ $( ( $( $foo:ident )* ) )* ] )* } )* ) => {
(
${count($foo, 0)},
${count($foo, 10)},
//~^ ERROR depth parameter of meta-variable expression `count` must be less than 4
)
};
}
macro_rules! b {
( $( { $( [ $( $foo:ident )* ] )* } )* ) => {
(
$( $( $(
${ignore($foo)}
${index(0)},
${index(10)},
//~^ ERROR depth parameter of meta-variable expression `index` must be less than 3
)* )* )*
)
};
}
macro_rules! c {
( $( { $( $foo:ident )* } )* ) => {
(
$( $(
${ignore($foo)}
${len(0)}
${len(10)}
//~^ ERROR depth parameter of meta-variable expression `len` must be less than 2
)* )*
)
};
}
fn main() {
a!( { [ (a) ] [ (b c) ] } );
b!( { [ a b ] } );
c!({ a });
}
|
