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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/issues/issue-29746.rs | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/src/test/ui/issues/issue-29746.rs b/src/test/ui/issues/issue-29746.rs new file mode 100644 index 000000000..428cc637f --- /dev/null +++ b/src/test/ui/issues/issue-29746.rs @@ -0,0 +1,36 @@ +// run-pass +// zip!(a1,a2,a3,a4) is equivalent to: +// a1.zip(a2).zip(a3).zip(a4).map(|(((x1,x2),x3),x4)| (x1,x2,x3,x4)) +macro_rules! zip { + // Entry point + ([$a:expr, $b:expr, $($rest:expr),*]) => { + zip!([$($rest),*], $a.zip($b), (x,y), [x,y]) + }; + + // Intermediate steps to build the zipped expression, the match pattern, and + // and the output tuple of the closure, using macro hygiene to repeatedly + // introduce new variables named 'x'. + ([$a:expr, $($rest:expr),*], $zip:expr, $pat:pat, [$($flat:expr),*]) => { + zip!([$($rest),*], $zip.zip($a), ($pat,x), [$($flat),*, x]) + }; + + // Final step + ([], $zip:expr, $pat:pat, [$($flat:expr),+]) => { + $zip.map(|$pat| ($($flat),+)) + }; + + // Comma + ([$a:expr], $zip:expr, $pat:pat, [$($flat:expr),*]) => { + zip!([$a,], $zip, $pat, [$($flat),*]) + }; +} + +fn main() { + let p1 = vec![1i32, 2].into_iter(); + let p2 = vec!["10", "20"].into_iter(); + let p3 = vec![100u16, 200].into_iter(); + let p4 = vec![1000i64, 2000].into_iter(); + + let e = zip!([p1,p2,p3,p4]).collect::<Vec<_>>(); + assert_eq!(e[0], (1i32,"10",100u16,1000i64)); +} |