Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 80 insertions, 0 deletions

diff --git a/src/test/ui/macros/type-macros-hlist.rs b/src/test/ui/macros/type-macros-hlist.rs
new file mode 100644
index 000000000..946b5bd5d
--- /dev/null
+++ b/src/test/ui/macros/type-macros-hlist.rs
@@ -0,0 +1,80 @@
+// run-pass
+#![allow(unused_macro_rules)]
+
+use std::ops::*;
+
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+struct Nil;
+ // empty HList
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+struct Cons<H, T: HList>(H, T);
+ // cons cell of HList
+
+ // trait to classify valid HLists
+trait HList { }
+impl HList for Nil { }
+impl <H, T: HList> HList for Cons<H, T> { }
+
+// term-level macro for HLists
+macro_rules! hlist({  } => { Nil } ; { $ head : expr } => {
+                   Cons ( $ head , Nil ) } ; {
+                   $ head : expr , $ ( $ tail : expr ) , * } => {
+                   Cons ( $ head , hlist ! ( $ ( $ tail ) , * ) ) } ;);
+
+// type-level macro for HLists
+macro_rules! HList({  } => { Nil } ; { $ head : ty } => {
+                   Cons < $ head , Nil > } ; {
+                   $ head : ty , $ ( $ tail : ty ) , * } => {
+                   Cons < $ head , HList ! ( $ ( $ tail ) , * ) > } ;);
+
+// nil case for HList append
+impl <Ys: HList> Add<Ys> for Nil {
+    type
+    Output
+    =
+    Ys;
+
+    fn add(self, rhs: Ys) -> Ys { rhs }
+}
+
+// cons case for HList append
+impl <Rec: HList + Sized, X, Xs: HList, Ys: HList> Add<Ys> for Cons<X, Xs>
+ where Xs: Add<Ys, Output = Rec> {
+    type
+    Output
+    =
+    Cons<X, Rec>;
+
+    fn add(self, rhs: Ys) -> Cons<X, Rec> { Cons(self.0, self.1 + rhs) }
+}
+
+// type macro Expr allows us to expand the + operator appropriately
+macro_rules! Expr({ ( $ ( $ LHS : tt ) + ) } => { Expr ! ( $ ( $ LHS ) + ) } ;
+                  { HList ! [ $ ( $ LHS : tt ) * ] + $ ( $ RHS : tt ) + } => {
+                  < Expr ! ( HList ! [ $ ( $ LHS ) * ] ) as Add < Expr ! (
+                  $ ( $ RHS ) + ) >> :: Output } ; {
+                  $ LHS : tt + $ ( $ RHS : tt ) + } => {
+                  < Expr ! ( $ LHS ) as Add < Expr ! ( $ ( $ RHS ) + ) >> ::
+                  Output } ; { $ LHS : ty } => { $ LHS } ;);
+
+// test demonstrating term level `xs + ys` and type level `Expr!(Xs + Ys)`
+fn main() {
+    fn aux<Xs: HList, Ys: HList>(xs: Xs, ys: Ys) -> Expr!(Xs + Ys) where
+     Xs: Add<Ys> {
+        xs + ys
+    }
+
+    let xs: HList!(& str , bool , Vec < u64 >) =
+        hlist!("foo" , false , vec ! [  ]);
+    let ys: HList!(u64 , [ u8 ; 3 ] , (  )) =
+        hlist!(0 , [ 0 , 1 , 2 ] , (  ));
+
+    // demonstrate recursive expansion of Expr!
+    let zs:
+            Expr!((
+                  HList ! [ & str ] + HList ! [ bool ] + HList ! [ Vec < u64 >
+                  ] ) + ( HList ! [ u64 ] + HList ! [ [ u8 ; 3 ] , (  ) ] ) +
+                  HList ! [  ]) = aux(xs, ys);
+    assert_eq!(zs , hlist ! [
+               "foo" , false , vec ! [  ] , 0 , [ 0 , 1 , 2 ] , (  ) ])
+}