Auto merge of #90602 - mbartlett21:const-intoiterator, r=oli-obk

Unstably constify `impl<I: Iterator> IntoIterator for I` This constifies the default `IntoIterator` implementation under the `const_intoiterator_identity` feature. Tracking Issue: #90603
rust-lang · Apr 23, 2022 · 6b4563b · 6b4563b
2 parents 1e9aa8a + b8ef1db
commit 6b4563b
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Showing 4 changed files with 8 additions and 7 deletions.
diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs
@@ -267,8 +267,9 @@ pub trait IntoIterator {
     fn into_iter(self) -> Self::IntoIter;
 }
 
+#[rustc_const_unstable(feature = "const_intoiterator_identity", issue = "90603")]
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<I: Iterator> IntoIterator for I {
+impl<I: ~const Iterator> const IntoIterator for I {
     type Item = I::Item;
     type IntoIter = I;
 

diff --git a/src/test/ui/consts/const-fn-error.stderr b/src/test/ui/consts/const-fn-error.stderr
@@ -22,8 +22,8 @@ LL |     for i in 0..x {
 note: impl defined here, but it is not `const`
   --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
    |
-LL | impl<I: Iterator> IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | impl<I: ~const Iterator> const IntoIterator for I {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
 
 error[E0658]: mutable references are not allowed in constant functions

diff --git a/src/test/ui/consts/const-for.stderr b/src/test/ui/consts/const-for.stderr
@@ -7,8 +7,8 @@ LL |     for _ in 0..5 {}
 note: impl defined here, but it is not `const`
   --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
    |
-LL | impl<I: Iterator> IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | impl<I: ~const Iterator> const IntoIterator for I {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
 error[E0015]: cannot call non-const fn `<std::ops::Range<i32> as Iterator>::next` in constants

diff --git a/src/test/ui/never_type/issue-52443.stderr b/src/test/ui/never_type/issue-52443.stderr
@@ -47,8 +47,8 @@ LL |     [(); { for _ in 0usize.. {}; 0}];
 note: impl defined here, but it is not `const`
   --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
    |
-LL | impl<I: Iterator> IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | impl<I: ~const Iterator> const IntoIterator for I {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: calls in constants are limited to constant functions, tuple structs and tuple variants
 
 error[E0658]: mutable references are not allowed in constants