internal: minimize minicore

We want to keep minicore small, so let's split out iterator adapters and
sources into a separate `iterators` region, and use them only when
needed.

crates/ide/src/inlay_hints.rs

@@ -818,7 +818,7 @@ fn main() {
     fn shorten_iterators_in_associated_params() {
         check_types(
             r#"
-//- minicore: iterator
+//- minicore: iterators
 use core::iter;
 
 pub struct SomeIter<T> {}
@@ -1126,7 +1126,7 @@ fn main() {
     fn shorten_iterator_hints() {
         check_types(
             r#"
-//- minicore: iterator
+//- minicore: iterators
 use core::iter;
 
 struct MyIter;
@@ -1357,7 +1357,7 @@ fn main() {
                 max_length: None,
             },
             r#"
-//- minicore: iterator
+//- minicore: iterators
 use core::iter;
 
 struct MyIter;

crates/ide_assists/src/handlers/replace_for_loop_with_for_each.rs

@@ -186,18 +186,14 @@ fn main() {
     fn test_for_borrowed() {
         check_assist(
             replace_for_loop_with_for_each,
-            r"
-//- minicore: iterator
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
+            r#"
+//- minicore: iterators
+use core::iter::{Repeat, repeat};
 
 struct S;
 impl S {
-    fn iter(&self) -> Iter { Iter }
-    fn iter_mut(&mut self) -> Iter { Iter }
+    fn iter(&self) -> Repeat<i32> { repeat(92) }
+    fn iter_mut(&mut self) -> Repeat<i32> { repeat(92) }
 }
 
 fn main() {
@@ -206,18 +202,14 @@ fn main() {
         let a = v * 2;
     }
 }
-",
-            r"
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
+"#,
+            r#"
+use core::iter::{Repeat, repeat};
 
 struct S;
 impl S {
-    fn iter(&self) -> Iter { Iter }
-    fn iter_mut(&mut self) -> Iter { Iter }
+    fn iter(&self) -> Repeat<i32> { repeat(92) }
+    fn iter_mut(&mut self) -> Repeat<i32> { repeat(92) }
 }
 
 fn main() {
@@ -226,7 +218,7 @@ fn main() {
         let a = v * 2;
     });
 }
-",
+"#,
         )
     }
 
@@ -259,18 +251,14 @@ fn main() {
     fn test_for_borrowed_mut() {
         check_assist(
             replace_for_loop_with_for_each,
-            r"
-//- minicore: iterator
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
+            r#"
+//- minicore: iterators
+use core::iter::{Repeat, repeat};
 
 struct S;
 impl S {
-    fn iter(&self) -> Iter { Iter }
-    fn iter_mut(&mut self) -> Iter { Iter }
+    fn iter(&self) -> Repeat<i32> { repeat(92) }
+    fn iter_mut(&mut self) -> Repeat<i32> { repeat(92) }
 }
 
 fn main() {
@@ -279,18 +267,14 @@ fn main() {
         let a = v * 2;
     }
 }
-",
-            r"
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
+"#,
+            r#"
+use core::iter::{Repeat, repeat};
 
 struct S;
 impl S {
-    fn iter(&self) -> Iter { Iter }
-    fn iter_mut(&mut self) -> Iter { Iter }
+    fn iter(&self) -> Repeat<i32> { repeat(92) }
+    fn iter_mut(&mut self) -> Repeat<i32> { repeat(92) }
 }
 
 fn main() {
@@ -299,7 +283,7 @@ fn main() {
         let a = v * 2;
     });
 }
-",
+"#,
         )
     }
 
@@ -332,28 +316,16 @@ fn main() {
         check_assist(
             replace_for_loop_with_for_each,
             r#"
-//- minicore: iterator
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
-
+//- minicore: iterators
 fn main() {
-    for$0 a in Iter.take(1) {
+    for$0 a in core::iter::repeat(92).take(1) {
         println!("{}", a);
     }
 }
 "#,
             r#"
-struct Iter;
-impl Iterator for Iter {
-    type Item = usize;
-    fn next(&mut self) -> Option<Self::Item> { None }
-}
-
 fn main() {
-    Iter.take(1).for_each(|a| {
+    core::iter::repeat(92).take(1).for_each(|a| {
         println!("{}", a);
     });
 }

crates/test_utils/src/minicore.rs

@@ -21,6 +21,7 @@
 //!     option:
 //!     result:
 //!     iterator: option
+//!     iterators: iterator
 
 pub mod marker {
     // region:sized
@@ -209,6 +210,7 @@ pub mod task {
 
 // region:iterator
 pub mod iter {
+    // region:iterators
     mod adapters {
         pub struct Take<I> {
             iter: I,
@@ -249,6 +251,7 @@ pub mod iter {
         pub use self::repeat::{repeat, Repeat};
     }
     pub use self::sources::{repeat, Repeat};
+    // endregion:iterators
 
     mod traits {
         mod iterator {
@@ -261,15 +264,17 @@ pub mod iter {
                 fn nth(&mut self, n: usize) -> Option<Self::Item> {
                     loop {}
                 }
-                fn take(self, n: usize) -> crate::iter::Take<Self> {
-                    loop {}
-                }
                 fn by_ref(&mut self) -> &mut Self
                 where
                     Self: Sized,
                 {
                     self
                 }
+                // region:iterators
+                fn take(self, n: usize) -> crate::iter::Take<Self> {
+                    loop {}
+                }
+                // endregion:iterators
             }
             impl<I: Iterator + ?Sized> Iterator for &mut I {
                 type Item = I::Item;