8 files changed, 109 insertions, 257 deletions

diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 335d57a0d..95f9edce4 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -661,9 +661,7 @@ fn main() {
     fn function_call_parameter_hint() {
         check_params(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
+//- minicore: option
 struct FileId {}
 struct SmolStr {}
 
@@ -872,7 +870,6 @@ fn main() {
         check_types(
             r#"
 //- minicore: fn, sized
-
 fn foo() -> impl Fn() { loop {} }
 fn foo1() -> impl Fn(f64) { loop {} }
 fn foo2() -> impl Fn(f64, f64) { loop {} }
@@ -908,9 +905,7 @@ fn main() {
     fn unit_structs_have_no_type_hints() {
         check_types(
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 struct SyntheticSyntax;
 
 fn main() {
@@ -962,9 +957,7 @@ fn main() {
     fn if_expr() {
         check_types(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
+//- minicore: option
 struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
@@ -994,9 +987,7 @@ fn main() {
     fn while_expr() {
         check_types(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
+//- minicore: option
 struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
@@ -1012,9 +1003,7 @@ fn main() {
     fn match_arm_list() {
         check_types(
             r#"
-enum Option<T> { None, Some(T) }
-use Option::*;
-
+//- minicore: option
 struct Test { a: Option<u32>, b: u8 }
 
 fn main() {
diff --git a/crates/ide_assists/src/handlers/fill_match_arms.rs b/crates/ide_assists/src/handlers/fill_match_arms.rs
index cd0f6dba9..318faa0fc 100644
--- a/crates/ide_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ide_assists/src/handlers/fill_match_arms.rs
@@ -481,26 +481,21 @@ fn main() {
         check_assist(
             fill_match_arms,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn main() {
     match None$0 {
         None => {}
     }
 }
-            "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn main() {
     match None {
         None => {}
         Some(${0:_}) => todo!(),
     }
 }
-            "#,
+"#,
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/replace_if_let_with_match.rs b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
index 9404aa26d..f37aa0d53 100644
--- a/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/ide_assists/src/handlers/replace_if_let_with_match.rs
@@ -262,9 +262,7 @@ impl VariantData {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0if let Some(x) = x {
         println!("{}", x)
@@ -272,18 +270,15 @@ fn foo(x: Option<i32>) {
         println!("none")
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     match x {
         Some(x) => println!("{}", x),
         None => println!("none"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -292,9 +287,7 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0if let None = x {
         println!("none")
@@ -302,18 +295,15 @@ fn foo(x: Option<i32>) {
         println!("some")
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     match x {
         None => println!("none"),
         Some(_) => println!("some"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -322,9 +312,7 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0if let Ok(x) = x {
         println!("{}", x)
@@ -332,18 +320,15 @@ fn foo(x: Result<i32, ()>) {
         println!("none")
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     match x {
         Ok(x) => println!("{}", x),
         Err(_) => println!("none"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -352,9 +337,7 @@ fn foo(x: Result<i32, ()>) {
         check_assist(
             replace_if_let_with_match,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0if let Err(x) = x {
         println!("{}", x)
@@ -362,18 +345,15 @@ fn foo(x: Result<i32, ()>) {
         println!("ok")
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     match x {
         Err(x) => println!("{}", x),
         Ok(_) => println!("ok"),
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -488,20 +468,15 @@ impl VariantData {
         check_assist(
             replace_match_with_if_let,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
+//- minicore: option
 fn foo(x: Option<i32>) {
     $0match x {
         Some(x) => println!("{}", x),
         None => println!("none"),
     }
 }
-           "#,
+"#,
             r#"
-enum Option<T> { Some(T), None }
-use Option::*;
-
 fn foo(x: Option<i32>) {
     if let Some(x) = x {
         println!("{}", x)
@@ -509,7 +484,7 @@ fn foo(x: Option<i32>) {
         println!("none")
     }
 }
-           "#,
+"#,
         );
     }
 
@@ -518,20 +493,15 @@ fn foo(x: Option<i32>) {
         check_assist(
             replace_match_with_if_let,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
+//- minicore: result
 fn foo(x: Result<i32, ()>) {
     $0match x {
         Ok(x) => println!("{}", x),
         Err(_) => println!("none"),
     }
 }
-           "#,
+"#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-use Result::*;
-
 fn foo(x: Result<i32, ()>) {
     if let Ok(x) = x {
         println!("{}", x)
@@ -539,7 +509,7 @@ fn foo(x: Result<i32, ()>) {
         println!("none")
     }
 }
-           "#,
+"#,
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs b/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
index a3bfa221c..7e57353c6 100644
--- a/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
+++ b/crates/ide_assists/src/handlers/replace_unwrap_with_match.rs
@@ -97,25 +97,24 @@ mod tests {
     fn test_replace_result_unwrap_with_match() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+            r#"
+//- minicore: result
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = i(x).$0unwrap();
 }
-            ",
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = match i(x) {
         Ok(it) => it,
         $0_ => unreachable!(),
     };
 }
-            ",
+"#,
         )
     }
 
@@ -123,25 +122,24 @@ fn main() {
     fn test_replace_option_unwrap_with_match() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Option<T> { Some(T), None }
+            r#"
+//- minicore: option
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = i(x).$0unwrap();
 }
-            ",
-            r"
-enum Option<T> { Some(T), None }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = match i(x) {
         Some(it) => it,
         $0_ => unreachable!(),
     };
 }
-            ",
+"#,
         );
     }
 
@@ -149,25 +147,24 @@ fn main() {
     fn test_replace_result_unwrap_with_match_chaining() {
         check_assist(
             replace_unwrap_with_match,
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+            r#"
+//- minicore: result
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = i(x).$0unwrap().count_zeroes();
 }
-            ",
-            r"
-enum Result<T, E> { Ok(T), Err(E) }
+"#,
+            r#"
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x: Result<i32, i32> = Result::Ok(92);
+    let x: Result<i32, i32> = Ok(92);
     let y = match i(x) {
         Ok(it) => it,
         $0_ => unreachable!(),
     }.count_zeroes();
 }
-            ",
+"#,
         )
     }
 
@@ -175,14 +172,14 @@ fn main() {
     fn replace_unwrap_with_match_target() {
         check_assist_target(
             replace_unwrap_with_match,
-            r"
-enum Option<T> { Some(T), None }
+            r#"
+//- minicore: option
 fn i<T>(a: T) -> T { a }
 fn main() {
-    let x = Option::Some(92);
+    let x = Some(92);
     let y = i(x).$0unwrap();
 }
-            ",
+"#,
             r"i(x).unwrap()",
         );
     }
diff --git a/crates/ide_completion/src/completions/postfix.rs b/crates/ide_completion/src/completions/postfix.rs
index c3c7e4589..4e20ec003 100644
--- a/crates/ide_completion/src/completions/postfix.rs
+++ b/crates/ide_completion/src/completions/postfix.rs
@@ -436,18 +436,15 @@ fn main() {
         check_edit(
             "ifl",
             r#"
-enum Option<T> { Some(T), None }
-
+//- minicore: option
 fn main() {
-    let bar = Option::Some(true);
+    let bar = Some(true);
     bar.$0
 }
 "#,
             r#"
-enum Option<T> { Some(T), None }
-
 fn main() {
-    let bar = Option::Some(true);
+    let bar = Some(true);
     if let Some($1) = bar {
     $0
 }
@@ -461,18 +458,15 @@ fn main() {
         check_edit(
             "match",
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-
+//- minicore: result
 fn main() {
-    let bar = Result::Ok(true);
+    let bar = Ok(true);
     bar.$0
 }
 "#,
             r#"
-enum Result<T, E> { Ok(T), Err(E) }
-
 fn main() {
-    let bar = Result::Ok(true);
+    let bar = Ok(true);
     match bar {
     Ok(${1:_}) => {$2},
     Err(${3:_}) => {$0},
@@ -515,18 +509,15 @@ fn main() {
         check_edit(
             "ifl",
             r#"
-enum Option<T> { Some(T), None }
-
+//- minicore: option
 fn main() {
-    let bar = &Option::Some(true);
+    let bar = &Some(true);
     bar.$0
 }
 "#,
             r#"
-enum Option<T> { Some(T), None }
-
 fn main() {
-    let bar = &Option::Some(true);
+    let bar = &Some(true);
     if let Some($1) = bar {
     $0
 }
diff --git a/crates/ide_diagnostics/src/handlers/missing_ok_or_some_in_tail_expr.rs b/crates/ide_diagnostics/src/handlers/missing_ok_or_some_in_tail_expr.rs
index 63de54570..c0edcd7d3 100644
--- a/crates/ide_diagnostics/src/handlers/missing_ok_or_some_in_tail_expr.rs
+++ b/crates/ide_diagnostics/src/handlers/missing_ok_or_some_in_tail_expr.rs
@@ -49,26 +49,15 @@ mod tests {
     fn test_wrap_return_type_option() {
         check_fix(
             r#"
-//- /main.rs crate:main deps:core
-use core::option::Option::{self, Some, None};
-
+//- minicore: option, result
 fn div(x: i32, y: i32) -> Option<i32> {
     if y == 0 {
         return None;
     }
     x / y$0
 }
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
             r#"
-use core::option::Option::{self, Some, None};
-
 fn div(x: i32, y: i32) -> Option<i32> {
     if y == 0 {
         return None;
@@ -83,26 +72,15 @@ fn div(x: i32, y: i32) -> Option<i32> {
     fn test_wrap_return_type() {
         check_fix(
             r#"
-//- /main.rs crate:main deps:core
-use core::result::Result::{self, Ok, Err};
-
+//- minicore: option, result
 fn div(x: i32, y: i32) -> Result<i32, ()> {
     if y == 0 {
         return Err(());
     }
     x / y$0
 }
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
             r#"
-use core::result::Result::{self, Ok, Err};
-
 fn div(x: i32, y: i32) -> Result<i32, ()> {
     if y == 0 {
         return Err(());
@@ -117,26 +95,15 @@ fn div(x: i32, y: i32) -> Result<i32, ()> {
     fn test_wrap_return_type_handles_generic_functions() {
         check_fix(
             r#"
-//- /main.rs crate:main deps:core
-use core::result::Result::{self, Ok, Err};
-
+//- minicore: option, result
 fn div<T>(x: T) -> Result<T, i32> {
     if x == 0 {
         return Err(7);
     }
     $0x
 }
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
             r#"
-use core::result::Result::{self, Ok, Err};
-
 fn div<T>(x: T) -> Result<T, i32> {
     if x == 0 {
         return Err(7);
@@ -151,9 +118,7 @@ fn div<T>(x: T) -> Result<T, i32> {
     fn test_wrap_return_type_handles_type_aliases() {
         check_fix(
             r#"
-//- /main.rs crate:main deps:core
-use core::result::Result::{self, Ok, Err};
-
+//- minicore: option, result
 type MyResult<T> = Result<T, ()>;
 
 fn div(x: i32, y: i32) -> MyResult<i32> {
@@ -162,17 +127,8 @@ fn div(x: i32, y: i32) -> MyResult<i32> {
     }
     x $0/ y
 }
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
             r#"
-use core::result::Result::{self, Ok, Err};
-
 type MyResult<T> = Result<T, ()>;
 
 fn div(x: i32, y: i32) -> MyResult<i32> {
@@ -189,18 +145,8 @@ fn div(x: i32, y: i32) -> MyResult<i32> {
     fn test_wrap_return_type_not_applicable_when_expr_type_does_not_match_ok_type() {
         check_diagnostics(
             r#"
-//- /main.rs crate:main deps:core
-use core::result::Result::{self, Ok, Err};
-
+//- minicore: option, result
 fn foo() -> Result<(), i32> { 0 }
-
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
         );
     }
@@ -209,20 +155,10 @@ pub mod option {
     fn test_wrap_return_type_not_applicable_when_return_type_is_not_result_or_option() {
         check_diagnostics(
             r#"
-//- /main.rs crate:main deps:core
-use core::result::Result::{self, Ok, Err};
-
+//- minicore: option, result
 enum SomeOtherEnum { Ok(i32), Err(String) }
 
 fn foo() -> SomeOtherEnum { 0 }
-
-//- /core/lib.rs crate:core
-pub mod result {
-    pub enum Result<T, E> { Ok(T), Err(E) }
-}
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
 "#,
         );
     }
diff --git a/crates/ide_diagnostics/src/handlers/replace_filter_map_next_with_find_map.rs b/crates/ide_diagnostics/src/handlers/replace_filter_map_next_with_find_map.rs
index cd87a10bb..839ceac03 100644
--- a/crates/ide_diagnostics/src/handlers/replace_filter_map_next_with_find_map.rs
+++ b/crates/ide_diagnostics/src/handlers/replace_filter_map_next_with_find_map.rs
@@ -55,44 +55,16 @@ fn fixes(
 
 #[cfg(test)]
 mod tests {
-    use crate::tests::check_fix;
-
-    // Register the required standard library types to make the tests work
-    #[track_caller]
-    fn check_diagnostics(ra_fixture: &str) {
-        let prefix = r#"
-//- /main.rs crate:main deps:core
-use core::iter::Iterator;
-use core::option::Option::{self, Some, None};
-"#;
-        let suffix = r#"
-//- /core/lib.rs crate:core
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
-pub mod iter {
-    pub trait Iterator {
-        type Item;
-        fn filter_map<B, F>(self, f: F) -> FilterMap where F: FnMut(Self::Item) -> Option<B> { FilterMap }
-        fn next(&mut self) -> Option<Self::Item>;
-    }
-    pub struct FilterMap {}
-    impl Iterator for FilterMap {
-        type Item = i32;
-        fn next(&mut self) -> i32 { 7 }
-    }
-}
-"#;
-        crate::tests::check_diagnostics(&format!("{}{}{}", prefix, ra_fixture, suffix))
-    }
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn replace_filter_map_next_with_find_map2() {
         check_diagnostics(
             r#"
-    fn foo() {
-        let m = [1, 2, 3].iter().filter_map(|x| Some(92)).next();
-    }         //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 💡 weak: replace filter_map(..).next() with find_map(..)
+//- minicore: iterators
+fn foo() {
+    let m = core::iter::repeat(()).filter_map(|()| Some(92)).next();
+}         //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 💡 weak: replace filter_map(..).next() with find_map(..)
 "#,
         );
     }
@@ -101,11 +73,11 @@ pub mod iter {
     fn replace_filter_map_next_with_find_map_no_diagnostic_without_next() {
         check_diagnostics(
             r#"
+//- minicore: iterators
 fn foo() {
-    let m = [1, 2, 3]
-        .iter()
-        .filter_map(|x| Some(92))
-        .len();
+    let m = core::iter::repeat(())
+        .filter_map(|()| Some(92))
+        .count();
 }
 "#,
         );
@@ -115,12 +87,12 @@ fn foo() {
     fn replace_filter_map_next_with_find_map_no_diagnostic_with_intervening_methods() {
         check_diagnostics(
             r#"
+//- minicore: iterators
 fn foo() {
-    let m = [1, 2, 3]
-        .iter()
-        .filter_map(|x| Some(92))
+    let m = core::iter::repeat(())
+        .filter_map(|()| Some(92))
         .map(|x| x + 2)
-        .len();
+        .next();
 }
 "#,
         );
@@ -130,10 +102,10 @@ fn foo() {
     fn replace_filter_map_next_with_find_map_no_diagnostic_if_not_in_chain() {
         check_diagnostics(
             r#"
+//- minicore: iterators
 fn foo() {
-    let m = [1, 2, 3]
-        .iter()
-        .filter_map(|x| Some(92));
+    let m = core::iter::repeat(())
+        .filter_map(|()| Some(92));
     let n = m.next();
 }
 "#,
@@ -144,34 +116,14 @@ fn foo() {
     fn replace_with_wind_map() {
         check_fix(
             r#"
-//- /main.rs crate:main deps:core
-use core::iter::Iterator;
-use core::option::Option::{self, Some, None};
+//- minicore: iterators
 fn foo() {
-    let m = [1, 2, 3].iter().$0filter_map(|x| Some(92)).next();
-}
-//- /core/lib.rs crate:core
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
-pub mod iter {
-    pub trait Iterator {
-        type Item;
-        fn filter_map<B, F>(self, f: F) -> FilterMap where F: FnMut(Self::Item) -> Option<B> { FilterMap }
-        fn next(&mut self) -> Option<Self::Item>;
-    }
-    pub struct FilterMap {}
-    impl Iterator for FilterMap {
-        type Item = i32;
-        fn next(&mut self) -> i32 { 7 }
-    }
+    let m = core::iter::repeat(()).$0filter_map(|()| Some(92)).next();
 }
 "#,
             r#"
-use core::iter::Iterator;
-use core::option::Option::{self, Some, None};
 fn foo() {
-    let m = [1, 2, 3].iter().find_map(|x| Some(92));
+    let m = core::iter::repeat(()).find_map(|()| Some(92));
 }
 "#,
         )
diff --git a/crates/test_utils/src/minicore.rs b/crates/test_utils/src/minicore.rs
index 71f07d38a..ce6ad8541 100644
--- a/crates/test_utils/src/minicore.rs
+++ b/crates/test_utils/src/minicore.rs
@@ -22,7 +22,7 @@
 //!     option:
 //!     result:
 //!     iterator: option
-//!     iterators: iterator
+//!     iterators: iterator, fn
 //!     default: sized
 //!     clone: sized
 //!     copy: clone
@@ -390,7 +390,6 @@ pub mod iter {
             iter: I,
             n: usize,
         }
-
         impl<I> Iterator for Take<I>
         where
             I: Iterator,
@@ -401,6 +400,22 @@ pub mod iter {
                 loop {}
             }
         }
+
+        pub struct FilterMap<I, F> {
+            iter: I,
+            f: F,
+        }
+        impl<B, I: Iterator, F> Iterator for FilterMap<I, F>
+        where
+            F: FnMut(I::Item) -> Option<B>,
+        {
+            type Item = B;
+
+            #[inline]
+            fn next(&mut self) -> Option<B> {
+                loop {}
+            }
+        }
     }
     pub use self::adapters::Take;
 
@@ -448,6 +463,13 @@ pub mod iter {
                 fn take(self, n: usize) -> crate::iter::Take<Self> {
                     loop {}
                 }
+                fn filter_map<B, F>(self, f: F) -> crate::iter::FilterMap<Self, F>
+                where
+                    Self: Sized,
+                    F: FnMut(Self::Item) -> Option<B>,
+                {
+                    loop {}
+                }
                 // endregion:iterators
             }
             impl<I: Iterator + ?Sized> Iterator for &mut I {