12 files changed, 29 insertions, 1432 deletions

diff --git a/crates/assists/src/assist_config.rs b/crates/assists/src/assist_config.rs
index b24527ec4..786224cfa 100644
--- a/crates/assists/src/assist_config.rs
+++ b/crates/assists/src/assist_config.rs
@@ -5,8 +5,9 @@
 //! assists if we are allowed to.
 
 use hir::PrefixKind;
+use ide_db::helpers::insert_use::MergeBehaviour;
 
-use crate::{utils::MergeBehaviour, AssistKind};
+use crate::AssistKind;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct AssistConfig {
diff --git a/crates/assists/src/ast_transform.rs b/crates/assists/src/ast_transform.rs
index ac72f3f02..66e4634b1 100644
--- a/crates/assists/src/ast_transform.rs
+++ b/crates/assists/src/ast_transform.rs
@@ -1,5 +1,6 @@
 //! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
 use hir::{HirDisplay, PathResolution, SemanticsScope};
+use ide_db::helpers::mod_path_to_ast;
 use rustc_hash::FxHashMap;
 use syntax::{
     algo::SyntaxRewriter,
@@ -7,8 +8,6 @@ use syntax::{
     SyntaxNode,
 };
 
-use crate::utils::mod_path_to_ast;
-
 pub fn apply<'a, N: AstNode>(transformer: &dyn AstTransform<'a>, node: N) -> N {
     SyntaxRewriter::from_fn(|element| match element {
         syntax::SyntaxElement::Node(n) => {
diff --git a/crates/assists/src/handlers/auto_import.rs b/crates/assists/src/handlers/auto_import.rs
index d665837a2..bd5bba646 100644
--- a/crates/assists/src/handlers/auto_import.rs
+++ b/crates/assists/src/handlers/auto_import.rs
@@ -1,8 +1,11 @@
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use syntax::ast;
 
 use crate::{
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::{insert_use, mod_path_to_ast, ImportScope},
     AssistContext, AssistId, AssistKind, Assists, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
index cac77c49b..d85767b4e 100644
--- a/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
+++ b/crates/assists/src/handlers/extract_struct_from_enum_variant.rs
@@ -2,6 +2,10 @@ use std::iter;
 
 use either::Either;
 use hir::{AsName, EnumVariant, Module, ModuleDef, Name};
+use ide_db::helpers::{
+    insert_use::{insert_use, ImportScope},
+    mod_path_to_ast,
+};
 use ide_db::{defs::Definition, search::Reference, RootDatabase};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
@@ -10,10 +14,7 @@ use syntax::{
     SourceFile, SyntaxElement, SyntaxNode, T,
 };
 
-use crate::{
-    utils::{insert_use, mod_path_to_ast, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: extract_struct_from_enum_variant
 //
@@ -236,10 +237,9 @@ fn update_reference(
 
 #[cfg(test)]
 mod tests {
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable},
-        utils::FamousDefs,
-    };
+    use ide_db::helpers::FamousDefs;
+
+    use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index eda45f5b3..ef12ef0cf 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -1,13 +1,14 @@
 use std::iter;
 
 use hir::{Adt, HasSource, ModuleDef, Semantics};
+use ide_db::helpers::{mod_path_to_ast, FamousDefs};
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 use test_utils::mark;
 
 use crate::{
-    utils::{mod_path_to_ast, render_snippet, Cursor, FamousDefs},
+    utils::{render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
@@ -212,12 +213,10 @@ fn build_pat(db: &RootDatabase, module: hir::Module, var: hir::EnumVariant) -> O
 
 #[cfg(test)]
 mod tests {
+    use ide_db::helpers::FamousDefs;
     use test_utils::mark;
 
-    use crate::{
-        tests::{check_assist, check_assist_not_applicable, check_assist_target},
-        utils::FamousDefs,
-    };
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
 
     use super::fill_match_arms;
 
diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index 674e5a175..3c374e5d9 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -1,8 +1,9 @@
+use ide_db::helpers::FamousDefs;
 use ide_db::RootDatabase;
 use syntax::ast::{self, AstNode, NameOwner};
 use test_utils::mark;
 
-use crate::{utils::FamousDefs, AssistContext, AssistId, AssistKind, Assists};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_from_impl_for_enum
 //
diff --git a/crates/assists/src/handlers/merge_imports.rs b/crates/assists/src/handlers/merge_imports.rs
index fd9c9e03c..b7e853994 100644
--- a/crates/assists/src/handlers/merge_imports.rs
+++ b/crates/assists/src/handlers/merge_imports.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::insert_use::{try_merge_imports, try_merge_trees, MergeBehaviour};
 use syntax::{
     algo::{neighbor, SyntaxRewriter},
     ast, AstNode,
@@ -5,10 +6,7 @@ use syntax::{
 
 use crate::{
     assist_context::{AssistContext, Assists},
-    utils::{
-        insert_use::{try_merge_imports, try_merge_trees},
-        next_prev, MergeBehaviour,
-    },
+    utils::next_prev,
     AssistId, AssistKind,
 };
 
diff --git a/crates/assists/src/handlers/qualify_path.rs b/crates/assists/src/handlers/qualify_path.rs
index d5bc4e574..6f9810fe8 100644
--- a/crates/assists/src/handlers/qualify_path.rs
+++ b/crates/assists/src/handlers/qualify_path.rs
@@ -1,6 +1,7 @@
 use std::iter;
 
 use hir::AsName;
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::RootDatabase;
 use syntax::{
     ast,
@@ -12,7 +13,6 @@ use test_utils::mark;
 use crate::{
     assist_context::{AssistContext, Assists},
     utils::import_assets::{ImportAssets, ImportCandidate},
-    utils::mod_path_to_ast,
     AssistId, AssistKind, GroupLabel,
 };
 
diff --git a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
index 453a6cebf..4d6a1956b 100644
--- a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -1,3 +1,4 @@
+use ide_db::helpers::mod_path_to_ast;
 use ide_db::imports_locator;
 use itertools::Itertools;
 use syntax::{
@@ -10,8 +11,7 @@ use syntax::{
 use crate::{
     assist_context::{AssistBuilder, AssistContext, Assists},
     utils::{
-        add_trait_assoc_items_to_impl, filter_assoc_items, mod_path_to_ast, render_snippet, Cursor,
-        DefaultMethods,
+        add_trait_assoc_items_to_impl, filter_assoc_items, render_snippet, Cursor, DefaultMethods,
     },
     AssistId, AssistKind,
 };
diff --git a/crates/assists/src/handlers/replace_qualified_name_with_use.rs b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
index a66db9ae3..8bdf9eea5 100644
--- a/crates/assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/assists/src/handlers/replace_qualified_name_with_use.rs
@@ -1,10 +1,8 @@
+use ide_db::helpers::insert_use::{insert_use, ImportScope};
 use syntax::{algo::SyntaxRewriter, ast, match_ast, AstNode, SyntaxNode};
 use test_utils::mark;
 
-use crate::{
-    utils::{insert_use, ImportScope},
-    AssistContext, AssistId, AssistKind, Assists,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: replace_qualified_name_with_use
 //
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 048746587..01f5c291f 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -1,10 +1,9 @@
 //! Assorted functions shared by several assists.
-pub(crate) mod insert_use;
 pub(crate) mod import_assets;
 
 use std::ops;
 
-use hir::{Crate, Enum, HasSource, Module, ScopeDef, Semantics, Trait};
+use hir::HasSource;
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::{
@@ -22,30 +21,6 @@ use crate::{
     ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
 };
 
-pub use insert_use::{insert_use, ImportScope, MergeBehaviour};
-
-pub fn mod_path_to_ast(path: &hir::ModPath) -> ast::Path {
-    let _p = profile::span("mod_path_to_ast");
-    let mut segments = Vec::new();
-    let mut is_abs = false;
-    match path.kind {
-        hir::PathKind::Plain => {}
-        hir::PathKind::Super(0) => segments.push(make::path_segment_self()),
-        hir::PathKind::Super(n) => segments.extend((0..n).map(|_| make::path_segment_super())),
-        hir::PathKind::DollarCrate(_) | hir::PathKind::Crate => {
-            segments.push(make::path_segment_crate())
-        }
-        hir::PathKind::Abs => is_abs = true,
-    }
-
-    segments.extend(
-        path.segments
-            .iter()
-            .map(|segment| make::path_segment(make::name_ref(&segment.to_string()))),
-    );
-    make::path_from_segments(segments, is_abs)
-}
-
 pub(crate) fn unwrap_trivial_block(block: ast::BlockExpr) -> ast::Expr {
     extract_trivial_expression(&block)
         .filter(|expr| !expr.syntax().text().contains_char('\n'))
@@ -260,179 +235,6 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
     }
 }
 
-/// Helps with finding well-know things inside the standard library. This is
-/// somewhat similar to the known paths infra inside hir, but it different; We
-/// want to make sure that IDE specific paths don't become interesting inside
-/// the compiler itself as well.
-pub struct FamousDefs<'a, 'b>(pub &'a Semantics<'b, RootDatabase>, pub Option<Crate>);
-
-#[allow(non_snake_case)]
-impl FamousDefs<'_, '_> {
-    pub const FIXTURE: &'static str = r#"//- /libcore.rs crate:core
-pub mod convert {
-    pub trait From<T> {
-        fn from(t: T) -> Self;
-    }
-}
-
-pub mod default {
-    pub trait Default {
-       fn default() -> Self;
-    }
-}
-
-pub mod iter {
-    pub use self::traits::{collect::IntoIterator, iterator::Iterator};
-    mod traits {
-        pub(crate) mod iterator {
-            use crate::option::Option;
-            pub trait Iterator {
-                type Item;
-                fn next(&mut self) -> Option<Self::Item>;
-                fn by_ref(&mut self) -> &mut Self {
-                    self
-                }
-                fn take(self, n: usize) -> crate::iter::Take<Self> {
-                    crate::iter::Take { inner: self }
-                }
-            }
-
-            impl<I: Iterator> Iterator for &mut I {
-                type Item = I::Item;
-                fn next(&mut self) -> Option<I::Item> {
-                    (**self).next()
-                }
-            }
-        }
-        pub(crate) mod collect {
-            pub trait IntoIterator {
-                type Item;
-            }
-        }
-    }
-
-    pub use self::sources::*;
-    pub(crate) mod sources {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Repeat<A> {
-            element: A,
-        }
-
-        pub fn repeat<T>(elt: T) -> Repeat<T> {
-            Repeat { element: elt }
-        }
-
-        impl<A> Iterator for Repeat<A> {
-            type Item = A;
-
-            fn next(&mut self) -> Option<A> {
-                None
-            }
-        }
-    }
-
-    pub use self::adapters::*;
-    pub(crate) mod adapters {
-        use super::Iterator;
-        use crate::option::Option::{self, *};
-        pub struct Take<I> { pub(crate) inner: I }
-        impl<I> Iterator for Take<I> where I: Iterator {
-            type Item = <I as Iterator>::Item;
-            fn next(&mut self) -> Option<<I as Iterator>::Item> {
-                None
-            }
-        }
-    }
-}
-
-pub mod option {
-    pub enum Option<T> { None, Some(T)}
-}
-
-pub mod prelude {
-    pub use crate::{convert::From, iter::{IntoIterator, Iterator}, option::Option::{self, *}, default::Default};
-}
-#[prelude_import]
-pub use prelude::*;
-"#;
-
-    pub fn core(&self) -> Option<Crate> {
-        self.find_crate("core")
-    }
-
-    pub(crate) fn core_convert_From(&self) -> Option<Trait> {
-        self.find_trait("core:convert:From")
-    }
-
-    pub(crate) fn core_option_Option(&self) -> Option<Enum> {
-        self.find_enum("core:option:Option")
-    }
-
-    pub fn core_default_Default(&self) -> Option<Trait> {
-        self.find_trait("core:default:Default")
-    }
-
-    pub fn core_iter_Iterator(&self) -> Option<Trait> {
-        self.find_trait("core:iter:traits:iterator:Iterator")
-    }
-
-    pub fn core_iter(&self) -> Option<Module> {
-        self.find_module("core:iter")
-    }
-
-    fn find_trait(&self, path: &str) -> Option<Trait> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Trait(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_enum(&self, path: &str) -> Option<Enum> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Adt(hir::Adt::Enum(it))) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_module(&self, path: &str) -> Option<Module> {
-        match self.find_def(path)? {
-            hir::ScopeDef::ModuleDef(hir::ModuleDef::Module(it)) => Some(it),
-            _ => None,
-        }
-    }
-
-    fn find_crate(&self, name: &str) -> Option<Crate> {
-        let krate = self.1?;
-        let db = self.0.db;
-        let res =
-            krate.dependencies(db).into_iter().find(|dep| dep.name.to_string() == name)?.krate;
-        Some(res)
-    }
-
-    fn find_def(&self, path: &str) -> Option<ScopeDef> {
-        let db = self.0.db;
-        let mut path = path.split(':');
-        let trait_ = path.next_back()?;
-        let std_crate = path.next()?;
-        let std_crate = self.find_crate(std_crate)?;
-        let mut module = std_crate.root_module(db);
-        for segment in path {
-            module = module.children(db).find_map(|child| {
-                let name = child.name(db)?;
-                if name.to_string() == segment {
-                    Some(child)
-                } else {
-                    None
-                }
-            })?;
-        }
-        let def =
-            module.scope(db, None).into_iter().find(|(name, _def)| name.to_string() == trait_)?.1;
-        Some(def)
-    }
-}
-
 pub(crate) fn next_prev() -> impl Iterator<Item = Direction> {
     [Direction::Next, Direction::Prev].iter().copied()
 }
diff --git a/crates/assists/src/utils/insert_use.rs b/crates/assists/src/utils/insert_use.rs
deleted file mode 100644
index 304adb93d..000000000
--- a/crates/assists/src/utils/insert_use.rs
+++ /dev/null
@@ -1,1204 +0,0 @@
-//! Handle syntactic aspects of inserting a new `use`.
-use std::{cmp::Ordering, iter::successors};
-
-use hir::Semantics;
-use ide_db::RootDatabase;
-use itertools::{EitherOrBoth, Itertools};
-use syntax::{
-    algo::SyntaxRewriter,
-    ast::{
-        self,
-        edit::{AstNodeEdit, IndentLevel},
-        make, AstNode, PathSegmentKind, VisibilityOwner,
-    },
-    AstToken, InsertPosition, NodeOrToken, SyntaxElement, SyntaxNode, SyntaxToken,
-};
-use test_utils::mark;
-
-#[derive(Debug, Clone)]
-pub enum ImportScope {
-    File(ast::SourceFile),
-    Module(ast::ItemList),
-}
-
-impl ImportScope {
-    pub(crate) fn from(syntax: SyntaxNode) -> Option<Self> {
-        if let Some(module) = ast::Module::cast(syntax.clone()) {
-            module.item_list().map(ImportScope::Module)
-        } else if let this @ Some(_) = ast::SourceFile::cast(syntax.clone()) {
-            this.map(ImportScope::File)
-        } else {
-            ast::ItemList::cast(syntax).map(ImportScope::Module)
-        }
-    }
-
-    /// Determines the containing syntax node in which to insert a `use` statement affecting `position`.
-    pub fn find_insert_use_container(
-        position: &SyntaxNode,
-        sema: &Semantics<'_, RootDatabase>,
-    ) -> Option<Self> {
-        sema.ancestors_with_macros(position.clone()).find_map(Self::from)
-    }
-
-    pub fn as_syntax_node(&self) -> &SyntaxNode {
-        match self {
-            ImportScope::File(file) => file.syntax(),
-            ImportScope::Module(item_list) => item_list.syntax(),
-        }
-    }
-
-    fn indent_level(&self) -> IndentLevel {
-        match self {
-            ImportScope::File(file) => file.indent_level(),
-            ImportScope::Module(item_list) => item_list.indent_level() + 1,
-        }
-    }
-
-    fn first_insert_pos(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
-        match self {
-            ImportScope::File(_) => (InsertPosition::First, AddBlankLine::AfterTwice),
-            // don't insert the imports before the item list's opening curly brace
-            ImportScope::Module(item_list) => item_list
-                .l_curly_token()
-                .map(|b| (InsertPosition::After(b.into()), AddBlankLine::Around))
-                .unwrap_or((InsertPosition::First, AddBlankLine::AfterTwice)),
-        }
-    }
-
-    fn insert_pos_after_last_inner_element(&self) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
-        self.as_syntax_node()
-            .children_with_tokens()
-            .filter(|child| match child {
-                NodeOrToken::Node(node) => is_inner_attribute(node.clone()),
-                NodeOrToken::Token(token) => is_inner_comment(token.clone()),
-            })
-            .last()
-            .map(|last_inner_element| {
-                (InsertPosition::After(last_inner_element.into()), AddBlankLine::BeforeTwice)
-            })
-            .unwrap_or_else(|| self.first_insert_pos())
-    }
-}
-
-fn is_inner_attribute(node: SyntaxNode) -> bool {
-    ast::Attr::cast(node).map(|attr| attr.kind()) == Some(ast::AttrKind::Inner)
-}
-
-fn is_inner_comment(token: SyntaxToken) -> bool {
-    ast::Comment::cast(token).and_then(|comment| comment.kind().doc)
-        == Some(ast::CommentPlacement::Inner)
-}
-
-/// Insert an import path into the given file/node. A `merge` value of none indicates that no import merging is allowed to occur.
-pub fn insert_use<'a>(
-    scope: &ImportScope,
-    path: ast::Path,
-    merge: Option<MergeBehaviour>,
-) -> SyntaxRewriter<'a> {
-    let _p = profile::span("insert_use");
-    let mut rewriter = SyntaxRewriter::default();
-    let use_item = make::use_(make::use_tree(path.clone(), None, None, false));
-    // merge into existing imports if possible
-    if let Some(mb) = merge {
-        for existing_use in scope.as_syntax_node().children().filter_map(ast::Use::cast) {
-            if let Some(merged) = try_merge_imports(&existing_use, &use_item, mb) {
-                rewriter.replace(existing_use.syntax(), merged.syntax());
-                return rewriter;
-            }
-        }
-    }
-
-    // either we weren't allowed to merge or there is no import that fits the merge conditions
-    // so look for the place we have to insert to
-    let (insert_position, add_blank) = find_insert_position(scope, path);
-
-    let indent = if let ident_level @ 1..=usize::MAX = scope.indent_level().0 as usize {
-        Some(make::tokens::whitespace(&" ".repeat(4 * ident_level)).into())
-    } else {
-        None
-    };
-
-    let to_insert: Vec<SyntaxElement> = {
-        let mut buf = Vec::new();
-
-        match add_blank {
-            AddBlankLine::Before | AddBlankLine::Around => {
-                buf.push(make::tokens::single_newline().into())
-            }
-            AddBlankLine::BeforeTwice => buf.push(make::tokens::blank_line().into()),
-            _ => (),
-        }
-
-        if add_blank.has_before() {
-            if let Some(indent) = indent.clone() {
-                mark::hit!(insert_use_indent_before);
-                buf.push(indent);
-            }
-        }
-
-        buf.push(use_item.syntax().clone().into());
-
-        match add_blank {
-            AddBlankLine::After | AddBlankLine::Around => {
-                buf.push(make::tokens::single_newline().into())
-            }
-            AddBlankLine::AfterTwice => buf.push(make::tokens::blank_line().into()),
-            _ => (),
-        }
-
-        // only add indentation *after* our stuff if there's another node directly after it
-        if add_blank.has_after() && matches!(insert_position, InsertPosition::Before(_)) {
-            if let Some(indent) = indent {
-                mark::hit!(insert_use_indent_after);
-                buf.push(indent);
-            }
-        } else if add_blank.has_after() && matches!(insert_position, InsertPosition::After(_)) {
-            mark::hit!(insert_use_no_indent_after);
-        }
-
-        buf
-    };
-
-    match insert_position {
-        InsertPosition::First => {
-            rewriter.insert_many_as_first_children(scope.as_syntax_node(), to_insert)
-        }
-        InsertPosition::Last => return rewriter, // actually unreachable
-        InsertPosition::Before(anchor) => rewriter.insert_many_before(&anchor, to_insert),
-        InsertPosition::After(anchor) => rewriter.insert_many_after(&anchor, to_insert),
-    }
-    rewriter
-}
-
-fn eq_visibility(vis0: Option<ast::Visibility>, vis1: Option<ast::Visibility>) -> bool {
-    match (vis0, vis1) {
-        (None, None) => true,
-        // FIXME: Don't use the string representation to check for equality
-        // spaces inside of the node would break this comparison
-        (Some(vis0), Some(vis1)) => vis0.to_string() == vis1.to_string(),
-        _ => false,
-    }
-}
-
-pub(crate) fn try_merge_imports(
-    lhs: &ast::Use,
-    rhs: &ast::Use,
-    merge_behaviour: MergeBehaviour,
-) -> Option<ast::Use> {
-    // don't merge imports with different visibilities
-    if !eq_visibility(lhs.visibility(), rhs.visibility()) {
-        return None;
-    }
-    let lhs_tree = lhs.use_tree()?;
-    let rhs_tree = rhs.use_tree()?;
-    let merged = try_merge_trees(&lhs_tree, &rhs_tree, merge_behaviour)?;
-    Some(lhs.with_use_tree(merged))
-}
-
-pub(crate) fn try_merge_trees(
-    lhs: &ast::UseTree,
-    rhs: &ast::UseTree,
-    merge: MergeBehaviour,
-) -> Option<ast::UseTree> {
-    let lhs_path = lhs.path()?;
-    let rhs_path = rhs.path()?;
-
-    let (lhs_prefix, rhs_prefix) = common_prefix(&lhs_path, &rhs_path)?;
-    let (lhs, rhs) = if is_simple_path(lhs)
-        && is_simple_path(rhs)
-        && lhs_path == lhs_prefix
-        && rhs_path == rhs_prefix
-    {
-        (lhs.clone(), rhs.clone())
-    } else {
-        (lhs.split_prefix(&lhs_prefix), rhs.split_prefix(&rhs_prefix))
-    };
-    recursive_merge(&lhs, &rhs, merge)
-}
-
-/// Recursively "zips" together lhs and rhs.
-fn recursive_merge(
-    lhs: &ast::UseTree,
-    rhs: &ast::UseTree,
-    merge: MergeBehaviour,
-) -> Option<ast::UseTree> {
-    let mut use_trees = lhs
-        .use_tree_list()
-        .into_iter()
-        .flat_map(|list| list.use_trees())
-        // we use Option here to early return from this function(this is not the same as a `filter` op)
-        .map(|tree| match merge.is_tree_allowed(&tree) {
-            true => Some(tree),
-            false => None,
-        })
-        .collect::<Option<Vec<_>>>()?;
-    use_trees.sort_unstable_by(|a, b| path_cmp_for_sort(a.path(), b.path()));
-    for rhs_t in rhs.use_tree_list().into_iter().flat_map(|list| list.use_trees()) {
-        if !merge.is_tree_allowed(&rhs_t) {
-            return None;
-        }
-        let rhs_path = rhs_t.path();
-        match use_trees.binary_search_by(|lhs_t| {
-            let (lhs_t, rhs_t) = match lhs_t
-                .path()
-                .zip(rhs_path.clone())
-                .and_then(|(lhs, rhs)| common_prefix(&lhs, &rhs))
-            {
-                Some((lhs_p, rhs_p)) => (lhs_t.split_prefix(&lhs_p), rhs_t.split_prefix(&rhs_p)),
-                None => (lhs_t.clone(), rhs_t.clone()),
-            };
-
-            path_cmp_bin_search(lhs_t.path(), rhs_t.path())
-        }) {
-            Ok(idx) => {
-                let lhs_t = &mut use_trees[idx];
-                let lhs_path = lhs_t.path()?;
-                let rhs_path = rhs_path?;
-                let (lhs_prefix, rhs_prefix) = common_prefix(&lhs_path, &rhs_path)?;
-                if lhs_prefix == lhs_path && rhs_prefix == rhs_path {
-                    let tree_is_self = |tree: ast::UseTree| {
-                        tree.path().as_ref().map(path_is_self).unwrap_or(false)
-                    };
-                    // check if only one of the two trees has a tree list, and whether that then contains `self` or not.
-                    // If this is the case we can skip this iteration since the path without the list is already included in the other one via `self`
-                    let tree_contains_self = |tree: &ast::UseTree| {
-                        tree.use_tree_list()
-                            .map(|tree_list| tree_list.use_trees().any(tree_is_self))
-                            .unwrap_or(false)
-                    };
-                    match (tree_contains_self(&lhs_t), tree_contains_self(&rhs_t)) {
-                        (true, false) => continue,
-                        (false, true) => {
-                            *lhs_t = rhs_t;
-                            continue;
-                        }
-                        _ => (),
-                    }
-
-                    // glob imports arent part of the use-tree lists so we need to special handle them here as well
-                    // this special handling is only required for when we merge a module import into a glob import of said module
-                    // see the `merge_self_glob` or `merge_mod_into_glob` tests
-                    if lhs_t.star_token().is_some() || rhs_t.star_token().is_some() {
-                        *lhs_t = make::use_tree(
-                            make::path_unqualified(make::path_segment_self()),
-                            None,
-                            None,
-                            false,
-                        );
-                        use_trees.insert(idx, make::glob_use_tree());
-                        continue;
-                    }
-
-                    if lhs_t.use_tree_list().is_none() && rhs_t.use_tree_list().is_none() {
-                        continue;
-                    }
-                }
-                let lhs = lhs_t.split_prefix(&lhs_prefix);
-                let rhs = rhs_t.split_prefix(&rhs_prefix);
-                match recursive_merge(&lhs, &rhs, merge) {
-                    Some(use_tree) => use_trees[idx] = use_tree,
-                    None => return None,
-                }
-            }
-            Err(_)
-                if merge == MergeBehaviour::Last
-                    && use_trees.len() > 0
-                    && rhs_t.use_tree_list().is_some() =>
-            {
-                return None
-            }
-            Err(idx) => {
-                use_trees.insert(idx, rhs_t);
-            }
-        }
-    }
-    Some(lhs.with_use_tree_list(make::use_tree_list(use_trees)))
-}
-
-/// Traverses both paths until they differ, returning the common prefix of both.
-fn common_prefix(lhs: &ast::Path, rhs: &ast::Path) -> Option<(ast::Path, ast::Path)> {
-    let mut res = None;
-    let mut lhs_curr = first_path(&lhs);
-    let mut rhs_curr = first_path(&rhs);
-    loop {
-        match (lhs_curr.segment(), rhs_curr.segment()) {
-            (Some(lhs), Some(rhs)) if lhs.syntax().text() == rhs.syntax().text() => (),
-            _ => break res,
-        }
-        res = Some((lhs_curr.clone(), rhs_curr.clone()));
-
-        match lhs_curr.parent_path().zip(rhs_curr.parent_path()) {
-            Some((lhs, rhs)) => {
-                lhs_curr = lhs;
-                rhs_curr = rhs;
-            }
-            _ => break res,
-        }
-    }
-}
-
-fn is_simple_path(use_tree: &ast::UseTree) -> bool {
-    use_tree.use_tree_list().is_none() && use_tree.star_token().is_none()
-}
-
-fn path_is_self(path: &ast::Path) -> bool {
-    path.segment().and_then(|seg| seg.self_token()).is_some() && path.qualifier().is_none()
-}
-
-#[inline]
-fn first_segment(path: &ast::Path) -> Option<ast::PathSegment> {
-    first_path(path).segment()
-}
-
-fn first_path(path: &ast::Path) -> ast::Path {
-    successors(Some(path.clone()), ast::Path::qualifier).last().unwrap()
-}
-
-fn segment_iter(path: &ast::Path) -> impl Iterator<Item = ast::PathSegment> + Clone {
-    // cant make use of SyntaxNode::siblings, because the returned Iterator is not clone
-    successors(first_segment(path), |p| p.parent_path().parent_path().and_then(|p| p.segment()))
-}
-
-fn path_len(path: ast::Path) -> usize {
-    segment_iter(&path).count()
-}
-
-/// Orders paths in the following way:
-/// the sole self token comes first, after that come uppercase identifiers, then lowercase identifiers
-// FIXME: rustfmt sorts lowercase idents before uppercase, in general we want to have the same ordering rustfmt has
-// which is `self` and `super` first, then identifier imports with lowercase ones first, then glob imports and at last list imports.
-// Example foo::{self, foo, baz, Baz, Qux, *, {Bar}}
-fn path_cmp_for_sort(a: Option<ast::Path>, b: Option<ast::Path>) -> Ordering {
-    match (a, b) {
-        (None, None) => Ordering::Equal,
-        (None, Some(_)) => Ordering::Less,
-        (Some(_), None) => Ordering::Greater,
-        (Some(ref a), Some(ref b)) => match (path_is_self(a), path_is_self(b)) {
-            (true, true) => Ordering::Equal,
-            (true, false) => Ordering::Less,
-            (false, true) => Ordering::Greater,
-            (false, false) => path_cmp_short(a, b),
-        },
-    }
-}
-
-/// Path comparison func for binary searching for merging.
-fn path_cmp_bin_search(lhs: Option<ast::Path>, rhs: Option<ast::Path>) -> Ordering {
-    match (lhs.and_then(|path| path.segment()), rhs.and_then(|path| path.segment())) {
-        (None, None) => Ordering::Equal,
-        (None, Some(_)) => Ordering::Less,
-        (Some(_), None) => Ordering::Greater,
-        (Some(ref a), Some(ref b)) => path_segment_cmp(a, b),
-    }
-}
-
-/// Short circuiting comparison, if both paths are equal until one of them ends they are considered
-/// equal
-fn path_cmp_short(a: &ast::Path, b: &ast::Path) -> Ordering {
-    let a = segment_iter(a);
-    let b = segment_iter(b);
-    // cmp_by would be useful for us here but that is currently unstable
-    // cmp doesnt work due the lifetimes on text's return type
-    a.zip(b)
-        .find_map(|(a, b)| match path_segment_cmp(&a, &b) {
-            Ordering::Equal => None,
-            ord => Some(ord),
-        })
-        .unwrap_or(Ordering::Equal)
-}
-
-/// Compares to paths, if one ends earlier than the other the has_tl parameters decide which is
-/// greater as a a path that has a tree list should be greater, while one that just ends without
-/// a tree list should be considered less.
-fn use_tree_path_cmp(a: &ast::Path, a_has_tl: bool, b: &ast::Path, b_has_tl: bool) -> Ordering {
-    let a_segments = segment_iter(a);
-    let b_segments = segment_iter(b);
-    // cmp_by would be useful for us here but that is currently unstable
-    // cmp doesnt work due the lifetimes on text's return type
-    a_segments
-        .zip_longest(b_segments)
-        .find_map(|zipped| match zipped {
-            EitherOrBoth::Both(ref a, ref b) => match path_segment_cmp(a, b) {
-                Ordering::Equal => None,
-                ord => Some(ord),
-            },
-            EitherOrBoth::Left(_) if !b_has_tl => Some(Ordering::Greater),
-            EitherOrBoth::Left(_) => Some(Ordering::Less),
-            EitherOrBoth::Right(_) if !a_has_tl => Some(Ordering::Less),
-            EitherOrBoth::Right(_) => Some(Ordering::Greater),
-        })
-        .unwrap_or(Ordering::Equal)
-}
-
-fn path_segment_cmp(a: &ast::PathSegment, b: &ast::PathSegment) -> Ordering {
-    let a = a.name_ref();
-    let b = b.name_ref();
-    a.as_ref().map(ast::NameRef::text).cmp(&b.as_ref().map(ast::NameRef::text))
-}
-
-/// What type of merges are allowed.
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-pub enum MergeBehaviour {
-    /// Merge everything together creating deeply nested imports.
-    Full,
-    /// Only merge the last import level, doesn't allow import nesting.
-    Last,
-}
-
-impl MergeBehaviour {
-    #[inline]
-    fn is_tree_allowed(&self, tree: &ast::UseTree) -> bool {
-        match self {
-            MergeBehaviour::Full => true,
-            // only simple single segment paths are allowed
-            MergeBehaviour::Last => {
-                tree.use_tree_list().is_none() && tree.path().map(path_len) <= Some(1)
-            }
-        }
-    }
-}
-
-#[derive(Eq, PartialEq, PartialOrd, Ord)]
-enum ImportGroup {
-    // the order here defines the order of new group inserts
-    Std,
-    ExternCrate,
-    ThisCrate,
-    ThisModule,
-    SuperModule,
-}
-
-impl ImportGroup {
-    fn new(path: &ast::Path) -> ImportGroup {
-        let default = ImportGroup::ExternCrate;
-
-        let first_segment = match first_segment(path) {
-            Some(it) => it,
-            None => return default,
-        };
-
-        let kind = first_segment.kind().unwrap_or(PathSegmentKind::SelfKw);
-        match kind {
-            PathSegmentKind::SelfKw => ImportGroup::ThisModule,
-            PathSegmentKind::SuperKw => ImportGroup::SuperModule,
-            PathSegmentKind::CrateKw => ImportGroup::ThisCrate,
-            PathSegmentKind::Name(name) => match name.text().as_str() {
-                "std" => ImportGroup::Std,
-                "core" => ImportGroup::Std,
-                _ => ImportGroup::ExternCrate,
-            },
-            PathSegmentKind::Type { .. } => unreachable!(),
-        }
-    }
-}
-
-#[derive(PartialEq, Eq)]
-enum AddBlankLine {
-    Before,
-    BeforeTwice,
-    Around,
-    After,
-    AfterTwice,
-}
-
-impl AddBlankLine {
-    fn has_before(&self) -> bool {
-        matches!(self, AddBlankLine::Before | AddBlankLine::BeforeTwice | AddBlankLine::Around)
-    }
-    fn has_after(&self) -> bool {
-        matches!(self, AddBlankLine::After | AddBlankLine::AfterTwice | AddBlankLine::Around)
-    }
-}
-
-fn find_insert_position(
-    scope: &ImportScope,
-    insert_path: ast::Path,
-) -> (InsertPosition<SyntaxElement>, AddBlankLine) {
-    let group = ImportGroup::new(&insert_path);
-    let path_node_iter = scope
-        .as_syntax_node()
-        .children()
-        .filter_map(|node| ast::Use::cast(node.clone()).zip(Some(node)))
-        .flat_map(|(use_, node)| {
-            let tree = use_.use_tree()?;
-            let path = tree.path()?;
-            let has_tl = tree.use_tree_list().is_some();
-            Some((path, has_tl, node))
-        });
-    // Iterator that discards anything thats not in the required grouping
-    // This implementation allows the user to rearrange their import groups as this only takes the first group that fits
-    let group_iter = path_node_iter
-        .clone()
-        .skip_while(|(path, ..)| ImportGroup::new(path) != group)
-        .take_while(|(path, ..)| ImportGroup::new(path) == group);
-
-    // track the last element we iterated over, if this is still None after the iteration then that means we never iterated in the first place
-    let mut last = None;
-    // find the element that would come directly after our new import
-    let post_insert = group_iter.inspect(|(.., node)| last = Some(node.clone())).find(
-        |&(ref path, has_tl, _)| {
-            use_tree_path_cmp(&insert_path, false, path, has_tl) != Ordering::Greater
-        },
-    );
-    match post_insert {
-        // insert our import before that element
-        Some((.., node)) => (InsertPosition::Before(node.into()), AddBlankLine::After),
-        // there is no element after our new import, so append it to the end of the group
-        None => match last {
-            Some(node) => (InsertPosition::After(node.into()), AddBlankLine::Before),
-            // the group we were looking for actually doesnt exist, so insert
-            None => {
-                // similar concept here to the `last` from above
-                let mut last = None;
-                // find the group that comes after where we want to insert
-                let post_group = path_node_iter
-                    .inspect(|(.., node)| last = Some(node.clone()))
-                    .find(|(p, ..)| ImportGroup::new(p) > group);
-                match post_group {
-                    Some((.., node)) => {
-                        (InsertPosition::Before(node.into()), AddBlankLine::AfterTwice)
-                    }
-                    // there is no such group, so append after the last one
-                    None => match last {
-                        Some(node) => {
-                            (InsertPosition::After(node.into()), AddBlankLine::BeforeTwice)
-                        }
-                        // there are no imports in this file at all
-                        None => scope.insert_pos_after_last_inner_element(),
-                    },
-                }
-            }
-        },
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    use test_utils::assert_eq_text;
-
-    #[test]
-    fn insert_existing() {
-        check_full("std::fs", "use std::fs;", "use std::fs;")
-    }
-
-    #[test]
-    fn insert_start() {
-        check_none(
-            "std::bar::AA",
-            r"
-use std::bar::B;
-use std::bar::D;
-use std::bar::F;
-use std::bar::G;",
-            r"
-use std::bar::AA;
-use std::bar::B;
-use std::bar::D;
-use std::bar::F;
-use std::bar::G;",
-        )
-    }
-
-    #[test]
-    fn insert_start_indent() {
-        mark::check!(insert_use_indent_after);
-        check_none(
-            "std::bar::AA",
-            r"
-    use std::bar::B;
-    use std::bar::D;",
-            r"
-    use std::bar::AA;
-    use std::bar::B;
-    use std::bar::D;",
-        )
-    }
-
-    #[test]
-    fn insert_middle() {
-        check_none(
-            "std::bar::EE",
-            r"
-use std::bar::A;
-use std::bar::D;
-use std::bar::F;
-use std::bar::G;",
-            r"
-use std::bar::A;
-use std::bar::D;
-use std::bar::EE;
-use std::bar::F;
-use std::bar::G;",
-        )
-    }
-
-    #[test]
-    fn insert_middle_indent() {
-        check_none(
-            "std::bar::EE",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-    use std::bar::F;
-    use std::bar::G;",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-    use std::bar::EE;
-    use std::bar::F;
-    use std::bar::G;",
-        )
-    }
-
-    #[test]
-    fn insert_end() {
-        check_none(
-            "std::bar::ZZ",
-            r"
-use std::bar::A;
-use std::bar::D;
-use std::bar::F;
-use std::bar::G;",
-            r"
-use std::bar::A;
-use std::bar::D;
-use std::bar::F;
-use std::bar::G;
-use std::bar::ZZ;",
-        )
-    }
-
-    #[test]
-    fn insert_end_indent() {
-        mark::check!(insert_use_indent_before);
-        check_none(
-            "std::bar::ZZ",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-    use std::bar::F;
-    use std::bar::G;",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-    use std::bar::F;
-    use std::bar::G;
-    use std::bar::ZZ;",
-        )
-    }
-
-    #[test]
-    fn insert_middle_nested() {
-        check_none(
-            "std::bar::EE",
-            r"
-use std::bar::A;
-use std::bar::{D, Z}; // example of weird imports due to user
-use std::bar::F;
-use std::bar::G;",
-            r"
-use std::bar::A;
-use std::bar::EE;
-use std::bar::{D, Z}; // example of weird imports due to user
-use std::bar::F;
-use std::bar::G;",
-        )
-    }
-
-    #[test]
-    fn insert_middle_groups() {
-        check_none(
-            "foo::bar::GG",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-
-    use foo::bar::F;
-    use foo::bar::H;",
-            r"
-    use std::bar::A;
-    use std::bar::D;
-
-    use foo::bar::F;
-    use foo::bar::GG;
-    use foo::bar::H;",
-        )
-    }
-
-    #[test]
-    fn insert_first_matching_group() {
-        check_none(
-            "foo::bar::GG",
-            r"
-    use foo::bar::A;
-    use foo::bar::D;
-
-    use std;
-
-    use foo::bar::F;
-    use foo::bar::H;",
-            r"
-    use foo::bar::A;
-    use foo::bar::D;
-    use foo::bar::GG;
-
-    use std;
-
-    use foo::bar::F;
-    use foo::bar::H;",
-        )
-    }
-
-    #[test]
-    fn insert_missing_group_std() {
-        check_none(
-            "std::fmt",
-            r"
-    use foo::bar::A;
-    use foo::bar::D;",
-            r"
-    use std::fmt;
-
-    use foo::bar::A;
-    use foo::bar::D;",
-        )
-    }
-
-    #[test]
-    fn insert_missing_group_self() {
-        check_none(
-            "self::fmt",
-            r"
-use foo::bar::A;
-use foo::bar::D;",
-            r"
-use foo::bar::A;
-use foo::bar::D;
-
-use self::fmt;",
-        )
-    }
-
-    #[test]
-    fn insert_no_imports() {
-        check_full(
-            "foo::bar",
-            "fn main() {}",
-            r"use foo::bar;
-
-fn main() {}",
-        )
-    }
-
-    #[test]
-    fn insert_empty_file() {
-        // empty files will get two trailing newlines
-        // this is due to the test case insert_no_imports above
-        check_full(
-            "foo::bar",
-            "",
-            r"use foo::bar;
-
-",
-        )
-    }
-
-    #[test]
-    fn insert_empty_module() {
-        mark::check!(insert_use_no_indent_after);
-        check(
-            "foo::bar",
-            "mod x {}",
-            r"{
-    use foo::bar;
-}",
-            None,
-            true,
-        )
-    }
-
-    #[test]
-    fn insert_after_inner_attr() {
-        check_full(
-            "foo::bar",
-            r"#![allow(unused_imports)]",
-            r"#![allow(unused_imports)]
-
-use foo::bar;",
-        )
-    }
-
-    #[test]
-    fn insert_after_inner_attr2() {
-        check_full(
-            "foo::bar",
-            r"#![allow(unused_imports)]
-
-#![no_std]
-fn main() {}",
-            r"#![allow(unused_imports)]
-
-#![no_std]
-
-use foo::bar;
-fn main() {}",
-        );
-    }
-
-    #[test]
-    fn inserts_after_single_line_inner_comments() {
-        check_none(
-            "foo::bar::Baz",
-            "//! Single line inner comments do not allow any code before them.",
-            r#"//! Single line inner comments do not allow any code before them.
-
-use foo::bar::Baz;"#,
-        );
-    }
-
-    #[test]
-    fn inserts_after_multiline_inner_comments() {
-        check_none(
-            "foo::bar::Baz",
-            r#"/*! Multiline inner comments do not allow any code before them. */
-
-/*! Still an inner comment, cannot place any code before. */
-fn main() {}"#,
-            r#"/*! Multiline inner comments do not allow any code before them. */
-
-/*! Still an inner comment, cannot place any code before. */
-
-use foo::bar::Baz;
-fn main() {}"#,
-        )
-    }
-
-    #[test]
-    fn inserts_after_all_inner_items() {
-        check_none(
-            "foo::bar::Baz",
-            r#"#![allow(unused_imports)]
-/*! Multiline line comment 2 */
-
-
-//! Single line comment 1
-#![no_std]
-//! Single line comment 2
-fn main() {}"#,
-            r#"#![allow(unused_imports)]
-/*! Multiline line comment 2 */
-
-
-//! Single line comment 1
-#![no_std]
-//! Single line comment 2
-
-use foo::bar::Baz;
-fn main() {}"#,
-        )
-    }
-
-    #[test]
-    fn merge_groups() {
-        check_last("std::io", r"use std::fmt;", r"use std::{fmt, io};")
-    }
-
-    #[test]
-    fn merge_groups_last() {
-        check_last(
-            "std::io",
-            r"use std::fmt::{Result, Display};",
-            r"use std::fmt::{Result, Display};
-use std::io;",
-        )
-    }
-
-    #[test]
-    fn merge_last_into_self() {
-        check_last("foo::bar::baz", r"use foo::bar;", r"use foo::bar::{self, baz};");
-    }
-
-    #[test]
-    fn merge_groups_full() {
-        check_full(
-            "std::io",
-            r"use std::fmt::{Result, Display};",
-            r"use std::{fmt::{Result, Display}, io};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_full() {
-        check_full(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::Qux;",
-            r"use std::foo::bar::{Baz, Qux};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_last() {
-        check_last(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::Qux;",
-            r"use std::foo::bar::{Baz, Qux};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_full_list() {
-        check_full(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::{Qux, Quux};",
-            r"use std::foo::bar::{Baz, Quux, Qux};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_last_list() {
-        check_last(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::{Qux, Quux};",
-            r"use std::foo::bar::{Baz, Quux, Qux};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_full_nested() {
-        check_full(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::{Qux, quux::{Fez, Fizz}};",
-            r"use std::foo::bar::{Baz, Qux, quux::{Fez, Fizz}};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_long_last_nested() {
-        check_last(
-            "std::foo::bar::Baz",
-            r"use std::foo::bar::{Qux, quux::{Fez, Fizz}};",
-            r"use std::foo::bar::Baz;
-use std::foo::bar::{Qux, quux::{Fez, Fizz}};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_full_nested_deep() {
-        check_full(
-            "std::foo::bar::quux::Baz",
-            r"use std::foo::bar::{Qux, quux::{Fez, Fizz}};",
-            r"use std::foo::bar::{Qux, quux::{Baz, Fez, Fizz}};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_full_nested_long() {
-        check_full(
-            "std::foo::bar::Baz",
-            r"use std::{foo::bar::Qux};",
-            r"use std::{foo::bar::{Baz, Qux}};",
-        );
-    }
-
-    #[test]
-    fn merge_groups_last_nested_long() {
-        check_full(
-            "std::foo::bar::Baz",
-            r"use std::{foo::bar::Qux};",
-            r"use std::{foo::bar::{Baz, Qux}};",
-        );
-    }
-
-    #[test]
-    fn merge_groups_skip_pub() {
-        check_full(
-            "std::io",
-            r"pub use std::fmt::{Result, Display};",
-            r"pub use std::fmt::{Result, Display};
-use std::io;",
-        )
-    }
-
-    #[test]
-    fn merge_groups_skip_pub_crate() {
-        check_full(
-            "std::io",
-            r"pub(crate) use std::fmt::{Result, Display};",
-            r"pub(crate) use std::fmt::{Result, Display};
-use std::io;",
-        )
-    }
-
-    #[test]
-    #[ignore] // FIXME: Support this
-    fn split_out_merge() {
-        check_last(
-            "std::fmt::Result",
-            r"use std::{fmt, io};",
-            r"use std::fmt::{self, Result};
-use std::io;",
-        )
-    }
-
-    #[test]
-    fn merge_into_module_import() {
-        check_full(
-            "std::fmt::Result",
-            r"use std::{fmt, io};",
-            r"use std::{fmt::{self, Result}, io};",
-        )
-    }
-
-    #[test]
-    fn merge_groups_self() {
-        check_full("std::fmt::Debug", r"use std::fmt;", r"use std::fmt::{self, Debug};")
-    }
-
-    #[test]
-    fn merge_mod_into_glob() {
-        check_full(
-            "token::TokenKind",
-            r"use token::TokenKind::*;",
-            r"use token::TokenKind::{*, self};",
-        )
-        // FIXME: have it emit `use token::TokenKind::{self, *}`?
-    }
-
-    #[test]
-    fn merge_self_glob() {
-        check_full("self", r"use self::*;", r"use self::{*, self};")
-        // FIXME: have it emit `use {self, *}`?
-    }
-
-    #[test]
-    fn merge_glob_nested() {
-        check_full(
-            "foo::bar::quux::Fez",
-            r"use foo::bar::{Baz, quux::*};",
-            r"use foo::bar::{Baz, quux::{self::*, Fez}};",
-        )
-    }
-
-    #[test]
-    fn skip_merge_last_too_long() {
-        check_last(
-            "foo::bar",
-            r"use foo::bar::baz::Qux;",
-            r"use foo::bar;
-use foo::bar::baz::Qux;",
-        );
-    }
-
-    #[test]
-    fn skip_merge_last_too_long2() {
-        check_last(
-            "foo::bar::baz::Qux",
-            r"use foo::bar;",
-            r"use foo::bar;
-use foo::bar::baz::Qux;",
-        );
-    }
-
-    #[test]
-    fn insert_short_before_long() {
-        check_none(
-            "foo::bar",
-            r"use foo::bar::baz::Qux;",
-            r"use foo::bar;
-use foo::bar::baz::Qux;",
-        );
-    }
-
-    #[test]
-    fn merge_last_fail() {
-        check_merge_only_fail(
-            r"use foo::bar::{baz::{Qux, Fez}};",
-            r"use foo::bar::{baaz::{Quux, Feez}};",
-            MergeBehaviour::Last,
-        );
-    }
-
-    #[test]
-    fn merge_last_fail1() {
-        check_merge_only_fail(
-            r"use foo::bar::{baz::{Qux, Fez}};",
-            r"use foo::bar::baaz::{Quux, Feez};",
-            MergeBehaviour::Last,
-        );
-    }
-
-    #[test]
-    fn merge_last_fail2() {
-        check_merge_only_fail(
-            r"use foo::bar::baz::{Qux, Fez};",
-            r"use foo::bar::{baaz::{Quux, Feez}};",
-            MergeBehaviour::Last,
-        );
-    }
-
-    #[test]
-    fn merge_last_fail3() {
-        check_merge_only_fail(
-            r"use foo::bar::baz::{Qux, Fez};",
-            r"use foo::bar::baaz::{Quux, Feez};",
-            MergeBehaviour::Last,
-        );
-    }
-
-    fn check(
-        path: &str,
-        ra_fixture_before: &str,
-        ra_fixture_after: &str,
-        mb: Option<MergeBehaviour>,
-        module: bool,
-    ) {
-        let mut syntax = ast::SourceFile::parse(ra_fixture_before).tree().syntax().clone();
-        if module {
-            syntax = syntax.descendants().find_map(ast::Module::cast).unwrap().syntax().clone();
-        }
-        let file = super::ImportScope::from(syntax).unwrap();
-        let path = ast::SourceFile::parse(&format!("use {};", path))
-            .tree()
-            .syntax()
-            .descendants()
-            .find_map(ast::Path::cast)
-            .unwrap();
-
-        let rewriter = insert_use(&file, path, mb);
-        let result = rewriter.rewrite(file.as_syntax_node()).to_string();
-        assert_eq_text!(&result, ra_fixture_after);
-    }
-
-    fn check_full(path: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
-        check(path, ra_fixture_before, ra_fixture_after, Some(MergeBehaviour::Full), false)
-    }
-
-    fn check_last(path: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
-        check(path, ra_fixture_before, ra_fixture_after, Some(MergeBehaviour::Last), false)
-    }
-
-    fn check_none(path: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
-        check(path, ra_fixture_before, ra_fixture_after, None, false)
-    }
-
-    fn check_merge_only_fail(ra_fixture0: &str, ra_fixture1: &str, mb: MergeBehaviour) {
-        let use0 = ast::SourceFile::parse(ra_fixture0)
-            .tree()
-            .syntax()
-            .descendants()
-            .find_map(ast::Use::cast)
-            .unwrap();
-
-        let use1 = ast::SourceFile::parse(ra_fixture1)
-            .tree()
-            .syntax()
-            .descendants()
-            .find_map(ast::Use::cast)
-            .unwrap();
-
-        let result = try_merge_imports(&use0, &use1, mb);
-        assert_eq!(result.map(|u| u.to_string()), None);
-    }
-}