4 files changed, 281 insertions, 44 deletions

diff --git a/crates/assists/src/handlers/auto_import.rs b/crates/assists/src/handlers/auto_import.rs
index 55620f0f3..4e2a4fcd9 100644
--- a/crates/assists/src/handlers/auto_import.rs
+++ b/crates/assists/src/handlers/auto_import.rs
@@ -1,13 +1,11 @@
 use ide_db::helpers::{
+    import_assets::{ImportAssets, ImportCandidate},
     insert_use::{insert_use, ImportScope},
     mod_path_to_ast,
 };
 use syntax::ast;
 
-use crate::{
-    utils::import_assets::{ImportAssets, ImportCandidate},
-    AssistContext, AssistId, AssistKind, Assists, GroupLabel,
-};
+use crate::{AssistContext, AssistId, AssistKind, Assists, GroupLabel};
 
 // Feature: Auto Import
 //
@@ -121,8 +119,7 @@ pub(crate) fn auto_import(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
 
 fn import_group_message(import_candidate: &ImportCandidate) -> GroupLabel {
     let name = match import_candidate {
-        ImportCandidate::UnqualifiedName(candidate)
-        | ImportCandidate::QualifierStart(candidate) => format!("Import {}", &candidate.name),
+        ImportCandidate::Path(candidate) => format!("Import {}", &candidate.name),
         ImportCandidate::TraitAssocItem(candidate) => {
             format!("Import a trait for item {}", &candidate.name)
         }
diff --git a/crates/assists/src/handlers/inline_local_variable.rs b/crates/assists/src/handlers/inline_local_variable.rs
index dc798daaa..0e63a60e8 100644
--- a/crates/assists/src/handlers/inline_local_variable.rs
+++ b/crates/assists/src/handlers/inline_local_variable.rs
@@ -79,29 +79,30 @@ pub(crate) fn inline_local_variable(acc: &mut Assists, ctx: &AssistContext) -> O
                 None => return Ok(false),
             };
 
-            Ok(!matches!((&initializer_expr, usage_parent),
+            Ok(!matches!(
+                (&initializer_expr, usage_parent),
                 (ast::Expr::CallExpr(_), _)
-                | (ast::Expr::IndexExpr(_), _)
-                | (ast::Expr::MethodCallExpr(_), _)
-                | (ast::Expr::FieldExpr(_), _)
-                | (ast::Expr::TryExpr(_), _)
-                | (ast::Expr::RefExpr(_), _)
-                | (ast::Expr::Literal(_), _)
-                | (ast::Expr::TupleExpr(_), _)
-                | (ast::Expr::ArrayExpr(_), _)
-                | (ast::Expr::ParenExpr(_), _)
-                | (ast::Expr::PathExpr(_), _)
-                | (ast::Expr::BlockExpr(_), _)
-                | (ast::Expr::EffectExpr(_), _)
-                | (_, ast::Expr::CallExpr(_))
-                | (_, ast::Expr::TupleExpr(_))
-                | (_, ast::Expr::ArrayExpr(_))
-                | (_, ast::Expr::ParenExpr(_))
-                | (_, ast::Expr::ForExpr(_))
-                | (_, ast::Expr::WhileExpr(_))
-                | (_, ast::Expr::BreakExpr(_))
-                | (_, ast::Expr::ReturnExpr(_))
-                | (_, ast::Expr::MatchExpr(_))
+                    | (ast::Expr::IndexExpr(_), _)
+                    | (ast::Expr::MethodCallExpr(_), _)
+                    | (ast::Expr::FieldExpr(_), _)
+                    | (ast::Expr::TryExpr(_), _)
+                    | (ast::Expr::RefExpr(_), _)
+                    | (ast::Expr::Literal(_), _)
+                    | (ast::Expr::TupleExpr(_), _)
+                    | (ast::Expr::ArrayExpr(_), _)
+                    | (ast::Expr::ParenExpr(_), _)
+                    | (ast::Expr::PathExpr(_), _)
+                    | (ast::Expr::BlockExpr(_), _)
+                    | (ast::Expr::EffectExpr(_), _)
+                    | (_, ast::Expr::CallExpr(_))
+                    | (_, ast::Expr::TupleExpr(_))
+                    | (_, ast::Expr::ArrayExpr(_))
+                    | (_, ast::Expr::ParenExpr(_))
+                    | (_, ast::Expr::ForExpr(_))
+                    | (_, ast::Expr::WhileExpr(_))
+                    | (_, ast::Expr::BreakExpr(_))
+                    | (_, ast::Expr::ReturnExpr(_))
+                    | (_, ast::Expr::MatchExpr(_))
             ))
         })
         .collect::<Result<Vec<_>, _>>()?;
diff --git a/crates/assists/src/handlers/qualify_path.rs b/crates/assists/src/handlers/qualify_path.rs
index f7fbf37f4..a7d9fd4dc 100644
--- a/crates/assists/src/handlers/qualify_path.rs
+++ b/crates/assists/src/handlers/qualify_path.rs
@@ -1,7 +1,10 @@
 use std::iter;
 
 use hir::AsName;
-use ide_db::helpers::mod_path_to_ast;
+use ide_db::helpers::{
+    import_assets::{ImportAssets, ImportCandidate},
+    mod_path_to_ast,
+};
 use ide_db::RootDatabase;
 use syntax::{
     ast,
@@ -12,7 +15,6 @@ use test_utils::mark;
 
 use crate::{
     assist_context::{AssistContext, Assists},
-    utils::import_assets::{ImportAssets, ImportCandidate},
     AssistId, AssistKind, GroupLabel,
 };
 
@@ -53,17 +55,18 @@ pub(crate) fn qualify_path(acc: &mut Assists, ctx: &AssistContext) -> Option<()>
     let range = ctx.sema.original_range(import_assets.syntax_under_caret()).range;
 
     let qualify_candidate = match candidate {
-        ImportCandidate::QualifierStart(_) => {
-            mark::hit!(qualify_path_qualifier_start);
-            let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
-            let (prev_segment, segment) = (path.qualifier()?.segment()?, path.segment()?);
-            QualifyCandidate::QualifierStart(segment, prev_segment.generic_arg_list())
-        }
-        ImportCandidate::UnqualifiedName(_) => {
-            mark::hit!(qualify_path_unqualified_name);
-            let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
-            let generics = path.segment()?.generic_arg_list();
-            QualifyCandidate::UnqualifiedName(generics)
+        ImportCandidate::Path(candidate) => {
+            if candidate.qualifier.is_some() {
+                mark::hit!(qualify_path_qualifier_start);
+                let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
+                let (prev_segment, segment) = (path.qualifier()?.segment()?, path.segment()?);
+                QualifyCandidate::QualifierStart(segment, prev_segment.generic_arg_list())
+            } else {
+                mark::hit!(qualify_path_unqualified_name);
+                let path = ast::Path::cast(import_assets.syntax_under_caret().clone())?;
+                let generics = path.segment()?.generic_arg_list();
+                QualifyCandidate::UnqualifiedName(generics)
+            }
         }
         ImportCandidate::TraitAssocItem(_) => {
             mark::hit!(qualify_path_trait_assoc_item);
@@ -186,7 +189,7 @@ fn item_as_trait(item: hir::ItemInNs) -> Option<hir::Trait> {
 
 fn group_label(candidate: &ImportCandidate) -> GroupLabel {
     let name = match candidate {
-        ImportCandidate::UnqualifiedName(it) | ImportCandidate::QualifierStart(it) => &it.name,
+        ImportCandidate::Path(it) => &it.name,
         ImportCandidate::TraitAssocItem(it) | ImportCandidate::TraitMethod(it) => &it.name,
     };
     GroupLabel(format!("Qualify {}", name))
@@ -194,8 +197,13 @@ fn group_label(candidate: &ImportCandidate) -> GroupLabel {
 
 fn label(candidate: &ImportCandidate, import: &hir::ModPath) -> String {
     match candidate {
-        ImportCandidate::UnqualifiedName(_) => format!("Qualify as `{}`", &import),
-        ImportCandidate::QualifierStart(_) => format!("Qualify with `{}`", &import),
+        ImportCandidate::Path(candidate) => {
+            if candidate.qualifier.is_some() {
+                format!("Qualify with `{}`", &import)
+            } else {
+                format!("Qualify as `{}`", &import)
+            }
+        }
         ImportCandidate::TraitAssocItem(_) => format!("Qualify `{}`", &import),
         ImportCandidate::TraitMethod(_) => format!("Qualify with cast as `{}`", &import),
     }
diff --git a/crates/assists/src/handlers/unmerge_use.rs b/crates/assists/src/handlers/unmerge_use.rs
new file mode 100644
index 000000000..3dbef8e51
--- /dev/null
+++ b/crates/assists/src/handlers/unmerge_use.rs
@@ -0,0 +1,231 @@
+use syntax::{
+    algo::SyntaxRewriter,
+    ast::{self, edit::AstNodeEdit, VisibilityOwner},
+    AstNode, SyntaxKind,
+};
+use test_utils::mark;
+
+use crate::{
+    assist_context::{AssistContext, Assists},
+    AssistId, AssistKind,
+};
+
+// Assist: unmerge_use
+//
+// Extracts single use item from use list.
+//
+// ```
+// use std::fmt::{Debug, Display$0};
+// ```
+// ->
+// ```
+// use std::fmt::{Debug};
+// use std::fmt::Display;
+// ```
+pub(crate) fn unmerge_use(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let tree: ast::UseTree = ctx.find_node_at_offset()?;
+
+    let tree_list = tree.syntax().parent().and_then(ast::UseTreeList::cast)?;
+    if tree_list.use_trees().count() < 2 {
+        mark::hit!(skip_single_use_item);
+        return None;
+    }
+
+    let use_: ast::Use = tree_list.syntax().ancestors().find_map(ast::Use::cast)?;
+    let path = resolve_full_path(&tree)?;
+
+    let target = tree.syntax().text_range();
+    acc.add(
+        AssistId("unmerge_use", AssistKind::RefactorRewrite),
+        "Unmerge use",
+        target,
+        |builder| {
+            let new_use = ast::make::use_(
+                use_.visibility(),
+                ast::make::use_tree(
+                    path,
+                    tree.use_tree_list(),
+                    tree.rename(),
+                    tree.star_token().is_some(),
+                ),
+            );
+
+            let mut rewriter = SyntaxRewriter::default();
+            rewriter += tree.remove();
+            rewriter.insert_after(use_.syntax(), &ast::make::tokens::single_newline());
+            if let ident_level @ 1..=usize::MAX = use_.indent_level().0 as usize {
+                rewriter.insert_after(
+                    use_.syntax(),
+                    &ast::make::tokens::whitespace(&" ".repeat(4 * ident_level)),
+                );
+            }
+            rewriter.insert_after(use_.syntax(), new_use.syntax());
+
+            builder.rewrite(rewriter);
+        },
+    )
+}
+
+fn resolve_full_path(tree: &ast::UseTree) -> Option<ast::Path> {
+    let mut paths = tree
+        .syntax()
+        .ancestors()
+        .take_while(|n| n.kind() != SyntaxKind::USE_KW)
+        .filter_map(ast::UseTree::cast)
+        .filter_map(|t| t.path());
+
+    let mut final_path = paths.next()?;
+    for path in paths {
+        final_path = ast::make::path_concat(path, final_path)
+    }
+    Some(final_path)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn skip_single_use_item() {
+        mark::check!(skip_single_use_item);
+        check_assist_not_applicable(
+            unmerge_use,
+            r"
+use std::fmt::Debug$0;
+",
+        );
+        check_assist_not_applicable(
+            unmerge_use,
+            r"
+use std::fmt::{Debug$0};
+",
+        );
+        check_assist_not_applicable(
+            unmerge_use,
+            r"
+use std::fmt::Debug as Dbg$0;
+",
+        );
+    }
+
+    #[test]
+    fn skip_single_glob_import() {
+        check_assist_not_applicable(
+            unmerge_use,
+            r"
+use std::fmt::*$0;
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_use_item() {
+        check_assist(
+            unmerge_use,
+            r"
+use std::fmt::{Debug, Display$0};
+",
+            r"
+use std::fmt::{Debug};
+use std::fmt::Display;
+",
+        );
+
+        check_assist(
+            unmerge_use,
+            r"
+use std::fmt::{Debug, format$0, Display};
+",
+            r"
+use std::fmt::{Debug, Display};
+use std::fmt::format;
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_glob_import() {
+        check_assist(
+            unmerge_use,
+            r"
+use std::fmt::{*$0, Display};
+",
+            r"
+use std::fmt::{Display};
+use std::fmt::*;
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_renamed_use_item() {
+        check_assist(
+            unmerge_use,
+            r"
+use std::fmt::{Debug, Display as Disp$0};
+",
+            r"
+use std::fmt::{Debug};
+use std::fmt::Display as Disp;
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_indented_use_item() {
+        check_assist(
+            unmerge_use,
+            r"
+mod format {
+    use std::fmt::{Debug, Display$0 as Disp, format};
+}
+",
+            r"
+mod format {
+    use std::fmt::{Debug, format};
+    use std::fmt::Display as Disp;
+}
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_nested_use_item() {
+        check_assist(
+            unmerge_use,
+            r"
+use foo::bar::{baz::{qux$0, foobar}, barbaz};
+",
+            r"
+use foo::bar::{baz::{foobar}, barbaz};
+use foo::bar::baz::qux;
+",
+        );
+        check_assist(
+            unmerge_use,
+            r"
+use foo::bar::{baz$0::{qux, foobar}, barbaz};
+",
+            r"
+use foo::bar::{barbaz};
+use foo::bar::baz::{qux, foobar};
+",
+        );
+    }
+
+    #[test]
+    fn unmerge_use_item_with_visibility() {
+        check_assist(
+            unmerge_use,
+            r"
+pub use std::fmt::{Debug, Display$0};
+",
+            r"
+pub use std::fmt::{Debug};
+pub use std::fmt::Display;
+",
+        );
+    }
+}