Merge #7295

7295: Share import_assets and related entities r=matklad a=SomeoneToIgnore

Part of https://github.com/rust-analyzer/rust-analyzer/pull/7293
Addresses https://github.com/rust-analyzer/rust-analyzer/pull/7293#issuecomment-761569558

Prepares `import_assets` and related to be used later for the trait fuzzy importing.
Also moves fuzzy imports into a separate completion module and renames them, as suggested in https://github.com/rust-analyzer/rust-analyzer/pull/7293#discussion_r558896685

Co-authored-by: Kirill Bulatov <[email protected]>

7 files changed, 34 insertions, 300 deletions

diff --git a/crates/assists/src/assist_config.rs b/crates/assists/src/assist_config.rs
index 4fe8ea761..9cabf037c 100644
--- a/crates/assists/src/assist_config.rs
+++ b/crates/assists/src/assist_config.rs
@@ -4,7 +4,7 @@
 //! module, and we use to statically check that we only produce snippet
 //! assists if we are allowed to.
 
-use ide_db::helpers::{insert_use::MergeBehavior, SnippetCap};
+use ide_db::helpers::{insert_use::InsertUseConfig, SnippetCap};
 
 use crate::AssistKind;
 
@@ -14,9 +14,3 @@ pub struct AssistConfig {
     pub allowed: Option<Vec<AssistKind>>,
     pub insert_use: InsertUseConfig,
 }
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub struct InsertUseConfig {
-    pub merge: Option<MergeBehavior>,
-    pub prefix_kind: hir::PrefixKind,
-}
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/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/lib.rs b/crates/assists/src/lib.rs
index 3d7971806..14178a651 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -24,7 +24,7 @@ use syntax::TextRange;
 
 pub(crate) use crate::assist_context::{AssistContext, Assists};
 
-pub use assist_config::{AssistConfig, InsertUseConfig};
+pub use assist_config::AssistConfig;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum AssistKind {
diff --git a/crates/assists/src/tests.rs b/crates/assists/src/tests.rs
index 71431b406..32bd8698b 100644
--- a/crates/assists/src/tests.rs
+++ b/crates/assists/src/tests.rs
@@ -3,16 +3,17 @@ mod generated;
 use hir::Semantics;
 use ide_db::{
     base_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt},
-    helpers::{insert_use::MergeBehavior, SnippetCap},
+    helpers::{
+        insert_use::{InsertUseConfig, MergeBehavior},
+        SnippetCap,
+    },
     source_change::FileSystemEdit,
     RootDatabase,
 };
 use syntax::TextRange;
 use test_utils::{assert_eq_text, extract_offset, extract_range};
 
-use crate::{
-    handlers::Handler, Assist, AssistConfig, AssistContext, AssistKind, Assists, InsertUseConfig,
-};
+use crate::{handlers::Handler, Assist, AssistConfig, AssistContext, AssistKind, Assists};
 use stdx::{format_to, trim_indent};
 
 pub(crate) const TEST_CONFIG: AssistConfig = AssistConfig {
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 9ea96eb73..fc9f83bab 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -1,5 +1,4 @@
 //! Assorted functions shared by several assists.
-pub(crate) mod import_assets;
 
 use std::ops;
 
diff --git a/crates/assists/src/utils/import_assets.rs b/crates/assists/src/utils/import_assets.rs
deleted file mode 100644
index 4ce82c1ba..000000000
--- a/crates/assists/src/utils/import_assets.rs
+++ /dev/null
@@ -1,265 +0,0 @@
-//! Look up accessible paths for items.
-use either::Either;
-use hir::{AsAssocItem, AssocItemContainer, ModuleDef, Semantics};
-use ide_db::{imports_locator, RootDatabase};
-use rustc_hash::FxHashSet;
-use syntax::{ast, AstNode, SyntaxNode};
-
-use crate::assist_config::InsertUseConfig;
-
-#[derive(Debug)]
-pub(crate) enum ImportCandidate {
-    /// Simple name like 'HashMap'
-    UnqualifiedName(PathImportCandidate),
-    /// First part of the qualified name.
-    /// For 'std::collections::HashMap', that will be 'std'.
-    QualifierStart(PathImportCandidate),
-    /// A trait associated function (with no self parameter) or associated constant.
-    /// For 'test_mod::TestEnum::test_function', `ty` is the `test_mod::TestEnum` expression type
-    /// and `name` is the `test_function`
-    TraitAssocItem(TraitImportCandidate),
-    /// A trait method with self parameter.
-    /// For 'test_enum.test_method()', `ty` is the `test_enum` expression type
-    /// and `name` is the `test_method`
-    TraitMethod(TraitImportCandidate),
-}
-
-#[derive(Debug)]
-pub(crate) struct TraitImportCandidate {
-    pub(crate) ty: hir::Type,
-    pub(crate) name: ast::NameRef,
-}
-
-#[derive(Debug)]
-pub(crate) struct PathImportCandidate {
-    pub(crate) name: ast::NameRef,
-}
-
-#[derive(Debug)]
-pub(crate) struct ImportAssets {
-    import_candidate: ImportCandidate,
-    module_with_name_to_import: hir::Module,
-    syntax_under_caret: SyntaxNode,
-}
-
-impl ImportAssets {
-    pub(crate) fn for_method_call(
-        method_call: ast::MethodCallExpr,
-        sema: &Semantics<RootDatabase>,
-    ) -> Option<Self> {
-        let syntax_under_caret = method_call.syntax().to_owned();
-        let module_with_name_to_import = sema.scope(&syntax_under_caret).module()?;
-        Some(Self {
-            import_candidate: ImportCandidate::for_method_call(sema, &method_call)?,
-            module_with_name_to_import,
-            syntax_under_caret,
-        })
-    }
-
-    pub(crate) fn for_regular_path(
-        path_under_caret: ast::Path,
-        sema: &Semantics<RootDatabase>,
-    ) -> Option<Self> {
-        let syntax_under_caret = path_under_caret.syntax().to_owned();
-        if syntax_under_caret.ancestors().find_map(ast::Use::cast).is_some() {
-            return None;
-        }
-
-        let module_with_name_to_import = sema.scope(&syntax_under_caret).module()?;
-        Some(Self {
-            import_candidate: ImportCandidate::for_regular_path(sema, &path_under_caret)?,
-            module_with_name_to_import,
-            syntax_under_caret,
-        })
-    }
-
-    pub(crate) fn syntax_under_caret(&self) -> &SyntaxNode {
-        &self.syntax_under_caret
-    }
-
-    pub(crate) fn import_candidate(&self) -> &ImportCandidate {
-        &self.import_candidate
-    }
-
-    fn get_search_query(&self) -> &str {
-        match &self.import_candidate {
-            ImportCandidate::UnqualifiedName(candidate)
-            | ImportCandidate::QualifierStart(candidate) => candidate.name.text(),
-            ImportCandidate::TraitAssocItem(candidate)
-            | ImportCandidate::TraitMethod(candidate) => candidate.name.text(),
-        }
-    }
-
-    pub(crate) fn search_for_imports(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        config: &InsertUseConfig,
-    ) -> Vec<(hir::ModPath, hir::ItemInNs)> {
-        let _p = profile::span("import_assists::search_for_imports");
-        self.search_for(sema, Some(config.prefix_kind))
-    }
-
-    /// This may return non-absolute paths if a part of the returned path is already imported into scope.
-    #[allow(dead_code)]
-    pub(crate) fn search_for_relative_paths(
-        &self,
-        sema: &Semantics<RootDatabase>,
-    ) -> Vec<(hir::ModPath, hir::ItemInNs)> {
-        let _p = profile::span("import_assists::search_for_relative_paths");
-        self.search_for(sema, None)
-    }
-
-    fn search_for(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        prefixed: Option<hir::PrefixKind>,
-    ) -> Vec<(hir::ModPath, hir::ItemInNs)> {
-        let db = sema.db;
-        let mut trait_candidates = FxHashSet::default();
-        let current_crate = self.module_with_name_to_import.krate();
-
-        let filter = |candidate: Either<hir::ModuleDef, hir::MacroDef>| {
-            trait_candidates.clear();
-            match &self.import_candidate {
-                ImportCandidate::TraitAssocItem(trait_candidate) => {
-                    let located_assoc_item = match candidate {
-                        Either::Left(ModuleDef::Function(located_function)) => {
-                            located_function.as_assoc_item(db)
-                        }
-                        Either::Left(ModuleDef::Const(located_const)) => {
-                            located_const.as_assoc_item(db)
-                        }
-                        _ => None,
-                    }
-                    .map(|assoc| assoc.container(db))
-                    .and_then(Self::assoc_to_trait)?;
-
-                    trait_candidates.insert(located_assoc_item.into());
-
-                    trait_candidate
-                        .ty
-                        .iterate_path_candidates(
-                            db,
-                            current_crate,
-                            &trait_candidates,
-                            None,
-                            |_, assoc| Self::assoc_to_trait(assoc.container(db)),
-                        )
-                        .map(ModuleDef::from)
-                        .map(Either::Left)
-                }
-                ImportCandidate::TraitMethod(trait_candidate) => {
-                    let located_assoc_item =
-                        if let Either::Left(ModuleDef::Function(located_function)) = candidate {
-                            located_function
-                                .as_assoc_item(db)
-                                .map(|assoc| assoc.container(db))
-                                .and_then(Self::assoc_to_trait)
-                        } else {
-                            None
-                        }?;
-
-                    trait_candidates.insert(located_assoc_item.into());
-
-                    trait_candidate
-                        .ty
-                        .iterate_method_candidates(
-                            db,
-                            current_crate,
-                            &trait_candidates,
-                            None,
-                            |_, function| {
-                                Self::assoc_to_trait(function.as_assoc_item(db)?.container(db))
-                            },
-                        )
-                        .map(ModuleDef::from)
-                        .map(Either::Left)
-                }
-                _ => Some(candidate),
-            }
-        };
-
-        let mut res = imports_locator::find_exact_imports(
-            sema,
-            current_crate,
-            self.get_search_query().to_string(),
-        )
-        .filter_map(filter)
-        .filter_map(|candidate| {
-            let item: hir::ItemInNs = candidate.either(Into::into, Into::into);
-            if let Some(prefix_kind) = prefixed {
-                self.module_with_name_to_import.find_use_path_prefixed(db, item, prefix_kind)
-            } else {
-                self.module_with_name_to_import.find_use_path(db, item)
-            }
-            .map(|path| (path, item))
-        })
-        .filter(|(use_path, _)| use_path.len() > 1)
-        .take(20)
-        .collect::<Vec<_>>();
-        res.sort_by_key(|(path, _)| path.clone());
-        res
-    }
-
-    fn assoc_to_trait(assoc: AssocItemContainer) -> Option<hir::Trait> {
-        if let AssocItemContainer::Trait(extracted_trait) = assoc {
-            Some(extracted_trait)
-        } else {
-            None
-        }
-    }
-}
-
-impl ImportCandidate {
-    fn for_method_call(
-        sema: &Semantics<RootDatabase>,
-        method_call: &ast::MethodCallExpr,
-    ) -> Option<Self> {
-        match sema.resolve_method_call(method_call) {
-            Some(_) => None,
-            None => Some(Self::TraitMethod(TraitImportCandidate {
-                ty: sema.type_of_expr(&method_call.receiver()?)?,
-                name: method_call.name_ref()?,
-            })),
-        }
-    }
-
-    fn for_regular_path(
-        sema: &Semantics<RootDatabase>,
-        path_under_caret: &ast::Path,
-    ) -> Option<Self> {
-        if sema.resolve_path(path_under_caret).is_some() {
-            return None;
-        }
-
-        let segment = path_under_caret.segment()?;
-        let candidate = if let Some(qualifier) = path_under_caret.qualifier() {
-            let qualifier_start = qualifier.syntax().descendants().find_map(ast::NameRef::cast)?;
-            let qualifier_start_path =
-                qualifier_start.syntax().ancestors().find_map(ast::Path::cast)?;
-            if let Some(qualifier_start_resolution) = sema.resolve_path(&qualifier_start_path) {
-                let qualifier_resolution = if qualifier_start_path == qualifier {
-                    qualifier_start_resolution
-                } else {
-                    sema.resolve_path(&qualifier)?
-                };
-                match qualifier_resolution {
-                    hir::PathResolution::Def(hir::ModuleDef::Adt(assoc_item_path)) => {
-                        ImportCandidate::TraitAssocItem(TraitImportCandidate {
-                            ty: assoc_item_path.ty(sema.db),
-                            name: segment.name_ref()?,
-                        })
-                    }
-                    _ => return None,
-                }
-            } else {
-                ImportCandidate::QualifierStart(PathImportCandidate { name: qualifier_start })
-            }
-        } else {
-            ImportCandidate::UnqualifiedName(PathImportCandidate {
-                name: segment.syntax().descendants().find_map(ast::NameRef::cast)?,
-            })
-        };
-        Some(candidate)
-    }
-}