Merge #6276

6276: Extract call_info and completion into separate crates r=matklad a=popzxc

As it was discussed in [zulip](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/Completion.20refactoring), we need to move `completions` into a separate crate.

Unfortunately, the dependency on `call_info::ActiveParameter` doesn't look easy to get rid of, and it seems to be a topic for a separate PR, thus I also extracted `call_info` into a separate crate (on which both `ide` and `completion` crates depend).

Additionally, a few `FIXME`s in doc-comments were resolved in order to make `tidy` happy.


Co-authored-by: Igor Aleksanov <popzxc@yandex.ru>

Cargo.lock

@@ -127,6 +127,20 @@ version = "1.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 
+[[package]]
+name = "call_info"
+version = "0.0.0"
+dependencies = [
+ "base_db",
+ "either",
+ "expect-test",
+ "hir",
+ "ide_db",
+ "stdx",
+ "syntax",
+ "test_utils",
+]
+
 [[package]]
 name = "cargo_metadata"
 version = "0.11.4"
@@ -249,6 +263,26 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "completion"
+version = "0.0.0"
+dependencies = [
+ "assists",
+ "base_db",
+ "call_info",
+ "expect-test",
+ "hir",
+ "ide_db",
+ "itertools",
+ "log",
+ "profile",
+ "rustc-hash",
+ "stdx",
+ "syntax",
+ "test_utils",
+ "text_edit",
+]
+
 [[package]]
 name = "const_fn"
 version = "0.4.2"
@@ -609,7 +643,9 @@ version = "0.0.0"
 dependencies = [
  "assists",
  "base_db",
+ "call_info",
  "cfg",
+ "completion",
  "either",
  "expect-test",
  "hir",

crates/call_info/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "call_info"
+version = "0.0.0"
+description = "TBD"
+license = "MIT OR Apache-2.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+
+[lib]
+doctest = false
+
+[dependencies]
+either = "1.5.3"
+
+stdx = { path = "../stdx", version = "0.0.0" }
+syntax = { path = "../syntax", version = "0.0.0" }
+base_db = { path = "../base_db", version = "0.0.0" }
+ide_db = { path = "../ide_db", version = "0.0.0" }
+test_utils = { path = "../test_utils", version = "0.0.0" }
+
+# call_info crate should depend only on the top-level `hir` package. if you need
+# something from some `hir_xxx` subpackage, reexport the API via `hir`.
+hir = { path = "../hir", version = "0.0.0" }
+
+[dev-dependencies]
+expect-test = "1.0"

crates/call_info/src/lib.rs

@@ -1,4 +1,5 @@
-//! FIXME: write short doc here
+//! This crate provides primitives for tracking the information about a call site.
+use base_db::FilePosition;
 use either::Either;
 use hir::{HasAttrs, HirDisplay, Semantics, Type};
 use ide_db::RootDatabase;
@@ -9,8 +10,6 @@ use syntax::{
 };
 use test_utils::mark;
 
-use crate::FilePosition;
-
 /// Contains information about a call site. Specifically the
 /// `FunctionSignature`and current parameter.
 #[derive(Debug)]
@@ -40,7 +39,7 @@ impl CallInfo {
 }
 
 /// Computes parameter information for the given call expression.
-pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo> {
+pub fn call_info(db: &RootDatabase, position: FilePosition) -> Option<CallInfo> {
     let sema = Semantics::new(db);
     let file = sema.parse(position.file_id);
     let file = file.syntax();
@@ -141,13 +140,13 @@ fn call_info_impl(
 }
 
 #[derive(Debug)]
-pub(crate) struct ActiveParameter {
-    pub(crate) ty: Type,
-    pub(crate) name: String,
+pub struct ActiveParameter {
+    pub ty: Type,
+    pub name: String,
 }
 
 impl ActiveParameter {
-    pub(crate) fn at(db: &RootDatabase, position: FilePosition) -> Option<Self> {
+    pub fn at(db: &RootDatabase, position: FilePosition) -> Option<Self> {
         let sema = Semantics::new(db);
         let file = sema.parse(position.file_id);
         let file = file.syntax();
@@ -156,7 +155,7 @@ impl ActiveParameter {
         Self::at_token(&sema, token)
     }
 
-    pub(crate) fn at_token(sema: &Semantics<RootDatabase>, token: SyntaxToken) -> Option<Self> {
+    pub fn at_token(sema: &Semantics<RootDatabase>, token: SyntaxToken) -> Option<Self> {
         let (signature, active_parameter) = call_info_impl(&sema, token)?;
 
         let idx = active_parameter?;
@@ -172,7 +171,7 @@ impl ActiveParameter {
 }
 
 #[derive(Debug)]
-pub(crate) enum FnCallNode {
+pub enum FnCallNode {
     CallExpr(ast::CallExpr),
     MethodCallExpr(ast::MethodCallExpr),
 }
@@ -196,7 +195,7 @@ impl FnCallNode {
         })
     }
 
-    pub(crate) fn with_node_exact(node: &SyntaxNode) -> Option<FnCallNode> {
+    pub fn with_node_exact(node: &SyntaxNode) -> Option<FnCallNode> {
         match_ast! {
             match node {
                 ast::CallExpr(it) => Some(FnCallNode::CallExpr(it)),
@@ -206,7 +205,7 @@ impl FnCallNode {
         }
     }
 
-    pub(crate) fn name_ref(&self) -> Option<ast::NameRef> {
+    pub fn name_ref(&self) -> Option<ast::NameRef> {
         match self {
             FnCallNode::CallExpr(call_expr) => Some(match call_expr.expr()? {
                 ast::Expr::PathExpr(path_expr) => path_expr.path()?.segment()?.name_ref()?,
@@ -229,14 +228,28 @@ impl FnCallNode {
 
 #[cfg(test)]
 mod tests {
+    use base_db::{fixture::ChangeFixture, FilePosition};
     use expect_test::{expect, Expect};
-    use test_utils::mark;
+    use ide_db::RootDatabase;
+    use test_utils::{mark, RangeOrOffset};
 
-    use crate::fixture;
+    /// Creates analysis from a multi-file fixture, returns positions marked with <|>.
+    pub(crate) fn position(ra_fixture: &str) -> (RootDatabase, FilePosition) {
+        let change_fixture = ChangeFixture::parse(ra_fixture);
+        let mut database = RootDatabase::default();
+        database.apply_change(change_fixture.change);
+        let (file_id, range_or_offset) =
+            change_fixture.file_position.expect("expected a marker (<|>)");
+        let offset = match range_or_offset {
+            RangeOrOffset::Range(_) => panic!(),
+            RangeOrOffset::Offset(it) => it,
+        };
+        (database, FilePosition { file_id, offset })
+    }
 
     fn check(ra_fixture: &str, expect: Expect) {
-        let (analysis, position) = fixture::position(ra_fixture);
-        let call_info = analysis.call_info(position).unwrap();
+        let (db, position) = position(ra_fixture);
+        let call_info = crate::call_info(&db, position);
         let actual = match call_info {
             Some(call_info) => {
                 let docs = match &call_info.doc {

crates/completion/Cargo.toml

@@ -0,0 +1,32 @@
+[package]
+name = "completion"
+version = "0.0.0"
+description = "TBD"
+license = "MIT OR Apache-2.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+
+[lib]
+doctest = false
+
+[dependencies]
+itertools = "0.9.0"
+log = "0.4.8"
+rustc-hash = "1.1.0"
+
+syntax = { path = "../syntax", version = "0.0.0" }
+text_edit = { path = "../text_edit", version = "0.0.0" }
+base_db = { path = "../base_db", version = "0.0.0" }
+ide_db = { path = "../ide_db", version = "0.0.0" }
+profile = { path = "../profile", version = "0.0.0" }
+test_utils = { path = "../test_utils", version = "0.0.0" }
+assists = { path = "../assists", version = "0.0.0" }
+call_info = { path = "../call_info", version = "0.0.0" }
+
+# completions crate should depend only on the top-level `hir` package. if you need
+# something from some `hir_xxx` subpackage, reexport the API via `hir`.
+hir = { path = "../hir", version = "0.0.0" }
+
+[dev-dependencies]
+expect-test = "1.0"
+stdx = { path = "../stdx", version = "0.0.0" }

crates/completion/src/complete_attribute.rs

@@ -6,7 +6,7 @@
 use rustc_hash::FxHashSet;
 use syntax::{ast, AstNode, SyntaxKind};
 
-use crate::completion::{
+use crate::{
     completion_context::CompletionContext,
     completion_item::{CompletionItem, CompletionItemKind, CompletionKind, Completions},
     generated_features::FEATURES,
@@ -389,7 +389,7 @@ const DEFAULT_LINT_COMPLETIONS: &[LintCompletion] = &[
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Attribute);

crates/completion/src/complete_dot.rs

@@ -4,7 +4,7 @@ use hir::{HasVisibility, Type};
 use rustc_hash::FxHashSet;
 use test_utils::mark;
 
-use crate::completion::{completion_context::CompletionContext, completion_item::Completions};
+use crate::{completion_context::CompletionContext, completion_item::Completions};
 
 /// Complete dot accesses, i.e. fields or methods.
 pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
@@ -64,7 +64,7 @@ mod tests {
     use expect_test::{expect, Expect};
     use test_utils::mark;
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Reference);

crates/completion/src/complete_fn_param.rs

@@ -6,7 +6,7 @@ use syntax::{
     match_ast, AstNode,
 };
 
-use crate::completion::{CompletionContext, CompletionItem, CompletionKind, Completions};
+use crate::{CompletionContext, CompletionItem, CompletionKind, Completions};
 
 /// Complete repeated parameters, both name and type. For example, if all
 /// functions in a file have a `spam: &mut Spam` parameter, a completion with
@@ -68,7 +68,7 @@ pub(super) fn complete_fn_param(acc: &mut Completions, ctx: &CompletionContext)
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Magic);

crates/completion/src/complete_keyword.rs

@@ -1,11 +1,9 @@
-//! FIXME: write short doc here
+//! Completes keywords.
 
 use syntax::{ast, SyntaxKind};
 use test_utils::mark;
 
-use crate::completion::{
-    CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions,
-};
+use crate::{CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions};
 
 pub(super) fn complete_use_tree_keyword(acc: &mut Completions, ctx: &CompletionContext) {
     // complete keyword "crate" in use stmt
@@ -177,7 +175,7 @@ fn complete_return(
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{
+    use crate::{
         test_utils::{check_edit, completion_list},
         CompletionKind,
     };

crates/completion/src/complete_macro_in_item_position.rs

@@ -1,6 +1,6 @@
-//! FIXME: write short doc here
+//! Completes macro invocations used in item position.
 
-use crate::completion::{CompletionContext, Completions};
+use crate::{CompletionContext, Completions};
 
 pub(super) fn complete_macro_in_item_position(acc: &mut Completions, ctx: &CompletionContext) {
     // Show only macros in top level.
@@ -17,7 +17,7 @@ pub(super) fn complete_macro_in_item_position(acc: &mut Completions, ctx: &Compl
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Reference);

crates/completion/src/complete_mod.rs

@@ -150,7 +150,7 @@ fn module_chain_to_containing_module_file(
 
 #[cfg(test)]
 mod tests {
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
     use expect_test::{expect, Expect};
 
     fn check(ra_fixture: &str, expect: Expect) {

crates/completion/src/complete_pattern.rs

@@ -1,6 +1,6 @@
-//! FIXME: write short doc here
+//! Completes constats and paths in patterns.
 
-use crate::completion::{CompletionContext, Completions};
+use crate::{CompletionContext, Completions};
 
 /// Completes constats and paths in patterns.
 pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
@@ -35,7 +35,7 @@ pub(super) fn complete_pattern(acc: &mut Completions, ctx: &CompletionContext) {
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Reference);

crates/completion/src/complete_postfix.rs

@@ -1,4 +1,4 @@
-//! FIXME: write short doc here
+//! Postfix completions, like `Ok(10).ifl<|>` => `if let Ok() = Ok(10) { <|> }`.
 
 mod format_like;
 
@@ -11,11 +11,9 @@ use text_edit::TextEdit;
 
 use self::format_like::add_format_like_completions;
 use crate::{
-    completion::{
-        completion_config::SnippetCap,
-        completion_context::CompletionContext,
-        completion_item::{Builder, CompletionKind, Completions},
-    },
+    completion_config::SnippetCap,
+    completion_context::CompletionContext,
+    completion_item::{Builder, CompletionKind, Completions},
     CompletionItem, CompletionItemKind,
 };
 
@@ -263,7 +261,7 @@ fn postfix_snippet(
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{
+    use crate::{
         test_utils::{check_edit, completion_list},
         CompletionKind,
     };

crates/completion/src/complete_postfix/format_like.rs

@@ -14,7 +14,7 @@
 //   + `logw` -> `log::warn!(...)`
 //   + `loge` -> `log::error!(...)`
 
-use crate::completion::{
+use crate::{
     complete_postfix::postfix_snippet, completion_config::SnippetCap,
     completion_context::CompletionContext, completion_item::Completions,
 };

crates/completion/src/complete_qualified_path.rs

@@ -5,7 +5,7 @@ use rustc_hash::FxHashSet;
 use syntax::AstNode;
 use test_utils::mark;
 
-use crate::completion::{CompletionContext, Completions};
+use crate::{CompletionContext, Completions};
 
 pub(super) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionContext) {
     let path = match &ctx.path_qual {
@@ -149,7 +149,7 @@ mod tests {
     use expect_test::{expect, Expect};
     use test_utils::mark;
 
-    use crate::completion::{
+    use crate::{
         test_utils::{check_edit, completion_list},
         CompletionKind,
     };

crates/completion/src/complete_record.rs

@@ -1,5 +1,5 @@
 //! Complete fields in record literals and patterns.
-use crate::completion::{CompletionContext, Completions};
+use crate::{CompletionContext, Completions};
 
 pub(super) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) -> Option<()> {
     let missing_fields = match (ctx.record_pat_syntax.as_ref(), ctx.record_lit_syntax.as_ref()) {
@@ -20,7 +20,7 @@ pub(super) fn complete_record(acc: &mut Completions, ctx: &CompletionContext) ->
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Reference);

crates/completion/src/complete_snippet.rs

@@ -1,6 +1,6 @@
-//! FIXME: write short doc here
+//! This file provides snippet completions, like `pd` => `eprintln!(...)`.
 
-use crate::completion::{
+use crate::{
     completion_config::SnippetCap, completion_item::Builder, CompletionContext, CompletionItem,
     CompletionItemKind, CompletionKind, Completions,
 };
@@ -71,7 +71,7 @@ fn ${1:feature}() {
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{test_utils::completion_list, CompletionKind};
+    use crate::{test_utils::completion_list, CompletionKind};
 
     fn check(ra_fixture: &str, expect: Expect) {
         let actual = completion_list(ra_fixture, CompletionKind::Snippet);

crates/completion/src/complete_trait_impl.rs

@@ -35,15 +35,18 @@ use assists::utils::get_missing_assoc_items;
 use hir::{self, HasAttrs, HasSource};
 use syntax::{
     ast::{self, edit, Impl},
+    display::function_declaration,
     AstNode, SyntaxKind, SyntaxNode, TextRange, T,
 };
 use text_edit::TextEdit;
 
 use crate::{
-    completion::{
-        CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions,
-    },
-    display::function_declaration,
+    CompletionContext,
+    CompletionItem,
+    CompletionItemKind,
+    CompletionKind,
+    Completions,
+    // display::function_declaration,
 };
 
 #[derive(Debug, PartialEq, Eq)]
@@ -237,7 +240,7 @@ fn make_const_compl_syntax(const_: &ast::Const) -> String {
 mod tests {
     use expect_test::{expect, Expect};
 
-    use crate::completion::{
+    use crate::{
         test_utils::{check_edit, completion_list},
         CompletionKind,
     };

crates/completion/src/complete_unqualified_path.rs

@@ -4,7 +4,7 @@ use hir::{Adt, ModuleDef, ScopeDef, Type};
 use syntax::AstNode;
 use test_utils::mark;
 
-use crate::completion::{CompletionContext, Completions};
+use crate::{CompletionContext, Completions};
 
 pub(super) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionContext) {
     if !(ctx.is_trivial_path || ctx.is_pat_binding_or_const) {
@@ -68,7 +68,7 @@ mod tests {
     use expect_test::{expect, Expect};
     use test_utils::mark;
 
-    use crate::completion::{
+    use crate::{
         test_utils::{check_edit, completion_list},
         CompletionKind,
     };

crates/completion/src/completion_context.rs

@@ -1,6 +1,7 @@
-//! FIXME: write short doc here
+//! See `CompletionContext` structure.
 
-use base_db::SourceDatabase;
+use base_db::{FilePosition, SourceDatabase};
+use call_info::ActiveParameter;
 use hir::{Local, ScopeDef, Semantics, SemanticsScope, Type};
 use ide_db::RootDatabase;
 use syntax::{
@@ -13,18 +14,14 @@ use test_utils::mark;
 use text_edit::Indel;
 
 use crate::{
-    call_info::ActiveParameter,
-    completion::{
-        patterns::{
-            fn_is_prev, for_is_prev2, has_bind_pat_parent, has_block_expr_parent,
-            has_field_list_parent, has_impl_as_prev_sibling, has_impl_parent,
-            has_item_list_or_source_file_parent, has_ref_parent, has_trait_as_prev_sibling,
-            has_trait_parent, if_is_prev, inside_impl_trait_block, is_in_loop_body, is_match_arm,
-            unsafe_is_prev,
-        },
-        CompletionConfig,
+    patterns::{
+        fn_is_prev, for_is_prev2, has_bind_pat_parent, has_block_expr_parent,
+        has_field_list_parent, has_impl_as_prev_sibling, has_impl_parent,
+        has_item_list_or_source_file_parent, has_ref_parent, has_trait_as_prev_sibling,
+        has_trait_parent, if_is_prev, inside_impl_trait_block, is_in_loop_body, is_match_arm,
+        unsafe_is_prev,
     },
-    FilePosition,
+    CompletionConfig,
 };
 
 /// `CompletionContext` is created early during completion to figure out, where

crates/completion/src/completion_item.rs

@@ -1,4 +1,4 @@
-//! FIXME: write short doc here
+//! See `CompletionItem` structure.
 
 use std::fmt;
 
@@ -6,7 +6,7 @@ use hir::Documentation;
 use syntax::TextRange;
 use text_edit::TextEdit;
 
-use crate::completion::completion_config::SnippetCap;
+use crate::completion_config::SnippetCap;
 
 /// `CompletionItem` describes a single completion variant in the editor pop-up.
 /// It is basically a POD with various properties. To construct a
@@ -360,15 +360,15 @@ impl<'a> Into<CompletionItem> for Builder {
 
 /// Represents an in-progress set of completions being built.
 #[derive(Debug, Default)]
-pub(crate) struct Completions {
+pub struct Completions {
     buf: Vec<CompletionItem>,
 }
 
 impl Completions {
-    pub(crate) fn add(&mut self, item: impl Into<CompletionItem>) {
+    pub fn add(&mut self, item: impl Into<CompletionItem>) {
         self.buf.push(item.into())
     }
-    pub(crate) fn add_all<I>(&mut self, items: I)
+    pub fn add_all<I>(&mut self, items: I)
     where
         I: IntoIterator,
         I::Item: Into<CompletionItem>,

crates/completion/src/lib.rs

@@ -1,3 +1,5 @@
+//! `completions` crate provides utilities for generating completions of user input.
+
 mod completion_config;
 mod completion_item;
 mod completion_context;
@@ -21,17 +23,15 @@ mod complete_macro_in_item_position;
 mod complete_trait_impl;
 mod complete_mod;
 
+use base_db::FilePosition;
 use ide_db::RootDatabase;
 
 use crate::{
-    completion::{
-        completion_context::CompletionContext,
-        completion_item::{CompletionKind, Completions},
-    },
-    FilePosition,
+    completion_context::CompletionContext,
+    completion_item::{CompletionKind, Completions},
 };
 
-pub use crate::completion::{
+pub use crate::{
     completion_config::CompletionConfig,
     completion_item::{CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat},
 };
@@ -105,7 +105,7 @@ pub use crate::completion::{
 /// `foo` *should* be present among the completion variants. Filtering by
 /// identifier prefix/fuzzy match should be done higher in the stack, together
 /// with ordering of completions (currently this is done by the client).
-pub(crate) fn completions(
+pub fn completions(
     db: &RootDatabase,
     config: &CompletionConfig,
     position: FilePosition,
@@ -139,8 +139,8 @@ pub(crate) fn completions(
 
 #[cfg(test)]
 mod tests {
-    use crate::completion::completion_config::CompletionConfig;
-    use crate::fixture;
+    use crate::completion_config::CompletionConfig;
+    use crate::test_utils;
 
     struct DetailAndDocumentation<'a> {
         detail: &'a str,
@@ -148,9 +148,9 @@ mod tests {
     }
 
     fn check_detail_and_documentation(ra_fixture: &str, expected: DetailAndDocumentation) {
-        let (analysis, position) = fixture::position(ra_fixture);
+        let (db, position) = test_utils::position(ra_fixture);
         let config = CompletionConfig::default();
-        let completions = analysis.completions(&config, position).unwrap().unwrap();
+        let completions: Vec<_> = crate::completions(&db, &config, position).unwrap().into();
         for item in completions {
             if item.detail() == Some(expected.detail) {
                 let opt = item.documentation();
@@ -163,14 +163,18 @@ mod tests {
     }
 
     fn check_no_completion(ra_fixture: &str) {
-        let (analysis, position) = fixture::position(ra_fixture);
+        let (db, position) = test_utils::position(ra_fixture);
         let config = CompletionConfig::default();
-        analysis.completions(&config, position).unwrap();
 
-        let completions: Option<Vec<String>> = analysis
-            .completions(&config, position)
-            .unwrap()
-            .and_then(|completions| if completions.is_empty() { None } else { Some(completions) })
+        let completions: Option<Vec<String>> = crate::completions(&db, &config, position)
+            .and_then(|completions| {
+                let completions: Vec<_> = completions.into();
+                if completions.is_empty() {
+                    None
+                } else {
+                    Some(completions)
+                }
+            })
             .map(|completions| {
                 completions.into_iter().map(|completion| format!("{:?}", completion)).collect()
             });

crates/completion/src/patterns.rs

@@ -9,7 +9,7 @@ use syntax::{
 };
 
 #[cfg(test)]
-use crate::completion::test_utils::{check_pattern_is_applicable, check_pattern_is_not_applicable};
+use crate::test_utils::{check_pattern_is_applicable, check_pattern_is_not_applicable};
 
 pub(crate) fn has_trait_parent(element: SyntaxElement) -> bool {
     not_same_range_ancestor(element)

crates/completion/src/presentation.rs

@@ -3,16 +3,17 @@
 
 use hir::{HasAttrs, HasSource, HirDisplay, ModPath, ScopeDef, StructKind, Type};
 use itertools::Itertools;
-use syntax::ast::NameOwner;
+use syntax::{ast::NameOwner, display::*};
 use test_utils::mark;
 
 use crate::{
-    completion::{
+    // display::{const_label, function_declaration, macro_label, type_label},
+    CompletionScore,
+    RootDatabase,
+    {
         completion_item::Builder, CompletionContext, CompletionItem, CompletionItemKind,
         CompletionKind, Completions,
     },
-    display::{const_label, function_declaration, macro_label, type_label},
-    CompletionScore, RootDatabase,
 };
 
 impl Completions {
@@ -487,13 +488,8 @@ mod tests {
     use test_utils::mark;
 
     use crate::{
-        completion::{
-            test_utils::{
-                check_edit, check_edit_with_config, do_completion, get_all_completion_items,
-            },
-            CompletionConfig, CompletionKind,
-        },
-        CompletionScore,
+        test_utils::{check_edit, check_edit_with_config, do_completion, get_all_completion_items},
+        CompletionConfig, CompletionKind, CompletionScore,
     };
 
     fn check(ra_fixture: &str, expect: Expect) {
@@ -1277,7 +1273,6 @@ fn go(world: &WorldSnapshot) { go(w<|>) }
 
     #[test]
     fn too_many_arguments() {
-        mark::check!(too_many_arguments);
         check_scores(
             r#"
 struct Foo;

crates/completion/src/test_utils.rs

@@ -1,15 +1,27 @@
 //! Runs completion for testing purposes.
 
+use base_db::{fixture::ChangeFixture, FileLoader, FilePosition};
 use hir::Semantics;
+use ide_db::RootDatabase;
 use itertools::Itertools;
 use stdx::{format_to, trim_indent};
 use syntax::{AstNode, NodeOrToken, SyntaxElement};
-use test_utils::assert_eq_text;
+use test_utils::{assert_eq_text, RangeOrOffset};
 
-use crate::{
-    completion::{completion_item::CompletionKind, CompletionConfig},
-    fixture, CompletionItem,
-};
+use crate::{completion_item::CompletionKind, CompletionConfig, CompletionItem};
+
+/// Creates analysis from a multi-file fixture, returns positions marked with <|>.
+pub(crate) fn position(ra_fixture: &str) -> (RootDatabase, FilePosition) {
+    let change_fixture = ChangeFixture::parse(ra_fixture);
+    let mut database = RootDatabase::default();
+    database.apply_change(change_fixture.change);
+    let (file_id, range_or_offset) = change_fixture.file_position.expect("expected a marker (<|>)");
+    let offset = match range_or_offset {
+        RangeOrOffset::Range(_) => panic!(),
+        RangeOrOffset::Offset(it) => it,
+    };
+    (database, FilePosition { file_id, offset })
+}
 
 pub(crate) fn do_completion(code: &str, kind: CompletionKind) -> Vec<CompletionItem> {
     do_completion_with_config(CompletionConfig::default(), code, kind)
@@ -79,47 +91,40 @@ pub(crate) fn check_edit_with_config(
     ra_fixture_after: &str,
 ) {
     let ra_fixture_after = trim_indent(ra_fixture_after);
-    let (analysis, position) = fixture::position(ra_fixture_before);
+    let (db, position) = position(ra_fixture_before);
     let completions: Vec<CompletionItem> =
-        analysis.completions(&config, position).unwrap().unwrap().into();
+        crate::completions(&db, &config, position).unwrap().into();
     let (completion,) = completions
         .iter()
         .filter(|it| it.lookup() == what)
         .collect_tuple()
         .unwrap_or_else(|| panic!("can't find {:?} completion in {:#?}", what, completions));
-    let mut actual = analysis.file_text(position.file_id).unwrap().to_string();
+    let mut actual = db.file_text(position.file_id).to_string();
     completion.text_edit().apply(&mut actual);
     assert_eq_text!(&ra_fixture_after, &actual)
 }
 
 pub(crate) fn check_pattern_is_applicable(code: &str, check: fn(SyntaxElement) -> bool) {
-    let (analysis, pos) = fixture::position(code);
-    analysis
-        .with_db(|db| {
-            let sema = Semantics::new(db);
-            let original_file = sema.parse(pos.file_id);
-            let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
-            assert!(check(NodeOrToken::Token(token)));
-        })
-        .unwrap();
+    let (db, pos) = position(code);
+
+    let sema = Semantics::new(&db);
+    let original_file = sema.parse(pos.file_id);
+    let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
+    assert!(check(NodeOrToken::Token(token)));
 }
 
 pub(crate) fn check_pattern_is_not_applicable(code: &str, check: fn(SyntaxElement) -> bool) {
-    let (analysis, pos) = fixture::position(code);
-    analysis
-        .with_db(|db| {
-            let sema = Semantics::new(db);
-            let original_file = sema.parse(pos.file_id);
-            let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
-            assert!(!check(NodeOrToken::Token(token)));
-        })
-        .unwrap();
+    let (db, pos) = position(code);
+    let sema = Semantics::new(&db);
+    let original_file = sema.parse(pos.file_id);
+    let token = original_file.syntax().token_at_offset(pos.offset).left_biased().unwrap();
+    assert!(!check(NodeOrToken::Token(token)));
 }
 
 pub(crate) fn get_all_completion_items(
     config: CompletionConfig,
     code: &str,
 ) -> Vec<CompletionItem> {
-    let (analysis, position) = fixture::position(code);
-    analysis.completions(&config, position).unwrap().unwrap().into()
+    let (db, position) = position(code);
+    crate::completions(&db, &config, position).unwrap().into()
 }

crates/ide/Cargo.toml

@@ -30,6 +30,8 @@ profile = { path = "../profile", version = "0.0.0" }
 test_utils = { path = "../test_utils", version = "0.0.0" }
 assists = { path = "../assists", version = "0.0.0" }
 ssr = { path = "../ssr", version = "0.0.0" }
+call_info = { path = "../call_info", version = "0.0.0" }
+completion = { path = "../completion", version = "0.0.0" }
 
 # ide should depend only on the top-level `hir` package. if you need
 # something from some `hir_xxx` subpackage, reexport the API via `hir`.

crates/ide/src/call_hierarchy.rs

@@ -2,13 +2,13 @@
 
 use indexmap::IndexMap;
 
+use call_info::FnCallNode;
 use hir::Semantics;
 use ide_db::RootDatabase;
 use syntax::{ast, match_ast, AstNode, TextRange};
 
 use crate::{
-    call_info::FnCallNode, display::ToNav, goto_definition, references, FilePosition,
-    NavigationTarget, RangeInfo,
+    display::ToNav, goto_definition, references, FilePosition, NavigationTarget, RangeInfo,
 };
 
 #[derive(Debug, Clone)]

crates/ide/src/display.rs

@@ -4,87 +4,8 @@
 mod navigation_target;
 mod short_label;
 
-use syntax::{
-    ast::{self, AstNode, AttrsOwner, GenericParamsOwner, NameOwner},
-    SyntaxKind::{ATTR, COMMENT},
-};
-
-use ast::VisibilityOwner;
-use stdx::format_to;
-
 pub use navigation_target::NavigationTarget;
 pub(crate) use navigation_target::{ToNav, TryToNav};
 pub(crate) use short_label::ShortLabel;
 
-pub(crate) fn function_declaration(node: &ast::Fn) -> String {
-    let mut buf = String::new();
-    if let Some(vis) = node.visibility() {
-        format_to!(buf, "{} ", vis);
-    }
-    if node.async_token().is_some() {
-        format_to!(buf, "async ");
-    }
-    if node.const_token().is_some() {
-        format_to!(buf, "const ");
-    }
-    if node.unsafe_token().is_some() {
-        format_to!(buf, "unsafe ");
-    }
-    if let Some(abi) = node.abi() {
-        // Keyword `extern` is included in the string.
-        format_to!(buf, "{} ", abi);
-    }
-    if let Some(name) = node.name() {
-        format_to!(buf, "fn {}", name)
-    }
-    if let Some(type_params) = node.generic_param_list() {
-        format_to!(buf, "{}", type_params);
-    }
-    if let Some(param_list) = node.param_list() {
-        let params: Vec<String> = param_list
-            .self_param()
-            .into_iter()
-            .map(|self_param| self_param.to_string())
-            .chain(param_list.params().map(|param| param.to_string()))
-            .collect();
-        // Useful to inline parameters
-        format_to!(buf, "({})", params.join(", "));
-    }
-    if let Some(ret_type) = node.ret_type() {
-        if ret_type.ty().is_some() {
-            format_to!(buf, " {}", ret_type);
-        }
-    }
-    if let Some(where_clause) = node.where_clause() {
-        format_to!(buf, "\n{}", where_clause);
-    }
-    buf
-}
-
-pub(crate) fn const_label(node: &ast::Const) -> String {
-    let label: String = node
-        .syntax()
-        .children_with_tokens()
-        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
-        .map(|node| node.to_string())
-        .collect();
-
-    label.trim().to_owned()
-}
-
-pub(crate) fn type_label(node: &ast::TypeAlias) -> String {
-    let label: String = node
-        .syntax()
-        .children_with_tokens()
-        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
-        .map(|node| node.to_string())
-        .collect();
-
-    label.trim().to_owned()
-}
-
-pub(crate) fn macro_label(node: &ast::MacroCall) -> String {
-    let name = node.name().map(|name| name.syntax().text().to_string()).unwrap_or_default();
-    let vis = if node.has_atom_attr("macro_export") { "#[macro_export]\n" } else { "" };
-    format!("{}macro_rules! {}", vis, name)
-}
+pub(crate) use syntax::display::{function_declaration, macro_label};

crates/ide/src/lib.rs

@@ -23,8 +23,6 @@ mod prime_caches;
 mod display;
 
 mod call_hierarchy;
-mod call_info;
-mod completion;
 mod diagnostics;
 mod expand_macro;
 mod extend_selection;
@@ -65,10 +63,6 @@ use crate::display::ToNav;
 
 pub use crate::{
     call_hierarchy::CallItem,
-    call_info::CallInfo,
-    completion::{
-        CompletionConfig, CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat,
-    },
     diagnostics::{Diagnostic, DiagnosticsConfig, Fix, Severity},
     display::NavigationTarget,
     expand_macro::ExpandedMacro,
@@ -86,6 +80,10 @@ pub use crate::{
         Highlight, HighlightModifier, HighlightModifiers, HighlightTag, HighlightedRange,
     },
 };
+pub use call_info::CallInfo;
+pub use completion::{
+    CompletionConfig, CompletionItem, CompletionItemKind, CompletionScore, InsertTextFormat,
+};
 
 pub use assists::{
     utils::MergeBehaviour, Assist, AssistConfig, AssistId, AssistKind, ResolvedAssist,

crates/ide/src/syntax_highlighting/injection.rs

@@ -3,14 +3,12 @@
 use std::{collections::BTreeMap, convert::TryFrom};
 
 use ast::{HasQuotes, HasStringValue};
+use call_info::ActiveParameter;
 use hir::Semantics;
 use itertools::Itertools;
 use syntax::{ast, AstToken, SyntaxNode, SyntaxToken, TextRange, TextSize};
 
-use crate::{
-    call_info::ActiveParameter, Analysis, Highlight, HighlightModifier, HighlightTag,
-    HighlightedRange, RootDatabase,
-};
+use crate::{Analysis, Highlight, HighlightModifier, HighlightTag, HighlightedRange, RootDatabase};
 
 use super::HighlightedRangeStack;
 

crates/syntax/src/display.rs

@@ -0,0 +1,83 @@
+//! This module contains utilities for turning SyntaxNodes and HIR types
+//! into types that may be used to render in a UI.
+
+use crate::{
+    ast::{self, AstNode, AttrsOwner, GenericParamsOwner, NameOwner},
+    SyntaxKind::{ATTR, COMMENT},
+};
+
+use ast::VisibilityOwner;
+use stdx::format_to;
+
+pub fn function_declaration(node: &ast::Fn) -> String {
+    let mut buf = String::new();
+    if let Some(vis) = node.visibility() {
+        format_to!(buf, "{} ", vis);
+    }
+    if node.async_token().is_some() {
+        format_to!(buf, "async ");
+    }
+    if node.const_token().is_some() {
+        format_to!(buf, "const ");
+    }
+    if node.unsafe_token().is_some() {
+        format_to!(buf, "unsafe ");
+    }
+    if let Some(abi) = node.abi() {
+        // Keyword `extern` is included in the string.
+        format_to!(buf, "{} ", abi);
+    }
+    if let Some(name) = node.name() {
+        format_to!(buf, "fn {}", name)
+    }
+    if let Some(type_params) = node.generic_param_list() {
+        format_to!(buf, "{}", type_params);
+    }
+    if let Some(param_list) = node.param_list() {
+        let params: Vec<String> = param_list
+            .self_param()
+            .into_iter()
+            .map(|self_param| self_param.to_string())
+            .chain(param_list.params().map(|param| param.to_string()))
+            .collect();
+        // Useful to inline parameters
+        format_to!(buf, "({})", params.join(", "));
+    }
+    if let Some(ret_type) = node.ret_type() {
+        if ret_type.ty().is_some() {
+            format_to!(buf, " {}", ret_type);
+        }
+    }
+    if let Some(where_clause) = node.where_clause() {
+        format_to!(buf, "\n{}", where_clause);
+    }
+    buf
+}
+
+pub fn const_label(node: &ast::Const) -> String {
+    let label: String = node
+        .syntax()
+        .children_with_tokens()
+        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
+        .map(|node| node.to_string())
+        .collect();
+
+    label.trim().to_owned()
+}
+
+pub fn type_label(node: &ast::TypeAlias) -> String {
+    let label: String = node
+        .syntax()
+        .children_with_tokens()
+        .filter(|child| !(child.kind() == COMMENT || child.kind() == ATTR))
+        .map(|node| node.to_string())
+        .collect();
+
+    label.trim().to_owned()
+}
+
+pub fn macro_label(node: &ast::MacroCall) -> String {
+    let name = node.name().map(|name| name.syntax().text().to_string()).unwrap_or_default();
+    let vis = if node.has_atom_attr("macro_export") { "#[macro_export]\n" } else { "" };
+    format!("{}macro_rules! {}", vis, name)
+}

crates/syntax/src/lib.rs

@@ -32,6 +32,7 @@ mod ptr;
 #[cfg(test)]
 mod tests;
 
+pub mod display;
 pub mod algo;
 pub mod ast;
 #[doc(hidden)]

xtask/tests/tidy.rs

@@ -213,7 +213,7 @@ fn check_todo(path: &Path, text: &str) {
         // `ast::make`.
         "ast/make.rs",
         // The documentation in string literals may contain anything for its own purposes
-        "completion/generated_features.rs",
+        "completion/src/generated_features.rs",
     ];
     if need_todo.iter().any(|p| path.ends_with(p)) {
         return;