Align config's API with usage

The config now is mostly immutable, optimize for that.

6 files changed, 37 insertions, 55 deletions

diff --git a/crates/assists/src/assist_config.rs b/crates/assists/src/assist_config.rs
index c458d9054..4fe8ea761 100644
--- a/crates/assists/src/assist_config.rs
+++ b/crates/assists/src/assist_config.rs
@@ -4,8 +4,7 @@
 //! module, and we use to statically check that we only produce snippet
 //! assists if we are allowed to.
 
-use hir::PrefixKind;
-use ide_db::helpers::insert_use::MergeBehavior;
+use ide_db::helpers::{insert_use::MergeBehavior, SnippetCap};
 
 use crate::AssistKind;
 
@@ -16,35 +15,8 @@ pub struct AssistConfig {
     pub insert_use: InsertUseConfig,
 }
 
-impl AssistConfig {
-    pub fn allow_snippets(&mut self, yes: bool) {
-        self.snippet_cap = if yes { Some(SnippetCap { _private: () }) } else { None }
-    }
-}
-
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub struct SnippetCap {
-    _private: (),
-}
-
-impl Default for AssistConfig {
-    fn default() -> Self {
-        AssistConfig {
-            snippet_cap: Some(SnippetCap { _private: () }),
-            allowed: None,
-            insert_use: InsertUseConfig::default(),
-        }
-    }
-}
-
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct InsertUseConfig {
     pub merge: Option<MergeBehavior>,
-    pub prefix_kind: PrefixKind,
-}
-
-impl Default for InsertUseConfig {
-    fn default() -> Self {
-        InsertUseConfig { merge: Some(MergeBehavior::Full), prefix_kind: PrefixKind::Plain }
-    }
+    pub prefix_kind: hir::PrefixKind,
 }
diff --git a/crates/assists/src/assist_context.rs b/crates/assists/src/assist_context.rs
index 4f59d39a9..91cc63427 100644
--- a/crates/assists/src/assist_context.rs
+++ b/crates/assists/src/assist_context.rs
@@ -4,7 +4,10 @@ use std::mem;
 
 use algo::find_covering_element;
 use hir::Semantics;
-use ide_db::base_db::{AnchoredPathBuf, FileId, FileRange};
+use ide_db::{
+    base_db::{AnchoredPathBuf, FileId, FileRange},
+    helpers::SnippetCap,
+};
 use ide_db::{
     label::Label,
     source_change::{FileSystemEdit, SourceChange, SourceFileEdit},
@@ -17,10 +20,7 @@ use syntax::{
 };
 use text_edit::{TextEdit, TextEditBuilder};
 
-use crate::{
-    assist_config::{AssistConfig, SnippetCap},
-    Assist, AssistId, AssistKind, GroupLabel,
-};
+use crate::{assist_config::AssistConfig, Assist, AssistId, AssistKind, GroupLabel};
 
 /// `AssistContext` allows to apply an assist or check if it could be applied.
 ///
diff --git a/crates/assists/src/handlers/generate_function.rs b/crates/assists/src/handlers/generate_function.rs
index f4cf155b6..d169abedb 100644
--- a/crates/assists/src/handlers/generate_function.rs
+++ b/crates/assists/src/handlers/generate_function.rs
@@ -1,5 +1,5 @@
 use hir::HirDisplay;
-use ide_db::base_db::FileId;
+use ide_db::{base_db::FileId, helpers::SnippetCap};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
     ast::{
@@ -11,7 +11,6 @@ use syntax::{
 };
 
 use crate::{
-    assist_config::SnippetCap,
     utils::{render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index 5e3a1b368..90009c55a 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;
+pub use assist_config::{AssistConfig, InsertUseConfig};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum AssistKind {
diff --git a/crates/assists/src/tests.rs b/crates/assists/src/tests.rs
index 21e448fb8..a4c6a7570 100644
--- a/crates/assists/src/tests.rs
+++ b/crates/assists/src/tests.rs
@@ -1,15 +1,29 @@
 mod generated;
 
 use hir::Semantics;
-use ide_db::base_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt};
-use ide_db::source_change::FileSystemEdit;
-use ide_db::RootDatabase;
+use ide_db::{
+    base_db::{fixture::WithFixture, FileId, FileRange, SourceDatabaseExt},
+    helpers::{insert_use::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};
+use crate::{
+    handlers::Handler, Assist, AssistConfig, AssistContext, AssistKind, Assists, InsertUseConfig,
+};
 use stdx::{format_to, trim_indent};
 
+pub(crate) const TEST_CONFIG: AssistConfig = AssistConfig {
+    snippet_cap: SnippetCap::new(true),
+    allowed: None,
+    insert_use: InsertUseConfig {
+        merge: Some(MergeBehavior::Full),
+        prefix_kind: hir::PrefixKind::Plain,
+    },
+};
+
 pub(crate) fn with_single_file(text: &str) -> (RootDatabase, FileId) {
     RootDatabase::with_single_file(text)
 }
@@ -48,14 +62,14 @@ fn check_doc_test(assist_id: &str, before: &str, after: &str) {
     let before = db.file_text(file_id).to_string();
     let frange = FileRange { file_id, range: selection.into() };
 
-    let assist = Assist::get(&db, &AssistConfig::default(), true, frange)
+    let assist = Assist::get(&db, &TEST_CONFIG, true, frange)
         .into_iter()
         .find(|assist| assist.id.0 == assist_id)
         .unwrap_or_else(|| {
             panic!(
                 "\n\nAssist is not applicable: {}\nAvailable assists: {}",
                 assist_id,
-                Assist::get(&db, &AssistConfig::default(), false, frange)
+                Assist::get(&db, &TEST_CONFIG, false, frange)
                     .into_iter()
                     .map(|assist| assist.id.0)
                     .collect::<Vec<_>>()
@@ -89,7 +103,7 @@ fn check(handler: Handler, before: &str, expected: ExpectedResult, assist_label:
     let frange = FileRange { file_id: file_with_caret_id, range: range_or_offset.into() };
 
     let sema = Semantics::new(&db);
-    let config = AssistConfig::default();
+    let config = TEST_CONFIG;
     let ctx = AssistContext::new(sema, &config, frange);
     let mut acc = Assists::new(&ctx, true);
     handler(&mut acc, &ctx);
@@ -156,7 +170,7 @@ fn assist_order_field_struct() {
     let (before_cursor_pos, before) = extract_offset(before);
     let (db, file_id) = with_single_file(&before);
     let frange = FileRange { file_id, range: TextRange::empty(before_cursor_pos) };
-    let assists = Assist::get(&db, &AssistConfig::default(), false, frange);
+    let assists = Assist::get(&db, &TEST_CONFIG, false, frange);
     let mut assists = assists.iter();
 
     assert_eq!(assists.next().expect("expected assist").label, "Change visibility to pub(crate)");
@@ -176,7 +190,7 @@ fn assist_order_if_expr() {
     let (range, before) = extract_range(before);
     let (db, file_id) = with_single_file(&before);
     let frange = FileRange { file_id, range };
-    let assists = Assist::get(&db, &AssistConfig::default(), false, frange);
+    let assists = Assist::get(&db, &TEST_CONFIG, false, frange);
     let mut assists = assists.iter();
 
     assert_eq!(assists.next().expect("expected assist").label, "Extract into variable");
@@ -198,7 +212,7 @@ fn assist_filter_works() {
     let frange = FileRange { file_id, range };
 
     {
-        let mut cfg = AssistConfig::default();
+        let mut cfg = TEST_CONFIG;
         cfg.allowed = Some(vec![AssistKind::Refactor]);
 
         let assists = Assist::get(&db, &cfg, false, frange);
@@ -209,7 +223,7 @@ fn assist_filter_works() {
     }
 
     {
-        let mut cfg = AssistConfig::default();
+        let mut cfg = TEST_CONFIG;
         cfg.allowed = Some(vec![AssistKind::RefactorExtract]);
         let assists = Assist::get(&db, &cfg, false, frange);
         assert_eq!(assists.len(), 1);
@@ -219,7 +233,7 @@ fn assist_filter_works() {
     }
 
     {
-        let mut cfg = AssistConfig::default();
+        let mut cfg = TEST_CONFIG;
         cfg.allowed = Some(vec![AssistKind::QuickFix]);
         let assists = Assist::get(&db, &cfg, false, frange);
         assert!(assists.is_empty(), "All asserts but quickfixes should be filtered out");
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 8212cd129..9ea96eb73 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -4,7 +4,7 @@ pub(crate) mod import_assets;
 use std::ops;
 
 use hir::HasSource;
-use ide_db::RootDatabase;
+use ide_db::{helpers::SnippetCap, RootDatabase};
 use itertools::Itertools;
 use syntax::{
     ast::edit::AstNodeEdit,
@@ -16,10 +16,7 @@ use syntax::{
     SyntaxNode, TextSize, T,
 };
 
-use crate::{
-    assist_config::SnippetCap,
-    ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams},
-};
+use crate::ast_transform::{self, AstTransform, QualifyPaths, SubstituteTypeParams};
 
 pub(crate) fn unwrap_trivial_block(block: ast::BlockExpr) -> ast::Expr {
     extract_trivial_expression(&block)