Align config's API with usage

The config now is mostly immutable, optimize for that.

11 files changed, 49 insertions, 68 deletions

diff --git a/crates/completion/src/completions/postfix.rs b/crates/completion/src/completions/postfix.rs
index 3883d6d21..4888f518a 100644
--- a/crates/completion/src/completions/postfix.rs
+++ b/crates/completion/src/completions/postfix.rs
@@ -2,7 +2,7 @@
 
 mod format_like;
 
-use ide_db::ty_filter::TryEnum;
+use ide_db::{helpers::SnippetCap, ty_filter::TryEnum};
 use syntax::{
     ast::{self, AstNode, AstToken},
     SyntaxKind::{BLOCK_EXPR, EXPR_STMT},
@@ -10,9 +10,8 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use self::format_like::add_format_like_completions;
 use crate::{
-    config::SnippetCap,
+    completions::postfix::format_like::add_format_like_completions,
     context::CompletionContext,
     item::{Builder, CompletionKind},
     CompletionItem, CompletionItemKind, Completions,
diff --git a/crates/completion/src/completions/postfix/format_like.rs b/crates/completion/src/completions/postfix/format_like.rs
index def4b13fb..3afc63021 100644
--- a/crates/completion/src/completions/postfix/format_like.rs
+++ b/crates/completion/src/completions/postfix/format_like.rs
@@ -14,12 +14,11 @@
 //   + `logw` -> `log::warn!(...)`
 //   + `loge` -> `log::error!(...)`
 
-use crate::{
-    completions::postfix::postfix_snippet, config::SnippetCap, context::CompletionContext,
-    Completions,
-};
+use ide_db::helpers::SnippetCap;
 use syntax::ast::{self, AstToken};
 
+use crate::{completions::postfix::postfix_snippet, context::CompletionContext, Completions};
+
 /// Mapping ("postfix completion item" => "macro to use")
 static KINDS: &[(&str, &str)] = &[
     ("format", "format!"),
diff --git a/crates/completion/src/completions/snippet.rs b/crates/completion/src/completions/snippet.rs
index 842590130..b5e704696 100644
--- a/crates/completion/src/completions/snippet.rs
+++ b/crates/completion/src/completions/snippet.rs
@@ -1,8 +1,10 @@
 //! This file provides snippet completions, like `pd` => `eprintln!(...)`.
 
+use ide_db::helpers::SnippetCap;
+
 use crate::{
-    config::SnippetCap, item::Builder, CompletionContext, CompletionItem, CompletionItemKind,
-    CompletionKind, Completions,
+    item::Builder, CompletionContext, CompletionItem, CompletionItemKind, CompletionKind,
+    Completions,
 };
 
 fn snippet(ctx: &CompletionContext, cap: SnippetCap, label: &str, snippet: &str) -> Builder {
diff --git a/crates/completion/src/completions/unqualified_path.rs b/crates/completion/src/completions/unqualified_path.rs
index 896f167ff..2da21b5c2 100644
--- a/crates/completion/src/completions/unqualified_path.rs
+++ b/crates/completion/src/completions/unqualified_path.rs
@@ -192,12 +192,14 @@ mod tests {
     use test_utils::mark;
 
     use crate::{
-        test_utils::{check_edit, check_edit_with_config, completion_list_with_config},
+        test_utils::{
+            check_edit, check_edit_with_config, completion_list_with_config, TEST_CONFIG,
+        },
         CompletionConfig, CompletionKind,
     };
 
     fn check(ra_fixture: &str, expect: Expect) {
-        check_with_config(CompletionConfig::default(), ra_fixture, expect);
+        check_with_config(TEST_CONFIG, ra_fixture, expect);
     }
 
     fn check_with_config(config: CompletionConfig, ra_fixture: &str, expect: Expect) {
@@ -205,10 +207,6 @@ mod tests {
         expect.assert_eq(&actual)
     }
 
-    fn fuzzy_completion_config() -> CompletionConfig {
-        CompletionConfig::default()
-    }
-
     #[test]
     fn self_fulfilling_completion() {
         mark::check!(self_fulfilling_completion);
@@ -832,7 +830,7 @@ impl My<|>
     #[test]
     fn function_fuzzy_completion() {
         check_edit_with_config(
-            fuzzy_completion_config(),
+            TEST_CONFIG,
             "stdin",
             r#"
 //- /lib.rs crate:dep
@@ -858,7 +856,7 @@ fn main() {
     #[test]
     fn macro_fuzzy_completion() {
         check_edit_with_config(
-            fuzzy_completion_config(),
+            TEST_CONFIG,
             "macro_with_curlies!",
             r#"
 //- /lib.rs crate:dep
@@ -886,7 +884,7 @@ fn main() {
     #[test]
     fn struct_fuzzy_completion() {
         check_edit_with_config(
-            fuzzy_completion_config(),
+            TEST_CONFIG,
             "ThirdStruct",
             r#"
 //- /lib.rs crate:dep
@@ -917,7 +915,7 @@ fn main() {
     fn fuzzy_completions_come_in_specific_order() {
         mark::check!(certain_fuzzy_order_test);
         check_with_config(
-            fuzzy_completion_config(),
+            TEST_CONFIG,
             r#"
 //- /lib.rs crate:dep
 pub struct FirstStruct;
diff --git a/crates/completion/src/config.rs b/crates/completion/src/config.rs
index 9f82b0346..b4439b7d1 100644
--- a/crates/completion/src/config.rs
+++ b/crates/completion/src/config.rs
@@ -4,7 +4,7 @@
 //! module, and we use to statically check that we only produce snippet
 //! completions if we are allowed to.
 
-use ide_db::helpers::insert_use::MergeBehavior;
+use ide_db::helpers::{insert_use::MergeBehavior, SnippetCap};
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct CompletionConfig {
@@ -15,27 +15,3 @@ pub struct CompletionConfig {
     pub snippet_cap: Option<SnippetCap>,
     pub merge: Option<MergeBehavior>,
 }
-
-impl CompletionConfig {
-    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 CompletionConfig {
-    fn default() -> Self {
-        CompletionConfig {
-            enable_postfix_completions: true,
-            enable_autoimport_completions: true,
-            add_call_parenthesis: true,
-            add_call_argument_snippets: true,
-            snippet_cap: Some(SnippetCap { _private: () }),
-            merge: Some(MergeBehavior::Full),
-        }
-    }
-}
diff --git a/crates/completion/src/item.rs b/crates/completion/src/item.rs
index 65f8353e7..7087fae37 100644
--- a/crates/completion/src/item.rs
+++ b/crates/completion/src/item.rs
@@ -5,13 +5,11 @@ use std::fmt;
 use hir::{Documentation, ModPath, Mutability};
 use ide_db::helpers::{
     insert_use::{self, ImportScope, MergeBehavior},
-    mod_path_to_ast,
+    mod_path_to_ast, SnippetCap,
 };
 use syntax::{algo, TextRange};
 use text_edit::TextEdit;
 
-use crate::config::SnippetCap;
-
 /// `CompletionItem` describes a single completion variant in the editor pop-up.
 /// It is basically a POD with various properties. To construct a
 /// `CompletionItem`, use `new` method and the `Builder` struct.
diff --git a/crates/completion/src/lib.rs b/crates/completion/src/lib.rs
index 366aced71..3c7d5a46c 100644
--- a/crates/completion/src/lib.rs
+++ b/crates/completion/src/lib.rs
@@ -158,8 +158,7 @@ pub fn resolve_completion_edits(
 
 #[cfg(test)]
 mod tests {
-    use crate::config::CompletionConfig;
-    use crate::test_utils;
+    use crate::test_utils::{self, TEST_CONFIG};
 
     struct DetailAndDocumentation<'a> {
         detail: &'a str,
@@ -168,7 +167,7 @@ mod tests {
 
     fn check_detail_and_documentation(ra_fixture: &str, expected: DetailAndDocumentation) {
         let (db, position) = test_utils::position(ra_fixture);
-        let config = CompletionConfig::default();
+        let config = TEST_CONFIG;
         let completions: Vec<_> = crate::completions(&db, &config, position).unwrap().into();
         for item in completions {
             if item.detail() == Some(expected.detail) {
@@ -183,7 +182,7 @@ mod tests {
 
     fn check_no_completion(ra_fixture: &str) {
         let (db, position) = test_utils::position(ra_fixture);
-        let config = CompletionConfig::default();
+        let config = TEST_CONFIG;
 
         let completions: Option<Vec<String>> = crate::completions(&db, &config, position)
             .and_then(|completions| {
diff --git a/crates/completion/src/render.rs b/crates/completion/src/render.rs
index ac0b2a513..7554c1565 100644
--- a/crates/completion/src/render.rs
+++ b/crates/completion/src/render.rs
@@ -11,13 +11,13 @@ pub(crate) mod type_alias;
 mod builder_ext;
 
 use hir::{Documentation, HasAttrs, HirDisplay, Mutability, ScopeDef, Type};
-use ide_db::RootDatabase;
+use ide_db::{helpers::SnippetCap, RootDatabase};
 use syntax::TextRange;
 use test_utils::mark;
 
 use crate::{
-    config::SnippetCap, item::ImportEdit, CompletionContext, CompletionItem, CompletionItemKind,
-    CompletionKind, CompletionScore,
+    item::ImportEdit, CompletionContext, CompletionItem, CompletionItemKind, CompletionKind,
+    CompletionScore,
 };
 
 use crate::render::{enum_variant::render_variant, function::render_fn, macro_::render_macro};
@@ -320,8 +320,8 @@ mod tests {
     use test_utils::mark;
 
     use crate::{
-        test_utils::{check_edit, do_completion, get_all_items},
-        CompletionConfig, CompletionKind, CompletionScore,
+        test_utils::{check_edit, do_completion, get_all_items, TEST_CONFIG},
+        CompletionKind, CompletionScore,
     };
 
     fn check(ra_fixture: &str, expect: Expect) {
@@ -338,7 +338,7 @@ mod tests {
             }
         }
 
-        let mut completions = get_all_items(CompletionConfig::default(), ra_fixture);
+        let mut completions = get_all_items(TEST_CONFIG, ra_fixture);
         completions.sort_by_key(|it| (Reverse(it.score()), it.label().to_string()));
         let actual = completions
             .into_iter()
diff --git a/crates/completion/src/render/function.rs b/crates/completion/src/render/function.rs
index 081be14f4..7b2f62b4b 100644
--- a/crates/completion/src/render/function.rs
+++ b/crates/completion/src/render/function.rs
@@ -113,7 +113,7 @@ mod tests {
     use test_utils::mark;
 
     use crate::{
-        test_utils::{check_edit, check_edit_with_config},
+        test_utils::{check_edit, check_edit_with_config, TEST_CONFIG},
         CompletionConfig,
     };
 
@@ -211,7 +211,7 @@ fn main() { S::foo(${1:&self})$0 }
     fn suppress_arg_snippets() {
         mark::check!(suppress_arg_snippets);
         check_edit_with_config(
-            CompletionConfig { add_call_argument_snippets: false, ..CompletionConfig::default() },
+            CompletionConfig { add_call_argument_snippets: false, ..TEST_CONFIG },
             "with_args",
             r#"
 fn with_args(x: i32, y: String) {}
diff --git a/crates/completion/src/render/pattern.rs b/crates/completion/src/render/pattern.rs
index a3b6a3cac..61d8a17e5 100644
--- a/crates/completion/src/render/pattern.rs
+++ b/crates/completion/src/render/pattern.rs
@@ -1,12 +1,10 @@
 //! Renderer for patterns.
 
 use hir::{db::HirDatabase, HasAttrs, HasVisibility, Name, StructKind};
+use ide_db::helpers::SnippetCap;
 use itertools::Itertools;
 
-use crate::{
-    config::SnippetCap, item::CompletionKind, render::RenderContext, CompletionItem,
-    CompletionItemKind,
-};
+use crate::{item::CompletionKind, render::RenderContext, CompletionItem, CompletionItemKind};
 
 fn visible_fields(
     ctx: &RenderContext<'_>,
diff --git a/crates/completion/src/test_utils.rs b/crates/completion/src/test_utils.rs
index eb0c16f52..b5e296777 100644
--- a/crates/completion/src/test_utils.rs
+++ b/crates/completion/src/test_utils.rs
@@ -1,8 +1,11 @@
 //! Runs completion for testing purposes.
 
 use hir::Semantics;
-use ide_db::base_db::{fixture::ChangeFixture, FileLoader, FilePosition};
-use ide_db::RootDatabase;
+use ide_db::{
+    base_db::{fixture::ChangeFixture, FileLoader, FilePosition},
+    helpers::{insert_use::MergeBehavior, SnippetCap},
+    RootDatabase,
+};
 use itertools::Itertools;
 use stdx::{format_to, trim_indent};
 use syntax::{AstNode, NodeOrToken, SyntaxElement};
@@ -10,6 +13,15 @@ use test_utils::{assert_eq_text, RangeOrOffset};
 
 use crate::{item::CompletionKind, CompletionConfig, CompletionItem};
 
+pub(crate) const TEST_CONFIG: CompletionConfig = CompletionConfig {
+    enable_postfix_completions: true,
+    enable_autoimport_completions: true,
+    add_call_parenthesis: true,
+    add_call_argument_snippets: true,
+    snippet_cap: SnippetCap::new(true),
+    merge: Some(MergeBehavior::Full),
+};
+
 /// 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);
@@ -24,7 +36,7 @@ pub(crate) fn position(ra_fixture: &str) -> (RootDatabase, FilePosition) {
 }
 
 pub(crate) fn do_completion(code: &str, kind: CompletionKind) -> Vec<CompletionItem> {
-    do_completion_with_config(CompletionConfig::default(), code, kind)
+    do_completion_with_config(TEST_CONFIG, code, kind)
 }
 
 pub(crate) fn do_completion_with_config(
@@ -39,7 +51,7 @@ pub(crate) fn do_completion_with_config(
 }
 
 pub(crate) fn completion_list(code: &str, kind: CompletionKind) -> String {
-    completion_list_with_config(CompletionConfig::default(), code, kind)
+    completion_list_with_config(TEST_CONFIG, code, kind)
 }
 
 pub(crate) fn completion_list_with_config(
@@ -76,7 +88,7 @@ fn monospace_width(s: &str) -> usize {
 }
 
 pub(crate) fn check_edit(what: &str, ra_fixture_before: &str, ra_fixture_after: &str) {
-    check_edit_with_config(CompletionConfig::default(), what, ra_fixture_before, ra_fixture_after)
+    check_edit_with_config(TEST_CONFIG, what, ra_fixture_before, ra_fixture_after)
 }
 
 pub(crate) fn check_edit_with_config(