More maintainable config

Rather than eagerly converting JSON, we losslessly keep it as is, and
change the shape of user-submitted data at the last moment.

This also allows us to remove a bunch of wrong Defaults

16 files changed, 422 insertions, 442 deletions

diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index f2ad95cb607..72c9c66feb0 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -17,7 +17,7 @@ use crate::{
     doc_links::{remove_links, rewrite_links},
     markdown_remove::remove_markdown,
     markup::Markup,
-    runnables::runnable,
+    runnables::{runnable, runnable_fn},
     FileId, FilePosition, NavigationTarget, RangeInfo, Runnable,
 };
 
@@ -31,19 +31,6 @@ pub struct HoverConfig {
     pub markdown: bool,
 }
 
-impl Default for HoverConfig {
-    fn default() -> Self {
-        Self {
-            implementations: true,
-            run: true,
-            debug: true,
-            goto_type_def: true,
-            links_in_hover: true,
-            markdown: true,
-        }
-    }
-}
-
 impl HoverConfig {
     pub const NO_ACTIONS: Self = Self {
         implementations: false,
@@ -204,22 +191,20 @@ fn runnable_action(
     match def {
         Definition::ModuleDef(it) => match it {
             ModuleDef::Module(it) => match it.definition_source(sema.db).value {
-                ModuleSource::Module(it) => runnable(&sema, it.syntax().clone(), file_id)
-                    .map(|it| HoverAction::Runnable(it)),
+                ModuleSource::Module(it) => {
+                    runnable(&sema, it.syntax().clone()).map(|it| HoverAction::Runnable(it))
+                }
                 _ => None,
             },
-            ModuleDef::Function(it) => {
-                #[allow(deprecated)]
-                let src = it.source(sema.db)?;
+            ModuleDef::Function(func) => {
+                let src = func.source(sema.db)?;
                 if src.file_id != file_id.into() {
                     mark::hit!(hover_macro_generated_struct_fn_doc_comment);
                     mark::hit!(hover_macro_generated_struct_fn_doc_attr);
-
                     return None;
                 }
 
-                runnable(&sema, src.value.syntax().clone(), file_id)
-                    .map(|it| HoverAction::Runnable(it))
+                runnable_fn(&sema, func).map(HoverAction::Runnable)
             }
             _ => None,
         },
diff --git a/crates/ide/src/inlay_hints.rs b/crates/ide/src/inlay_hints.rs
index 65df7979cfa..fe60abfc856 100644
--- a/crates/ide/src/inlay_hints.rs
+++ b/crates/ide/src/inlay_hints.rs
@@ -18,12 +18,6 @@ pub struct InlayHintsConfig {
     pub max_length: Option<usize>,
 }
 
-impl Default for InlayHintsConfig {
-    fn default() -> Self {
-        Self { type_hints: true, parameter_hints: true, chaining_hints: true, max_length: None }
-    }
-}
-
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum InlayKind {
     TypeHint,
@@ -433,8 +427,15 @@ mod tests {
 
     use crate::{fixture, inlay_hints::InlayHintsConfig};
 
+    const TEST_CONFIG: InlayHintsConfig = InlayHintsConfig {
+        type_hints: true,
+        parameter_hints: true,
+        chaining_hints: true,
+        max_length: None,
+    };
+
     fn check(ra_fixture: &str) {
-        check_with_config(InlayHintsConfig::default(), ra_fixture);
+        check_with_config(TEST_CONFIG, ra_fixture);
     }
 
     fn check_with_config(config: InlayHintsConfig, ra_fixture: &str) {
@@ -748,7 +749,7 @@ fn main() {
     #[test]
     fn hint_truncation() {
         check_with_config(
-            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
             r#"
 struct Smol<T>(T);
 
@@ -831,7 +832,7 @@ fn main() {
     #[test]
     fn omitted_parameters_hints_heuristics() {
         check_with_config(
-            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
             r#"
 fn map(f: i32) {}
 fn filter(predicate: i32) {}
@@ -924,7 +925,7 @@ fn main() {
     #[test]
     fn unit_structs_have_no_type_hints() {
         check_with_config(
-            InlayHintsConfig { max_length: Some(8), ..Default::default() },
+            InlayHintsConfig { max_length: Some(8), ..TEST_CONFIG },
             r#"
 enum Result<T, E> { Ok(T), Err(E) }
 use Result::*;
diff --git a/crates/ide/src/runnables.rs b/crates/ide/src/runnables.rs
index c893afc7cf7..f4030f3ef2e 100644
--- a/crates/ide/src/runnables.rs
+++ b/crates/ide/src/runnables.rs
@@ -2,11 +2,11 @@ use std::fmt;
 
 use assists::utils::test_related_attribute;
 use cfg::CfgExpr;
-use hir::{AsAssocItem, HasAttrs, InFile, Semantics};
+use hir::{AsAssocItem, HasAttrs, HasSource, Semantics};
 use ide_db::RootDatabase;
 use itertools::Itertools;
 use syntax::{
-    ast::{self, AstNode, AttrsOwner, ModuleItemOwner, NameOwner},
+    ast::{self, AstNode, AttrsOwner, ModuleItemOwner},
     match_ast, SyntaxNode,
 };
 
@@ -96,17 +96,16 @@ impl Runnable {
 pub(crate) fn runnables(db: &RootDatabase, file_id: FileId) -> Vec<Runnable> {
     let sema = Semantics::new(db);
     let source_file = sema.parse(file_id);
-    source_file.syntax().descendants().filter_map(|i| runnable(&sema, i, file_id)).collect()
+    source_file.syntax().descendants().filter_map(|i| runnable(&sema, i)).collect()
 }
 
-pub(crate) fn runnable(
-    sema: &Semantics<RootDatabase>,
-    item: SyntaxNode,
-    file_id: FileId,
-) -> Option<Runnable> {
+pub(crate) fn runnable(sema: &Semantics<RootDatabase>, item: SyntaxNode) -> Option<Runnable> {
     let runnable_item = match_ast! {
         match (item.clone()) {
-            ast::Fn(it) => runnable_fn(sema, it, file_id),
+            ast::Fn(func) => {
+                let def = sema.to_def(&func)?;
+                runnable_fn(sema, def)
+            },
             ast::Module(it) => runnable_mod(sema, it),
             _ => None,
         }
@@ -114,23 +113,23 @@ pub(crate) fn runnable(
     runnable_item.or_else(|| runnable_doctest(sema, item))
 }
 
-fn runnable_fn(sema: &Semantics<RootDatabase>, func: ast::Fn, file_id: FileId) -> Option<Runnable> {
-    let def = sema.to_def(&func)?;
-    let name_string = func.name()?.text().to_string();
+pub(crate) fn runnable_fn(sema: &Semantics<RootDatabase>, def: hir::Function) -> Option<Runnable> {
+    let func = def.source(sema.db)?;
+    let name_string = def.name(sema.db).to_string();
 
     let kind = if name_string == "main" {
         RunnableKind::Bin
     } else {
-        let canonical_path = sema.to_def(&func).and_then(|def| {
+        let canonical_path = {
             let def: hir::ModuleDef = def.into();
             def.canonical_path(sema.db)
-        });
+        };
         let test_id = canonical_path.map(TestId::Path).unwrap_or(TestId::Name(name_string));
 
-        if test_related_attribute(&func).is_some() {
-            let attr = TestAttr::from_fn(&func);
+        if test_related_attribute(&func.value).is_some() {
+            let attr = TestAttr::from_fn(&func.value);
             RunnableKind::Test { test_id, attr }
-        } else if func.has_atom_attr("bench") {
+        } else if func.value.has_atom_attr("bench") {
             RunnableKind::Bench { test_id }
         } else {
             return None;
@@ -139,7 +138,7 @@ fn runnable_fn(sema: &Semantics<RootDatabase>, func: ast::Fn, file_id: FileId) -
 
     let nav = NavigationTarget::from_named(
         sema.db,
-        InFile::new(file_id.into(), &func),
+        func.as_ref().map(|it| it as &dyn ast::NameOwner),
         SymbolKind::Function,
     );
     let cfg = def.attrs(sema.db).cfg();
diff --git a/crates/project_model/src/project_json.rs b/crates/project_model/src/project_json.rs
index af884eb84a1..41a2ac03e0b 100644
--- a/crates/project_model/src/project_json.rs
+++ b/crates/project_model/src/project_json.rs
@@ -110,13 +110,13 @@ impl ProjectJson {
     }
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 pub struct ProjectJsonData {
     sysroot_src: Option<PathBuf>,
     crates: Vec<CrateData>,
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 struct CrateData {
     display_name: Option<String>,
     root_module: PathBuf,
@@ -132,7 +132,7 @@ struct CrateData {
     source: Option<CrateSource>,
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename = "edition")]
 enum EditionData {
     #[serde(rename = "2015")]
@@ -153,7 +153,7 @@ impl From<EditionData> for Edition {
     }
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 struct DepData {
     /// Identifies a crate by position in the crates array.
     #[serde(rename = "crate")]
@@ -162,7 +162,7 @@ struct DepData {
     name: CrateName,
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 struct CrateSource {
     include_dirs: Vec<PathBuf>,
     exclude_dirs: Vec<PathBuf>,
diff --git a/crates/rust-analyzer/src/bin/main.rs b/crates/rust-analyzer/src/bin/main.rs
index defdcbd748b..3af3c59d88b 100644
--- a/crates/rust-analyzer/src/bin/main.rs
+++ b/crates/rust-analyzer/src/bin/main.rs
@@ -8,11 +8,7 @@ use std::{convert::TryFrom, env, fs, path::PathBuf, process};
 
 use lsp_server::Connection;
 use project_model::ProjectManifest;
-use rust_analyzer::{
-    cli,
-    config::{Config, LinkedProject},
-    from_json, Result,
-};
+use rust_analyzer::{cli, config::Config, from_json, Result};
 use vfs::AbsPathBuf;
 
 #[cfg(all(feature = "mimalloc"))]
@@ -138,13 +134,12 @@ fn run_server() -> Result<()> {
             }
         };
 
-        let mut config = Config::new(root_path);
+        let mut config = Config::new(root_path, initialize_params.capabilities);
         if let Some(json) = initialize_params.initialization_options {
             config.update(json);
         }
-        config.update_caps(&initialize_params.capabilities);
 
-        if config.linked_projects.is_empty() {
+        if config.linked_projects().is_empty() {
             let workspace_roots = initialize_params
                 .workspace_folders
                 .map(|workspaces| {
@@ -163,7 +158,7 @@ fn run_server() -> Result<()> {
                 log::error!("failed to find any projects in {:?}", workspace_roots);
             }
 
-            config.linked_projects = discovered.into_iter().map(LinkedProject::from).collect();
+            config.discovered_projects = Some(discovered);
         }
 
         config
diff --git a/crates/rust-analyzer/src/cargo_target_spec.rs b/crates/rust-analyzer/src/cargo_target_spec.rs
index 8a8b4a32cb4..5af0802a2f0 100644
--- a/crates/rust-analyzer/src/cargo_target_spec.rs
+++ b/crates/rust-analyzer/src/cargo_target_spec.rs
@@ -84,14 +84,15 @@ impl CargoTargetSpec {
             }
         }
 
-        if snap.config.cargo.all_features {
+        let cargo_config = snap.config.cargo();
+        if cargo_config.all_features {
             args.push("--all-features".to_string());
         } else {
             let mut features = Vec::new();
             if let Some(cfg) = cfg.as_ref() {
                 required_features(cfg, &mut features);
             }
-            for feature in &snap.config.cargo.features {
+            for feature in cargo_config.features {
                 features.push(feature.clone());
             }
             features.dedup();
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index a80652e8399..24e7936fc9e 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -148,13 +148,19 @@ config_data! {
         /// of projects.\n\nElements must be paths pointing to `Cargo.toml`,
         /// `rust-project.json`, or JSON objects in `rust-project.json` format.
         linkedProjects: Vec<ManifestOrProjectJson> = "[]",
+
         /// Number of syntax trees rust-analyzer keeps in memory.  Defaults to 128.
         lruCapacity: Option<usize>                 = "null",
+
         /// Whether to show `can't find Cargo.toml` error message.
         notifications_cargoTomlNotFound: bool      = "true",
+
         /// Enable Proc macro support, `#rust-analyzer.cargo.loadOutDirsFromCheck#` must be
         /// enabled.
         procMacro_enable: bool                     = "false",
+        /// Internal config, path to proc-macro server executable (typically,
+        /// this is rust-analyzer itself, but we override this in tests).
+        procMacro_server: Option<PathBuf>          = "null",
 
         /// Command to be executed instead of 'cargo' for runnables.
         runnables_overrideCargo: Option<String> = "null",
@@ -163,7 +169,7 @@ config_data! {
         runnables_cargoExtraArgs: Vec<String>   = "[]",
 
         /// Path to the rust compiler sources, for usage in rustc_private projects.
-        rustcSource : Option<String> = "null",
+        rustcSource : Option<PathBuf> = "null",
 
         /// Additional arguments to `rustfmt`.
         rustfmt_extraArgs: Vec<String>               = "[]",
@@ -173,34 +179,17 @@ config_data! {
     }
 }
 
+impl Default for ConfigData {
+    fn default() -> Self {
+        ConfigData::from_json(serde_json::Value::Null)
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct Config {
-    pub caps: lsp_types::ClientCapabilities,
-
-    pub publish_diagnostics: bool,
-    pub diagnostics: DiagnosticsConfig,
-    pub diagnostics_map: DiagnosticsMapConfig,
-    pub lru_capacity: Option<usize>,
-    pub proc_macro_srv: Option<(PathBuf, Vec<OsString>)>,
-    pub files: FilesConfig,
-    pub notifications: NotificationsConfig,
-
-    pub cargo_autoreload: bool,
-    pub cargo: CargoConfig,
-    pub rustfmt: RustfmtConfig,
-    pub flycheck: Option<FlycheckConfig>,
-    pub runnables: RunnablesConfig,
-
-    pub inlay_hints: InlayHintsConfig,
-    pub completion: CompletionConfig,
-    pub assist: AssistConfig,
-    pub call_info_full: bool,
-    pub lens: LensConfig,
-    pub hover: HoverConfig,
-    pub semantic_tokens_refresh: bool,
-    pub code_lens_refresh: bool,
-
-    pub linked_projects: Vec<LinkedProject>,
+    caps: lsp_types::ClientCapabilities,
+    data: ConfigData,
+    pub discovered_projects: Option<Vec<ProjectManifest>>,
     pub root_path: AbsPathBuf,
 }
 
@@ -230,12 +219,6 @@ pub struct LensConfig {
     pub method_refs: bool,
 }
 
-impl Default for LensConfig {
-    fn default() -> Self {
-        Self { run: true, debug: true, implementations: true, method_refs: false }
-    }
-}
-
 impl LensConfig {
     pub fn any(&self) -> bool {
         self.implementations || self.runnable() || self.references()
@@ -278,7 +261,7 @@ pub enum RustfmtConfig {
 }
 
 /// Configuration for runnable items, such as `main` function or tests.
-#[derive(Debug, Clone, Default)]
+#[derive(Debug, Clone)]
 pub struct RunnablesConfig {
     /// Custom command to be executed instead of `cargo` for runnables.
     pub override_cargo: Option<String>,
@@ -287,250 +270,15 @@ pub struct RunnablesConfig {
 }
 
 impl Config {
-    pub fn new(root_path: AbsPathBuf) -> Self {
-        // Defaults here don't matter, we'll immediately re-write them with
-        // ConfigData.
-        let mut res = Config {
-            caps: lsp_types::ClientCapabilities::default(),
-
-            publish_diagnostics: false,
-            diagnostics: DiagnosticsConfig::default(),
-            diagnostics_map: DiagnosticsMapConfig::default(),
-            lru_capacity: None,
-            proc_macro_srv: None,
-            files: FilesConfig { watcher: FilesWatcher::Notify, exclude: Vec::new() },
-            notifications: NotificationsConfig { cargo_toml_not_found: false },
-
-            cargo_autoreload: false,
-            cargo: CargoConfig::default(),
-            rustfmt: RustfmtConfig::Rustfmt { extra_args: Vec::new() },
-            flycheck: Some(FlycheckConfig::CargoCommand {
-                command: String::new(),
-                target_triple: None,
-                no_default_features: false,
-                all_targets: false,
-                all_features: false,
-                extra_args: Vec::new(),
-                features: Vec::new(),
-            }),
-            runnables: RunnablesConfig::default(),
-
-            inlay_hints: InlayHintsConfig {
-                type_hints: false,
-                parameter_hints: false,
-                chaining_hints: false,
-                max_length: None,
-            },
-            completion: CompletionConfig::default(),
-            assist: AssistConfig::default(),
-            call_info_full: false,
-            lens: LensConfig::default(),
-            hover: HoverConfig::default(),
-            semantic_tokens_refresh: false,
-            code_lens_refresh: false,
-            linked_projects: Vec::new(),
-            root_path,
-        };
-        res.do_update(serde_json::json!({}));
-        res
+    pub fn new(root_path: AbsPathBuf, caps: ClientCapabilities) -> Self {
+        Config { caps, data: ConfigData::default(), discovered_projects: None, root_path }
     }
     pub fn update(&mut self, json: serde_json::Value) {
         log::info!("updating config from JSON: {:#}", json);
         if json.is_null() || json.as_object().map_or(false, |it| it.is_empty()) {
             return;
         }
-        self.do_update(json);
-        log::info!("updated config: {:#?}", self);
-    }
-    fn do_update(&mut self, json: serde_json::Value) {
-        let data = ConfigData::from_json(json);
-
-        self.publish_diagnostics = data.diagnostics_enable;
-        self.diagnostics = DiagnosticsConfig {
-            disable_experimental: !data.diagnostics_enableExperimental,
-            disabled: data.diagnostics_disabled,
-        };
-        self.diagnostics_map = DiagnosticsMapConfig {
-            warnings_as_info: data.diagnostics_warningsAsInfo,
-            warnings_as_hint: data.diagnostics_warningsAsHint,
-        };
-        self.lru_capacity = data.lruCapacity;
-        self.files.watcher = match data.files_watcher.as_str() {
-            "notify" => FilesWatcher::Notify,
-            "client" | _ => FilesWatcher::Client,
-        };
-        self.notifications =
-            NotificationsConfig { cargo_toml_not_found: data.notifications_cargoTomlNotFound };
-        self.cargo_autoreload = data.cargo_autoreload;
-
-        let rustc_source = if let Some(rustc_source) = data.rustcSource {
-            let rustpath: PathBuf = rustc_source.into();
-            AbsPathBuf::try_from(rustpath)
-                .map_err(|_| {
-                    log::error!("rustc source directory must be an absolute path");
-                })
-                .ok()
-        } else {
-            None
-        };
-
-        self.cargo = CargoConfig {
-            no_default_features: data.cargo_noDefaultFeatures,
-            all_features: data.cargo_allFeatures,
-            features: data.cargo_features.clone(),
-            load_out_dirs_from_check: data.cargo_loadOutDirsFromCheck,
-            target: data.cargo_target.clone(),
-            rustc_source: rustc_source,
-            no_sysroot: data.cargo_noSysroot,
-        };
-        self.runnables = RunnablesConfig {
-            override_cargo: data.runnables_overrideCargo,
-            cargo_extra_args: data.runnables_cargoExtraArgs,
-        };
-
-        self.proc_macro_srv = if data.procMacro_enable {
-            std::env::current_exe().ok().map(|path| (path, vec!["proc-macro".into()]))
-        } else {
-            None
-        };
-
-        self.rustfmt = match data.rustfmt_overrideCommand {
-            Some(mut args) if !args.is_empty() => {
-                let command = args.remove(0);
-                RustfmtConfig::CustomCommand { command, args }
-            }
-            Some(_) | None => RustfmtConfig::Rustfmt { extra_args: data.rustfmt_extraArgs },
-        };
-
-        self.flycheck = if data.checkOnSave_enable {
-            let flycheck_config = match data.checkOnSave_overrideCommand {
-                Some(mut args) if !args.is_empty() => {
-                    let command = args.remove(0);
-                    FlycheckConfig::CustomCommand { command, args }
-                }
-                Some(_) | None => FlycheckConfig::CargoCommand {
-                    command: data.checkOnSave_command,
-                    target_triple: data.checkOnSave_target.or(data.cargo_target),
-                    all_targets: data.checkOnSave_allTargets,
-                    no_default_features: data
-                        .checkOnSave_noDefaultFeatures
-                        .unwrap_or(data.cargo_noDefaultFeatures),
-                    all_features: data.checkOnSave_allFeatures.unwrap_or(data.cargo_allFeatures),
-                    features: data.checkOnSave_features.unwrap_or(data.cargo_features),
-                    extra_args: data.checkOnSave_extraArgs,
-                },
-            };
-            Some(flycheck_config)
-        } else {
-            None
-        };
-
-        self.inlay_hints = InlayHintsConfig {
-            type_hints: data.inlayHints_typeHints,
-            parameter_hints: data.inlayHints_parameterHints,
-            chaining_hints: data.inlayHints_chainingHints,
-            max_length: data.inlayHints_maxLength,
-        };
-
-        self.assist.insert_use.merge = match data.assist_importMergeBehaviour {
-            MergeBehaviorDef::None => None,
-            MergeBehaviorDef::Full => Some(MergeBehavior::Full),
-            MergeBehaviorDef::Last => Some(MergeBehavior::Last),
-        };
-        self.assist.insert_use.prefix_kind = match data.assist_importPrefix {
-            ImportPrefixDef::Plain => PrefixKind::Plain,
-            ImportPrefixDef::ByCrate => PrefixKind::ByCrate,
-            ImportPrefixDef::BySelf => PrefixKind::BySelf,
-        };
-
-        self.completion.enable_postfix_completions = data.completion_postfix_enable;
-        self.completion.enable_autoimport_completions = data.completion_autoimport_enable;
-        self.completion.add_call_parenthesis = data.completion_addCallParenthesis;
-        self.completion.add_call_argument_snippets = data.completion_addCallArgumentSnippets;
-        self.completion.merge = self.assist.insert_use.merge;
-
-        self.call_info_full = data.callInfo_full;
-
-        self.lens = LensConfig {
-            run: data.lens_enable && data.lens_run,
-            debug: data.lens_enable && data.lens_debug,
-            implementations: data.lens_enable && data.lens_implementations,
-            method_refs: data.lens_enable && data.lens_methodReferences,
-        };
-
-        if !data.linkedProjects.is_empty() {
-            self.linked_projects.clear();
-            for linked_project in data.linkedProjects {
-                let linked_project = match linked_project {
-                    ManifestOrProjectJson::Manifest(it) => {
-                        let path = self.root_path.join(it);
-                        match ProjectManifest::from_manifest_file(path) {
-                            Ok(it) => it.into(),
-                            Err(e) => {
-                                log::error!("failed to load linked project: {}", e);
-                                continue;
-                            }
-                        }
-                    }
-                    ManifestOrProjectJson::ProjectJson(it) => {
-                        ProjectJson::new(&self.root_path, it).into()
-                    }
-                };
-                self.linked_projects.push(linked_project);
-            }
-        }
-
-        self.hover = HoverConfig {
-            implementations: data.hoverActions_enable && data.hoverActions_implementations,
-            run: data.hoverActions_enable && data.hoverActions_run,
-            debug: data.hoverActions_enable && data.hoverActions_debug,
-            goto_type_def: data.hoverActions_enable && data.hoverActions_gotoTypeDef,
-            links_in_hover: data.hoverActions_linksInHover,
-            markdown: true,
-        };
-    }
-
-    pub fn update_caps(&mut self, caps: &ClientCapabilities) {
-        self.caps = caps.clone();
-        if let Some(doc_caps) = caps.text_document.as_ref() {
-            if let Some(value) = doc_caps.hover.as_ref().and_then(|it| it.content_format.as_ref()) {
-                self.hover.markdown = value.contains(&MarkupKind::Markdown)
-            }
-
-            self.completion.allow_snippets(false);
-            self.completion.active_resolve_capabilities =
-                enabled_completions_resolve_capabilities(caps).unwrap_or_default();
-            if let Some(completion) = &doc_caps.completion {
-                if let Some(completion_item) = &completion.completion_item {
-                    if let Some(value) = completion_item.snippet_support {
-                        self.completion.allow_snippets(value);
-                    }
-                }
-            }
-        }
-
-        self.assist.allow_snippets(false);
-        if let Some(experimental) = &caps.experimental {
-            let get_bool =
-                |index: &str| experimental.get(index).and_then(|it| it.as_bool()) == Some(true);
-
-            let snippet_text_edit = get_bool("snippetTextEdit");
-            self.assist.allow_snippets(snippet_text_edit);
-        }
-
-        if let Some(workspace_caps) = caps.workspace.as_ref() {
-            if let Some(refresh_support) =
-                workspace_caps.semantic_tokens.as_ref().and_then(|it| it.refresh_support)
-            {
-                self.semantic_tokens_refresh = refresh_support;
-            }
-
-            if let Some(refresh_support) =
-                workspace_caps.code_lens.as_ref().and_then(|it| it.refresh_support)
-            {
-                self.code_lens_refresh = refresh_support;
-            }
-        }
+        self.data = ConfigData::from_json(json);
     }
 
     pub fn json_schema() -> serde_json::Value {
@@ -550,6 +298,38 @@ macro_rules! try_or {
 }
 
 impl Config {
+    pub fn linked_projects(&self) -> Vec<LinkedProject> {
+        if self.data.linkedProjects.is_empty() {
+            self.discovered_projects
+                .as_ref()
+                .into_iter()
+                .flatten()
+                .cloned()
+                .map(LinkedProject::from)
+                .collect()
+        } else {
+            self.data
+                .linkedProjects
+                .iter()
+                .filter_map(|linked_project| {
+                    let res = match linked_project {
+                        ManifestOrProjectJson::Manifest(it) => {
+                            let path = self.root_path.join(it);
+                            ProjectManifest::from_manifest_file(path)
+                                .map_err(|e| log::error!("failed to load linked project: {}", e))
+                                .ok()?
+                                .into()
+                        }
+                        ManifestOrProjectJson::ProjectJson(it) => {
+                            ProjectJson::new(&self.root_path, it.clone()).into()
+                        }
+                    };
+                    Some(res)
+                })
+                .collect()
+        }
+    }
+
     pub fn location_link(&self) -> bool {
         try_or!(self.caps.text_document.as_ref()?.definition?.link_support?, false)
     }
@@ -625,16 +405,217 @@ impl Config {
     pub fn status_notification(&self) -> bool {
         self.experimental("statusNotification")
     }
+
+    pub fn publish_diagnostics(&self) -> bool {
+        self.data.diagnostics_enable
+    }
+    pub fn diagnostics(&self) -> DiagnosticsConfig {
+        DiagnosticsConfig {
+            disable_experimental: !self.data.diagnostics_enableExperimental,
+            disabled: self.data.diagnostics_disabled.clone(),
+        }
+    }
+    pub fn diagnostics_map(&self) -> DiagnosticsMapConfig {
+        DiagnosticsMapConfig {
+            warnings_as_info: self.data.diagnostics_warningsAsInfo.clone(),
+            warnings_as_hint: self.data.diagnostics_warningsAsHint.clone(),
+        }
+    }
+    pub fn lru_capacity(&self) -> Option<usize> {
+        self.data.lruCapacity
+    }
+    pub fn proc_macro_srv(&self) -> Option<(PathBuf, Vec<OsString>)> {
+        if !self.data.procMacro_enable {
+            return None;
+        }
+
+        let path = self.data.procMacro_server.clone().or_else(|| std::env::current_exe().ok())?;
+        Some((path, vec!["proc-macro".into()]))
+    }
+    pub fn files(&self) -> FilesConfig {
+        FilesConfig {
+            watcher: match self.data.files_watcher.as_str() {
+                "notify" => FilesWatcher::Notify,
+                "client" | _ => FilesWatcher::Client,
+            },
+            exclude: Vec::new(),
+        }
+    }
+    pub fn notifications(&self) -> NotificationsConfig {
+        NotificationsConfig { cargo_toml_not_found: self.data.notifications_cargoTomlNotFound }
+    }
+    pub fn cargo_autoreload(&self) -> bool {
+        self.data.cargo_autoreload
+    }
+    pub fn cargo(&self) -> CargoConfig {
+        let rustc_source = self.data.rustcSource.clone().and_then(|it| {
+            AbsPathBuf::try_from(it)
+                .map_err(|_| log::error!("rustc source directory must be an absolute path"))
+                .ok()
+        });
+
+        CargoConfig {
+            no_default_features: self.data.cargo_noDefaultFeatures,
+            all_features: self.data.cargo_allFeatures,
+            features: self.data.cargo_features.clone(),
+            load_out_dirs_from_check: self.data.cargo_loadOutDirsFromCheck,
+            target: self.data.cargo_target.clone(),
+            rustc_source,
+            no_sysroot: self.data.cargo_noSysroot,
+        }
+    }
+    pub fn rustfmt(&self) -> RustfmtConfig {
+        match &self.data.rustfmt_overrideCommand {
+            Some(args) if !args.is_empty() => {
+                let mut args = args.clone();
+                let command = args.remove(0);
+                RustfmtConfig::CustomCommand { command, args }
+            }
+            Some(_) | None => {
+                RustfmtConfig::Rustfmt { extra_args: self.data.rustfmt_extraArgs.clone() }
+            }
+        }
+    }
+    pub fn flycheck(&self) -> Option<FlycheckConfig> {
+        if !self.data.checkOnSave_enable {
+            return None;
+        }
+        let flycheck_config = match &self.data.checkOnSave_overrideCommand {
+            Some(args) if !args.is_empty() => {
+                let mut args = args.clone();
+                let command = args.remove(0);
+                FlycheckConfig::CustomCommand { command, args }
+            }
+            Some(_) | None => FlycheckConfig::CargoCommand {
+                command: self.data.checkOnSave_command.clone(),
+                target_triple: self
+                    .data
+                    .checkOnSave_target
+                    .clone()
+                    .or(self.data.cargo_target.clone()),
+                all_targets: self.data.checkOnSave_allTargets,
+                no_default_features: self
+                    .data
+                    .checkOnSave_noDefaultFeatures
+                    .unwrap_or(self.data.cargo_noDefaultFeatures),
+                all_features: self
+                    .data
+                    .checkOnSave_allFeatures
+                    .unwrap_or(self.data.cargo_allFeatures),
+                features: self
+                    .data
+                    .checkOnSave_features
+                    .clone()
+                    .unwrap_or(self.data.cargo_features.clone()),
+                extra_args: self.data.checkOnSave_extraArgs.clone(),
+            },
+        };
+        Some(flycheck_config)
+    }
+    pub fn runnables(&self) -> RunnablesConfig {
+        RunnablesConfig {
+            override_cargo: self.data.runnables_overrideCargo.clone(),
+            cargo_extra_args: self.data.runnables_cargoExtraArgs.clone(),
+        }
+    }
+    pub fn inlay_hints(&self) -> InlayHintsConfig {
+        InlayHintsConfig {
+            type_hints: self.data.inlayHints_typeHints,
+            parameter_hints: self.data.inlayHints_parameterHints,
+            chaining_hints: self.data.inlayHints_chainingHints,
+            max_length: self.data.inlayHints_maxLength,
+        }
+    }
+    fn merge_behavior(&self) -> Option<MergeBehavior> {
+        match self.data.assist_importMergeBehaviour {
+            MergeBehaviorDef::None => None,
+            MergeBehaviorDef::Full => Some(MergeBehavior::Full),
+            MergeBehaviorDef::Last => Some(MergeBehavior::Last),
+        }
+    }
+    pub fn completion(&self) -> CompletionConfig {
+        let mut res = CompletionConfig::default();
+        res.enable_postfix_completions = self.data.completion_postfix_enable;
+        res.enable_autoimport_completions = self.data.completion_autoimport_enable;
+        res.add_call_parenthesis = self.data.completion_addCallParenthesis;
+        res.add_call_argument_snippets = self.data.completion_addCallArgumentSnippets;
+        res.merge = self.merge_behavior();
+        res.active_resolve_capabilities =
+            enabled_completions_resolve_capabilities(&self.caps).unwrap_or_default();
+
+        res.allow_snippets(try_or!(
+            self.caps
+                .text_document
+                .as_ref()?
+                .completion
+                .as_ref()?
+                .completion_item
+                .as_ref()?
+                .snippet_support?,
+            false
+        ));
+        res
+    }
+    pub fn assist(&self) -> AssistConfig {
+        let mut res = AssistConfig::default();
+        res.insert_use.merge = self.merge_behavior();
+        res.insert_use.prefix_kind = match self.data.assist_importPrefix {
+            ImportPrefixDef::Plain => PrefixKind::Plain,
+            ImportPrefixDef::ByCrate => PrefixKind::ByCrate,
+            ImportPrefixDef::BySelf => PrefixKind::BySelf,
+        };
+        res.allow_snippets(self.experimental("snippetTextEdit"));
+        res
+    }
+    pub fn call_info_full(&self) -> bool {
+        self.data.callInfo_full
+    }
+    pub fn lens(&self) -> LensConfig {
+        LensConfig {
+            run: self.data.lens_enable && self.data.lens_run,
+            debug: self.data.lens_enable && self.data.lens_debug,
+            implementations: self.data.lens_enable && self.data.lens_implementations,
+            method_refs: self.data.lens_enable && self.data.lens_methodReferences,
+        }
+    }
+    pub fn hover(&self) -> HoverConfig {
+        HoverConfig {
+            implementations: self.data.hoverActions_enable
+                && self.data.hoverActions_implementations,
+            run: self.data.hoverActions_enable && self.data.hoverActions_run,
+            debug: self.data.hoverActions_enable && self.data.hoverActions_debug,
+            goto_type_def: self.data.hoverActions_enable && self.data.hoverActions_gotoTypeDef,
+            links_in_hover: self.data.hoverActions_linksInHover,
+            markdown: try_or!(
+                self.caps
+                    .text_document
+                    .as_ref()?
+                    .hover
+                    .as_ref()?
+                    .content_format
+                    .as_ref()?
+                    .as_slice(),
+                &[]
+            )
+            .contains(&MarkupKind::Markdown),
+        }
+    }
+    pub fn semantic_tokens_refresh(&self) -> bool {
+        try_or!(self.caps.workspace.as_ref()?.semantic_tokens.as_ref()?.refresh_support?, false)
+    }
+    pub fn code_lens_refresh(&self) -> bool {
+        try_or!(self.caps.workspace.as_ref()?.code_lens.as_ref()?.refresh_support?, false)
+    }
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(untagged)]
 enum ManifestOrProjectJson {
     Manifest(PathBuf),
     ProjectJson(ProjectJsonData),
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "snake_case")]
 enum MergeBehaviorDef {
     None,
@@ -642,7 +623,7 @@ enum MergeBehaviorDef {
     Last,
 }
 
-#[derive(Deserialize)]
+#[derive(Deserialize, Debug, Clone)]
 #[serde(rename_all = "snake_case")]
 enum ImportPrefixDef {
     Plain,
@@ -658,6 +639,7 @@ macro_rules! _config_data {
         )*
     }) => {
         #[allow(non_snake_case)]
+        #[derive(Debug, Clone)]
         struct $name { $($field: $ty,)* }
         impl $name {
             fn from_json(mut json: serde_json::Value) -> $name {
@@ -763,6 +745,9 @@ fn field_props(field: &str, ty: &str, doc: &[&str], default: &str) -> serde_json
         "Option<String>" => set! {
             "type": ["null", "string"],
         },
+        "Option<PathBuf>" => set! {
+            "type": ["null", "string"],
+        },
         "Option<bool>" => set! {
             "type": ["null", "boolean"],
         },
diff --git a/crates/rust-analyzer/src/global_state.rs b/crates/rust-analyzer/src/global_state.rs
index 71dc5691579..19ab4d596a4 100644
--- a/crates/rust-analyzer/src/global_state.rs
+++ b/crates/rust-analyzer/src/global_state.rs
@@ -109,7 +109,7 @@ impl GlobalState {
             Handle { handle, receiver }
         };
 
-        let analysis_host = AnalysisHost::new(config.lru_capacity);
+        let analysis_host = AnalysisHost::new(config.lru_capacity());
         let (flycheck_sender, flycheck_receiver) = unbounded();
         GlobalState {
             sender,
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 071b34cda5a..33661325a4d 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -9,9 +9,9 @@ use std::{
 };
 
 use ide::{
-    AssistConfig, CompletionResolveCapability, FileId, FilePosition, FileRange, HoverAction,
-    HoverGotoTypeData, LineIndex, NavigationTarget, Query, RangeInfo, Runnable, RunnableKind,
-    SearchScope, SourceChange, SymbolKind, TextEdit,
+    CompletionResolveCapability, FileId, FilePosition, FileRange, HoverAction, HoverGotoTypeData,
+    LineIndex, NavigationTarget, Query, RangeInfo, Runnable, RunnableKind, SearchScope,
+    SourceChange, SymbolKind, TextEdit,
 };
 use itertools::Itertools;
 use lsp_server::ErrorCode;
@@ -548,7 +548,7 @@ pub(crate) fn handle_runnables(
     }
 
     // Add `cargo check` and `cargo test` for all targets of the whole package
-    let config = &snap.config.runnables;
+    let config = snap.config.runnables();
     match cargo_spec {
         Some(spec) => {
             for &cmd in ["check", "test"].iter() {
@@ -579,9 +579,9 @@ pub(crate) fn handle_runnables(
                 kind: lsp_ext::RunnableKind::Cargo,
                 args: lsp_ext::CargoRunnable {
                     workspace_root: None,
-                    override_cargo: config.override_cargo.clone(),
+                    override_cargo: config.override_cargo,
                     cargo_args: vec!["check".to_string(), "--workspace".to_string()],
-                    cargo_extra_args: config.cargo_extra_args.clone(),
+                    cargo_extra_args: config.cargo_extra_args,
                     executable_args: Vec::new(),
                     expect_test: None,
                 },
@@ -620,7 +620,8 @@ pub(crate) fn handle_completion(
         return Ok(None);
     }
 
-    let items = match snap.analysis.completions(&snap.config.completion, position)? {
+    let completion_config = &snap.config.completion();
+    let items = match snap.analysis.completions(completion_config, position)? {
         None => return Ok(None),
         Some(items) => items,
     };
@@ -633,7 +634,7 @@ pub(crate) fn handle_completion(
             let mut new_completion_items =
                 to_proto::completion_item(&line_index, line_endings, item.clone());
 
-            if snap.config.completion.resolve_additional_edits_lazily() {
+            if completion_config.resolve_additional_edits_lazily() {
                 for new_item in &mut new_completion_items {
                     let _ = fill_resolve_data(&mut new_item.data, &item, &text_document_position)
                         .take();
@@ -663,9 +664,8 @@ pub(crate) fn handle_completion_resolve(
     }
 
     // FIXME resolve the other capabilities also?
-    if !snap
-        .config
-        .completion
+    let completion_config = &snap.config.completion();
+    if !completion_config
         .active_resolve_capabilities
         .contains(&CompletionResolveCapability::AdditionalTextEdits)
     {
@@ -690,7 +690,7 @@ pub(crate) fn handle_completion_resolve(
     let additional_edits = snap
         .analysis
         .resolve_completion_edits(
-            &snap.config.completion,
+            &completion_config,
             FilePosition { file_id, offset },
             &resolve_data.full_import_path,
             resolve_data.imported_name,
@@ -746,7 +746,7 @@ pub(crate) fn handle_signature_help(
         Some(it) => it,
         None => return Ok(None),
     };
-    let concise = !snap.config.call_info_full;
+    let concise = !snap.config.call_info_full();
     let res =
         to_proto::signature_help(call_info, concise, snap.config.signature_help_label_offsets());
     Ok(Some(res))
@@ -758,14 +758,12 @@ pub(crate) fn handle_hover(
 ) -> Result<Option<lsp_ext::Hover>> {
     let _p = profile::span("handle_hover");
     let position = from_proto::file_position(&snap, params.text_document_position_params)?;
-    let info = match snap.analysis.hover(
-        position,
-        snap.config.hover.links_in_hover,
-        snap.config.hover.markdown,
-    )? {
-        None => return Ok(None),
-        Some(info) => info,
-    };
+    let hover_config = snap.config.hover();
+    let info =
+        match snap.analysis.hover(position, hover_config.links_in_hover, hover_config.markdown)? {
+            None => return Ok(None),
+            Some(info) => info,
+        };
     let line_index = snap.analysis.file_line_index(position.file_id)?;
     let range = to_proto::range(&line_index, info.range);
     let hover = lsp_ext::Hover {
@@ -851,7 +849,7 @@ pub(crate) fn handle_formatting(
     let file_line_index = snap.analysis.file_line_index(file_id)?;
     let file_line_endings = snap.file_line_endings(file_id);
 
-    let mut rustfmt = match &snap.config.rustfmt {
+    let mut rustfmt = match snap.config.rustfmt() {
         RustfmtConfig::Rustfmt { extra_args } => {
             let mut cmd = process::Command::new(toolchain::rustfmt());
             cmd.args(extra_args);
@@ -947,14 +945,12 @@ pub(crate) fn handle_code_action(
     let range = from_proto::text_range(&line_index, params.range);
     let frange = FileRange { file_id, range };
 
-    let assists_config = AssistConfig {
-        allowed: params
-            .clone()
-            .context
-            .only
-            .map(|it| it.into_iter().filter_map(from_proto::assist_kind).collect()),
-        ..snap.config.assist
-    };
+    let mut assists_config = snap.config.assist();
+    assists_config.allowed = params
+        .clone()
+        .context
+        .only
+        .map(|it| it.into_iter().filter_map(from_proto::assist_kind).collect());
 
     let mut res: Vec<lsp_ext::CodeAction> = Vec::new();
 
@@ -989,7 +985,7 @@ fn add_quick_fixes(
     line_index: &Arc<LineIndex>,
     acc: &mut Vec<lsp_ext::CodeAction>,
 ) -> Result<()> {
-    let diagnostics = snap.analysis.diagnostics(&snap.config.diagnostics, frange.file_id)?;
+    let diagnostics = snap.analysis.diagnostics(&snap.config.diagnostics(), frange.file_id)?;
 
     for fix in diagnostics
         .into_iter()
@@ -1018,7 +1014,7 @@ fn add_quick_fixes(
 }
 
 pub(crate) fn handle_code_action_resolve(
-    mut snap: GlobalStateSnapshot,
+    snap: GlobalStateSnapshot,
     mut code_action: lsp_ext::CodeAction,
 ) -> Result<lsp_ext::CodeAction> {
     let _p = profile::span("handle_code_action_resolve");
@@ -1032,13 +1028,14 @@ pub(crate) fn handle_code_action_resolve(
     let range = from_proto::text_range(&line_index, params.code_action_params.range);
     let frange = FileRange { file_id, range };
 
-    snap.config.assist.allowed = params
+    let mut assists_config = snap.config.assist();
+    assists_config.allowed = params
         .code_action_params
         .context
         .only
         .map(|it| it.into_iter().filter_map(from_proto::assist_kind).collect());
 
-    let assists = snap.analysis.assists(&snap.config.assist, true, frange)?;
+    let assists = snap.analysis.assists(&assists_config, true, frange)?;
     let (id, index) = split_once(&params.id, ':').unwrap();
     let index = index.parse::<usize>().unwrap();
     let assist = &assists[index];
@@ -1055,7 +1052,8 @@ pub(crate) fn handle_code_lens(
     let _p = profile::span("handle_code_lens");
     let mut lenses: Vec<CodeLens> = Default::default();
 
-    if snap.config.lens.none() {
+    let lens_config = snap.config.lens();
+    if lens_config.none() {
         // early return before any db query!
         return Ok(Some(lenses));
     }
@@ -1064,7 +1062,7 @@ pub(crate) fn handle_code_lens(
     let line_index = snap.analysis.file_line_index(file_id)?;
     let cargo_spec = CargoTargetSpec::for_file(&snap, file_id)?;
 
-    if snap.config.lens.runnable() {
+    if lens_config.runnable() {
         // Gather runnables
         for runnable in snap.analysis.runnables(file_id)? {
             if should_skip_target(&runnable, cargo_spec.as_ref()) {
@@ -1074,7 +1072,7 @@ pub(crate) fn handle_code_lens(
             let action = runnable.action();
             let range = to_proto::range(&line_index, runnable.nav.full_range);
             let r = to_proto::runnable(&snap, file_id, runnable)?;
-            if snap.config.lens.run {
+            if lens_config.run {
                 let lens = CodeLens {
                     range,
                     command: Some(run_single_command(&r, action.run_title)),
@@ -1083,7 +1081,7 @@ pub(crate) fn handle_code_lens(
                 lenses.push(lens);
             }
 
-            if action.debugee && snap.config.lens.debug {
+            if action.debugee && lens_config.debug {
                 let debug_lens =
                     CodeLens { range, command: Some(debug_single_command(&r)), data: None };
                 lenses.push(debug_lens);
@@ -1091,7 +1089,7 @@ pub(crate) fn handle_code_lens(
         }
     }
 
-    if snap.config.lens.implementations {
+    if lens_config.implementations {
         // Handle impls
         lenses.extend(
             snap.analysis
@@ -1126,7 +1124,7 @@ pub(crate) fn handle_code_lens(
         );
     }
 
-    if snap.config.lens.references() {
+    if lens_config.references() {
         lenses.extend(snap.analysis.find_all_methods(file_id)?.into_iter().map(|it| {
             let range = to_proto::range(&line_index, it.range);
             let position = to_proto::position(&line_index, it.range.start());
@@ -1272,7 +1270,7 @@ pub(crate) fn publish_diagnostics(
 
     let diagnostics: Vec<Diagnostic> = snap
         .analysis
-        .diagnostics(&snap.config.diagnostics, file_id)?
+        .diagnostics(&snap.config.diagnostics(), file_id)?
         .into_iter()
         .map(|d| Diagnostic {
             range: to_proto::range(&line_index, d.range),
@@ -1305,7 +1303,7 @@ pub(crate) fn handle_inlay_hints(
     let line_index = snap.analysis.file_line_index(file_id)?;
     Ok(snap
         .analysis
-        .inlay_hints(file_id, &snap.config.inlay_hints)?
+        .inlay_hints(file_id, &snap.config.inlay_hints())?
         .into_iter()
         .map(|it| to_proto::inlay_hint(&line_index, it))
         .collect())
@@ -1575,7 +1573,7 @@ fn show_impl_command_link(
     snap: &GlobalStateSnapshot,
     position: &FilePosition,
 ) -> Option<lsp_ext::CommandLinkGroup> {
-    if snap.config.hover.implementations {
+    if snap.config.hover().implementations {
         if let Some(nav_data) = snap.analysis.goto_implementation(*position).unwrap_or(None) {
             let uri = to_proto::url(snap, position.file_id);
             let line_index = snap.analysis.file_line_index(position.file_id).ok()?;
@@ -1603,7 +1601,8 @@ fn runnable_action_links(
     runnable: Runnable,
 ) -> Option<lsp_ext::CommandLinkGroup> {
     let cargo_spec = CargoTargetSpec::for_file(&snap, file_id).ok()?;
-    if !snap.config.hover.runnable() || should_skip_target(&runnable, cargo_spec.as_ref()) {
+    let hover_config = snap.config.hover();
+    if !hover_config.runnable() || should_skip_target(&runnable, cargo_spec.as_ref()) {
         return None;
     }
 
@@ -1611,12 +1610,12 @@ fn runnable_action_links(
     to_proto::runnable(snap, file_id, runnable).ok().map(|r| {
         let mut group = lsp_ext::CommandLinkGroup::default();
 
-        if snap.config.hover.run {
+        if hover_config.run {
             let run_command = run_single_command(&r, action.run_title);
             group.commands.push(to_command_link(run_command, r.label.clone()));
         }
 
-        if snap.config.hover.debug {
+        if hover_config.debug {
             let dbg_command = debug_single_command(&r);
             group.commands.push(to_command_link(dbg_command, r.label));
         }
@@ -1629,7 +1628,7 @@ fn goto_type_action_links(
     snap: &GlobalStateSnapshot,
     nav_targets: &[HoverGotoTypeData],
 ) -> Option<lsp_ext::CommandLinkGroup> {
-    if !snap.config.hover.goto_type_def || nav_targets.is_empty() {
+    if !snap.config.hover().goto_type_def || nav_targets.is_empty() {
         return None;
     }
 
@@ -1650,7 +1649,7 @@ fn prepare_hover_actions(
     file_id: FileId,
     actions: &[HoverAction],
 ) -> Vec<lsp_ext::CommandLinkGroup> {
-    if snap.config.hover.none() || !snap.config.hover_actions() {
+    if snap.config.hover().none() || !snap.config.hover_actions() {
         return Vec::new();
     }
 
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index 8eca79f7ee4..53f9546b869 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -99,7 +99,8 @@ impl fmt::Debug for Event {
 
 impl GlobalState {
     fn run(mut self, inbox: Receiver<lsp_server::Message>) -> Result<()> {
-        if self.config.linked_projects.is_empty() && self.config.notifications.cargo_toml_not_found
+        if self.config.linked_projects().is_empty()
+            && self.config.notifications().cargo_toml_not_found
         {
             self.show_message(
                 lsp_types::MessageType::Error,
@@ -296,7 +297,7 @@ impl GlobalState {
                         flycheck::Message::AddDiagnostic { workspace_root, diagnostic } => {
                             let diagnostics =
                                 crate::diagnostics::to_proto::map_rust_diagnostic_to_lsp(
-                                    &self.config.diagnostics_map,
+                                    &self.config.diagnostics_map(),
                                     &diagnostic,
                                     &workspace_root,
                                 );
@@ -365,13 +366,13 @@ impl GlobalState {
             self.update_file_notifications_on_threadpool();
 
             // Refresh semantic tokens if the client supports it.
-            if self.config.semantic_tokens_refresh {
+            if self.config.semantic_tokens_refresh() {
                 self.semantic_tokens_cache.lock().clear();
                 self.send_request::<lsp_types::request::SemanticTokensRefesh>((), |_, _| ());
             }
 
             // Refresh code lens if the client supports it.
-            if self.config.code_lens_refresh {
+            if self.config.code_lens_refresh() {
                 self.send_request::<lsp_types::request::CodeLensRefresh>((), |_, _| ());
             }
         }
@@ -658,7 +659,7 @@ impl GlobalState {
             .collect::<Vec<_>>();
 
         log::trace!("updating notifications for {:?}", subscriptions);
-        if self.config.publish_diagnostics {
+        if self.config.publish_diagnostics() {
             let snapshot = self.snapshot();
             self.task_pool.handle.spawn(move || {
                 let diagnostics = subscriptions
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index ce5cedeb347..51c24e966d6 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -19,12 +19,12 @@ impl GlobalState {
     pub(crate) fn update_configuration(&mut self, config: Config) {
         let _p = profile::span("GlobalState::update_configuration");
         let old_config = mem::replace(&mut self.config, config);
-        if self.config.lru_capacity != old_config.lru_capacity {
-            self.analysis_host.update_lru_capacity(old_config.lru_capacity);
+        if self.config.lru_capacity() != old_config.lru_capacity() {
+            self.analysis_host.update_lru_capacity(self.config.lru_capacity());
         }
-        if self.config.linked_projects != old_config.linked_projects {
+        if self.config.linked_projects() != old_config.linked_projects() {
             self.fetch_workspaces()
-        } else if self.config.flycheck != old_config.flycheck {
+        } else if self.config.flycheck() != old_config.flycheck() {
             self.reload_flycheck();
         }
     }
@@ -36,7 +36,7 @@ impl GlobalState {
             Status::Loading | Status::NeedsReload => return,
             Status::Ready | Status::Invalid => (),
         }
-        if self.config.cargo_autoreload {
+        if self.config.cargo_autoreload() {
             self.fetch_workspaces();
         } else {
             self.transition(Status::NeedsReload);
@@ -94,8 +94,8 @@ impl GlobalState {
     pub(crate) fn fetch_workspaces(&mut self) {
         log::info!("will fetch workspaces");
         self.task_pool.handle.spawn({
-            let linked_projects = self.config.linked_projects.clone();
-            let cargo_config = self.config.cargo.clone();
+            let linked_projects = self.config.linked_projects();
+            let cargo_config = self.config.cargo();
             move || {
                 let workspaces = linked_projects
                     .iter()
@@ -143,7 +143,7 @@ impl GlobalState {
             return;
         }
 
-        if let FilesWatcher::Client = self.config.files.watcher {
+        if let FilesWatcher::Client = self.config.files().watcher {
             let registration_options = lsp_types::DidChangeWatchedFilesRegistrationOptions {
                 watchers: workspaces
                     .iter()
@@ -170,9 +170,9 @@ impl GlobalState {
 
         let project_folders = ProjectFolders::new(&workspaces);
 
-        self.proc_macro_client = match &self.config.proc_macro_srv {
+        self.proc_macro_client = match self.config.proc_macro_srv() {
             None => None,
-            Some((path, args)) => match ProcMacroClient::extern_process(path.into(), args) {
+            Some((path, args)) => match ProcMacroClient::extern_process(path.clone(), args) {
                 Ok(it) => Some(it),
                 Err(err) => {
                     log::error!(
@@ -185,7 +185,7 @@ impl GlobalState {
             },
         };
 
-        let watch = match self.config.files.watcher {
+        let watch = match self.config.files().watcher {
             FilesWatcher::Client => vec![],
             FilesWatcher::Notify => project_folders.watch,
         };
@@ -211,7 +211,7 @@ impl GlobalState {
             };
             for ws in workspaces.iter() {
                 crate_graph.extend(ws.to_crate_graph(
-                    self.config.cargo.target.as_deref(),
+                    self.config.cargo().target.as_deref(),
                     self.proc_macro_client.as_ref(),
                     &mut load,
                 ));
@@ -231,7 +231,7 @@ impl GlobalState {
     }
 
     fn reload_flycheck(&mut self) {
-        let config = match self.config.flycheck.clone() {
+        let config = match self.config.flycheck() {
             Some(it) => it,
             None => {
                 self.flycheck = Vec::new();
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index e0413ec06e1..a5f7e3af726 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -818,7 +818,7 @@ pub(crate) fn runnable(
     file_id: FileId,
     runnable: Runnable,
 ) -> Result<lsp_ext::Runnable> {
-    let config = &snap.config.runnables;
+    let config = snap.config.runnables();
     let spec = CargoTargetSpec::for_file(snap, file_id)?;
     let workspace_root = spec.as_ref().map(|it| it.workspace_root.clone());
     let target = spec.as_ref().map(|s| s.target.clone());
@@ -833,9 +833,9 @@ pub(crate) fn runnable(
         kind: lsp_ext::RunnableKind::Cargo,
         args: lsp_ext::CargoRunnable {
             workspace_root: workspace_root.map(|it| it.into()),
-            override_cargo: config.override_cargo.clone(),
+            override_cargo: config.override_cargo,
             cargo_args,
-            cargo_extra_args: config.cargo_extra_args.clone(),
+            cargo_extra_args: config.cargo_extra_args,
             executable_args,
             expect_test: None,
         },
diff --git a/crates/rust-analyzer/tests/rust-analyzer/main.rs b/crates/rust-analyzer/tests/rust-analyzer/main.rs
index 84db0856d48..38d09f3ee36 100644
--- a/crates/rust-analyzer/tests/rust-analyzer/main.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/main.rs
@@ -13,6 +13,7 @@ mod support;
 
 use std::{collections::HashMap, path::PathBuf, time::Instant};
 
+use expect_test::expect;
 use lsp_types::{
     notification::DidOpenTextDocument,
     request::{CodeActionRequest, Completion, Formatting, GotoTypeDefinition, HoverRequest},
@@ -569,9 +570,9 @@ fn main() {
 }
 "###,
     )
-    .with_config(|config| {
-        config.cargo.load_out_dirs_from_check = true;
-    })
+    .with_config(serde_json::json!({
+        "cargo": { "loadOutDirsFromCheck": true }
+    }))
     .server()
     .wait_until_workspace_is_loaded();
 
@@ -712,12 +713,13 @@ pub fn foo(_input: TokenStream) -> TokenStream {
 
 "###,
     )
-    .with_config(|config| {
-        let macro_srv_path = PathBuf::from(env!("CARGO_BIN_EXE_rust-analyzer"));
-
-        config.cargo.load_out_dirs_from_check = true;
-        config.proc_macro_srv = Some((macro_srv_path, vec!["proc-macro".into()]));
-    })
+    .with_config(serde_json::json!({
+        "cargo": { "loadOutDirsFromCheck": true },
+        "procMacro": {
+            "enable": true,
+            "server": PathBuf::from(env!("CARGO_BIN_EXE_rust-analyzer")),
+        }
+    }))
     .root("foo")
     .root("bar")
     .server()
@@ -731,5 +733,5 @@ pub fn foo(_input: TokenStream) -> TokenStream {
         work_done_progress_params: Default::default(),
     });
     let value = res.get("contents").unwrap().get("value").unwrap().to_string();
-    assert_eq!(value, r#""\n```rust\nfoo::Bar\n```\n\n```rust\nfn bar()\n```""#)
+    expect![[r#""\n```rust\nfoo::Bar\n```\n\n```rust\nfn bar()\n```""#]].assert_eq(&value);
 }
diff --git a/crates/rust-analyzer/tests/rust-analyzer/support.rs b/crates/rust-analyzer/tests/rust-analyzer/support.rs
index aac7dbccec0..2658ee1859c 100644
--- a/crates/rust-analyzer/tests/rust-analyzer/support.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/support.rs
@@ -12,11 +12,8 @@ use lsp_types::{
     notification::Exit, request::Shutdown, TextDocumentIdentifier, Url, WorkDoneProgress,
 };
 use lsp_types::{ProgressParams, ProgressParamsValue};
-use project_model::{CargoConfig, ProjectManifest};
-use rust_analyzer::{
-    config::{Config, FilesConfig, FilesWatcher, LinkedProject},
-    main_loop,
-};
+use project_model::ProjectManifest;
+use rust_analyzer::{config::Config, main_loop};
 use serde::Serialize;
 use serde_json::{to_string_pretty, Value};
 use test_utils::{find_mismatch, Fixture};
@@ -29,12 +26,18 @@ pub(crate) struct Project<'a> {
     with_sysroot: bool,
     tmp_dir: Option<TestDir>,
     roots: Vec<PathBuf>,
-    config: Option<Box<dyn Fn(&mut Config)>>,
+    config: serde_json::Value,
 }
 
 impl<'a> Project<'a> {
     pub(crate) fn with_fixture(fixture: &str) -> Project {
-        Project { fixture, tmp_dir: None, roots: vec![], with_sysroot: false, config: None }
+        Project {
+            fixture,
+            tmp_dir: None,
+            roots: vec![],
+            with_sysroot: false,
+            config: serde_json::Value::Null,
+        }
     }
 
     pub(crate) fn tmp_dir(mut self, tmp_dir: TestDir) -> Project<'a> {
@@ -52,8 +55,8 @@ impl<'a> Project<'a> {
         self
     }
 
-    pub(crate) fn with_config(mut self, config: impl Fn(&mut Config) + 'static) -> Project<'a> {
-        self.config = Some(Box::new(config));
+    pub(crate) fn with_config(mut self, config: serde_json::Value) -> Project<'a> {
+        self.config = config;
         self
     }
 
@@ -77,14 +80,14 @@ impl<'a> Project<'a> {
         if roots.is_empty() {
             roots.push(tmp_dir_path.clone());
         }
-        let linked_projects = roots
+        let discovered_projects = roots
             .into_iter()
             .map(|it| ProjectManifest::discover_single(&it).unwrap())
-            .map(LinkedProject::from)
             .collect::<Vec<_>>();
 
-        let mut config = Config {
-            caps: lsp_types::ClientCapabilities {
+        let mut config = Config::new(
+            tmp_dir_path,
+            lsp_types::ClientCapabilities {
                 text_document: Some(lsp_types::TextDocumentClientCapabilities {
                     definition: Some(lsp_types::GotoCapability {
                         link_support: Some(true),
@@ -96,6 +99,10 @@ impl<'a> Project<'a> {
                         ),
                         ..Default::default()
                     }),
+                    hover: Some(lsp_types::HoverClientCapabilities {
+                        content_format: Some(vec![lsp_types::MarkupKind::Markdown]),
+                        ..Default::default()
+                    }),
                     ..Default::default()
                 }),
                 window: Some(lsp_types::WindowClientCapabilities {
@@ -104,14 +111,9 @@ impl<'a> Project<'a> {
                 }),
                 ..Default::default()
             },
-            cargo: CargoConfig { no_sysroot: !self.with_sysroot, ..Default::default() },
-            linked_projects,
-            files: FilesConfig { watcher: FilesWatcher::Client, exclude: Vec::new() },
-            ..Config::new(tmp_dir_path)
-        };
-        if let Some(f) = &self.config {
-            f(&mut config)
-        }
+        );
+        config.discovered_projects = Some(discovered_projects);
+        config.update(self.config);
 
         Server::new(tmp_dir, config)
     }
diff --git a/docs/user/generated_config.adoc b/docs/user/generated_config.adoc
index e109f2b0166..e45ea5c3510 100644
--- a/docs/user/generated_config.adoc
+++ b/docs/user/generated_config.adoc
@@ -94,6 +94,8 @@
  Whether to show `can't find Cargo.toml` error message.
 [[rust-analyzer.procMacro.enable]]rust-analyzer.procMacro.enable (default: `false`)::
  Enable Proc macro support, `#rust-analyzer.cargo.loadOutDirsFromCheck#` must be  enabled.
+[[rust-analyzer.procMacro.server]]rust-analyzer.procMacro.server (default: `null`)::
+ Internal config, path to proc-macro server executable (typically,  this is rust-analyzer itself, but we override this in tests).
 [[rust-analyzer.runnables.overrideCargo]]rust-analyzer.runnables.overrideCargo (default: `null`)::
  Command to be executed instead of 'cargo' for runnables.
 [[rust-analyzer.runnables.cargoExtraArgs]]rust-analyzer.runnables.cargoExtraArgs (default: `[]`)::
diff --git a/editors/code/package.json b/editors/code/package.json
index 63db8706476..ea7f0990c0d 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -663,6 +663,14 @@
                     "default": false,
                     "type": "boolean"
                 },
+                "rust-analyzer.procMacro.server": {
+                    "markdownDescription": "Internal config, path to proc-macro server executable (typically, this is rust-analyzer itself, but we override this in tests).",
+                    "default": null,
+                    "type": [
+                        "null",
+                        "string"
+                    ]
+                },
                 "rust-analyzer.runnables.overrideCargo": {
                     "markdownDescription": "Command to be executed instead of 'cargo' for runnables.",
                     "default": null,