Parameter inlay hint separate from variable type inlay? #2876

Add setting to allow enabling either type inlay hints or parameter
inlay hints or both. Group the the max inlay hint length option
into the object.

- Add a new type for the inlayHint options.
- Add tests to ensure the inlays don't happen on the server side

13 files changed, 155 insertions, 34 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 330bdd1cb..6173741b1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1028,6 +1028,7 @@ dependencies = [
  "ra_hir",
  "ra_ide_db",
  "ra_prof",
+ "ra_project_model",
  "ra_syntax",
  "ra_text_edit",
  "rand",
diff --git a/crates/ra_ide/Cargo.toml b/crates/ra_ide/Cargo.toml
index 7235c944c..486832529 100644
--- a/crates/ra_ide/Cargo.toml
+++ b/crates/ra_ide/Cargo.toml
@@ -21,6 +21,7 @@ rustc-hash = "1.1.0"
 rand = { version = "0.7.3", features = ["small_rng"] }
 
 ra_syntax = { path = "../ra_syntax" }
+ra_project_model = { path = "../ra_project_model" }
 ra_text_edit = { path = "../ra_text_edit" }
 ra_db = { path = "../ra_db" }
 ra_ide_db = { path = "../ra_ide_db" }
diff --git a/crates/ra_ide/src/inlay_hints.rs b/crates/ra_ide/src/inlay_hints.rs
index cf0cbdbd0..0f1c13c14 100644
--- a/crates/ra_ide/src/inlay_hints.rs
+++ b/crates/ra_ide/src/inlay_hints.rs
@@ -3,6 +3,7 @@
 use hir::{Adt, HirDisplay, Semantics, Type};
 use ra_ide_db::RootDatabase;
 use ra_prof::profile;
+use ra_project_model::{InlayHintDisplayType, InlayHintOptions};
 use ra_syntax::{
     ast::{self, ArgListOwner, AstNode, TypeAscriptionOwner},
     match_ast, SmolStr, TextRange,
@@ -26,7 +27,7 @@ pub struct InlayHint {
 pub(crate) fn inlay_hints(
     db: &RootDatabase,
     file_id: FileId,
-    max_inlay_hint_length: Option<usize>,
+    inlay_hint_opts: &InlayHintOptions,
 ) -> Vec<InlayHint> {
     let _p = profile("inlay_hints");
     let sema = Semantics::new(db);
@@ -36,9 +37,9 @@ pub(crate) fn inlay_hints(
     for node in file.syntax().descendants() {
         match_ast! {
             match node {
-                ast::CallExpr(it) => { get_param_name_hints(&mut res, &sema, ast::Expr::from(it)); },
-                ast::MethodCallExpr(it) => { get_param_name_hints(&mut res, &sema, ast::Expr::from(it)); },
-                ast::BindPat(it) => { get_bind_pat_hints(&mut res, &sema, max_inlay_hint_length, it); },
+                ast::CallExpr(it) => { get_param_name_hints(&mut res, &sema, inlay_hint_opts, ast::Expr::from(it)); },
+                ast::MethodCallExpr(it) => { get_param_name_hints(&mut res, &sema, inlay_hint_opts, ast::Expr::from(it)); },
+                ast::BindPat(it) => { get_bind_pat_hints(&mut res, &sema, inlay_hint_opts, it); },
                 _ => (),
             }
         }
@@ -49,8 +50,14 @@ pub(crate) fn inlay_hints(
 fn get_param_name_hints(
     acc: &mut Vec<InlayHint>,
     sema: &Semantics<RootDatabase>,
+    inlay_hint_opts: &InlayHintOptions,
     expr: ast::Expr,
 ) -> Option<()> {
+    match inlay_hint_opts.display_type {
+        InlayHintDisplayType::Off | InlayHintDisplayType::TypeHints => return None,
+        _ => {}
+    }
+
     let args = match &expr {
         ast::Expr::CallExpr(expr) => expr.arg_list()?.args(),
         ast::Expr::MethodCallExpr(expr) => expr.arg_list()?.args(),
@@ -84,9 +91,14 @@ fn get_param_name_hints(
 fn get_bind_pat_hints(
     acc: &mut Vec<InlayHint>,
     sema: &Semantics<RootDatabase>,
-    max_inlay_hint_length: Option<usize>,
+    inlay_hint_opts: &InlayHintOptions,
     pat: ast::BindPat,
 ) -> Option<()> {
+    match inlay_hint_opts.display_type {
+        InlayHintDisplayType::Off | InlayHintDisplayType::ParameterHints => return None,
+        _ => {}
+    }
+
     let ty = sema.type_of_pat(&pat.clone().into())?;
 
     if should_not_display_type_hint(sema.db, &pat, &ty) {
@@ -96,7 +108,7 @@ fn get_bind_pat_hints(
     acc.push(InlayHint {
         range: pat.syntax().text_range(),
         kind: InlayKind::TypeHint,
-        label: ty.display_truncated(sema.db, max_inlay_hint_length).to_string().into(),
+        label: ty.display_truncated(sema.db, inlay_hint_opts.max_length).to_string().into(),
     });
     Some(())
 }
@@ -205,8 +217,63 @@ mod tests {
     use insta::assert_debug_snapshot;
 
     use crate::mock_analysis::single_file;
+    use ra_project_model::{InlayHintDisplayType, InlayHintOptions};
 
     #[test]
+    fn param_hints_only() {
+        let (analysis, file_id) = single_file(
+            r#"
+            fn foo(a: i32, b: i32) -> i32 { a + b }
+            fn main() {
+                let _x = foo(4, 4);
+            }"#,
+        );
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions{ display_type: InlayHintDisplayType::ParameterHints, max_length: None}).unwrap(), @r###"
+        [
+            InlayHint {
+                range: [106; 107),
+                kind: ParameterHint,
+                label: "a",
+            },
+            InlayHint {
+                range: [109; 110),
+                kind: ParameterHint,
+                label: "b",
+            },
+        ]"###);
+    }
+
+    #[test]
+    fn hints_disabled() {
+        let (analysis, file_id) = single_file(
+            r#"
+            fn foo(a: i32, b: i32) -> i32 { a + b }
+            fn main() {
+                let _x = foo(4, 4);
+            }"#,
+        );
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions{ display_type: InlayHintDisplayType::Off, max_length: None}).unwrap(), @r###"[]"###);
+    }
+
+    #[test]
+    fn type_hints_only() {
+        let (analysis, file_id) = single_file(
+            r#"
+            fn foo(a: i32, b: i32) -> i32 { a + b }
+            fn main() {
+                let _x = foo(4, 4);
+            }"#,
+        );
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions{ display_type: InlayHintDisplayType::TypeHints, max_length: None}).unwrap(), @r###"
+        [
+            InlayHint {
+                range: [97; 99),
+                kind: TypeHint,
+                label: "i32",
+            },
+        ]"###);
+    }
+    #[test]
     fn default_generic_types_should_not_be_displayed() {
         let (analysis, file_id) = single_file(
             r#"
@@ -221,7 +288,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [69; 71),
@@ -278,7 +345,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [193; 197),
@@ -358,7 +425,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [21; 30),
@@ -422,7 +489,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [21; 30),
@@ -472,7 +539,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [188; 192),
@@ -567,7 +634,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [188; 192),
@@ -662,7 +729,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [252; 256),
@@ -734,7 +801,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, Some(8)).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(Some(8))).unwrap(), @r###"
         [
             InlayHint {
                 range: [74; 75),
@@ -822,7 +889,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, None).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(None)).unwrap(), @r###"
         [
             InlayHint {
                 range: [798; 809),
@@ -944,7 +1011,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, Some(8)).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(Some(8))).unwrap(), @r###"
         []
         "###
         );
@@ -970,7 +1037,7 @@ fn main() {
 }"#,
         );
 
-        assert_debug_snapshot!(analysis.inlay_hints(file_id, Some(8)).unwrap(), @r###"
+        assert_debug_snapshot!(analysis.inlay_hints(file_id, &InlayHintOptions::new(Some(8))).unwrap(), @r###"
         []
         "###
         );
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index 9f45003d3..8b1292a41 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -44,6 +44,7 @@ mod marks;
 #[cfg(test)]
 mod test_utils;
 
+use ra_project_model::InlayHintOptions;
 use std::sync::Arc;
 
 use ra_cfg::CfgOptions;
@@ -318,9 +319,9 @@ impl Analysis {
     pub fn inlay_hints(
         &self,
         file_id: FileId,
-        max_inlay_hint_length: Option<usize>,
+        inlay_hint_opts: &InlayHintOptions,
     ) -> Cancelable<Vec<InlayHint>> {
-        self.with_db(|db| inlay_hints::inlay_hints(db, file_id, max_inlay_hint_length))
+        self.with_db(|db| inlay_hints::inlay_hints(db, file_id, inlay_hint_opts))
     }
 
     /// Returns the set of folding ranges.
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 37845ca56..a5012c0ef 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -16,6 +16,7 @@ use anyhow::{bail, Context, Result};
 use ra_cfg::CfgOptions;
 use ra_db::{CrateGraph, CrateName, Edition, Env, FileId};
 use rustc_hash::FxHashMap;
+use serde::Deserialize;
 use serde_json::from_reader;
 
 pub use crate::{
@@ -24,6 +25,34 @@ pub use crate::{
     sysroot::Sysroot,
 };
 
+#[derive(Deserialize, Clone, Debug, PartialEq, Eq)]
+#[serde(rename_all = "lowercase")]
+pub enum InlayHintDisplayType {
+    Off,
+    TypeHints,
+    ParameterHints,
+    Full,
+}
+
+#[derive(Deserialize, Clone, Debug, PartialEq, Eq)]
+#[serde(rename_all = "camelCase", default)]
+pub struct InlayHintOptions {
+    pub display_type: InlayHintDisplayType,
+    pub max_length: Option<usize>,
+}
+
+impl InlayHintOptions {
+    pub fn new(max_length: Option<usize>) -> Self {
+        Self { display_type: InlayHintDisplayType::Full, max_length }
+    }
+}
+
+impl Default for InlayHintOptions {
+    fn default() -> Self {
+        Self { display_type: InlayHintDisplayType::Full, max_length: None }
+    }
+}
+
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub struct CargoTomlNotFoundError {
     pub searched_at: PathBuf,
diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 3314269ec..1617eab0b 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -7,6 +7,7 @@
 //! configure the server itself, feature flags are passed into analysis, and
 //! tweak things like automatic insertion of `()` in completions.
 
+use ra_project_model::InlayHintOptions;
 use rustc_hash::FxHashMap;
 
 use ra_project_model::CargoFeatures;
@@ -30,7 +31,7 @@ pub struct ServerConfig {
 
     pub lru_capacity: Option<usize>,
 
-    pub max_inlay_hint_length: Option<usize>,
+    pub inlay_hint_opts: InlayHintOptions,
 
     pub cargo_watch_enable: bool,
     pub cargo_watch_args: Vec<String>,
@@ -57,7 +58,7 @@ impl Default for ServerConfig {
             exclude_globs: Vec::new(),
             use_client_watching: false,
             lru_capacity: None,
-            max_inlay_hint_length: None,
+            inlay_hint_opts: Default::default(),
             cargo_watch_enable: true,
             cargo_watch_args: Vec::new(),
             cargo_watch_command: "check".to_string(),
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index f9de712a0..91fb66abb 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -177,7 +177,7 @@ pub fn main_loop(
                     .and_then(|it| it.folding_range.as_ref())
                     .and_then(|it| it.line_folding_only)
                     .unwrap_or(false),
-                max_inlay_hint_length: config.max_inlay_hint_length,
+                inlay_hint_opts: config.inlay_hint_opts.clone(),
                 cargo_watch: CheckOptions {
                     enable: config.cargo_watch_enable,
                     args: config.cargo_watch_args,
diff --git a/crates/rust-analyzer/src/world.rs b/crates/rust-analyzer/src/world.rs
index 1ddc3c1a5..8043a6cd3 100644
--- a/crates/rust-analyzer/src/world.rs
+++ b/crates/rust-analyzer/src/world.rs
@@ -15,7 +15,7 @@ use ra_cargo_watch::{url_from_path_with_drive_lowercasing, CheckOptions, CheckWa
 use ra_ide::{
     Analysis, AnalysisChange, AnalysisHost, CrateGraph, FileId, LibraryData, SourceRootId,
 };
-use ra_project_model::{get_rustc_cfg_options, ProjectWorkspace};
+use ra_project_model::{get_rustc_cfg_options, InlayHintOptions, ProjectWorkspace};
 use ra_vfs::{LineEndings, RootEntry, Vfs, VfsChange, VfsFile, VfsRoot, VfsTask, Watch};
 use relative_path::RelativePathBuf;
 
@@ -32,7 +32,7 @@ pub struct Options {
     pub publish_decorations: bool,
     pub supports_location_link: bool,
     pub line_folding_only: bool,
-    pub max_inlay_hint_length: Option<usize>,
+    pub inlay_hint_opts: InlayHintOptions,
     pub rustfmt_args: Vec<String>,
     pub cargo_watch: CheckOptions,
 }
diff --git a/docs/user/features.md b/docs/user/features.md
index ba4d50fa8..06bc7ded5 100644
--- a/docs/user/features.md
+++ b/docs/user/features.md
@@ -191,8 +191,8 @@ Two types of inlay hints are displayed currently:
 
 In VS Code, the following settings can be used to configure the inlay hints:
 
-* `rust-analyzer.displayInlayHints` — toggles inlay hints display on or off
-* `rust-analyzer.maxInlayHintLength` — shortens the hints if their length exceeds the value specified. If no value is specified (`null`), no shortening is applied.
+* `rust-analyzer.inlayHintOpts.displayType` configure which types of inlay hints are shown.
+* `rust-analyzer.inlayHintOpts.maxLength` — shortens the hints if their length exceeds the value specified. If no value is specified (`null`), no shortening is applied.
 
 **Note:** VS Code does not have native support for inlay hints [yet](https://github.com/microsoft/vscode/issues/16221) and the hints are implemented using decorations.
 This approach has limitations, the caret movement and bracket highlighting near the edges of the hint may be weird:
diff --git a/editors/code/package.json b/editors/code/package.json
index 512885454..6f2275062 100644
--- a/editors/code/package.json
+++ b/editors/code/package.json
@@ -307,12 +307,24 @@
                     "exclusiveMinimum": true,
                     "description": "Number of syntax trees rust-analyzer keeps in memory"
                 },
-                "rust-analyzer.displayInlayHints": {
-                    "type": "boolean",
-                    "default": true,
+                "rust-analyzer.inlayHintOpts.displayType": {
+                    "type": "string",
+                    "enum": [
+                        "off",
+                        "typeHints",
+                        "parameterHints",
+                        "full"
+                    ],
+                    "enumDescriptions": [
+                        "No type inlay hints",
+                        "Type inlays hints only",
+                        "Parameter inlays hints only",
+                        "All inlay hints types"
+                    ],
+                    "default": "full",
                     "description": "Display additional type and parameter information in the editor"
                 },
-                "rust-analyzer.maxInlayHintLength": {
+                "rust-analyzer.inlayHintOpts.maxLength": {
                     "type": [
                         "null",
                         "integer"
diff --git a/editors/code/src/client.ts b/editors/code/src/client.ts
index 540f7c9ea..ac4417c61 100644
--- a/editors/code/src/client.ts
+++ b/editors/code/src/client.ts
@@ -29,7 +29,7 @@ export async function createClient(config: Config, serverPath: string): Promise<
         initializationOptions: {
             publishDecorations: !config.highlightingSemanticTokens,
             lruCapacity: config.lruCapacity,
-            maxInlayHintLength: config.maxInlayHintLength,
+            inlayHintOpts: config.inlayHintOpts,
             cargoWatchEnable: cargoWatchOpts.enable,
             cargoWatchArgs: cargoWatchOpts.arguments,
             cargoWatchCommand: cargoWatchOpts.command,
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index b72206d3c..5acce0752 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -5,6 +5,11 @@ import { log } from "./util";
 
 const RA_LSP_DEBUG = process.env.__RA_LSP_SERVER_DEBUG;
 
+export interface InlayHintOptions {
+    displayType: string;
+    maxLength: number;
+}
+
 export interface CargoWatchOptions {
     enable: boolean;
     arguments: string[];
@@ -149,8 +154,12 @@ export class Config {
     get highlightingOn() { return this.cfg.get("highlightingOn") as boolean; }
     get rainbowHighlightingOn() { return this.cfg.get("rainbowHighlightingOn") as boolean; }
     get lruCapacity() { return this.cfg.get("lruCapacity") as null | number; }
-    get displayInlayHints() { return this.cfg.get("displayInlayHints") as boolean; }
-    get maxInlayHintLength() { return this.cfg.get("maxInlayHintLength") as number; }
+    get inlayHintOpts(): InlayHintOptions {
+        return {
+            displayType: this.cfg.get("inlayHintOpts.displayType") as string,
+            maxLength: this.cfg.get("inlayHintOpts.maxLength") as number,
+        };
+    }
     get excludeGlobs() { return this.cfg.get("excludeGlobs") as string[]; }
     get useClientWatching() { return this.cfg.get("useClientWatching") as boolean; }
     get featureFlags() { return this.cfg.get("featureFlags") as Record<string, boolean>; }
diff --git a/editors/code/src/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index e1a82e03e..8d291406d 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -10,7 +10,7 @@ export function activateInlayHints(ctx: Ctx) {
     const maybeUpdater = {
         updater: null as null | HintsUpdater,
         onConfigChange() {
-            if (!ctx.config.displayInlayHints) {
+            if (ctx.config.inlayHintOpts.displayType === 'off') {
                 return this.dispose();
             }
             if (!this.updater) this.updater = new HintsUpdater(ctx);