Merge #2716

2716: Allow assists with multiple selectable actions r=SomeoneToIgnore a=SomeoneToIgnore

This PR prepares an infra for https://github.com/rust-analyzer/rust-analyzer/issues/2180 task by adding a possibility to specify multiple actions in one assist as multiple edit parameters to the `applySourceChange` command.

When this is done, the command opens a selection dialog, allowing the user to pick the edit to be applied.

I have no working example to test in this PR, but here's a demo of an auto import feature (a separate PR coming later for that one) using this functionality:

![out](https://user-images.githubusercontent.com/2690773/71633614-f8ea4d80-2c1d-11ea-9b15-0e13611a7aa4.gif)

The PR is not that massive as it may seem: all the assist files' changes are very generic and similar.

Co-authored-by: Kirill Bulatov <[email protected]>

2 files changed, 21 insertions, 8 deletions

diff --git a/crates/ra_lsp_server/Cargo.toml b/crates/ra_lsp_server/Cargo.toml
index c08e67b8e..579158780 100644
--- a/crates/ra_lsp_server/Cargo.toml
+++ b/crates/ra_lsp_server/Cargo.toml
@@ -28,6 +28,7 @@ ra_prof = { path = "../ra_prof" }
 ra_vfs_glob = { path = "../ra_vfs_glob" }
 env_logger = { version = "0.7.1", default-features = false, features = ["humantime"] }
 ra_cargo_watch = { path = "../ra_cargo_watch" }
+either = "1.5"
 
 [dev-dependencies]
 tempfile = "3"
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index f2db575ea..9e9964880 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -3,6 +3,7 @@
 
 use std::{fmt::Write as _, io::Write as _};
 
+use either::Either;
 use lsp_server::ErrorCode;
 use lsp_types::{
     CallHierarchyIncomingCall, CallHierarchyIncomingCallsParams, CallHierarchyItem,
@@ -644,7 +645,6 @@ pub fn handle_code_action(
     let line_index = world.analysis().file_line_index(file_id)?;
     let range = params.range.conv_with(&line_index);
 
-    let assists = world.analysis().assists(FileRange { file_id, range })?.into_iter();
     let diagnostics = world.analysis().diagnostics(file_id)?;
     let mut res = CodeActionResponse::default();
 
@@ -697,15 +697,27 @@ pub fn handle_code_action(
         res.push(action.into());
     }
 
-    for assist in assists {
-        let title = assist.change.label.clone();
-        let edit = assist.change.try_conv_with(&world)?;
+    for assist in world.analysis().assists(FileRange { file_id, range })?.into_iter() {
+        let title = assist.label.clone();
 
-        let command = Command {
-            title,
-            command: "rust-analyzer.applySourceChange".to_string(),
-            arguments: Some(vec![to_value(edit).unwrap()]),
+        let command = match assist.change_data {
+            Either::Left(change) => Command {
+                title,
+                command: "rust-analyzer.applySourceChange".to_string(),
+                arguments: Some(vec![to_value(change.try_conv_with(&world)?)?]),
+            },
+            Either::Right(changes) => Command {
+                title,
+                command: "rust-analyzer.selectAndApplySourceChange".to_string(),
+                arguments: Some(vec![to_value(
+                    changes
+                        .into_iter()
+                        .map(|change| change.try_conv_with(&world))
+                        .collect::<Result<Vec<_>>>()?,
+                )?]),
+            },
         };
+
         let action = CodeAction {
             title: command.title.clone(),
             kind: match assist.id {