Auto merge of #14307 - davidbarsky:davidbarsky/add-cargo-style-project-discovery-for-buck-and-bazel-sickos, r=Veykril

Add Cargo-style project discovery for Buck and Bazel Users

This feature requires the user to add a command that generates a `rust-project.json` from a set of files. Project discovery can be invoked in two ways:

1. At extension activation time, which includes the generated `rust-project.json` as part of the linkedProjects argument in `InitializeParams`.
2. Through a new command titled "rust-analyzer: Add current file to workspace", which makes use of a new, rust-analyzer-specific LSP request that adds the workspace without erasing any existing workspaces. Note that there is no mechanism to _remove_ workspaces other than "quit the rust-analyzer server".

Few notes:
-  I think that the command-running functionality _could_ merit being placed into its own extension (and expose it via extension contribution points) to provide build-system idiomatic progress reporting and status handling, but I haven't (yet) made an extension that does this nor does Buck expose this sort of functionality.
-  This approach would _just work_ for Bazel. I'll try and get the tool that's responsible for Buck integration open-sourced soon.
- On the testing side of things, I've used this in around my employer's Buck-powered monorepo and it's a nice experience. That being said, I can't think of an open-source repository where this can be tested in public, so you might need to trust me on this one.

I'd love to get feedback on:
- Naming of LSP extensions/new commands. I'm not too pleased with how "rust-analyzer: Add current file to workspace" is named, in that it's creating a _new_ workspace. I think that this command being added should be gated on `rust-analyzer.discoverProjectCommand` on being set, so I can add this in sequent commits.
- My Typescript. It's not particularly good.
- Suggestions on handling folders with _both_ Cargo and non-Cargo build systems and if I make activation a bit better.

(I previously tried to add this functionality entirely within rust-analyzer-the-LSP server itself, but matklad was right—an extension side approach is much, much easier.)

1 files changed, 17 insertions, 0 deletions

diff --git a/editors/code/src/util.ts b/editors/code/src/util.ts
index d93b9caeb16..922fbcbcf35 100644
--- a/editors/code/src/util.ts
+++ b/editors/code/src/util.ts
@@ -150,9 +150,11 @@ export function memoizeAsync<Ret, TThis, Param extends string>(
 
 /** Awaitable wrapper around `child_process.exec` */
 export function execute(command: string, options: ExecOptions): Promise<string> {
+    log.info(`running command: ${command}`);
     return new Promise((resolve, reject) => {
         exec(command, options, (err, stdout, stderr) => {
             if (err) {
+                log.error(err);
                 reject(err);
                 return;
             }
@@ -167,6 +169,21 @@ export function execute(command: string, options: ExecOptions): Promise<string>
     });
 }
 
+export function executeDiscoverProject(command: string, options: ExecOptions): Promise<string> {
+    log.info(`running command: ${command}`);
+    return new Promise((resolve, reject) => {
+        exec(command, options, (err, stdout, _) => {
+            if (err) {
+                log.error(err);
+                reject(err);
+                return;
+            }
+
+            resolve(stdout.trimEnd());
+        });
+    });
+}
+
 export class LazyOutputChannel implements vscode.OutputChannel {
     constructor(name: string) {
         this.name = name;