Merge #4329

4329: Look for `cargo`, `rustc`, and `rustup` in standard installation path r=matklad a=cdisselkoen

Discussed in #3118.  This is approximately a 90% fix for the issue described there.

This PR creates a new crate `ra_env` with a function `get_path_for_executable()`; see docs there.  `get_path_for_executable()` improves and generalizes the function `cargo_binary()` which was previously duplicated in the `ra_project_model` and `ra_flycheck` crates.  (Both of those crates now depend on the new `ra_env` crate.)  The new function checks (e.g.) `$CARGO` and `$PATH`, but also falls back on `~/.cargo/bin` manually before erroring out.  This should allow most users to not have to worry about setting the `$CARGO` or `$PATH` variables for VSCode, which can be difficult e.g. on macOS as discussed in #3118.

I've attempted to replace all calls to `cargo`, `rustc`, and `rustup` in rust-analyzer with appropriate invocations of `get_path_for_executable()`; I don't think I've missed any in Rust code, but there is at least one invocation in TypeScript code which I haven't fixed.  (I'm not sure whether it's affected by the same problem or not.) https://github.com/rust-analyzer/rust-analyzer/blob/a4778ddb7a00f552a8e653bbf56ae9fd69cfe1d3/editors/code/src/cargo.ts#L79

I'm sure this PR could be improved a bunch, so I'm happy to take feedback/suggestions on how to solve this problem better, or just bikeshedding variable/function/crate names etc.

cc @Veetaha 

Fixes #3118.

Co-authored-by: Craig Disselkoen <[email protected]>
Co-authored-by: veetaha <[email protected]>

1 files changed, 19 insertions, 0 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 264b9b7fb..36cff6402 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -465,6 +465,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "home"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2456aef2e6b6a9784192ae780c0f15bc57df0e918585282325e8c8ac27737654"
+dependencies = [
+ "winapi 0.3.8",
+]
+
+[[package]]
 name = "idna"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -949,6 +958,14 @@ dependencies = [
 ]
 
 [[package]]
+name = "ra_env"
+version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "home",
+]
+
+[[package]]
 name = "ra_flycheck"
 version = "0.1.0"
 dependencies = [
@@ -958,6 +975,7 @@ dependencies = [
  "jod-thread",
  "log",
  "lsp-types",
+ "ra_env",
  "serde_json",
 ]
 
@@ -1162,6 +1180,7 @@ dependencies = [
  "ra_arena",
  "ra_cfg",
  "ra_db",
+ "ra_env",
  "ra_proc_macro",
  "rustc-hash",
  "serde",