fix(debugger): run debug adapters on the tool search path

Debug adapters were found on the tool search path but ran with the
app's own PATH. When the login shell's PATH didn't reach the app, what an
adapter starts in turn was missing although Run found it: js-debug's
wrapper failed with "exec: node: not found", and Delve's go build with
"exec: go: executable file not found in $PATH". Adapters now get the
search path language servers get, unless the launch sets its own PATH
(a selected SDK's bin first), and adapter binaries are resolved on it.

Fixes #1690
Fixes #1707

crates/ide-dap/src/adapter.rs

@@ -196,10 +196,18 @@ fn managed_dirs(root: &Path) -> Vec<PathBuf> {
     dirs
 }
 
+/// The `PATH` an adapter runs with, unless its launch sets one: the search path language servers
+/// get, so what it starts in turn (js-debug's wrapper runs `node`, Delve runs `go build`) is
+/// found like Run finds it, even when the login shell's `PATH` didn't reach the app.
+fn adapter_path(env: &[(String, String)]) -> Option<std::ffi::OsString> {
+    let own = env.iter().any(|(k, _)| if cfg!(windows) { k.eq_ignore_ascii_case("PATH") } else { k == "PATH" });
+    (!own).then(ide_core::tool_path::search_path)
+}
+
 /// Directories searched for adapter binaries: managed tools first, then `PATH` and the usual install spots.
 fn search_dirs() -> Vec<PathBuf> {
     let mut dirs: Vec<PathBuf> = tools_root().map(|r| managed_dirs(&r)).unwrap_or_default();
-    dirs.extend(std::env::var_os("PATH").map(|p| std::env::split_paths(&p).collect::<Vec<_>>()).unwrap_or_default());
+    dirs.extend(std::env::split_paths(&ide_core::tool_path::search_path()));
     if let Some(home) = std::env::var_os("HOME").map(PathBuf::from) {
         for rel in [".cargo/bin", ".local/bin", "go/bin", ".dotnet/tools", ".bun/bin", ".npm-global/bin", ".volta/bin"]
         {
@@ -464,6 +472,9 @@ impl AdapterLauncher for ProcessLauncher {
                 None => args,
             };
             let mut cmd = Command::new(&binary);
+            if let Some(path) = adapter_path(&spec.env) {
+                cmd.env("PATH", path);
+            }
             ide_core::process::prepare(cmd.as_std_mut());
             cmd.args(&args)
                 .envs(spec.env.iter().map(|(k, v)| (k, v)))
@@ -592,6 +603,21 @@ async fn connect_with_retries(
 mod tests {
     use super::*;
 
+    #[test]
+    fn adapters_run_on_the_tool_search_path() {
+        let search = ide_core::tool_path::search_path();
+        assert_eq!(adapter_path(&[]), Some(search.clone()));
+        assert_eq!(adapter_path(&[("GOFLAGS".into(), "-mod=mod".into())]), Some(search));
+        // A launch that sets its own (a selected Go SDK's bin first) keeps it.
+        assert_eq!(adapter_path(&[("PATH".into(), "/sdk/go/bin:/usr/bin".into())]), None);
+        // The search path reaches the usual install spots even when this process's `PATH` doesn't.
+        #[cfg(unix)]
+        {
+            let dirs: Vec<PathBuf> = std::env::split_paths(&ide_core::tool_path::search_path()).collect();
+            assert!(dirs.contains(&PathBuf::from("/usr/local/bin")), "{dirs:?}");
+        }
+    }
+
     #[tokio::test]
     async fn program_output_is_forwarded_without_the_adapter_banner() {
         let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel();