fix(go): sweep Delve's leftover __debug_bin files when a session ends (#1829)

Delve compiles the debuggee to __debug_bin in the session's cwd (on
Windows __debug_bin.exe plus __debug_bin.exe<digits> in DAP mode) and
removes it on a graceful exit. When shutdown doesn't reach that cleanup
the binaries pile up in the project directory.

After the session is down — the adapter disconnected and its process
reaped — remove the leftover files matching Delve's own names from the
session's cwd. Only a locally started adapter (no debugServer) is swept:
a remote Delve's cwd may be on another machine. Files that merely share
the prefix (__debug_bin.go sources, in-progress names with other
suffixes, directories) are left alone.

Fixes #1790

crates/ide-dap/src/lib.rs

@@ -530,6 +530,34 @@ fn unverified(enabled: impl Iterator<Item = bool>) -> Vec<BreakpointState> {
         .collect()
 }
 
+/// Delve compiles the debuggee to `__debug_bin` in the session's cwd (on Windows
+/// `__debug_bin.exe` plus `__debug_bin.exe<digits>` in DAP mode) and removes it on a
+/// graceful exit — a shutdown it doesn't always reach, so the files pile up. Sweep
+/// the leftovers once the session is down. Runs after `session_closed`, so Delve
+/// has already exited or been killed and holds no file locks; a leftover of a
+/// still-building run is removed on that run's own shutdown.
+fn remove_delve_binaries(cwd: &Path) {
+    let Ok(entries) = std::fs::read_dir(cwd) else { return };
+    for entry in entries.flatten() {
+        let name = entry.file_name();
+        let Some(name) = name.to_str() else { continue };
+        // Windows writes `__debug_bin.exe` (and `.exe<digits>` in DAP mode); other
+        // platforms keep the bare name. Suffixes like `.go` are user files.
+        let suffix = name.strip_prefix("__debug_bin");
+        let leftover = suffix.is_some_and(|s| {
+            s.is_empty()
+                || s == ".exe"
+                || (s.starts_with(".exe") && s[".exe".len()..].chars().all(|c| c.is_ascii_digit()))
+        });
+        if leftover
+            && entry.file_type().is_ok_and(|t| t.is_file())
+            && let Err(e) = std::fs::remove_file(entry.path())
+        {
+            tracing::debug!("could not remove Delve leftover {}: {e}", entry.path().display());
+        }
+    }
+}
+
 pub(crate) fn variable_from(v: &Value) -> Variable {
     let s = |k: &str| v.get(k).and_then(Value::as_str).map(str::to_owned);
     Variable {
@@ -981,6 +1009,10 @@ impl DebugManager {
         }
         s.conn.close();
         self.session_closed(s);
+        if s.adapter == "delve" && s.spec.server_host.is_none() {
+            let cwd = s.spec.cwd.clone();
+            tokio::task::spawn_blocking(move || remove_delve_binaries(&cwd));
+        }
     }
 
     /// Breakpoints are kept per file even without a session and sent on start.

crates/ide-dap/src/tests.rs

@@ -1347,3 +1347,26 @@ fn flutter_projects_are_found_from_the_program_or_the_working_directory() {
     assert!(!is_flutter_project(&root, None));
     std::fs::remove_dir_all(&root).unwrap();
 }
+
+#[test]
+fn delve_leftovers_are_removed_without_touching_other_files() {
+    let dir = std::env::temp_dir().join(format!("openidea-delve-bin-{}", std::process::id()));
+    std::fs::create_dir_all(&dir).unwrap();
+    for name in ["__debug_bin", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
+        std::fs::write(dir.join(name), b"bin").unwrap();
+    }
+    // Lookalikes that are not Delve's own binaries stay: sources, a future
+    // in-progress build, and a directory that happens to share the name.
+    for name in ["__debug_bin.go", "__debug_bin.go.exe", "main.go"] {
+        std::fs::write(dir.join(name), b"keep").unwrap();
+    }
+    std::fs::create_dir(dir.join("__debug_bin.dir")).unwrap();
+    remove_delve_binaries(&dir);
+    for name in ["__debug_bin", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
+        assert!(!dir.join(name).exists(), "{name} should be gone");
+    }
+    for name in ["__debug_bin.go", "__debug_bin.go.exe", "main.go", "__debug_bin.dir"] {
+        assert!(dir.join(name).exists(), "{name} should stay");
+    }
+    std::fs::remove_dir_all(&dir).unwrap();
+}