feat: add cleanup option for auto-installed dependencies in build command

- Introduced a new `cleanup_deps` flag in the build command to remove dependencies that were automatically installed during the build process.
- Implemented an `InterruptWatcher` to handle Ctrl-C interruptions gracefully during the build process.
- Enhanced the `AutoInstalledDependencyTracker` to track and manage auto-installed dependencies, allowing for cleanup after the build.
- Updated the CLI to parse the new `cleanup_deps` flag and integrated it into the build workflow.
- Added tests to ensure the correct parsing of the `cleanup_deps` flag and the functionality of the dependency tracking and cleanup process.
- Improved logging for package removal operations to include a verbose mode controlled by the `DEPOT_VERBOSE_REMOVE` environment variable.

src/builder/mod.rs

@@ -111,10 +111,33 @@ fn apply_replacement_rules(current: &mut [String], replacements: &[String], labe
     }
 }
 
+fn sanitize_flag_list(values: Vec<String>, label: &str) -> Vec<String> {
+    let mut sanitized = Vec::with_capacity(values.len());
+    for value in values {
+        let trimmed = value.trim();
+        if trimmed.is_empty() {
+            continue;
+        }
+        if trimmed == "-" {
+            crate::log_warn!(
+                "Dropping invalid {} entry '-'; compiler/linker flag lists cannot contain a bare dash",
+                label
+            );
+            continue;
+        }
+        sanitized.push(trimmed.to_string());
+    }
+    sanitized
+}
+
 fn replaced_flags(values: &[String], replacements: &[String], label: &str) -> Vec<String> {
     let mut current = values.to_vec();
-    apply_replacement_rules(&mut current, replacements, label);
-    current
+    apply_replacement_rules(
+        &mut current,
+        replacements,
+        &format!("{label} replacement rules"),
+    );
+    sanitize_flag_list(current, label)
 }
 
 pub(crate) fn install_dirs(flags: &crate::package::BuildFlags) -> InstallDirs {
@@ -145,25 +168,21 @@ pub(crate) fn install_dirs(flags: &crate::package::BuildFlags) -> InstallDirs {
 fn compiler_flag_sets(
     flags: &crate::package::BuildFlags,
 ) -> (Vec<String>, Vec<String>, Vec<String>, Vec<String>) {
-    let mut cflags = replaced_flags(
-        &flags.cflags,
-        &flags.replace_cflags,
-        "build.flags.replace_cflags",
-    );
+    let mut cflags = replaced_flags(&flags.cflags, &flags.replace_cflags, "build.flags.cflags");
     let mut cxxflags = replaced_flags(
         &flags.cxxflags,
         &flags.replace_cxxflags,
-        "build.flags.replace_cxxflags",
+        "build.flags.cxxflags",
     );
     let mut ldflags = replaced_flags(
         &flags.ldflags,
         &flags.replace_ldflags,
-        "build.flags.replace_ldflags",
+        "build.flags.ldflags",
     );
     let ltoflags = replaced_flags(
         &flags.ltoflags,
         &flags.replace_ltoflags,
-        "build.flags.replace_ltoflags",
+        "build.flags.ltoflags",
     );
 
     if flags.use_lto && !ltoflags.is_empty() {
@@ -179,7 +198,7 @@ pub(crate) fn effective_rustflags(flags: &crate::package::BuildFlags) -> Vec<Str
     replaced_flags(
         &flags.rustflags,
         &flags.replace_rustflags,
-        "build.flags.replace_rustflags",
+        "build.flags.rustflags",
     )
 }
 
@@ -663,6 +682,36 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_standard_build_env_drops_bare_dash_flags() {
+        let mut spec = mk_spec(vec!["-O2", "-", ""], vec!["-Wl,--as-needed", "  "]);
+        spec.build.flags.cxxflags = vec!["-O2".into(), "-".into(), "-fno-exceptions".into()];
+        spec.build.flags.ltoflags = vec!["-".into(), "-flto=thin".into()];
+        spec.build.flags.use_lto = true;
+
+        let env = standard_build_env(&spec, None, true, true);
+        assert!(
+            env.iter()
+                .any(|(k, v)| k == "CFLAGS" && v == "-O2 -flto=thin"),
+            "expected bare dash entries to be removed from CFLAGS"
+        );
+        assert!(
+            env.iter()
+                .any(|(k, v)| k == "CXXFLAGS" && v == "-O2 -fno-exceptions -flto=thin"),
+            "expected bare dash entries to be removed from CXXFLAGS"
+        );
+        assert!(
+            env.iter()
+                .any(|(k, v)| k == "LDFLAGS" && v == "-Wl,--as-needed -flto=thin"),
+            "expected blank and bare dash entries to be removed from LDFLAGS"
+        );
+        assert!(
+            env.iter()
+                .any(|(k, v)| k == "LTOFLAGS" && v == "-flto=thin"),
+            "expected bare dash entries to be removed from LTOFLAGS"
+        );
+    }
+
     #[test]
     fn test_standard_build_env_skips_lto_injection_when_disabled() {
         let mut spec = mk_spec(vec!["-O2"], vec!["-Wl,--as-needed"]);

src/cli.rs

@@ -97,6 +97,10 @@ pub enum Commands {
         /// Automatically install missing dependencies before building
         #[arg(long)]
         install_deps: bool,
+
+        /// Remove dependencies auto-installed for this build after the command finishes
+        #[arg(long)]
+        cleanup_deps: bool,
     },
     /// Update installed packages from configured repositories
     Update {
@@ -360,4 +364,13 @@ mod tests {
             _ => panic!("expected build command"),
         }
     }
+
+    #[test]
+    fn build_cleanup_deps_flag_is_parsed() {
+        let cli = Cli::try_parse_from(["depot", "build", "--cleanup-deps", "pkg.toml"]).unwrap();
+        match cli.command {
+            Commands::Build { cleanup_deps, .. } => assert!(cleanup_deps),
+            _ => panic!("expected build command"),
+        }
+    }
 }

src/db/mod.rs

@@ -14,6 +14,10 @@ fn format_licenses(licenses: &[String]) -> String {
     licenses.join(", ")
 }
 
+fn verbose_remove_output() -> bool {
+    std::env::var_os("DEPOT_VERBOSE_REMOVE").is_some()
+}
+
 /// Installed package row from the local package database.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct InstalledPackageRecord {
@@ -268,7 +272,9 @@ pub fn remove_package(db_path: &Path, name: &str, rootfs: &Path) -> Result<()> {
         let path = rootfs.join(file);
         match fs::remove_file(&path) {
             Ok(()) => {
-                crate::log_info!("  Removed file: {}", file);
+                if verbose_remove_output() {
+                    crate::log_info!("  Removed file: {}", file);
+                }
             }
             Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
                 // Already gone, keep going.
@@ -297,14 +303,15 @@ pub fn remove_package(db_path: &Path, name: &str, rootfs: &Path) -> Result<()> {
         )?;
 
         if other_owners > 0 {
-            crate::log_info!("  Keeping directory (owned by other package): {}", dir);
             continue;
         }
 
         // Try to remove (will fail if not empty, which is fine)
         match fs::remove_dir(&path) {
             Ok(()) => {
-                crate::log_info!("  Removed directory: {}", dir);
+                if verbose_remove_output() {
+                    crate::log_info!("  Removed directory: {}", dir);
+                }
                 dirs_removed += 1;
             }
             Err(e) if e.kind() == std::io::ErrorKind::NotFound => {
@@ -312,7 +319,9 @@ pub fn remove_package(db_path: &Path, name: &str, rootfs: &Path) -> Result<()> {
             }
             Err(e) if e.raw_os_error() == Some(39) || e.raw_os_error() == Some(66) => {
                 // ENOTEMPTY (39 on Linux, 66 on macOS) - directory not empty
-                crate::log_info!("  Keeping directory (not empty): {}", dir);
+                if verbose_remove_output() {
+                    crate::log_info!("  Keeping directory (not empty): {}", dir);
+                }
             }
             Err(_) => {
                 // Other errors (permission, etc.) - just skip silently

src/ui.rs

@@ -96,6 +96,10 @@ pub fn set_assume_yes(assume_yes: bool) {
     ASSUME_YES.store(assume_yes, Ordering::Relaxed);
 }
 
+pub fn assume_yes_enabled() -> bool {
+    ASSUME_YES.load(Ordering::Relaxed)
+}
+
 pub fn prompt_yes_no(prompt: &str, default_yes: bool) -> Result<bool> {
     if ASSUME_YES.load(Ordering::Relaxed) {
         info(format!("{} [auto-yes]", prompt));