new: ignore vendored rust artifacts in the generated gitignore

src/new/debian.rs

@@ -323,15 +323,25 @@ pub const ROOT_GITIGNORE_ENTRIES: [&str; 6] = [
     "target/",
 ];
 
-/// Merge the root `.gitignore` entries into `existing` (the current file
-/// contents, when there is one): missing entries are appended, an existing
-/// file is never overwritten just to duplicate entries. Returns the new
-/// contents, or `None` when nothing has to be written.
-pub fn merge_root_gitignore(existing: Option<&str>) -> Option<String> {
+/// Comment heading a root `.gitignore` freshly created by pkh (the skeleton
+/// build-artifact section).
+pub const ROOT_GITIGNORE_HEADER: &str = "# pkh build artifacts";
+
+/// Merge `entries` into the root `.gitignore` contents `existing` (the
+/// current file contents, when there is one): missing entries are appended,
+/// an existing file is never overwritten just to duplicate entries. A fresh
+/// file is headed by the `header` comment when one is given; appending to a
+/// user file adds bare entries. Returns the new contents, or `None` when
+/// nothing has to be written.
+pub fn merge_gitignore_entries(
+    existing: Option<&str>,
+    entries: &[&str],
+    header: Option<&str>,
+) -> Option<String> {
     let have: HashSet<&str> = existing
         .map(|content| content.lines().map(str::trim).collect())
         .unwrap_or_default();
-    let missing: Vec<&str> = ROOT_GITIGNORE_ENTRIES
+    let missing: Vec<&str> = entries
         .iter()
         .copied()
         .filter(|entry| !have.contains(entry))
@@ -346,8 +356,11 @@ pub fn merge_root_gitignore(existing: Option<&str>) -> Option<String> {
     }
     // Section comment only for a fresh file; appending to a user file adds
     // bare entries.
-    if existing.is_none() {
-        out.push_str("# pkh build artifacts\n");
+    if existing.is_none()
+        && let Some(header) = header
+    {
+        out.push_str(header);
+        out.push('\n');
     }
     for entry in missing {
         out.push_str(entry);
@@ -746,17 +759,30 @@ mod tests {
     }
 
     #[test]
-    fn root_gitignore_merge() {
+    fn gitignore_merge() {
         // Fresh file: header + all entries.
-        let fresh = merge_root_gitignore(None).unwrap();
+        let fresh =
+            merge_gitignore_entries(None, &ROOT_GITIGNORE_ENTRIES, Some(ROOT_GITIGNORE_HEADER))
+                .unwrap();
         assert!(fresh.starts_with("# pkh build artifacts\n"));
         for entry in ROOT_GITIGNORE_ENTRIES {
             assert!(fresh.contains(entry), "{entry} missing");
         }
 
+        // A fresh file without a header carries the bare entries.
+        assert_eq!(
+            merge_gitignore_entries(None, &["a/", "b"], None).unwrap(),
+            "a/\nb\n"
+        );
+
         // Existing file: only the missing entries are appended, nothing lost.
         let existing = "*.deb\nnode_modules/\n";
-        let merged = merge_root_gitignore(Some(existing)).unwrap();
+        let merged = merge_gitignore_entries(
+            Some(existing),
+            &ROOT_GITIGNORE_ENTRIES,
+            Some(ROOT_GITIGNORE_HEADER),
+        )
+        .unwrap();
         assert!(merged.starts_with(existing));
         assert!(merged.contains("*.dsc\n"));
         assert!(!merged.contains("*.deb\n*.deb"));
@@ -766,7 +792,31 @@ mod tests {
             .iter()
             .map(|e| format!("{e}\n"))
             .collect();
-        assert!(merge_root_gitignore(Some(&full)).is_none());
+        assert!(
+            merge_gitignore_entries(
+                Some(&full),
+                &ROOT_GITIGNORE_ENTRIES,
+                Some(ROOT_GITIGNORE_HEADER),
+            )
+            .is_none()
+        );
+    }
+
+    /// The vendoring entries of the rust template merge into an existing
+    /// user `.gitignore` like any other entry set: appended after the
+    /// user's lines, no header comment, idempotent.
+    #[test]
+    fn gitignore_merge_appends_template_entries() {
+        let entries = ["vendor/", ".cargo/config.toml"];
+        let merged =
+            merge_gitignore_entries(Some("# my project\n*.log\n"), &entries, None).unwrap();
+        assert_eq!(merged, "# my project\n*.log\nvendor/\n.cargo/config.toml\n");
+
+        // Already ignored: nothing to write.
+        assert!(
+            merge_gitignore_entries(Some("vendor/\n.cargo/config.toml\n"), &entries, None)
+                .is_none()
+        );
     }
 
     #[test]

src/new/mod.rs

@@ -3,7 +3,9 @@
 //!
 //! This module orchestrates a scaffold run: target directory checks, project
 //! detection, in-memory rendering of every file (all-or-nothing write), the
-//! template post-write hook (e.g. `cargo vendor`), orig tarball creation
+//! root `.gitignore` merge (skeleton build artifacts plus the template's own
+//! entries, e.g. the rust vendored layout), the template post-write hook
+//! (e.g. `cargo vendor`), orig tarball creation
 //! (from the origin the run decided on — see [`origin`] and [`orig`]), git
 //! initialization, structural verification and the next-steps message.
 //! The interactive wizard ([`questions`]) fills a [`options::NewCli`] from
@@ -35,8 +37,10 @@ use templates::{OutputFile, ScaffoldOutcome};
 /// 1. resolve the template from the registry,
 /// 2. check the target directory (refuse an existing `debian/control`),
 /// 3. render every file in memory and check for collisions,
-/// 4. write the files all-or-nothing (plus the root `.gitignore` in skeleton
-///    mode, appending to an existing one),
+/// 4. write the files all-or-nothing (plus the root `.gitignore` merge:
+///    the skeleton build-artifact entries in skeleton mode and the
+///    template's own entries — rust: the vendored layout — in every mode,
+///    appending to an existing file),
 /// 5. run the template post-write hook (e.g. `cargo vendor`, so the vendored
 ///    sources land inside the orig tarball created next),
 /// 6. create the orig tarball (quilt only, refusing overwrites),
@@ -171,13 +175,25 @@ fn scaffold_steps(opts: &NewOptions, pb: &ProgressBar) -> Result<ScaffoldOutcome
     pb.set_message("Writing files");
     debian::write_files(&target, &files)?;
 
-    // Root .gitignore: skeleton mode only, never overwriting an existing
-    // file (append the missing entries instead).
-    if skeleton
-        && let Some(contents) = debian::merge_root_gitignore(
+    // Root .gitignore: the skeleton build-artifact entries in skeleton
+    // mode, plus the template's own entries (rust: the vendored layout) in
+    // every mode — missing ones appended, an existing file never
+    // overwritten.
+    let template_gitignore = template.gitignore_entries(opts);
+    let mut entries: Vec<&str> = Vec::new();
+    let mut header = None;
+    if skeleton {
+        entries.extend(debian::ROOT_GITIGNORE_ENTRIES);
+        header = Some(debian::ROOT_GITIGNORE_HEADER);
+    }
+    entries.extend(template_gitignore.iter().map(String::as_str));
+    if !entries.is_empty()
+        && let Some(contents) = debian::merge_gitignore_entries(
             std::fs::read_to_string(target.join(".gitignore"))
                 .ok()
                 .as_deref(),
+            &entries,
+            header,
         )
     {
         std::fs::write(target.join(".gitignore"), contents)?;
@@ -502,7 +518,8 @@ mod tests {
         scaffold_in(&tree, opts(TemplateId::Shell, "runtool", SourceDir::Here)).unwrap();
 
         // debian/ lands directly in the directory; no skeleton file, no
-        // root .gitignore (skeleton mode only), no debian/install (the
+        // root .gitignore (the shell template contributes none and the
+        // artifact entries are skeleton-only), no debian/install (the
         // generated one would reference the non-existent skeleton script),
         // and the existing script is left alone.
         assert!(tree.join("debian/control").exists());
@@ -662,6 +679,40 @@ mod tests {
             assert!(config.contains("[source.crates-io]"), "{config}");
             assert!(config.contains("[net]\noffline = true"), "{config}");
         }
+
+        // Root .gitignore: the skeleton build-artifact entries plus the
+        // template's vendoring entries (contributed in every mode).
+        let gitignore = std::fs::read_to_string(tree.join(".gitignore")).unwrap();
+        assert!(gitignore.contains("# pkh build artifacts"), "{gitignore}");
+        assert!(gitignore.contains("*.deb"), "{gitignore}");
+        assert!(gitignore.contains("target/"), "{gitignore}");
+        assert!(gitignore.contains("vendor/\n"), "{gitignore}");
+        assert!(gitignore.contains(".cargo/config.toml\n"), "{gitignore}");
+    }
+
+    /// The rust template's vendoring entries land in the root `.gitignore`
+    /// in every mode: a Here-mode tree gets them appended to its existing
+    /// file (custom lines kept, no header comment), while the skeleton-only
+    /// build-artifact entries do not appear.
+    #[test]
+    #[serial]
+    fn scaffold_rust_here_merges_vendoring_gitignore_entries() {
+        let dir = tempdir().unwrap();
+        let tree = dir.path().join("packdir");
+        std::fs::create_dir_all(&tree).unwrap();
+        std::fs::write(tree.join(".gitignore"), "# my project\n*.log\n").unwrap();
+        scaffold_in(&tree, opts(TemplateId::Rust, "mytool", SourceDir::Here)).unwrap();
+
+        let gitignore = std::fs::read_to_string(tree.join(".gitignore")).unwrap();
+        assert!(
+            gitignore.starts_with("# my project\n*.log\n"),
+            "{gitignore}"
+        );
+        assert!(gitignore.contains("vendor/\n"), "{gitignore}");
+        assert!(gitignore.contains(".cargo/config.toml\n"), "{gitignore}");
+        // The build-artifact entries stay skeleton-only.
+        assert!(!gitignore.contains("*.deb"), "{gitignore}");
+        assert!(!gitignore.contains("# pkh build artifacts"), "{gitignore}");
     }
 
     /// End-to-end vendored rust quilt package: the vendoring hook creates

src/new/templates/mod.rs

@@ -137,6 +137,15 @@ pub trait Template: Sync {
         Vec::new()
     }
 
+    /// Root `.gitignore` entries the template contributes in every mode
+    /// (the skeleton-mode build-artifact entries of
+    /// [`crate::new::debian::ROOT_GITIGNORE_ENTRIES`] are separate), merged
+    /// into the root `.gitignore` after the files are written — missing
+    /// ones appended, an existing file never overwritten. Default: none.
+    fn gitignore_entries(&self, _opts: &NewOptions) -> Vec<String> {
+        Vec::new()
+    }
+
     /// Extra defaults derived from project metadata in `dir` (detect.rs);
     /// `None` when the project carries nothing this template can read.
     fn probe(&self, _dir: &Path) -> Option<ProbeResult> {
@@ -248,6 +257,48 @@ mod tests {
         );
     }
 
+    /// Only the rust template contributes root `.gitignore` entries of its
+    /// own — exactly the vendoring pair, and unconditionally (its vendoring
+    /// hook runs in every mode); every other template contributes nothing.
+    #[test]
+    fn gitignore_entries_are_rust_only() {
+        let o = NewOptions {
+            name: "mytool".into(),
+            template: TemplateId::Rust,
+            source_dir: SourceDir::Here,
+            upstream_version: "0.1.0".into(),
+            revision: 1,
+            summary: "A tool".into(),
+            long_description: "A tool".into(),
+            homepage: None,
+            license: crate::new::options::License::Mit,
+            command: "mytool".into(),
+            maintainer: ("Jane".into(), "jane@example.com".into()),
+            dist: "ubuntu".into(),
+            series: "resolute".into(),
+            release: false,
+            depends: Vec::new(),
+            source_format: crate::new::options::SourceFormat::Quilt,
+            orig: None,
+            git: false,
+            autopkgtest: false,
+            pkg_config: false,
+            watch: None,
+        };
+
+        for id in TemplateId::all() {
+            let entries = get(id).unwrap().gitignore_entries(&o);
+            if id == TemplateId::Rust {
+                assert_eq!(
+                    entries,
+                    vec!["vendor/".to_string(), ".cargo/config.toml".to_string()]
+                );
+            } else {
+                assert!(entries.is_empty(), "{id} contributes {entries:?}");
+            }
+        }
+    }
+
     /// The final `debian/rules` of every template must be valid-looking
     /// make: `#!/usr/bin/make -f` shebang, exactly one `%:` target whose
     /// recipe is the template's dh line, tab-indented recipes only, and no

src/new/templates/rust.rs

@@ -75,6 +75,17 @@ impl Template for Rust {
         vec!["cargo:native".to_string(), "rustc:native".to_string()]
     }
 
+    /// Root `.gitignore` entries contributed in every mode: the vendoring
+    /// hook runs unconditionally for this template, so `vendor/` and
+    /// `.cargo/config.toml` exist (or will exist) in every scaffolded rust
+    /// tree and must stay out of the repository. `.cargo/config.toml` is
+    /// the subtle one: it points cargo at `vendor/`, so committing it would
+    /// break plain `cargo build` for anyone cloning the repository without
+    /// the vendored sources.
+    fn gitignore_entries(&self, _opts: &NewOptions) -> Vec<String> {
+        vec!["vendor/".to_string(), ".cargo/config.toml".to_string()]
+    }
+
     fn architecture(&self, _opts: &NewOptions) -> &'static str {
         "any"
     }