Replace checkout_tree_ex() with stupid checkout

This affects transaction-time checkout and the various checkouts performed
by `stg branch`.

This further improves StGit support for sparse checkout worktrees (#195).

Author: jpgrayson

src/cmd/branch.rs

@@ -4,14 +4,14 @@
 
 use std::io::Write;
 
-use anyhow::{anyhow, Context, Result};
+use anyhow::{anyhow, Result};
 use bstr::ByteSlice;
 use clap::{Arg, ArgMatches};
 use termcolor::WriteColor;
 
 use crate::{
     argset::{self, get_one_str},
-    print_info_message, print_warning_message,
+    print_info_message,
     repo::RepositoryExtended,
     stack::{get_branch_name, state_refname_from_branch_name, Stack, StackStateAccess},
     stupid::Stupid,
@@ -248,12 +248,14 @@ fn run(matches: &ArgMatches) -> Result<()> {
             if target_branchname == current_branchname {
                 Err(anyhow!("{target_branchname} is already the current branch"))
             } else {
+                let stupid = repo.stupid();
+                let statuses = stupid.statuses(None)?;
                 if !matches.contains_id("merge") {
-                    let statuses = repo.stupid().statuses(None)?;
                     statuses.check_worktree_clean()?;
                 }
+                statuses.check_conflicts()?;
                 let target_branch = repo.get_branch(Some(target_branchname))?;
-                switch_to(matches, &repo, &target_branch)
+                stupid.checkout(target_branch.name().unwrap().unwrap())
             }
         } else {
             println!("{current_branchname}");
@@ -313,31 +315,6 @@ fn set_stgit_parent(
     }
 }
 
-fn switch_to(matches: &ArgMatches, repo: &git2::Repository, branch: &git2::Branch) -> Result<()> {
-    let target_commit = branch.get().peel_to_commit()?;
-    let branch_refname = branch.get().name().expect("new branch has UTF-8 name");
-    let mut opts = git2::build::CheckoutBuilder::new();
-    opts.notify_on(
-        git2::CheckoutNotificationType::CONFLICT | git2::CheckoutNotificationType::DIRTY,
-    );
-    opts.notify(|notification_type, path, _diff0, _diff1, _diff2| {
-        if let Some(path) = path {
-            let path_string = path.to_string_lossy();
-            print_warning_message(matches, &format!("{notification_type:?} {path_string}"));
-        } else {
-            print_warning_message(matches, &format!("{notification_type:?}"));
-        }
-        true
-    });
-    repo.checkout_tree_ex(target_commit.as_object(), Some(&mut opts))?;
-    repo.set_head(branch_refname)
-        .with_context(|| format!("switching to `{branch_refname}`"))?;
-    Ok(())
-
-    // let branchname = get_branch_name(branch)?;
-    // repo.stupid().checkout(&branchname)
-}
-
 fn list(repo: git2::Repository, matches: &ArgMatches) -> Result<()> {
     let mut branchnames = Vec::new();
     for branch_result in repo.branches(Some(git2::BranchType::Local))? {
@@ -503,7 +480,7 @@ fn create(repo: git2::Repository, matches: &ArgMatches) -> Result<()> {
         }
     }
 
-    match switch_to(matches, &repo, &new_branch) {
+    match stupid.checkout(new_branch.name().unwrap().unwrap()) {
         Ok(()) => Ok(()),
         Err(e) => {
             new_branch.delete()?;
@@ -561,8 +538,7 @@ fn clone(repo: git2::Repository, matches: &ArgMatches) -> Result<()> {
     )?;
 
     let new_branch = repo.get_branch(Some(&new_branchname))?;
-
-    switch_to(matches, &repo, &new_branch)
+    stupid.checkout(new_branch.name().unwrap().unwrap())
 }
 
 fn rename(repo: git2::Repository, matches: &ArgMatches) -> Result<()> {

src/repo.rs

@@ -4,8 +4,6 @@
 
 use anyhow::{anyhow, Context, Result};
 
-use crate::stack::Error;
-
 /// Extends [`git2::Repository`] with additional methods.
 pub(crate) trait RepositoryExtended {
     /// Determine whether the repository is in a clean state.
@@ -18,13 +16,6 @@ pub(crate) trait RepositoryExtended {
     ///
     /// Gets the current branch if the provided `branch_name` is `None`,
     fn get_branch(&self, branch_name: Option<&str>) -> Result<git2::Branch<'_>>;
-
-    /// [`git2::Repository::checkout_tree()`] with StGit-specfic error mapping.
-    fn checkout_tree_ex(
-        &self,
-        treeish: &git2::Object<'_>,
-        opts: Option<&mut git2::build::CheckoutBuilder<'_>>,
-    ) -> Result<()>;
 }
 
 impl RepositoryExtended for git2::Repository {
@@ -91,20 +82,4 @@ impl RepositoryExtended for git2::Repository {
             }
         }
     }
-
-    fn checkout_tree_ex(
-        &self,
-        treeish: &git2::Object<'_>,
-        opts: Option<&mut git2::build::CheckoutBuilder<'_>>,
-    ) -> Result<()> {
-        self.checkout_tree(treeish, opts)
-            .map_err(|e| -> anyhow::Error {
-                if e.class() == git2::ErrorClass::Checkout && e.code() == git2::ErrorCode::Conflict
-                {
-                    Error::CheckoutConflicts(e.message().to_string()).into()
-                } else {
-                    e.into()
-                }
-            })
-    }
 }

src/stack/transaction.rs

@@ -38,7 +38,6 @@ use crate::{
     commit::{CommitExtended, RepositoryCommitExtended},
     index::TemporaryIndex,
     patchname::PatchName,
-    repo::RepositoryExtended,
     signature::SignatureExtended,
     stack::{PatchState, Stack, StackStateAccess},
     stupid::Stupid,
@@ -441,9 +440,7 @@ impl<'repo> StackTransaction<'repo> {
         }
 
         if self.options.discard_changes {
-            let mut checkout_builder = git2::build::CheckoutBuilder::new();
-            checkout_builder.force();
-            repo.checkout_tree_ex(commit.as_object(), Some(&mut checkout_builder))?;
+            stupid.read_tree_checkout_hard(commit.tree_id())?;
         } else {
             stupid.update_index_refresh()?;
             stupid

src/stupid/mod.rs

@@ -343,7 +343,7 @@ impl<'repo, 'index> StupidContext<'repo, 'index> {
     }
 
     /// Checkout a branch.
-    pub(crate) fn _checkout(&self, branch_name: &str) -> Result<()> {
+    pub(crate) fn checkout(&self, branch_name: &str) -> Result<()> {
         self.git()
             .arg("checkout")
             .arg(branch_name)

t/t1000-branch-create.sh

@@ -143,7 +143,7 @@ test_expect_success \
 
 test_expect_success \
     'Create branch down the stack, behind the conflict caused by the generated file' '
-    conflict stg branch --create foo4 master^
+    command_error stg branch --create foo4 master^
 '
 
 test_expect_success \