support conflict-free merge-commit (#561)

* support conflict-free merge-commit

Author: Stephan Dilly

asyncgit/src/sync/branch/merge_commit.rs

@@ -0,0 +1,250 @@
+//! merging from upstream
+
+use super::BranchType;
+use crate::{
+    error::{Error, Result},
+    sync::{utils, CommitId},
+};
+use git2::MergeOptions;
+use scopetime::scope_time;
+
+/// merge upstream using a merge commit without conflicts. fails if not possible without conflicts
+pub fn merge_upstream_commit(
+    repo_path: &str,
+    branch_name: &str,
+) -> Result<CommitId> {
+    scope_time!("merge_upstream_commit");
+
+    let repo = utils::repo(repo_path)?;
+
+    let branch = repo.find_branch(branch_name, BranchType::Local)?;
+    let upstream = branch.upstream()?;
+
+    let upstream_commit = upstream.get().peel_to_commit()?;
+
+    let annotated_upstream =
+        repo.find_annotated_commit(upstream_commit.id())?;
+
+    let (analysis, _) =
+        repo.merge_analysis(&[&annotated_upstream])?;
+
+    if !analysis.is_normal() {
+        return Err(Error::Generic(
+            "normal merge not possible".into(),
+        ));
+    }
+
+    //TODO: support merge on unborn
+    if analysis.is_unborn() {
+        return Err(Error::Generic("head is unborn".into()));
+    }
+
+    let mut opt = MergeOptions::default();
+    opt.fail_on_conflict(true);
+
+    repo.merge(&[&annotated_upstream], Some(&mut opt), None)?;
+
+    assert!(!repo.index()?.has_conflicts());
+
+    let signature =
+        crate::sync::commit::signature_allow_undefined_name(&repo)?;
+    let mut index = repo.index()?;
+    let tree_id = index.write_tree()?;
+    let tree = repo.find_tree(tree_id)?;
+
+    let head_commit = repo.find_commit(
+        crate::sync::utils::get_head_repo(&repo)?.into(),
+    )?;
+    let parents = vec![&head_commit, &upstream_commit];
+
+    //find remote url for this branch
+    let remote_url = {
+        let branch_refname =
+            branch.get().name().ok_or_else(|| {
+                Error::Generic(String::from(
+                    "branch refname not found",
+                ))
+            })?;
+        let buf = repo.branch_upstream_remote(branch_refname)?;
+        let remote =
+            repo.find_remote(buf.as_str().ok_or_else(|| {
+                Error::Generic(String::from("remote name not found"))
+            })?)?;
+        remote.url().unwrap_or_default().to_string()
+    };
+
+    let commit_id = repo
+        .commit(
+            Some("HEAD"),
+            &signature,
+            &signature,
+            format!("Merge '{}' from {}", branch_name, remote_url)
+                .as_str(),
+            &tree,
+            parents.as_slice(),
+        )?
+        .into();
+
+    repo.cleanup_state()?;
+
+    Ok(commit_id)
+}
+
+#[cfg(test)]
+mod test {
+    use super::super::merge_ff::test::write_commit_file;
+    use super::*;
+    use crate::sync::{
+        branch_compare_upstream,
+        remotes::{fetch_origin, push::push},
+        tests::{
+            debug_cmd_print, get_commit_ids, repo_clone,
+            repo_init_bare,
+        },
+        RepoState,
+    };
+
+    #[test]
+    fn test_merge_normal() {
+        let (r1_dir, _repo) = repo_init_bare().unwrap();
+
+        let (clone1_dir, clone1) =
+            repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+
+        let (clone2_dir, clone2) =
+            repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+
+        let clone2_dir = clone2_dir.path().to_str().unwrap();
+
+        // clone1
+
+        let commit1 =
+            write_commit_file(&clone1, "test.txt", "test", "commit1");
+
+        push(
+            clone1_dir.path().to_str().unwrap(),
+            "origin",
+            "master",
+            false,
+            None,
+            None,
+        )
+        .unwrap();
+
+        // clone2
+
+        let commit2 = write_commit_file(
+            &clone2,
+            "test2.txt",
+            "test",
+            "commit2",
+        );
+
+        //push should fail since origin diverged
+        assert!(push(
+            clone2_dir, "origin", "master", false, None, None,
+        )
+        .is_err());
+
+        //lets fetch from origin
+        let bytes =
+            fetch_origin(clone2_dir, "master", None, None).unwrap();
+        assert!(bytes > 0);
+
+        //we should be one commit behind
+        assert_eq!(
+            branch_compare_upstream(clone2_dir, "master")
+                .unwrap()
+                .behind,
+            1
+        );
+
+        let merge_commit =
+            merge_upstream_commit(clone2_dir, "master").unwrap();
+
+        let state = crate::sync::repo_state(clone2_dir).unwrap();
+
+        assert_eq!(state, RepoState::Clean);
+
+        let commits = get_commit_ids(&clone2, 10);
+        assert_eq!(commits.len(), 3);
+        assert_eq!(commits[0], merge_commit);
+        assert_eq!(commits[1], commit2);
+        assert_eq!(commits[2], commit1);
+
+        //verify commit msg
+        let details =
+            crate::sync::get_commit_details(clone2_dir, merge_commit)
+                .unwrap();
+        assert_eq!(
+            details.message.unwrap().combine(),
+            format!(
+                "Merge 'master' from {}",
+                r1_dir.path().to_str().unwrap()
+            )
+        );
+    }
+
+    #[test]
+    fn test_merge_normal_conflict() {
+        let (r1_dir, _repo) = repo_init_bare().unwrap();
+
+        let (clone1_dir, clone1) =
+            repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+
+        let (clone2_dir, clone2) =
+            repo_clone(r1_dir.path().to_str().unwrap()).unwrap();
+
+        // clone1
+
+        write_commit_file(&clone1, "test.bin", "test", "commit1");
+
+        debug_cmd_print(
+            clone2_dir.path().to_str().unwrap(),
+            "git status",
+        );
+
+        push(
+            clone1_dir.path().to_str().unwrap(),
+            "origin",
+            "master",
+            false,
+            None,
+            None,
+        )
+        .unwrap();
+
+        // clone2
+
+        write_commit_file(&clone2, "test.bin", "foobar", "commit2");
+
+        let bytes = fetch_origin(
+            clone2_dir.path().to_str().unwrap(),
+            "master",
+            None,
+            None,
+        )
+        .unwrap();
+        assert!(bytes > 0);
+
+        let res = merge_upstream_commit(
+            clone2_dir.path().to_str().unwrap(),
+            "master",
+        );
+
+        //this should have failed cause it would create a conflict
+        assert!(res.is_err());
+
+        let state = crate::sync::repo_state(
+            clone2_dir.path().to_str().unwrap(),
+        )
+        .unwrap();
+
+        //make sure we left the repo not in some merging state
+        assert_eq!(state, RepoState::Clean);
+
+        //check that we still only have the first commit
+        let commits = get_commit_ids(&clone1, 10);
+        assert_eq!(commits.len(), 1);
+    }
+}

asyncgit/src/sync/branch/merge.rs renamed to asyncgit/src/sync/branch/merge_ff.rs

@@ -33,6 +33,7 @@ pub fn branch_merge_upstream_fastforward(
         ));
     }
 
+    //TODO: support merge on unborn
     if analysis.is_unborn() {
         return Err(Error::Generic("head is unborn".into()));
     }
@@ -45,7 +46,7 @@ pub fn branch_merge_upstream_fastforward(
 }
 
 #[cfg(test)]
-mod test {
+pub mod test {
     use super::*;
     use crate::sync::{
         commit,
@@ -61,7 +62,7 @@ mod test {
     use std::{fs::File, io::Write, path::Path};
 
     // write, stage and commit a file
-    fn write_commit_file(
+    pub fn write_commit_file(
         repo: &Repository,
         file: &str,
         content: &str,
@@ -85,7 +86,7 @@ mod test {
     }
 
     #[test]
-    fn test_merge() {
+    fn test_merge_fastforward() {
         let (r1_dir, _repo) = repo_init_bare().unwrap();
 
         let (clone1_dir, clone1) =

asyncgit/src/sync/branch/mod.rs

@@ -1,6 +1,7 @@
 //! branch functions
 
-pub mod merge;
+pub mod merge_commit;
+pub mod merge_ff;
 pub mod rename;
 
 use super::{

asyncgit/src/sync/commit.rs

@@ -33,7 +33,7 @@ pub fn amend(
 /// Wrap Repository::signature to allow unknown user.name.
 ///
 /// See <https://github.com/extrawurst/gitui/issues/79>.
-fn signature_allow_undefined_name(
+pub(crate) fn signature_allow_undefined_name(
     repo: &Repository,
 ) -> std::result::Result<Signature<'_>, git2::Error> {
     let signature = repo.signature();

asyncgit/src/sync/mod.rs

@@ -25,8 +25,9 @@ pub mod utils;
 pub use branch::{
     branch_compare_upstream, checkout_branch, create_branch,
     delete_branch, get_branches_info,
-    merge::branch_merge_upstream_fastforward, rename::rename_branch,
-    BranchCompare, BranchInfo,
+    merge_commit::merge_upstream_commit,
+    merge_ff::branch_merge_upstream_fastforward,
+    rename::rename_branch, BranchCompare, BranchInfo,
 };
 pub use commit::{amend, commit, tag};
 pub use commit_details::{

src/components/pull.rs

@@ -1,11 +1,12 @@
+use super::PushComponent;
 use crate::{
     components::{
         cred::CredComponent, visibility_blocking, CommandBlocking,
         CommandInfo, Component, DrawableComponent,
     },
     keys::SharedKeyConfig,
     queue::{InternalEvent, Queue},
-    strings,
+    strings, try_or_popup,
     ui::{self, style::SharedTheme},
 };
 use anyhow::Result;
@@ -30,8 +31,6 @@ use tui::{
     Frame,
 };
 
-use super::PushComponent;
-
 ///
 pub struct PullComponent {
     visible: bool,
@@ -158,11 +157,12 @@ impl PullComponent {
                 &self.branch,
             );
             if let Err(err) = merge_res {
-                self.queue.borrow_mut().push_back(
-                    InternalEvent::ShowErrorMsg(format!(
-                        "merge failed:\n{}",
-                        err
-                    )),
+                log::error!("ff merge failed: {}", err);
+
+                try_or_popup!(
+                    self,
+                    "merge failed:",
+                    sync::merge_upstream_commit(CWD, &self.branch)
                 );
             }
         }