feat: add --tree-favor to gix merge tree|commit.

With it one can decide which side to favor in case of
irreconcilable tree-conflicts.

gitoxide-core/src/repository/merge/commit.rs

@@ -17,6 +17,7 @@ pub fn commit(
     Options {
         format,
         file_favor,
+        tree_favor,
         in_memory,
         debug,
     }: Options,
@@ -31,7 +32,10 @@ pub fn commit(
     let (ours_ref, ours_id) = refname_and_commit(&repo, ours)?;
     let (theirs_ref, theirs_id) = refname_and_commit(&repo, theirs)?;
 
-    let options = repo.tree_merge_options()?.with_file_favor(file_favor);
+    let options = repo
+        .tree_merge_options()?
+        .with_file_favor(file_favor)
+        .with_tree_favor(tree_favor);
     let ours_id_str = ours_id.to_string();
     let theirs_id_str = theirs_id.to_string();
     let labels = gix::merge::blob::builtin_driver::text::Labels {

gitoxide-core/src/repository/merge/tree.rs

@@ -3,6 +3,7 @@ use crate::OutputFormat;
 pub struct Options {
     pub format: OutputFormat,
     pub file_favor: Option<gix::merge::tree::FileFavor>,
+    pub tree_favor: Option<gix::merge::tree::TreeFavor>,
     pub in_memory: bool,
     pub debug: bool,
 }
@@ -29,6 +30,7 @@ pub(super) mod function {
         Options {
             format,
             file_favor,
+            tree_favor,
             in_memory,
             debug,
         }: Options,
@@ -44,7 +46,10 @@ pub(super) mod function {
         let (ours_ref, ours_id) = refname_and_tree(&repo, ours)?;
         let (theirs_ref, theirs_id) = refname_and_tree(&repo, theirs)?;
 
-        let options = repo.tree_merge_options()?.with_file_favor(file_favor);
+        let options = repo
+            .tree_merge_options()?
+            .with_file_favor(file_favor)
+            .with_tree_favor(tree_favor);
         let base_id_str = base_id.to_string();
         let ours_id_str = ours_id.to_string();
         let theirs_id_str = theirs_id.to_string();

src/plumbing/main.rs

@@ -172,9 +172,13 @@ pub fn main() -> Result<()> {
                 },
             ),
             merge::SubCommands::Tree {
-                in_memory,
-                file_favor,
-                debug,
+                opts:
+                    merge::SharedOptions {
+                        in_memory,
+                        file_favor,
+                        tree_favor,
+                        debug,
+                    },
                 ours,
                 base,
                 theirs,
@@ -197,15 +201,20 @@ pub fn main() -> Result<()> {
                             format,
                             file_favor: file_favor.map(Into::into),
                             in_memory,
+                            tree_favor: tree_favor.map(Into::into),
                             debug,
                         },
                     )
                 },
             ),
             merge::SubCommands::Commit {
-                in_memory,
-                file_favor,
-                debug,
+                opts:
+                    merge::SharedOptions {
+                        in_memory,
+                        file_favor,
+                        tree_favor,
+                        debug,
+                    },
                 ours,
                 theirs,
             } => prepare_and_run(
@@ -225,6 +234,7 @@ pub fn main() -> Result<()> {
                         core::repository::merge::tree::Options {
                             format,
                             file_favor: file_favor.map(Into::into),
+                            tree_favor: tree_favor.map(Into::into),
                             in_memory,
                             debug,
                         },

src/plumbing/options/mod.rs

@@ -375,6 +375,14 @@ pub mod merge {
         Theirs,
     }
 
+    #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, clap::ValueEnum)]
+    pub enum TreeFavor {
+        /// Use only the previous tree entry in case of conflict.
+        Ancestor,
+        /// Use only ours tree entry in case of conflict.
+        Ours,
+    }
+
     impl From<FileFavor> for gix::merge::tree::FileFavor {
         fn from(value: FileFavor) -> Self {
             match value {
@@ -384,6 +392,33 @@ pub mod merge {
         }
     }
 
+    impl From<TreeFavor> for gix::merge::tree::TreeFavor {
+        fn from(value: TreeFavor) -> Self {
+            match value {
+                TreeFavor::Ancestor => gix::merge::tree::TreeFavor::Ancestor,
+                TreeFavor::Ours => gix::merge::tree::TreeFavor::Ours,
+            }
+        }
+    }
+
+    #[derive(Debug, clap::Parser)]
+    pub struct SharedOptions {
+        /// Keep all objects to be written in memory to avoid any disk IO.
+        ///
+        /// Note that the resulting tree won't be available or inspectable.
+        #[clap(long, short = 'm')]
+        pub in_memory: bool,
+        /// Decide how to resolve content conflicts in files. If unset, write conflict markers and fail.
+        #[clap(long, short = 'f')]
+        pub file_favor: Option<FileFavor>,
+        /// Decide how to resolve conflicts in trees, i.e. modification/deletion. If unset, try to preserve both states and fail.
+        #[clap(long, short = 't')]
+        pub tree_favor: Option<TreeFavor>,
+        /// Print additional information about conflicts for debugging.
+        #[clap(long, short = 'd')]
+        pub debug: bool,
+    }
+
     #[derive(Debug, clap::Parser)]
     #[command(about = "perform merges of various kinds")]
     pub struct Platform {
@@ -412,17 +447,8 @@ pub mod merge {
 
         /// Merge a tree by specifying ours, base and theirs, writing it to the object database.
         Tree {
-            /// Keep all objects to be written in memory to avoid any disk IO.
-            ///
-            /// Note that the resulting tree won't be available or inspectable.
-            #[clap(long, short = 'm')]
-            in_memory: bool,
-            /// Decide how to resolve content conflicts in files. If unset, write conflict markers and fail.
-            #[clap(long, short = 'f')]
-            file_favor: Option<FileFavor>,
-            /// Print additional information about conflicts for debugging.
-            #[clap(long, short = 'd')]
-            debug: bool,
+            #[clap(flatten)]
+            opts: SharedOptions,
 
             /// A revspec to our treeish.
             #[clap(value_name = "OURS", value_parser = crate::shared::AsBString)]
@@ -436,17 +462,8 @@ pub mod merge {
         },
         /// Merge a commits by specifying ours, and theirs, writing the tree to the object database.
         Commit {
-            /// Keep all objects to be written in memory to avoid any disk IO.
-            ///
-            /// Note that the resulting tree won't be available or inspectable.
-            #[clap(long, short = 'm')]
-            in_memory: bool,
-            /// Decide how to resolve content conflicts in files. If unset, write conflict markers and fail.
-            #[clap(long, short = 'f')]
-            file_favor: Option<FileFavor>,
-            /// Print additional information about conflicts for debugging.
-            #[clap(long, short = 'd')]
-            debug: bool,
+            #[clap(flatten)]
+            opts: SharedOptions,
 
             /// A revspec to our committish.
             #[clap(value_name = "OURS", value_parser = crate::shared::AsBString)]