fix(git): use GitHunkRemoved for the delete-hunk sign

lua/git/hunks.lua

@@ -42,15 +42,34 @@ local function resolve_buf(buf)
     return buf and buf ~= 0 and buf or vim.api.nvim_get_current_buf()
 end
 
+---Mirror the hunk-affecting parts of the user's 'diffopt' so the gutter
+---lines up with what `:diffsplit` shows.
+---@return table
+local function diff_opts()
+    local opts = { result_type = "indices", algorithm = "myers" }
+    for _, item in ipairs(vim.split(vim.o.diffopt, ",", { plain = true })) do
+        if item == "indent-heuristic" then
+            opts.indent_heuristic = true
+        else
+            local algorithm = item:match("^algorithm:(.+)$")
+            if algorithm then
+                opts.algorithm = algorithm
+            end
+            local linematch = item:match("^linematch:(%d+)$")
+            if linematch then
+                opts.linematch = tonumber(linematch)
+            end
+        end
+    end
+    return opts
+end
+
 ---@param state ow.Git.Hunks.BufState
 ---@param new_lines string[]
 local function compute_hunks(state, new_lines)
     local old = table.concat(state.index or {}, "\n")
     local new = table.concat(new_lines, "\n")
-    local raw = vim.text.diff(old, new, {
-        result_type = "indices",
-        algorithm = "histogram",
-    })
+    local raw = vim.text.diff(old, new, diff_opts())
     ---@type ow.Git.Hunks.Hunk[]
     local hunks = {}
     if type(raw) ~= "table" then
@@ -127,11 +146,11 @@ local function render_signs(buf)
             end
             pcall(vim.api.nvim_buf_set_extmark, buf, NS_SIGNS, row, 0, {
                 sign_text = signs.delete,
-                sign_hl_group = "GitHunkDelete",
+                sign_hl_group = "GitHunkRemoved",
                 priority = 100,
             })
         else
-            local hl = h.type == "add" and "GitHunkAdd" or "GitHunkChange"
+            local hl = h.type == "add" and "GitHunkAdded" or "GitHunkChanged"
             local sign = h.type == "add" and signs.add or signs.change
             for r = h.new_start, h.new_start + h.new_count - 1 do
                 local row = r - 1
@@ -380,6 +399,11 @@ end
 
 local schedule, sched_handle = util.keyed_debounce(recompute, 100)
 
+---@param buf integer
+function M._flush(buf)
+    sched_handle.flush(buf)
+end
+
 ---@param buf integer
 function M.attach(buf)
     if states[buf] then

lua/git/object.lua

@@ -184,8 +184,7 @@ local function populate(buf, r, rev, state, rev_sha)
             local patch = util.git({
                 "diff-tree",
                 "-p",
-                "-m",
-                "--first-parent",
+                "--diff-merges=first-parent",
                 "--root",
                 "--no-commit-id",
                 commit_sha,

plugin/git.lua

@@ -35,9 +35,9 @@ local DEFAULT_HIGHLIGHTS = {
     GitUnmergedDeletedByThem = "GitUnmerged",
     GitUnmergedDeletedByUs = "GitUnmerged",
 
-    GitHunkAdd = "Added",
-    GitHunkChange = "Changed",
-    GitHunkDelete = "Removed",
+    GitHunkAdded = "Added",
+    GitHunkChanged = "Changed",
+    GitHunkRemoved = "Removed",
     GitHunkAddLine = "DiffAdd",
     GitHunkDeleteLine = "DiffDelete",
 }

test/git/hunks_test.lua

@@ -15,6 +15,7 @@ local function setup(committed, worktree, file)
     vim.cmd.edit(dir .. "/" .. file)
     local buf = vim.api.nvim_get_current_buf()
     hunks.attach(buf)
+    hunks._flush(buf)
     t.wait_for(function()
         local s = hunks.state(buf)
         return s ~= nil and s.index ~= nil
@@ -69,8 +70,8 @@ t.test("pure add: hunk shape and add signs", function()
     t.eq(hk.new_start, 2)
     t.eq(hk.new_count, 2)
     t.eq(sign_marks(buf), {
-        { row = 1, sign = "┃", hl = "GitHunkAdd" },
-        { row = 2, sign = "┃", hl = "GitHunkAdd" },
+        { row = 1, sign = "┃", hl = "GitHunkAdded" },
+        { row = 2, sign = "┃", hl = "GitHunkAdded" },
     })
 end)
 
@@ -82,7 +83,7 @@ t.test("pure delete (middle): hunk shape and delete sign", function()
     t.eq(hk.new_count, 0)
     t.eq(hk.old_lines, { "b" })
     t.eq(sign_marks(buf), {
-        { row = 0, sign = "▁", hl = "GitHunkDelete" },
+        { row = 0, sign = "▁", hl = "GitHunkRemoved" },
     })
 end)
 
@@ -94,7 +95,7 @@ t.test("top-of-file delete: sign anchors on line 1", function()
     t.eq(hk.new_start, 0)
     t.eq(hk.old_lines, { "a" })
     t.eq(sign_marks(buf), {
-        { row = 0, sign = "▁", hl = "GitHunkDelete" },
+        { row = 0, sign = "▁", hl = "GitHunkRemoved" },
     })
 end)
 
@@ -110,8 +111,8 @@ t.test("change of N lines: hunk shape and change signs", function()
     t.eq(hk.old_lines, { "b", "c" })
     t.eq(hk.new_lines, { "B", "C" })
     t.eq(sign_marks(buf), {
-        { row = 1, sign = "┃", hl = "GitHunkChange" },
-        { row = 2, sign = "┃", hl = "GitHunkChange" },
+        { row = 1, sign = "┃", hl = "GitHunkChanged" },
+        { row = 2, sign = "┃", hl = "GitHunkChanged" },
     })
 end)
 
@@ -119,8 +120,8 @@ t.test("multi-hunk file: two separate change hunks", function()
     local _, buf, state = setup("a\nb\nc\nd\ne\n", "A\nb\nc\nd\nE\n")
     t.eq(#state.hunks, 2, "two hunks for two disjoint changes")
     t.eq(sign_marks(buf), {
-        { row = 0, sign = "┃", hl = "GitHunkChange" },
-        { row = 4, sign = "┃", hl = "GitHunkChange" },
+        { row = 0, sign = "┃", hl = "GitHunkChanged" },
+        { row = 4, sign = "┃", hl = "GitHunkChanged" },
     })
 end)
 
@@ -135,6 +136,7 @@ t.test("editing the buffer refreshes signs", function()
     t.eq(#state.hunks, 0)
     vim.api.nvim_buf_set_lines(buf, 1, 2, false, { "CHANGED" })
     vim.api.nvim_exec_autocmds("TextChanged", { buffer = buf })
+    hunks._flush(buf)
     t.wait_for(function()
         local s = assert(hunks.state(buf))
         return #s.hunks == 1
@@ -327,7 +329,7 @@ t.test("git_hunk_signs overrides the sign character per kind", function()
     end)
     local _, buf = setup("a\nb\nc\n", "a\nB\nc\n")
     t.eq(sign_marks(buf), {
-        { row = 1, sign = "C", hl = "GitHunkChange" },
+        { row = 1, sign = "C", hl = "GitHunkChanged" },
     })
 end)
 
@@ -339,7 +341,7 @@ t.test("git_hunk_signs falls back to the default for unset kinds", function()
     end)
     local _, buf = setup("a\nb\nc\n", "a\nB\nc\n")
     t.eq(sign_marks(buf), {
-        { row = 1, sign = "┃", hl = "GitHunkChange" },
+        { row = 1, sign = "┃", hl = "GitHunkChanged" },
     })
 end)
 

test/git/object_test.lua

@@ -86,6 +86,23 @@ t.test("M.open(HEAD:<path>) loads file content at HEAD", function()
     )
 end)
 
+t.test("M.open on a merge commit diffs against the first parent only", function()
+    local dir = h.make_repo({ ["a.txt"] = "one\n" })
+    t.write(dir, "a.txt", "two\n")
+    h.git(dir, "stash")
+    local stash = h.git(dir, "rev-parse", "stash@{0}").stdout
+    local r = assert(require("git.core.repo").resolve(dir))
+
+    object.open(r, stash, { split = false })
+    local count = 0
+    for _, l in ipairs(vim.api.nvim_buf_get_lines(0, 0, -1, false)) do
+        if l:match("^diff %-%-git ") then
+            count = count + 1
+        end
+    end
+    t.eq(count, 1, "the stashed file's diff appears once, not per-parent")
+end)
+
 t.test("M.open errors on a bogus base, no buffer is opened", function()
     local dir = h.make_repo({ a = "first\n" })
     local r = assert(require("git.core.repo").resolve(dir))