From 90b312e8df26d3c628aeb61c1b6a40219d7cac5d Mon Sep 17 00:00:00 2001 From: Barrett Ruth <62671086+barrettruth@users.noreply.github.com> Date: Thu, 5 Mar 2026 09:16:04 -0500 Subject: [PATCH] fix(highlight): prevent duplicate extmarks from two-pass rendering (#145) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ## Problem Two-pass rendering (Pass 1: backgrounds + intra-line; Pass 2: treesitter) caused Pass 2 to re-apply all extmarks that Pass 1 already set, doubling the extmark count on affected lines. ## Solution Add `syntax_only` mode to `highlight_hunk`. When `syntax_only = true`, only treesitter syntax and content `DiffsClear` extmarks are applied — backgrounds, intra-line, prefix clears, and per-char prefix highlights are skipped. Pass 2 now uses `syntax_only = true` and no longer calls `nvim_buf_clear_namespace`, so Pass 1's extmarks persist while Pass 2 layers syntax on top. Closes #143 --- lua/diffs/highlight.lua | 131 +++++++++++++++++++++------------------- lua/diffs/init.lua | 11 +--- spec/highlight_spec.lua | 117 +++++++++++++++++++++++++++++++++++ 3 files changed, 190 insertions(+), 69 deletions(-) diff --git a/lua/diffs/highlight.lua b/lua/diffs/highlight.lua index 806fb0a..836a9f4 100644 --- a/lua/diffs/highlight.lua +++ b/lua/diffs/highlight.lua @@ -65,6 +65,7 @@ end ---@field hide_prefix boolean ---@field highlights diffs.Highlights ---@field defer_vim_syntax? boolean +---@field syntax_only? boolean ---@param bufnr integer ---@param ns integer @@ -381,7 +382,13 @@ function M.highlight_hunk(bufnr, ns, hunk, opts) ---@type diffs.IntraChanges? local intra = nil local intra_cfg = opts.highlights.intra - if intra_cfg and intra_cfg.enabled and pw == 1 and #hunk.lines <= intra_cfg.max_lines then + if + not opts.syntax_only + and intra_cfg + and intra_cfg.enabled + and pw == 1 + and #hunk.lines <= intra_cfg.max_lines + then dbg('computing intra for hunk %s:%d (%d lines)', hunk.filename, hunk.start_line, #hunk.lines) intra = diff.compute_intra_hunks(hunk.lines, intra_cfg.algorithm) if intra then @@ -494,28 +501,70 @@ function M.highlight_hunk(bufnr, ns, hunk, opts) or content:match('^|||||||') end - if opts.hide_prefix then - local virt_hl = (opts.highlights.background and line_hl) or nil - pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { - virt_text = { { string.rep(' ', pw), virt_hl } }, - virt_text_pos = 'overlay', - }) - end + if not opts.syntax_only then + if opts.hide_prefix then + local virt_hl = (opts.highlights.background and line_hl) or nil + pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { + virt_text = { { string.rep(' ', pw), virt_hl } }, + virt_text_pos = 'overlay', + }) + end - if pw > 1 then - pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { - end_col = pw, - hl_group = 'DiffsClear', - priority = p.clear, - }) - for ci = 0, pw - 1 do - local ch = line:sub(ci + 1, ci + 1) - if ch == '+' or ch == '-' then - pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, ci, { - end_col = ci + 1, - hl_group = ch == '+' and '@diff.plus' or '@diff.minus', - priority = p.syntax, + if pw > 1 then + pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { + end_col = pw, + hl_group = 'DiffsClear', + priority = p.clear, + }) + for ci = 0, pw - 1 do + local ch = line:sub(ci + 1, ci + 1) + if ch == '+' or ch == '-' then + pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, ci, { + end_col = ci + 1, + hl_group = ch == '+' and '@diff.plus' or '@diff.minus', + priority = p.syntax, + }) + end + end + end + + if opts.highlights.background and is_diff_line then + pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { + line_hl_group = line_hl, + number_hl_group = opts.highlights.gutter and number_hl or nil, + priority = p.line_bg, + }) + end + + if is_marker and line_len > pw then + pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, pw, { + end_col = line_len, + hl_group = 'DiffsConflictMarker', + priority = p.char_bg, + }) + end + + if char_spans_by_line[i] then + local char_hl = has_add and 'DiffsAddText' or 'DiffsDeleteText' + for _, span in ipairs(char_spans_by_line[i]) do + dbg( + 'char extmark: line=%d buf_line=%d col=%d..%d hl=%s text="%s"', + i, + buf_line, + span.col_start, + span.col_end, + char_hl, + line:sub(span.col_start + 1, span.col_end) + ) + local ok, err = pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, span.col_start, { + end_col = span.col_end, + hl_group = char_hl, + priority = p.char_bg, }) + if not ok then + dbg('char extmark FAILED: %s', err) + end + extmark_count = extmark_count + 1 end end end @@ -527,46 +576,6 @@ function M.highlight_hunk(bufnr, ns, hunk, opts) priority = p.clear, }) end - - if opts.highlights.background and is_diff_line then - pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, { - line_hl_group = line_hl, - number_hl_group = opts.highlights.gutter and number_hl or nil, - priority = p.line_bg, - }) - end - - if is_marker and line_len > pw then - pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, pw, { - end_col = line_len, - hl_group = 'DiffsConflictMarker', - priority = p.char_bg, - }) - end - - if char_spans_by_line[i] then - local char_hl = has_add and 'DiffsAddText' or 'DiffsDeleteText' - for _, span in ipairs(char_spans_by_line[i]) do - dbg( - 'char extmark: line=%d buf_line=%d col=%d..%d hl=%s text="%s"', - i, - buf_line, - span.col_start, - span.col_end, - char_hl, - line:sub(span.col_start + 1, span.col_end) - ) - local ok, err = pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, span.col_start, { - end_col = span.col_end, - hl_group = char_hl, - priority = p.char_bg, - }) - if not ok then - dbg('char extmark FAILED: %s', err) - end - extmark_count = extmark_count + 1 - end - end end dbg('hunk %s:%d applied %d extmarks', hunk.filename, hunk.start_line, extmark_count) diff --git a/lua/diffs/init.lua b/lua/diffs/init.lua index 6af7e1a..242c247 100644 --- a/lua/diffs/init.lua +++ b/lua/diffs/init.lua @@ -797,18 +797,13 @@ local function init() return end local t1 = config.debug and vim.uv.hrtime() or nil - local full_opts = { + local syntax_opts = { hide_prefix = config.hide_prefix, highlights = config.highlights, + syntax_only = true, } for _, hunk in ipairs(deferred_syntax) do - local start_row = hunk.start_line - 1 - local end_row = hunk.start_line + #hunk.lines - if hunk.header_start_line then - start_row = hunk.header_start_line - 1 - end - vim.api.nvim_buf_clear_namespace(bufnr, ns, start_row, end_row) - highlight.highlight_hunk(bufnr, ns, hunk, full_opts) + highlight.highlight_hunk(bufnr, ns, hunk, syntax_opts) end if t1 then dbg('deferred pass: %d hunks in %.2fms', #deferred_syntax, (vim.uv.hrtime() - t1) / 1e6) diff --git a/spec/highlight_spec.lua b/spec/highlight_spec.lua index 5d4b94e..39cc23c 100644 --- a/spec/highlight_spec.lua +++ b/spec/highlight_spec.lua @@ -1249,6 +1249,123 @@ describe('highlight', function() end delete_buffer(bufnr) end) + + it('two-pass rendering produces no duplicate extmarks', function() + vim.api.nvim_set_hl(0, 'DiffsAddText', { bg = 0x00FF00 }) + vim.api.nvim_set_hl(0, 'DiffsDeleteText', { bg = 0xFF0000 }) + vim.api.nvim_set_hl(0, 'DiffsAddNr', { fg = 0x80c080, bg = 0x2e4a3a }) + vim.api.nvim_set_hl(0, 'DiffsDeleteNr', { fg = 0xc08080, bg = 0x4a2e3a }) + + local bufnr = create_buffer({ + '@@ -1,2 +1,2 @@', + '-local x = 1', + '+local x = 2', + }) + + local hunk = { + filename = 'test.lua', + lang = 'lua', + start_line = 1, + lines = { '-local x = 1', '+local x = 2' }, + } + + local fast = default_opts({ + highlights = { + treesitter = { enabled = false }, + background = true, + gutter = true, + intra = { enabled = true, algorithm = 'default', max_lines = 500 }, + }, + }) + + local syntax = default_opts({ + highlights = { + treesitter = { enabled = true }, + background = true, + gutter = true, + intra = { enabled = true, algorithm = 'default', max_lines = 500 }, + }, + }) + syntax.syntax_only = true + + highlight.highlight_hunk(bufnr, ns, hunk, fast) + highlight.highlight_hunk(bufnr, ns, hunk, syntax) + + local extmarks = get_extmarks(bufnr) + for row = 1, 2 do + local line_hl_count = 0 + local number_hl_count = 0 + local intra_count = 0 + for _, mark in ipairs(extmarks) do + if mark[2] == row then + local d = mark[4] + if d.line_hl_group then + line_hl_count = line_hl_count + 1 + end + if d.number_hl_group then + number_hl_count = number_hl_count + 1 + end + if d.hl_group == 'DiffsAddText' or d.hl_group == 'DiffsDeleteText' then + intra_count = intra_count + 1 + end + end + end + assert.are.equal(1, line_hl_count, 'row ' .. row .. ' has duplicate line_hl_group') + assert.are.equal(1, number_hl_count, 'row ' .. row .. ' has duplicate number_hl_group') + assert.is_true(intra_count <= 1, 'row ' .. row .. ' has duplicate intra extmarks') + end + delete_buffer(bufnr) + end) + + it('syntax_only pass adds treesitter without duplicating backgrounds', function() + local bufnr = create_buffer({ + '@@ -1,2 +1,3 @@', + ' local x = 1', + '+local y = 2', + ' return x', + }) + + local hunk = { + filename = 'test.lua', + lang = 'lua', + start_line = 1, + lines = { ' local x = 1', '+local y = 2', ' return x' }, + } + + local fast = default_opts({ + highlights = { + treesitter = { enabled = false }, + background = true, + }, + }) + + local syntax = default_opts({ + highlights = { + treesitter = { enabled = true }, + background = true, + }, + }) + syntax.syntax_only = true + + highlight.highlight_hunk(bufnr, ns, hunk, fast) + highlight.highlight_hunk(bufnr, ns, hunk, syntax) + + local extmarks = get_extmarks(bufnr) + local has_ts = false + local line_hl_count = 0 + for _, mark in ipairs(extmarks) do + local d = mark[4] + if d and d.hl_group and d.hl_group:match('^@.*%.lua$') then + has_ts = true + end + if d and d.line_hl_group then + line_hl_count = line_hl_count + 1 + end + end + assert.is_true(has_ts) + assert.are.equal(1, line_hl_count) + delete_buffer(bufnr) + end) end) describe('diff header highlighting', function()