lsp: Fix bad sortText comparison (#12485)

The spec indicates we have to fallback to comparing by label
if sortText is falsy.

Closes #12431

2 files changed, 23 insertions, 24 deletions

diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 3ec7311d65..cedb0b2824 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -299,10 +299,9 @@ end
 ---
 --@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
 local function sort_completion_items(items)
-  if items[1] and items[1].sortText then
-    table.sort(items, function(a, b) return a.sortText < b.sortText
-    end)
-  end
+  table.sort(items, function(a, b)
+    return (a.sortText or a.label) < (b.sortText or b.label)
+  end)
 end
 
 --@private
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 1002011999..f514f4ea6f 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -971,34 +971,34 @@ describe('LSP', function()
       local prefix = 'foo'
       local completion_list = {
         -- resolves into label
-        { label='foobar' },
-        { label='foobar', textEdit={} },
+        { label='foobar', sortText="a" },
+        { label='foobar', sortText="b", textEdit={} },
         -- resolves into insertText
-        { label='foocar', insertText='foobar' },
-        { label='foocar', insertText='foobar', textEdit={} },
+        { label='foocar', sortText="c", insertText='foobar' },
+        { label='foocar', sortText="d", insertText='foobar', textEdit={} },
         -- resolves into textEdit.newText
-        { label='foocar', insertText='foodar', textEdit={newText='foobar'} },
-        { label='foocar', textEdit={newText='foobar'} },
+        { label='foocar', sortText="e", insertText='foodar', textEdit={newText='foobar'} },
+        { label='foocar', sortText="f", textEdit={newText='foobar'} },
         -- real-world snippet text
-        { label='foocar', insertText='foodar', textEdit={newText='foobar(${1:place holder}, ${2:more ...holder{\\}})'} },
-        { label='foocar', insertText='foodar(${1:var1} typ1, ${2:var2} *typ2) {$0\\}', textEdit={} },
+        { label='foocar', sortText="g", insertText='foodar', textEdit={newText='foobar(${1:place holder}, ${2:more ...holder{\\}})'} },
+        { label='foocar', sortText="h", insertText='foodar(${1:var1} typ1, ${2:var2} *typ2) {$0\\}', textEdit={} },
         -- nested snippet tokens
-        { label='foocar', insertText='foodar(${1:var1 ${2|typ2,typ3|} ${3:tail}}) {$0\\}', textEdit={} },
+        { label='foocar', sortText="i", insertText='foodar(${1:var1 ${2|typ2,typ3|} ${3:tail}}) {$0\\}', textEdit={} },
         -- plain text
-        { label='foocar', insertText='foodar(${1:var1})', insertTextFormat=1, textEdit={} },
+        { label='foocar', sortText="j", insertText='foodar(${1:var1})', insertTextFormat=1, textEdit={} },
       }
       local completion_list_items = {items=completion_list}
       local expected = {
-        { abbr = 'foobar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label = 'foobar' } } } } },
-        { abbr = 'foobar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foobar', textEdit={} } } }  } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foobar' } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foobar', textEdit={} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foodar', textEdit={newText='foobar'} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', textEdit={newText='foobar'} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar(place holder, more ...holder{})', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foodar', textEdit={newText='foobar(${1:place holder}, ${2:more ...holder{\\}})'} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(var1 typ1, var2 *typ2) {}', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foodar(${1:var1} typ1, ${2:var2} *typ2) {$0\\}', textEdit={} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(var1 typ2,typ3 tail) {}', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foodar(${1:var1 ${2|typ2,typ3|} ${3:tail}}) {$0\\}', textEdit={} } } } } },
-        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(${1:var1})', user_data = { nvim = { lsp = { completion_item = { label='foocar', insertText='foodar(${1:var1})', insertTextFormat=1, textEdit={} } } } } },
+        { abbr = 'foobar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label = 'foobar', sortText="a" } } } } },
+        { abbr = 'foobar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foobar', sortText="b", textEdit={} } } }  } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="c", insertText='foobar' } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="d", insertText='foobar', textEdit={} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="e", insertText='foodar', textEdit={newText='foobar'} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="f", textEdit={newText='foobar'} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foobar(place holder, more ...holder{})', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="g", insertText='foodar', textEdit={newText='foobar(${1:place holder}, ${2:more ...holder{\\}})'} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(var1 typ1, var2 *typ2) {}', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="h", insertText='foodar(${1:var1} typ1, ${2:var2} *typ2) {$0\\}', textEdit={} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(var1 typ2,typ3 tail) {}', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="i", insertText='foodar(${1:var1 ${2|typ2,typ3|} ${3:tail}}) {$0\\}', textEdit={} } } } } },
+        { abbr = 'foocar', dup = 1, empty = 1, icase = 1, info = ' ', kind = 'Unknown', menu = '', word = 'foodar(${1:var1})', user_data = { nvim = { lsp = { completion_item = { label='foocar', sortText="j", insertText='foodar(${1:var1})', insertTextFormat=1, textEdit={} } } } } },
       }
 
       eq(expected, exec_lua([[return vim.lsp.util.text_document_completion_list_to_complete_items(...)]], completion_list, prefix))