fix(lsp): handle absence of a trailing newline #25194

Fixes #24339

rust-analyzer sends "Invalid offset" error in such cases. Some other
servers handle it specially.

LSP spec mentions that "A range is comparable to a selection in an
editor". Most editors don't handle trailing newlines the same way
Neovim/Vim does, it's clearly visible if it's present or not. With that
in mind it's understandable why sending end position as simply the start
of the line after the last one is considered invalid in such cases.

2 files changed, 83 insertions, 0 deletions

diff --git a/test/functional/fixtures/fake-lsp-server.lua b/test/functional/fixtures/fake-lsp-server.lua
index ef87f6c21a..0db9265a29 100644
--- a/test/functional/fixtures/fake-lsp-server.lua
+++ b/test/functional/fixtures/fake-lsp-server.lua
@@ -949,6 +949,28 @@ function tests.set_defaults_all_capabilities()
   }
 end
 
+function tests.inlay_hint()
+  skeleton {
+    on_init = function(params)
+      local expected_capabilities = protocol.make_client_capabilities()
+      assert_eq(params.capabilities, expected_capabilities)
+      return {
+        capabilities = {
+          inlayHintProvider = true;
+        }
+      }
+    end;
+    body = function()
+      notify('start')
+      expect_request('textDocument/inlayHint', function()
+        return nil, {}
+      end)
+      expect_notification("finish")
+      notify('finish')
+    end;
+  }
+end
+
 -- Tests will be indexed by test_name
 local test_name = arg[1]
 local timeout = arg[2]
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 7e30af5058..155c9ad96c 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -1244,6 +1244,67 @@ describe('LSP', function()
       }
     end)
 
+    it('should send correct range for inlay hints with noeol', function()
+      local expected_handlers = {
+        {NIL, {}, {method="shutdown", client_id=1}};
+        {NIL, {}, {method="finish", client_id=1}};
+        {NIL, {}, {
+          method="textDocument/inlayHint",
+          params = {
+            textDocument = {
+              uri = 'file://',
+            },
+            range = {
+              start = { line = 0, character = 0 },
+              ['end'] = { line = 1, character = 3 },
+            }
+          },
+          bufnr=2,
+          client_id=1,
+        }};
+        {NIL, {}, {method="start", client_id=1}};
+      }
+      local client
+      test_rpc_server {
+        test_name = "inlay_hint";
+        on_setup = function()
+          exec_lua [[
+            BUFFER = vim.api.nvim_create_buf(false, true)
+            vim.api.nvim_buf_set_lines(BUFFER, 0, -1, false, {
+              "testing";
+              "123";
+            })
+            vim.bo[BUFFER].eol = false
+          ]]
+        end;
+        on_init = function(_client)
+          client = _client
+          eq(true, client.supports_method('textDocument/inlayHint'))
+          exec_lua [[
+            assert(lsp.buf_attach_client(BUFFER, TEST_RPC_CLIENT_ID))
+          ]]
+        end;
+        on_exit = function(code, signal)
+          eq(0, code, "exit code")
+          eq(0, signal, "exit signal")
+        end;
+        on_handler = function(err, result, ctx)
+          if ctx.method == 'start' then
+            exec_lua [[
+              vim.lsp.inlay_hint(BUFFER, true)
+            ]]
+          end
+          if ctx.method == 'textDocument/inlayHint' then
+            client.notify('finish')
+          end
+          eq(table.remove(expected_handlers), {err, result, ctx}, "expected handler")
+          if ctx.method == 'finish' then
+            client.stop()
+          end
+        end;
+      }
+    end)
+
     it('should check the body and didChange incremental', function()
       local expected_handlers = {
         {NIL, {}, {method="shutdown", client_id=1}};