Handle label in a signature help when it is a list

autoload/lsp/signature.vim

@@ -90,13 +90,36 @@ export def SignatureHelp(lspserver: dict<any>, sighelp: any): void
   var hllen: number = 0
   var startcol: number = 0
   if sig->has_key('parameters') && sighelp->has_key('activeParameter')
-    var params_len = sig.parameters->len()
-    if params_len > 0 && sighelp.activeParameter < params_len
-      var label: string = sig.parameters[sighelp.activeParameter].label
-      hllen = label->len()
-      startcol = text->stridx(label)
+    var params: list<dict<any>> = sig.parameters
+    var params_len: number = params->len()
+    var activeParam: number = sighelp.activeParameter
+    if params_len > 0 && activeParam < params_len
+      var paramInfo: dict<any> = params[activeParam]
+      var label: any = paramInfo.label
+      if label->type() == v:t_string
+	# label string
+	var label_str: string = label
+	hllen = label_str->len()
+	startcol = text->stridx(label_str)
+      else
+	# [inclusive start offset, exclusive end offset]
+	var label_offset: list<number> = params[activeParam].label
+	var start_offset: number = label_offset[0]
+	var end_offset: number = label_offset[1]
+
+	if has('patch-9.0.1629')
+	  # Convert UTF-16 offsets
+	  startcol = text->byteidx(start_offset, true)
+	  var endcol: number = text->byteidx(end_offset, true)
+	  hllen = endcol - startcol
+	else
+	  startcol = start_offset
+	  hllen = end_offset - start_offset
+	endif
+      endif
     endif
   endif
+
   if opt.lspOptions.echoSignature
     :echon "\r\r"
     :echon ''