title: Error in mutate_impl(.data, dots) : Evaluation error: unused argument
body: <p>I'm testing this code that implement a function to return a calendar chart with a xts dataset:</p>
  
  <pre><code>xts_heatmap &lt;- function(x){
    data.frame(Date=as.Date(index(x)), x[,1]) %&gt;%
      setNames(c("Date","Value")) %&gt;%
      dplyr::mutate(
        Year=lubridate::year(Date),
        Month=lubridate::month(Date),
        # I use factors here to get plot ordering in the right order
        # without worrying about locale
        MonthTag=factor(Month,levels=as.character(1:12),
                        labels=c("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"),ordered=TRUE),
        # week start on Monday in my world
        Wday=lubridate::wday(Date,week_start=1),
        # the rev reverse here is just for the plotting order
        WdayTag=factor(Wday,levels=rev(1:7),labels=rev(c("Mon","Tue","Wed","Thu","Fri","Sat","Sun")),ordered=TRUE),
        Week=as.numeric(format(Date,"%W"))
      ) %&gt;%
      # ok here we group by year and month and then calculate the week of the month 
      # we are currently in
      dplyr::group_by(Year,Month) %&gt;% 
      dplyr::mutate(Wmonth=1+Week-min(Week)) %&gt;% 
      dplyr::ungroup() %&gt;% 
      ggplot(aes(x=Wmonth, y=WdayTag, fill = Value)) + 
      geom_tile(colour = "white") + 
      facet_grid(Year~MonthTag) + 
      scale_fill_gradient(low="red", high="yellow") +
      labs(x="Week of Month", y=NULL)
  }
  </code></pre>
  
  <p>The usage:</p>
  
  <pre><code>quantmod::getSymbols("^VIX",src="yahoo")
  xts_heatmap(Cl(VIX)) + labs(title="Heatmap of VIX")
  </code></pre>
  
  <p>The error:</p>
  
  <pre><code>Error in mutate_impl(.data, dots) : 
    Evaluation error: unused argument (week_start = 1).
  </code></pre>
  
  <p>Looking for a possible solution, discover that .data and .env are now reserved words in dplyr verbs (<a href="https://github.com/tidyverse/dplyr/issues/2324" rel="nofollow noreferrer">link</a>), but I don't know how to fix this.</p>