unnest fails when tibble contains glue column

[DanOvando]

I was using glue to create a new vector with class glue in a nested tibble, and then using unnest on the resulting tibble. It used to work, but since upgrading to tidyr 1.0.0 I started getting an error

Error: Only bare vectors have shapes.
Call `rlang::last_error()` to see a backtrace

I confirmed that I get the same error with tidyr 1.0.0 as with 1.0.0.9000. I can very easily move away from glue for this particular problem, but seeing as it used to work thought I'd file an issue. Simple reprex reproduces the problem

---

library(tidyr)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(glue)
#> 
#> Attaching package: 'glue'
#> The following object is masked from 'package:dplyr':
#> 
#>     collapse
df <- tibble(
  x = 1:3,
  y = list(
    NULL,
    tibble(a = 1, b = 2,c = glue::glue("{a}-{b}")),
    tibble(a = 1:3, b = 3:1,c =  glue::glue("{a}-{b}"))
  )
)
df %>% unnest(y)
#> Only bare vectors have shapes.


devtools::package_info()
#>  package     * version date       lib source        
#>  assertthat    0.2.1   2019-03-21 [1] CRAN (R 3.6.0)
#>  backports     1.1.5   2019-10-02 [1] CRAN (R 3.6.1)
#>  callr         3.3.2   2019-09-22 [1] CRAN (R 3.6.0)
#>  cli           1.1.0   2019-03-19 [1] CRAN (R 3.6.0)
#>  crayon        1.3.4   2017-09-16 [1] CRAN (R 3.6.0)
#>  desc          1.2.0   2018-05-01 [1] CRAN (R 3.6.0)
#>  devtools      2.2.0   2019-09-07 [1] CRAN (R 3.6.0)
#>  digest        0.6.21  2019-09-20 [1] CRAN (R 3.6.0)
#>  dplyr       * 0.8.3   2019-07-04 [1] CRAN (R 3.6.0)
#>  DT            0.9     2019-09-17 [1] CRAN (R 3.6.1)
#>  ellipsis      0.3.0   2019-09-20 [1] CRAN (R 3.6.0)
#>  evaluate      0.14    2019-05-28 [1] CRAN (R 3.6.0)
#>  fs            1.3.1   2019-05-06 [1] CRAN (R 3.6.0)
#>  glue        * 1.3.1   2019-03-12 [1] CRAN (R 3.6.0)
#>  highr         0.8     2019-03-20 [1] CRAN (R 3.6.0)
#>  htmltools     0.3.6   2017-04-28 [1] CRAN (R 3.6.0)
#>  htmlwidgets   1.3     2018-09-30 [1] CRAN (R 3.6.0)
#>  knitr         1.25    2019-09-18 [1] CRAN (R 3.6.1)
#>  lifecycle     0.1.0   2019-08-01 [1] CRAN (R 3.6.0)
#>  magrittr      1.5     2014-11-22 [1] CRAN (R 3.6.0)
#>  memoise       1.1.0   2017-04-21 [1] CRAN (R 3.6.0)
#>  pillar        1.4.2   2019-06-29 [1] CRAN (R 3.6.0)
#>  pkgbuild      1.0.5   2019-08-26 [1] CRAN (R 3.6.0)
#>  pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 3.6.0)
#>  pkgload       1.0.2   2018-10-29 [1] CRAN (R 3.6.0)
#>  prettyunits   1.0.2   2015-07-13 [1] CRAN (R 3.6.0)
#>  processx      3.4.1   2019-07-18 [1] CRAN (R 3.6.0)
#>  ps            1.3.0   2018-12-21 [1] CRAN (R 3.6.0)
#>  purrr         0.3.2   2019-03-15 [1] CRAN (R 3.6.0)
#>  R6            2.4.0   2019-02-14 [1] CRAN (R 3.6.0)
#>  Rcpp          1.0.2   2019-07-25 [1] CRAN (R 3.6.0)
#>  remotes       2.1.0   2019-06-24 [1] CRAN (R 3.6.0)
#>  rlang         0.4.0   2019-06-25 [1] CRAN (R 3.6.0)
#>  rmarkdown     1.16    2019-10-01 [1] CRAN (R 3.6.1)
#>  rprojroot     1.3-2   2018-01-03 [1] CRAN (R 3.6.0)
#>  sessioninfo   1.1.1   2018-11-05 [1] CRAN (R 3.6.0)
#>  stringi       1.4.3   2019-03-12 [1] CRAN (R 3.6.0)
#>  stringr       1.4.0   2019-02-10 [1] CRAN (R 3.6.0)
#>  testthat      2.2.1   2019-07-25 [1] CRAN (R 3.6.0)
#>  tibble        2.1.3   2019-06-06 [1] CRAN (R 3.6.0)
#>  tidyr       * 1.0.0   2019-09-11 [1] CRAN (R 3.6.0)
#>  tidyselect    0.2.5   2018-10-11 [1] CRAN (R 3.6.0)
#>  usethis       1.5.1   2019-07-04 [1] CRAN (R 3.6.0)
#>  vctrs         0.2.0   2019-07-05 [1] CRAN (R 3.6.0)
#>  withr         2.1.2   2018-03-15 [1] CRAN (R 3.6.0)
#>  xfun          0.10    2019-10-01 [1] CRAN (R 3.6.1)
#>  yaml          2.2.0   2018-07-25 [1] CRAN (R 3.6.0)
#>  zeallot       0.1.0   2018-01-28 [1] CRAN (R 3.6.0)
#> 
#> [1] /Library/Frameworks/R.framework/Versions/3.6/Resources/library

^{Created on 2019-10-07 by the reprex package (v0.3.0)}

[hadley]

Thanks for the report! We're tracking the underlying problem here: r-lib/vctrs#614