rlang 1.1.0

Life cycle changes

• dots_splice() is deprecated. This function was previously in
  the questioning lifecycle stage as we were moving towards the
  explicit !!! splicing style.

• flatten(), squash(), and their variants are deprecated in favour
  of purrr::list_flatten() and purrr::list_c().

• child_env() is deprecated in favour of env() which has supported
  creating child environments for several years now.

Main new features

• last_error() and options(rlang_backtrace_on_error = "full") now
  print the full backtrace tree by default (except for some hidden
  frames). The simplified backtraces tended to hide important context
  too often. Now we show intervening frames in a lighter colour so
  that they don't distract from the important parts of the backtraces
  but are still easily inspectable.

• global_entrace(), last_warnings(), and last_messages() now
  support knitr documents.

• New rlang_backtrace_on_warning_report global option. This is
  useful in conjunction with global_entrace() to get backtraces on
  warnings inside RMarkdown documents.

• global_entrace() and entrace() now stop entracing warnings and
  messages after 20 times. This is to avoid a large overhead when 100s
  or 1000s of warnings are signalled in a loop (#1473).

• abort(), warn(), and inform() gain an .inherit parameter.
  This controls whether parent is inherited. If FALSE,
  cnd_inherits() and try_fetch() do not match chained conditions
  across parents.

  It's normally TRUE by default, but if a warning is chained to an
  error or a message is chained to a warning or error (downgraded
  chaining), .inherit defaults to FALSE (#1573).

• try_fetch() now looks up condition classes across chained errors
  (#1534). This makes try_fetch() insensitive to changes of
  implementation or context of evaluation that cause a classed error
  to suddenly get chained to a contextual error.

• englue() gained env, error_arg, and error_call arguments to
  support being wrapped in another function (#1565).

• The data-masking documentation for arguments has been imported from
  dplyr. You can link to it by starting an argument documentation with
  this button:

  <[`data-masking`][rlang::args_data_masking]>
  

• enquos() and friends gain a .ignore_null argument (#1450).

• New env_is_user_facing() function to determine if an evaluation
  frame corresponds to a direct usage by the end user (from the global
  environment or a package being tested) or indirect usage by a third
  party function. The return value can be overridden by setting the
  "rlang_user_facing" global option.

Miscellaneous fixes and features

• New check_data_frame() and check_logical() functions in
  standalone-types-check.R (#1587, @mgirlich).

• Added allow_infinite argument to check_number_whole() (#1588, @mgirlich).

• The lifecycle standalone file has been updated to match the modern
  lifecycle tools.

• parse_expr() now supports vectors of lines (#1540).

• Quosures can now be consistently concatenated to lists of quosures (#1446).

• Fixed a memory issue that caused excessive duplication in list2()
  and friends (#1491).

• Embraced empty arguments are now properly detected and trimmed by
  quos() (#1421).

• Fixed an edge case that caused enquos(.named = NULL) to return a
  named list (#1505).

• expr_deparse() now deparses the embrace operator {{ on a single
  line (#1511).

• zap_srcref() has been rewritten in C for efficiency (#1513).

• zap_srcref() now supports expression vectors.

• The non-error path of check_dots_unnamed() has been rewritten in C
  for efficiency (#1528).

• Improved error messages in englue() (#1531) and in glue strings in
  the LHS of := (#1526).

• englue() now requires size 1 outputs (#1492). This prevents
  surprising errors or inconsistencies when an interpolated input of
  size != 1 makes its way into the glue string.

• arg_match() now throws correct error when supplied a missing value
  or an empty vector (#1519).

• is_integerish() now handles negative doubles more consistently
  with positive ones (@sorhawell, #1530).

• New check_logical() in standalone-types-check.R (#1560).

• quo_squash() now squashes quosures in function position (#1509).

• is_expression() now recognises quoted functions (#1499).
  It now also recognises non-parsable attributes (#1475).

• obj_address() now supports the missing argument (#1521).

• Fixed a check_installed() issue with packages removed during the
  current R session (#1561).

• new_data_mask() is now slightly faster due to a smaller initial mask size
  and usage of the C level function R_NewEnv() on R >=4.1.0 (#1553).

• The C level r_dyn_*_push_back() utilities are now faster (#1542).

• The C level r_lgl_sum() and r_lgl_which() helpers are now faster
  (#1577, with contributions from @mgirlich).

• rlang is now compliant with -Wstrict-prototypes as requested by CRAN
  (#1508).