• Package documentation now converts ROR IDs into a useful link (#1698, @maelle).

• The check for unexported S3 methods was improved, so it does not hang any more
  if a largish data object is in the package (#1593, @jranke).

• Custom @family
  titles now support
  Markdown syntax (#1608, @salim-b).

• Unqualified markdown links to topics in external packages are now
  automatically resolved (#1612).

• @examplesIf always uses withAutoprint() (@MichaelChirico, #1581). The raw Rd
  will be cleaner, but such examples will now only run under R>=3.4.0 (2017).

• @includeRmd now additionally sets options(cli.hyperlink = FALSE) to make
  code run in included .Rmds even more consistent across sessions (#1620).

• S3 method export warning no longer fails if class contains { or } (#1575).

• @family lists are now ordered more carefully, "foo1" comes after "foo"
  (#1563, @krlmlr).

• @importFrom works again for quoted non-syntactic names, e.g.
  @importFrom magrittr "%>%" or @importFrom rlang `:=`
  (#1570, @MichaelChirico). The unquoted form @importFrom magrittr %>%
  continues to work. Relatedly, @importFrom directives matching no known
  functions (e.g. @importFrom utils plot pdf) produce valid NAMESPACE files
  again.

• Multi-line @rawNamespace no longer break re-runs of namespace_roclet()
  (#1572, @MichaelChirico).

New features

• @docType package now works more like documenting "_PACKAGE",
  creating a {packagename}-package alias and clearly suggesting that
  you should switch to "_PACKAGE" instead (#1491).

• _PACKAGE will no longer generate an alias for your package name if
  a function of the same name exists (#1160).

• The NAMESPACE roclet now reports if you have S3 methods that are missing
  an @export tag. All S3 methods need to be @exported (which confusingly
  really registers the method) even if the generic is not. This avoids rare,
  but hard to debug, problems (#1175). You can suppress the warning with
  @exportS3Method NULL (#1550).

• The NAMESPACE roclet once again regenerates imports before loading
  package code and parsing roxygen blocks. This has been the goal for a long
  time (#372), but we accidentally broke it when adding support for code
  execution in markdown blocks. This resolves a family of problems where you
  somehow bork your NAMESPACE and can't easily get out of it because you
  can't re-document the package because your code doesn't reload.

Minor improvements and bug fixes

• If you document a function from another package it is automatically
  imported. Additionally, if you set @rdname or @name you can opt out
  of the default reexports topic generation and provide your own docs
  (#1408).

• Generate correct usage for S4 methods with non-syntactic class names.

• The ROXYGEN_PKG env var provides the name of the package being documented
  (#1517).

• @describeIn foo now suggests that you might want @rdname instead
  (#1493). It also gives a more informative warning if you use it with an
  unsupported type (#1490).

• In DESCRIPTION, URLs containing escapes in URL and BugReports are
  now correctly handled (@HenningLorenzen-ext-bayer, #1415). Authors can now
  have multiple email addresses (@jmbarbone, #1487).

• escape_examples() is now exported (#1450).

• @exportS3Method provides the needed metadata to generate correct usage
  for S3 methods, just like @method (#1202).

• is_s3_generic() now ignores non-function objects when looking for a
  candidate function. I believe this is closer to how R operates.

• @import and friends are now ignored if they try to import from the
  package being documented. This is useful to add self-dependencies in
  standalone files meant to be used in other packages (r-lib/usethis#1853).

• @importFrom throws a friendlier error if you try and import a non-existing
  functions (@MichaelChirico, #1409).

• @include now gives an informative warning if you use a path that doesn't
  exist (#1497).

• @inherit can now also inherit from @format (#1293).

• @family lists are now ordered more carefully, "foo1" comes after "foo" (#1563, @krlmlr).

• roxygen2 now supports HTML blocks in markdown. They are only included
  in the HTML manual. They can also be produced as the output of code
  chunks.

• Improved support for RStudio IDE.

• @includeRmd calls local_reproducible_output() to make code run in
  included .Rmds more consistent with other sources (#1431).

• Fix duplicated argument in roxy_block() to avoid CRAN removal.

Tags

• All built-in tags are now documented so that you can do (e.g.) ?"@param"
  to get a basic description of @param and a pointer where to learn more
  (#1165). This is powered by a new tags_list() lists all tags defined by
  roxygen2 and tags_metadata() provides some useful information about them
  for use by (e.g.) IDEs (#1375).

• @describeIn can now be used to combine more types of functions
  (generics, methods and other functions) into a single topic.
  The resulting section organises the functions by type (#1181)
  and displays methods like function calls. Methods are recognized only if
  they extend the generic in the destination,or if the destination can
  heuristically be identified as a constructor.

• Code evaluated in inline markdown code chunks and @eval/@evalRd/
  @evalNamespace is now evaluated in an environment designed to be more
  reproducible and to suppress output that won't work in Rd (e.g. turning
  off colour and unicode support in cli) (#1351). They now also set
  knitr options comment = #> (#1380) and collapse = TRUE (#1376).

• @export will now export both the class and constructor function when
  applied to expressions like foo <- setClass("foo") (#1216).

• @includeRmd now gives better feedback when it fails (#1089).

(R)markdown

• New knitr_chunk_options option (in the Roxygen entry of
  DESCRIPTION or in man/roxygen/meta.R) is added to the knitr chunk
  options that roxygen2 uses for markdown code blocks and inline
  code (#1390).

• PDF figures are only included the PDF manual, and SVG figures are only
  included in the HTML manual (#1399).

• You can now use alternative knitr engines in markdown code blocks (#1149).

• Generated HTML for code blocks never includes "NA" for language (#1251).

• Using a level 1 heading in the wrong tag now gives a more useful warning
  (#1374).

• Fix bug interpolating the results of indented inline RMarkdown (#1353).

Other

• If you have a daily build of RStudio, the lists of changed Rd files are
  now clickable so you can immediately see the rendered development
  documentation (#1354).

• R6 documentation no longer shows inherited methods if there aren't any
  (#1371), and only links to superclass docs if they're actually available
  (#1236).

• Automated usage no longer mangles nbsp in default arguments (#1342).

New features

• The NAMESPACE roclet now preserves all existing non-import directives during
  it's first pre-processing pass. This eliminates the "NAMESPACE has changed"
  messages and reduces the incidence of namespace borking (#1254).

• @inheritParams now only inherits exact multiparameter matches, so if you're
  inheriting from a function with @param x,y you'll only get the parameter
  documentation if your function needs docs for both x and y (#950).

• All warning messages have been reviewed to be more informative and
  actionable (#1317). @title now checks for multiple paragraphs.
  @export gives a more informative warning if it contains too many lines.
  (#1074). All tags warn now if only provide whitespace (#1228), and
  problems with the first tag in each block are reported with the correct line
  number (#1235).

• If you have a daily build of RStudio, roxygen2 warnings will now include a
  clickable hyperlink that will take you directly to the problem (#1323).
  This technology is under active development across the IDE and the cli
  package but is extremely exciting.

Minor improvements and bug fixes

• roxygen2 can once again read UTF-8 paths on windows (#1277).

• @authors are de-duplicated in merged documentation (@DanChaltiel, #1333).

• @exportS3method pkg::generic now works when pkg::generic isn't
  imported by your package (#1085).

• @includeRmd is now adapted to change in rmarkdown 2.12 regarding math
  support in github_document() (#1304).

• @inherit and friends perform less aggressive link tweaking, eliminating
  many spurious warnings. Additionally, when you do get a warning, you'll
  now always learn which topic it's coming from (#1135). Inherited
  \ifelse{}{}{} tags are now inserted correctly (without additional {})
  (#1062).

• @inhert now supports inheriting "Notes" with @inherit pkg::fun note
  (@pat-s, #1218)

• Automatic @usage now correctly wraps arguments containing syntactically
  significant whitespace (e.g anonymous functions) (#1281) and non-syntactic
  values surrounded by backticks (#1257).

• Markdown:

  • Code blocks are always wrapped in <div class="sourceCode">
    even if the language is unknown (#1234).

  • Links with markup (e.g. [foo `bar`][target]) now cause an informative
    warning instead of generating invalid Rd.

  • Curly braces in links are now escaped (#1259).

  • Inline R code is now powered by knitr. Where available, (knit) print
    methods are applied (#1179). This change alters outputs and brings roxygen
    in line with console and R markdown behavior. x <- "foo" no longer
    inserts anything into the resulting documentation, but x <- "foo"; x
    will.

• roxygen2 no longer generates invalid HTML (#1290).

• DOIs, arXiv links, and urls in the Description field of the DESCRIPTION
  are now converted to the appropriate Rd markup (@dieghernan, #1265, #1164).
  DOIs in the URL field of the DESCRIPTION are now converted to Rd's
  special \doi{} tag (@ThierryO, #1296).

• The new @examplesIf tag can be used to create conditional
  examples. These examples only run if a specified condition
  holds (#962).

• roxygen2 is now licensed as MIT (#1163).

• Bug fix for upcoming stringr 2.0.0 release.

• Code blocks with language now add sourceCode to the generated div; this
  makes syntax highlighting more consistent across downlit/pandoc/knitr/roxygen2.

• Percent signs in markdown link targets, e.g. [text](https://foo/ba%20r)
  are now handled correctly (#1209).

• When processing cross package markdown links (e.g. [pkg::fun()]),
  roxygen2 now looks up the file it needs to link to, instead of linking to
  the topic, to avoid "Non-file package-anchored links" R CMD check warnings.

• R6 methods and re-exported functions are always sorted in the C locale;
  this ensures they're always sorted the same way in every environment (#1077).

• roxygen2 now supports inline markdown code and code chunks inside
  Rd tags. In particular in \out{} (#1115).