cpp11 0.4.3

Modernized the GitHub Actions workflows and updated some internal tests to better align with changes in those workflows and the latest version of R (#279).
cpp_source() errors on non-existent file (#261).
cpp_register() is quiet by default when R is non interactive (#289).
updated test to adapt to changes in R 4.2.1 (#290).

cpp11 0.4.2

New opt-in message formatting with the {fmt} C++ library for cpp11::messages() cpp11::stop() and cpp11::warning(). Set the CPP11_USE_FMT macro to use this feature in your package. (@sbearrows, #169, #208)
New as_double() and as_integer() methods to coerce integers to doubles and doubles to integers to doubles (@sbearrows, #46)
cpp11::matrix iterators can now be used either row-wise or column-wise (the default) depending on the user’s choice (@alyst, #229)

Read-only matrix accessors are now marked const (#234)
writable::r_vector default constructors now return a 0 length vector when converted to SEXP (#166)
Read-only r_vector constructors now disallow implicit construction with named arguments (#237)
Read-only r_vector.attr() methods now return const objects, so it is a compile time error to try to assign to them (#237)
Fixed + and += operators of r_vector::[const_]iterator to conform the iterators concept: += updates the iterator, and + returns the updated copy, while keeping the original unchanged (@alyst, #231)
Remove undefined behavior when constructing global cpp11::sexps (#224)
Removed redundant .Call calls in cpp11.cpp file (@sbearrows, #170)
Error messages now output original file name rather than the temporary file name (@sbearrows, #194)
cpp_register() now includes attribute_visible in the init function, so packages compiled with C_VISIBILITY will find the init function.
Fixed bug when running cpp_source() on the same file more than once (@sbearrows, #202)
Allow cpp11 decorators of the form cpp11::linking_to (@sbearrows, #193)
Removed internal instances of cpp11::stop() and replaced with C++ exceptions (@sbearrows, #203)
Names of named lists are now resized along with the list elements (@sbearrows, #206)

New x.empty() method to check if a vector is empty (@sbearrows, #182)
New x.named() method to check if a vector is named (@sbearrows, #186)
New na() free function to return the NA sentinels for R objects (@sbearrows, #179)

Incorrectly formatted cpp11 decorators now output a more informative error message (@sbearrows, #127)
Generated registration code now uses C collation to avoid spurious changes from tools::package_native_routine_registration_skeleton() (@sbearrows, #171)
Makevars files which include filenames now handle spaces in paths properly (@klmr, #160)

Fix a transient memory leak for functions that return values from cpp11::unwind_protect() and cpp11::safe (#154)
cpp_source() now gets an argument dir to allow customized temporary directory to store generated source files. It makes it easier to debug C++ source files in non-package project via source mapping. (@renkun-ken, #156)

cpp_register() now uses symbols exclusively in the .Call() interface. This allows it to be more robust in interactive use with the pkgload package.

cpp_source() gains a cxx_std argument to control which C++ standard is used. This allows you to use code from C++14 and later standards with cpp_source(). (#100)
The cpp11 knitr engine now allows you to set the cxx_std chunk option to control the C++ standard used.
cpp_source() now has much more informative error messages when compilation fails (#125, #139)
cpp_source() now uses a unique name for the DLL, so works when run multiple times on the same source file on Windows (#143)
writable::list_of<T> now supports modification of vectors as intended (#131).
Errors when running tools::package_native_routine_registration_skeleton() are no longer swallowed (#134)
cpp_source() can now accept a source file called cpp11.cpp (#133)
named_arg now explicitly protect their values, avoiding protection issues when using large inputs. tidyverse/readr#1145
r_string(std::string) now uses Rf_mkCharLenCE() instead of Rf_mkChar(), which avoids the performance cost of checking the string length.
Writable vector classes now properly set their lengths as intended when being copied to a read only class (#128).

The preserve list is now more robust to invalid values, such as when the XPtr has no address or if non-xptr’s are stored in the option. This fixes errors when reloading packages using cpp11 and RStudio’s session restores.
The preserve list is now more robust to invalid values, such as null pointers when the XPtr is serialized. This situation occurs during ‘Install and Restart’ in RStudio (#121)

r_vector::const_iterator::operator* is now a const method (#113, @bkietz, @xhochy)
The preserve list is now stored in an XPtr, rather than an environment, to avoid issues when serializing the preserve environment, which happens implicitly when RStudio or RStudio Cloud saves all options when resuming a session (#116)

r_bool added as an adapter between bool and Rboolean values (#57, @bkietz)
data_frame() objects now have the number of rows correctly set as real length, not the reserved length (#91)
Fixed potential memory leak in cpp11::writable classes.

cpp11 is now able to compile on gcc 4.8.5 (#69, @bkietz)
cpp_source(), cpp_function() and cpp_eval() now support [[cpp11::linking_to()]] syntax to link to third party packages with C++ headers. (#48)

as_cpp<E>() now works with enumeration types (#52, @bkietz)
as_cpp<int>() and as_cpp<double>() now implicitly coerce between all 3 types of single NA values (#53).
list::const_iterator::operator*() added so iterators could be used on list objects (#60, @romainfrancois)
safe[] can now work with functions that return any type (#70, @bkietz)
The END_CPP macro now includes a catch(...) block to catch all C++ exceptions that do not inherit from std::exception (#47).
Improve consistency of inserting NA values in r_string objects (#45)
Added a NEWS.md file to track changes to the package.