Remove checks for R versions older than 3.5.0

[eddelbuettel]

Closes #1425

This updates a few of the older version comparisons used in the package to provide conditional code and establishes a new baseline of R 3.5.0 -- which is also the oldest version we test in CI.

There is no formal test for R 3.5.0 or later now. I sort-of dislike declaring it in DESCRIPTION though that is the place for it. I would be fine to be more cheeky and just check in configure (though we currently have no configure ...). Or is that too clandestine?

Checklist

• Code compiles correctly
• R CMD check still passes all tests
• Preferably, new tests were added which fail without the change
• Document the changes by file in ChangeLog

[Copilot]

Pull request overview

This PR removes conditional code checks for R versions older than 3.5.0, establishing R 3.5.0 as the new baseline version requirement for the Rcpp package. This aligns with the minimum R version already tested in CI.

Key changes:

• Removed R version guards from C++ headers that checked for R >= 3.1.2, 3.2.0, and 3.5.0
• Simplified R code by removing getRversion() conditionals for R < 3.4.0 and R < 3.5.0
• Refactored cleanup script to use inline file patterns instead of loops

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/barrier.cpp	Removed R_VERSION check for DATAPTR_RO, now always using the R 3.5.0+ version
inst/include/Rcpp/r/headers.h	Simplified RCPP_USING_UNWIND_PROTECT definition by removing R version check
inst/include/Rcpp/exceptions.h	Removed conditional compilation for R_ContinueUnwind, now always available
inst/include/Rcpp/Symbol.h	Removed version checks for Rf_installChar availability
inst/include/Rcpp/Rmath.h	Removed check for dnbinom_mu family functions (available since R 3.1.2)
R/Attributes.R	Removed getRversion() checks for C++ plugin configuration and native routine registration
R/Rcpp.package.skeleton.R	Removed version checks for useDynLib registration and init.c generation
inst/tinytest/testRcppInterfaceUser/tests/tests.R	Removed R 3.5.0 version guard around test assertions
cleanup	Refactored testRcppAttributePackage cleanup from loop-based to inline patterns
ChangeLog	Documented the version check removals across all affected files

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[Copilot]

The cleanup script changes are not documented in the ChangeLog. While these changes appear to be a refactoring of how test package files are cleaned up (moving from loop-based to inline patterns), they should be mentioned for completeness, especially since the cleanup script is included in the PR.

[Copilot]

This comment is outdated. It references "we have at least R 3.4" but this PR establishes R 3.5.0 as the baseline. The comment should be updated to either remove the version reference entirely or update it to reflect the new R 3.5.0 baseline.

[Copilot]

This comment references "R 3.4 or higher" but this PR establishes R 3.5.0 as the baseline. The comment should be updated to reflect the new minimum version requirement or simply state that the internal utility function is available without referencing a specific version.

[Enchufa2]

LGTM!

[eddelbuettel]

Thanks!

I also poked around for a (new, added) configure snippet; it may just be easier to add Depends: R (>= 3.5.0).

[eddelbuettel]

I will wait a few hours in case any one of us changes their minds over 'Depends: R (>= 3.5.0)' but otherwise this is ready, will become 1.1.0.11 and is likely the basis for 1.1.1 come January. Yay. We got a fair number of things done this cycle.