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The deprecated support for PCRE versions older than 8.20 will be removed in R 3.4.1.
An alternative compiler for C++11 is now specified with ‘CXX11’, not ‘CXX1X’. Likewise C++11 flags are specified with ‘CXX11FLAGS’ and the standard (e.g., ‘-std=gnu++11’ is specified with ‘CXX11STD’.
Make variables with names containing ‘CXX1X’ are deprecated in favour of those using ‘CXX11’, but for the time being are still made available _via_ file ‘etc/Makeconf’. Packages using them should be converted to the new forms and made dependence on ‘R (>= 3.4.0)’.