This blog is updated daily.
A general description is here.
for GCC >= 8, ‘FC_LEN_T’ is defined in ‘config.h’ and hence character lengths are passed from C to Fortran in _inter alia_ BLAS and LAPACK calls.
There is a new text file ‘src/gnuwin32/README.compilation’, which outlines how C/Fortran code compilation is organized and documents two new features:
• R can be built with Link-Time Optimization with a suitable compiler - doing so with GCC 9.2 showed inconsistencies which have been corrected.
• There is support for cross-compiling the C and Fortran code in R and standard packages on suitable (Linux) platforms. This is mainly intended to allow developers to test later versions of compilers - for example using GCC 9.2.1 has detected issues that GCC 8.3 in Rtools40 does not.