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The minimum version requirement for an external LAPACK has been reduced to 3.9.0.
The minimum ‘autoconf’ requirement for a maintainer build has been increased to ‘autoconf’ 2.71, and it is intended to increase to 2.72 before release. (The issue is better support for ‘C23’: ‘autoconf’ 2.72 requires a C version of C90 or later, but R has long required C99 or later.)