无法在R中安装deSolve pacakge,库未加载:libgcc_s.1.dylib

我使用的是MacOSX sierra,我使用brew安装了fortrun:

brew install gcc
brew update && brew reinstall r
brew link --overwrite r

现在我需要安装deSolve,但我不能:

> install.packages("deSolve")
Installing package into '/usr/local/lib/R/site-library'
(as 'lib' is unspecified)
trying URL 'https://cran.rstudio.com/src/contrib/deSolve_1.21.tar.gz'
Content type 'application/x-gzip' length 2172444 bytes (2.1 MB)
==================================================
downloaded 2.1 MB

dyld: Library not loaded: /usr/local/lib/gcc/8/libgcc_s.1.dylib
  Referenced from: /usr/local/opt/gcc/lib/gcc/8/libgfortran.5.dylib
  Reason: image not found
/usr/local/Cellar/r/3.5.1/lib/R/bin/INSTALL: line 34:   837 Done                    echo 'tools:::.install_packages()'
       838 Abort trap: 6           | R_DEFAULT_PACKAGES= LC_COLLATE=C "${R_HOME}/bin/R" $myArgs --slave --args ${args}
Warning in install.packages :
  installation of package 'deSolve' had non-zero exit status

The downloaded source packages are in
    '/private/var/folders/39/88clnp910zlg54lrgy0d7qm40000gn/T/RtmpSezlE0/downloaded_packages'
> install.packages("dylib")
Installing package into '/usr/local/lib/R/site-library'
(as 'lib' is unspecified)
Warning in install.packages :
  package 'dylib' is not available (for R version 3.5.1)

知道怎么解决吗?