Error: Could not find build tools necessary to build dplyr
<p>I'm trying to install dplyr from its repository, but I getting the following error.
I'm using MBP with Yosemite and Xcode 6.2 (it's a bit outdate).  I found this curious, apparently, it's not a common issue as I didn't find any thread on this error message. I'm wondering what is the build tools I'm lacking here.</p>

<pre><code>&gt; devtools::install_github("hadley/dplyr")
Downloading GitHub repo hadley/dplyr@master
from URL https://api.github.com/repos/hadley/dplyr/zipball/master
Error: Could not find build tools necessary to build dplyr
</code></pre>

<p>This is the error I'm receiving from terminal when I try to install a package from source locally:</p>

<pre><code>clang -I/Library/Frameworks/R.framework/Resources/include -DNDEBUG  -I/usr/local/include -I/usr/local/include/freetype2 -I/opt/X11/include -DPLATFORM_PKGTYPE='"mac.binary.mavericks"'    -fPIC  -Wall -mtune=core2 -g -O2  -c pause.c -o pause.o
clang -dynamiclib -Wl,-headerpad_max_install_names -undefined dynamic_lookup -single_module -multiply_defined suppress -L/Library/Frameworks/R.framework/Resources/lib -L/opt/X11/lib -L/usr/local/lib /usr/local/lib/libcairo.a /usr/local/lib/libpixman-1.a /usr/local/lib/libfreetype.a /usr/local/lib/libfontconfig.a -lxml2 /usr/local/lib/libreadline.a -o profvis.so pause.o -F/Library/Frameworks/R.framework/.. -framework R -Wl,-framework -Wl,CoreFoundation
clang: error: no such file or directory: '/usr/local/lib/libreadline.a'
</code></pre>