[MacPorts] #38305: Homeport selfupdate error, please help me to resolve

[MacPorts]

#38305: Homeport  selfupdate error,please help me to resolve
--------------------------------+--------------------------------
 Reporter:  jinleicrazysweet@…  |      Owner:  macports-tickets@…
     Type:  defect              |     Status:  new
 Priority:  Normal              |  Milestone:
Component:  ports               |    Version:  2.1.3
 Keywords:                      |       Port:
--------------------------------+--------------------------------
 --->  Updating MacPorts base sources using rsync
 receiving file list ... done

 sent 36 bytes  received 69 bytes  14.00 bytes/sec
 total size is 3594240  speedup is 34230.86
 receiving file list ... done

 sent 36 bytes  received 76 bytes  5.74 bytes/sec
 total size is 512  speedup is 4.57
 MacPorts base version 2.1.1 installed,
 MacPorts base version 2.1.3 downloaded.
 --->  Updating the ports tree
 Synchronizing local ports tree from
 rsync://rsync.macports.org/release/tarballs/ports.tar
 receiving file list ... done

 sent 36 bytes  received 70 bytes  30.29 bytes/sec
 total size is 54753280  speedup is 516540.38
 receiving file list ... done

 sent 36 bytes  received 77 bytes  45.20 bytes/sec
 total size is 512  speedup is 4.53
 receiving file list ... done

 sent 36 bytes  received 70 bytes  30.29 bytes/sec
 total size is 9346970  speedup is 88178.96
 receiving file list ... done

 sent 36 bytes  received 77 bytes  32.29 bytes/sec
 total size is 512  speedup is 4.53
 --->  MacPorts base is outdated, installing new version 2.1.3
 Installing new MacPorts release in /opt/local as root:admin; permissions
 0755; Tcl-Package in /Library/Tcl

 checking build system type... i386-apple-darwin11.4.2
 checking host system type... i386-apple-darwin11.4.2
 checking target system type... i386-apple-darwin11.4.2
 checking MacPorts version... 2.1.3
 checking for sw_vers... /usr/bin/sw_vers
 checking for defaults... /usr/bin/defaults
 checking for xcode-select... /usr/bin/xcode-select
 checking Mac OS X version... 10.7.5
 checking Xcode location... /Applications/Xcode.app/Contents/Developer
 checking Xcode version... 4.6
 checking for gcc... /usr/bin/cc
 checking whether the C compiler works... no
 configure: error: in
 `/opt/local/var/macports/sources/rsync.macports.org/release/tarballs/base':
 configure: error: C compiler cannot create executables
 See `config.log' for more details
 Command failed: cd
 /opt/local/var/macports/sources/rsync.macports.org/release/tarballs/base
 && CC=/usr/bin/cc ./configure --prefix=/opt/local --with-
 tclpackage=/Library/Tcl --with-install-user=root --with-install-
 group=admin --with-directory-mode=0755 --enable-readline && make && make
 install SELFUPDATING=1
 Exit code: 77
 Error: /opt/local/bin/port: port selfupdate failed: Error installing new
 MacPorts base: command execution failed

 I installed Xcode,so I want know the reason for the error

-- 
Ticket URL: <https://trac.macports.org/ticket/38305>
MacPorts <http://www.macports.org/>
Ports system for OS X