BIND 10 #3378: Apple LLVM compiler 5.1 (clang 5.1) command line option changes break configure script

[BIND 10 Development]

#3378: Apple LLVM compiler 5.1 (clang 5.1) command line option changes break
configure script
-------------------------------------+-------------------------------------
                   Reporter:  tmark  |                 Owner:  UnAssigned
                       Type:         |                Status:  new
  defect                             |             Milestone:  New Tasks
                   Priority:         |              Keywords:
  medium                             |             Sensitive:  0
                  Component:  build  |           Sub-Project:  DHCP
  system                             |  Estimated Difficulty:  0
               CVSS Scoring:         |           Total Hours:  0
            Defect Severity:  N/A    |
Feature Depending on Ticket:         |
        Add Hours to Ticket:  0      |
                  Internal?:  0      |
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 After updating to Xcode 5.1, which includes a compiler update, I was no
 longer able to run "configure".   The check for the "-R" compiler option
 succeeds even though it is no longer supported. There are two tests for it
 configure:

 1. Checks if -Wl,R is available in the linker.   The result of this
 test is "no", which is correct.  clang outputs an error stating that -R is
 not supported.

 2. Checks if -R is available in the linker.  The result of this is "yes"
 which is not actually correct.  clang sets $? to 0 BUT there is a warning
 to stderr that unused option is being ignored.

 This second test causes the -R option to be included in compile flags
 which causes subsequent tests for building with botan to fail.

 After manually altering the configure script to suppress the -R, configure
 completes successfully, however building the project then fails with link
 errors.  Specifically, I believe it was libdhcp's unit tests which failed
 to link.  So while the -R option
 can be suppressed it's effect is something we need?

 The following is an excerpt from Xcode 5.1 release notes:

 {{{
     The Apple LLVM compiler in Xcode 5.1 treats unrecognized command-line
 options as errors. This issue has been seen when building both Python
 native extensions and Ruby Gems, where some invalid compiler options are
 currently specified.

     Projects using invalid compiler options will need to be changed to
 remove those options. To help ease that transition, the compiler will
 temporarily accept an option to downgrade the error to a warning:

     -Wno-error=unused-command-line-argument-hard-error-in-future

     Note: This option will not be supported in the future.

     To workaround this issue, set the ARCHFLAGS environment variable to
 downgrade the error to a warning. For example, you can install a Python
 native extension with:

     $ ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-
 future easy_install ExtensionName

     Similarly, you can install a Ruby Gem with:

     $ ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-
 future gem install GemName 16214764 updated
 }}}

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Ticket URL: <http://bind10.isc.org/ticket/3378>
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