[commit: ghc] master: Require 'libdw' for '--enable-dwarf-unwind' (cb882fc)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/cb882fc993b4972f7f212b291229ef9e9ade0af9/ghc

>---------------------------------------------------------------

commit cb882fc993b4972f7f212b291229ef9e9ade0af9
Author: Alec Theriault <alec.theriault at gmail.com>
Date:   Fri Dec 7 23:18:15 2018 -0500

    Require 'libdw' for '--enable-dwarf-unwind'
    
    This causes './configure --enable-dwarf-unwind' to exit with a helpful
    error message when 'libdw' cannot be found (compared to the previous
    behaviour of silently pretending the user hadn't requested DWARF support
    at all).
    
    Test Plan: ./configure --enable-dwarf-unwind # on systems with/without
    libdw
    
    Reviewers: bgamari, nh2
    
    Reviewed By: nh2
    
    Subscribers: nh2, rwbarton, erikd, carter
    
    GHC Trac Issues: #15968
    
    Differential Revision: https://phabricator.haskell.org/D5424


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cb882fc993b4972f7f212b291229ef9e9ade0af9
 configure.ac | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 88eddca..2cf98a7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1248,7 +1248,9 @@ USE_LIBDW=0
 AC_ARG_ENABLE(dwarf-unwind,
     [AC_HELP_STRING([--enable-dwarf-unwind],
         [Enable DWARF unwinding support in the runtime system via elfutils' libdw [default=no]])],
-    [AC_CHECK_LIB(dw, dwfl_attach_state, [UseLibdw=YES], [UseLibdw=NO])],
+    [AC_CHECK_LIB(dw, dwfl_attach_state,
+      [UseLibdw=YES],
+      [AC_MSG_ERROR([Cannot find system libdw (required by --enable-dwarf-unwind)])])]
     [UseLibdw=NO]
 )
 AC_SUBST(UseLibdw)