[PATCH] build: improve default build for non-gcc

[Eric Blake]

Dagobert Michelsen reported that in a setup that uses git to
track patches on top of the distributed tarball, we ended up
having configure defaults that did not play nicely with the
Sun Studio 12.3 compiler.  Gnulib has fixed the problems with
detecting (un-)supported compiler flags, and additionally we
can use a better witness file of whether we are likely to be
a developer where it is worth enabling warnings by default.

* gnulib: Update to latest gnulib.
* configure.ac (gl_WARN_ADD): Drop flags now guaranteed by gnulib.
(--enable-gcc-warnings): Set default based on a tarball-only file,
rather than whether .git exists.
* THANKS: Update.

Signed-off-by: Eric Blake <address@hidden>
---

* gnulib 798e9bc...4a5ee89 (5):
  > manywarnings: enable nicer gcc warning messages
  > timespec: use the new TIMESPEC_RESOLUTION in a few more places
  > warnings: port --enable-gcc-warnings to Solaris Studio 12.3
  > configmake: support new --runstatedir option
  > ctype, string: depend on extern-inline


 ChangeLog    | 9 +++++++++
 THANKS       | 1 +
 configure.ac | 9 +++------
 gnulib       | 2 +-
 4 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 09c1333..3ac0ea4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2013-09-24  Eric Blake  <address@hidden>
+
+       build: improve default build for non-gcc
+       * gnulib: Update to latest gnulib.
+       * configure.ac (gl_WARN_ADD): Drop flags now guaranteed by gnulib.
+       (--enable-gcc-warnings): Set default based on a tarball-only file,
+       rather than whether .git exists.
+       * THANKS: Update.
+
 2013-09-15  Gary V. Vaughan  <address@hidden>

        configury: specify subdir-objects for future automake releases.
diff --git a/THANKS b/THANKS
index 71bfaf3..4af4c39 100644
--- a/THANKS
+++ b/THANKS
@@ -28,6 +28,7 @@ Carlo Teubner           address@hidden
 Cesar Strauss           address@hidden
 Chris McGuire           address@hidden
 Chris Penev             address@hidden
+Dagobert Michelsen      address@hidden
 Damian Menscher         address@hidden
 Dan Jacobson            address@hidden
 David J. MacKenzie      address@hidden
diff --git a/configure.ac b/configure.ac
index 2defd94..6fc2755 100644
--- a/configure.ac
+++ b/configure.ac
@@ -50,10 +50,10 @@ AC_ARG_ENABLE([gcc-warnings],
      *)      AC_MSG_ERROR([bad value $enableval for gcc-warnings option]) ;;
    esac
    gl_gcc_warnings=$enableval],
-  [if test -d "$srcdir"/.git; then
-     gl_gcc_warnings=yes
-   else
+  [if test -f "$srcdir"/.tarball-version; then
      gl_gcc_warnings=no
+   else
+     gl_gcc_warnings=yes
    fi]
 )

@@ -122,9 +122,6 @@ if test "$gl_gcc_warnings" = yes; then
     gl_WARN_ADD([-Wno-format-nonliteral])
   fi

-  gl_WARN_ADD([-fdiagnostics-show-option])
-  gl_WARN_ADD([-funit-at-a-time])
-
   AC_SUBST([WARN_CFLAGS])

   AH_VERBATIM([FORTIFY_SOURCE],
diff --git a/gnulib b/gnulib
index 798e9bc..4a5ee89 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 798e9bc8b86c1032105682771539bae4ea1e9128
+Subproject commit 4a5ee89c8a8be7350a8fd8ca1bacb196a190e492
-- 
1.8.3.1