Clean up warning flag handling.

configure.in

@@ -12,12 +12,15 @@ V_REV=4
 PACKAGE=sane-backends
 VERSION=${V_MAJOR}.${V_MINOR}.${V_REV}
 PACKAGE_VERSION="$PACKAGE-$VERSION"
-AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
-AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
-AC_DEFINE_UNQUOTED(PACKAGE_VERSION, "$PACKAGE_VERSION")
-AC_DEFINE_UNQUOTED(SANE_DLL_V_MAJOR, $V_MAJOR)
-AC_DEFINE_UNQUOTED(SANE_DLL_V_MINOR, $V_MINOR)
-AC_DEFINE_UNQUOTED(SANE_DLL_V_BUILD, $V_REV)
+AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE",
+                   [Define to the name of the distribution.])
+AC_DEFINE_UNQUOTED(VERSION, "$VERSION",
+                   [Define to the version of the distribution.])
+AC_DEFINE_UNQUOTED(PACKAGE_VERSION, "$PACKAGE_VERSION",
+                 [The concatenation of the strings PACKAGE, "-", and VERSION.])
+AC_DEFINE_UNQUOTED(SANE_DLL_V_MAJOR, $V_MAJOR, [SANE DLL major number])
+AC_DEFINE_UNQUOTED(SANE_DLL_V_MINOR, $V_MINOR, [SANE DLL minor number])
+AC_DEFINE_UNQUOTED(SANE_DLL_V_BUILD, $V_REV, [SANE DLL revision number])
 AC_SUBST(PACKAGE)
 AC_SUBST(VERSION)
 AC_SUBST(PACKAGE_VERSION)
@@ -38,9 +41,20 @@ INCLUDES="${INCLUDES} -I/usr/local/include"
 CPPFLAGS="${CPPFLAGS} -D_GNU_SOURCE"
 
 if test "${ac_cv_prog_gcc}" = "yes"; then
-  NORMAL_CFLAGS="${CFLAGS} -W -Wall"
-  WARN_CFLAGS="${CFLAGS} -W -Wall -Wstrict-prototypes -Wreturn-type \
-    -Wcast-align -Wpointer-arith -Wcast-qual -pedantic"
+  NORMAL_CFLAGS="\
+      -W \
+      -Wall"
+  WARN_CFLAGS="\
+      -W \
+      -Wall \
+      -Wcast-align \
+      -Wcast-qual \
+      -Wmissing-declarations \
+      -Wmissing-prototypes \
+      -Wpointer-arith \
+      -Wreturn-type \
+      -Wstrict-prototypes \
+      -pedantic"
 
   dnl OS/2 doesn't include some headers with -ansi enabled
   AC_CHECK_HEADER(os2.h,,[WARN_CFLAGS="${WARN_CFLAGS} -ansi"])
@@ -51,27 +65,27 @@ if test "${ac_cv_prog_gcc}" = "yes"; then
                           [default=yes]],
     [
       if eval "test x$enable_warnings = xyes"; then 
-        CFLAGS="${WARN_CFLAGS}"
-     else
-        CFLAGS="${NORMAL_CFLAGS}"
+        for flag in $WARN_CFLAGS; do
+          JAPHAR_GREP_CFLAGS($flag, [ CFLAGS="$CFLAGS $flag" ])
+        done
+      else
+        for flag in $NORMAL_CFLAGS; do
+          JAPHAR_GREP_CFLAGS($flag, [ CFLAGS="$CFLAGS $flag" ])
+        done
       fi
     ],
-    [CFLAGS="${WARN_CFLAGS}"])
-
-dnl  # Warnings disabled by default (release)
-dnl  AC_ARG_ENABLE(warnings,
-dnl    [  --enable-warnings       turn on tons of compiler warnings (GCC only)
-dnl                            [default=no]],
-dnl    [
-dnl      if eval "test x$enable_warnings = xyes"; then 
-dnl        CFLAGS="${WARN_CFLAGS}"
-dnl      else
-dnl        CFLAGS="${NORMAL_CFLAGS}"
-dnl      fi
-dnl    ],
-dnl    [CFLAGS="${NORMAL_CFLAGS}"])
-  
-fi
+    [if true; then # release (false) or development (true)
+       # Warnings enabled by default (development)
+       for flag in $WARN_CFLAGS; do
+         JAPHAR_GREP_CFLAGS($flag, [ CFLAGS="$CFLAGS $flag" ])
+       done
+    else
+       # Warnings disabled by default (release)
+       for flag in $NORMAL_CFLAGS; do
+         JAPHAR_GREP_CFLAGS($flag, [ CFLAGS="$CFLAGS $flag" ])
+       done
+    fi])
+fi # ac_cv_prog_gcc
 
 dnl Checks for header files.
 AC_HEADER_STDC