Restore deprecation warnings, except for older libpng.

* configure.in (WARN_CFLAGS): Remove -Wno-deprecated-declarations.
(HAVE_LIBPNG_PNG_H): Don't bother checking for this if we have png.h.
(PNG_DEPRECATED): Define when compiling with older PNG versions.

2 files changed, 21 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index d201b0ba12e..b883a4e000a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2012-07-08  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Restore deprecation warnings, except for older libpng.
+        * configure.in (WARN_CFLAGS): Remove -Wno-deprecated-declarations.
+        (HAVE_LIBPNG_PNG_H): Don't bother checking for this if we have png.h.
+        (PNG_DEPRECATED): Define when compiling with older PNG versions.
+
 2012-07-07  Andreas Schwab  <schwab@linux-m68k.org>
 
         * configure.in (WARN_CFLAGS): Add -Wno-deprecated-declarations.
diff --git a/configure.in b/configure.in
index 6a90c4869e5..4df12844b1d 100644
--- a/configure.in
+++ b/configure.in
@@ -697,7 +697,6 @@ else
   gl_WARN_ADD([-Wno-switch])           # Too many warnings for now
   gl_WARN_ADD([-Wno-unused-parameter]) # Too many warnings for now
   gl_WARN_ADD([-Wno-format-nonliteral])
-  gl_WARN_ADD([-Wno-deprecated-declarations]) # triggered by libpng
 
   # In spite of excluding -Wlogical-op above, it is enabled, as of
   # gcc 4.5.0 20090517.
@@ -2451,7 +2450,7 @@ if test "${HAVE_X11}" = "yes"; then
   if test "${with_png}" != "no"; then
     # Debian unstable as of July 2003 has multiple libpngs, and puts png.h
     # in /usr/include/libpng.
-    AC_CHECK_HEADERS(png.h libpng/png.h)
+    AC_CHECK_HEADERS(png.h libpng/png.h, break)
     if test "$ac_cv_header_png_h" = yes || test "$ac_cv_header_libpng_png_h" = yes ; then
       AC_CHECK_LIB(png, png_get_channels, HAVE_PNG=yes, , -lz -lm)
     fi
@@ -2460,6 +2459,19 @@ if test "${HAVE_X11}" = "yes"; then
   if test "${HAVE_PNG}" = "yes"; then
     AC_DEFINE(HAVE_PNG, 1, [Define to 1 if you have the png library (-lpng).])
     LIBPNG="-lpng -lz -lm"
+
+    AC_CHECK_DECL(png_longjmp,
+      [],
+      [AC_DEFINE(PNG_DEPRECATED, [],
+         [Define to empty to suppress deprecation warnings when building
+          with --enable-gcc-warnings and with libpng versions before 1.5,
+          which lack png_longjmp.])],
+      [[#ifdef HAVE_LIBPNG_PNG_H
+        # include <libpng/png.h>
+        #else
+        # include <png.h>
+        #endif
+      ]])
   fi
 fi
 AC_SUBST(LIBPNG)