[libpng16] Removed or marked PNG_UNUSED some harmless "dead assignments"

reported by clang scan-build.

ANNOUNCE

 
-Libpng 1.6.8beta02 - November 24, 2013
+Libpng 1.6.8beta02 - November 25, 2013
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -26,7 +26,7 @@ Other information:
 
 Changes since the last public release (1.6.7):
 
-Version 1.6.8beta01 [November 24, 2013]
+Version 1.6.8beta01 [November 25, 2013]
   Changed #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED in pngpread.c to
     #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED to be consistent with
     what is in pngpriv.h.
@@ -35,16 +35,18 @@ Version 1.6.8beta01 [November 24, 2013]
   Added "-Wall" to CFLAGS in contrib/pngminim/*/makefile
   Conditionally compile some unused functions reported by -Wall in pngminim.
   Fixed 'minimal' builds. Various obviously useful minimal configurations
-    don't build because of missing contrib/libtests test programs and overly
-    complex dependencies in scripts/pnglibconf.dfa. This change adds
-    contrib/conftest/*.dfa files that can be used in automatic build
+    don't build because of missing contrib/libtests test programs and
+    overly complex dependencies in scripts/pnglibconf.dfa. This change
+    adds contrib/conftest/*.dfa files that can be used in automatic build
     scripts to ensure that these configurations continue to build.
   Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
   Fixed pngvalid 'fail' function declaration on the Intel C Compiler.
     This reverts to the previous 'static' implementation and works round
     the 'unused static function' warning by using PNG_UNUSED().
 
-Version 1.6.8beta02 [November 24, 2013]
+Version 1.6.8beta02 [November 25, 2013]
+  Removed or marked PNG_UNUSED some harmless "dead assignments" reported
+    by clang scan-build.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4721,16 +4721,18 @@ Version 1.6.8beta01 [November 24, 2013]
   Conditionally compile some unused functions reported by -Wall in
     pngminim.
   Fixed 'minimal' builds. Various obviously useful minimal configurations
-    don't build because of missing contrib/libtests test programs and overly
-    complex dependencies in scripts/pnglibconf.dfa. This change adds
-    contrib/conftest/*.dfa files that can be used in automatic build
+    don't build because of missing contrib/libtests test programs and
+    overly complex dependencies in scripts/pnglibconf.dfa. This change
+    adds contrib/conftest/*.dfa files that can be used in automatic build
     scripts to ensure that these configurations continue to build.
   Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
   Fixed pngvalid 'fail' function declaration on the Intel C Compiler.
     This reverts to the previous 'static' implementation and works round
     the 'unused static function' warning by using PNG_UNUSED().
 
-Version 1.6.8beta02 [November 24, 2013]
+Version 1.6.8beta02 [November 25, 2013]
+  Removed or marked PNG_UNUSED some harmless "dead assignments" reported
+    by clang scan-build.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

png.c

@@ -201,6 +201,7 @@ png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
          pos = png_safecat(m, (sizeof m), pos, user_png_ver);
          pos = png_safecat(m, (sizeof m), pos, " but running with ");
          pos = png_safecat(m, (sizeof m), pos, png_libpng_ver);
+         PNG_UNUSED(pos)
 
          png_warning(png_ptr, m);
 #endif
@@ -772,13 +773,13 @@ png_get_copyright(png_const_structrp png_ptr)
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-     "libpng version 1.6.8beta02 - November 24, 2013" PNG_STRING_NEWLINE \
+     "libpng version 1.6.8beta02 - November 25, 2013" PNG_STRING_NEWLINE \
      "Copyright (c) 1998-2013 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE;
 #  else
-      return "libpng version 1.6.8beta02 - November 24, 2013\
+      return "libpng version 1.6.8beta02 - November 25, 2013\
       Copyright (c) 1998-2013 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -1726,6 +1727,7 @@ png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
 #  endif
    /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
    pos = png_safecat(message, (sizeof message), pos, reason);
+   PNG_UNUSED(pos)
 
    /* This is recoverable, but make it unconditionally an app_error on write to
     * avoid writing invalid ICC profiles into PNG files.  (I.e.  we handle them

pngread.c

@@ -2811,7 +2811,6 @@ png_image_read_and_map(png_voidp argument)
          break;
 
       default:
-         passes = 0;
          png_error(png_ptr, "unknown interlace type");
    }
 
@@ -3130,7 +3129,6 @@ png_image_read_composite(png_voidp argument)
          break;
 
       default:
-         passes = 0;
          png_error(png_ptr, "unknown interlace type");
    }
 
@@ -3279,7 +3277,6 @@ png_image_read_background(png_voidp argument)
          break;
 
       default:
-         passes = 0;
          png_error(png_ptr, "unknown interlace type");
    }
 

pngrutil.c

@@ -3876,7 +3876,6 @@ png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
       if (pb < pa) pa = pb, a = b;
       if (pc < pa) a = c;
 
-      c = b;
       a += *row;
       *row++ = (png_byte)a;
    }