external: libpng: fix numerous compiler warnings

Clean up the code for unused variables to handle them
a bit more elegantly.

Change-Id: I8b01c27673128719dad74276599d5a286c4dd412

9 files changed, 23 insertions, 18 deletions

diff --git a/png.c b/png.c
index 5fea8b1..3f3ae0b 100644
--- a/png.c
+++ b/png.c
@@ -719,7 +719,7 @@ png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
 png_charp PNGAPI
 png_get_copyright(png_structp png_ptr)
 {
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   UNUSED(png_ptr);  /* Silence compiler warning about unused png_ptr */
 #ifdef PNG_STRING_COPYRIGHT
       return PNG_STRING_COPYRIGHT
 #else
@@ -751,7 +751,7 @@ png_charp PNGAPI
 png_get_libpng_ver(png_structp png_ptr)
 {
    /* Version of *.c files used when building libpng */
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   UNUSED(png_ptr);  /* Silence compiler warning about unused png_ptr */
    return ((png_charp) PNG_LIBPNG_VER_STRING);
 }
 
@@ -759,7 +759,7 @@ png_charp PNGAPI
 png_get_header_ver(png_structp png_ptr)
 {
    /* Version of *.h files used when building libpng */
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   UNUSED(png_ptr);  /* Silence compiler warning about unused png_ptr */
    return ((png_charp) PNG_LIBPNG_VER_STRING);
 }
 
@@ -767,7 +767,7 @@ png_charp PNGAPI
 png_get_header_version(png_structp png_ptr)
 {
    /* Returns longer string containing both version and date */
-   png_ptr = png_ptr;  /* Silence compiler warning about unused png_ptr */
+   UNUSED(png_ptr);  /* Silence compiler warning about unused png_ptr */
 #ifdef __STDC__
    return ((png_charp) PNG_HEADER_VERSION_STRING
 #ifndef PNG_READ_SUPPORTED
diff --git a/png.h b/png.h
index d379dea..a968e94 100644
--- a/png.h
+++ b/png.h
@@ -468,6 +468,9 @@
 #ifndef PNG_H
 #define PNG_H
 
+/* This is used to quiet the compiler for unused variables */
+#define UNUSED(x) (void)(x);
+
 /* This is not the place to learn how to use libpng.  The file libpng.txt
  * describes how to use libpng, and the file example.c summarizes it
  * with some code on which to build.  This file is useful for looking
diff --git a/pngerror.c b/pngerror.c
index 025d52e..5b43790 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -348,7 +348,7 @@ png_default_warning(png_structp png_ptr, png_const_charp warning_message)
 #else
    warning_message = warning_message; /* Make compiler happy */
 #endif
-   png_ptr = png_ptr; /* Make compiler happy */
+   UNUSED(png_ptr); /* Make compiler happy */
 }
 #endif /* PNG_WARNINGS_SUPPORTED */
 
diff --git a/pngget.c b/pngget.c
index d397329..1d61491 100644
--- a/pngget.c
+++ b/pngget.c
@@ -893,7 +893,7 @@ png_uint_32 PNGAPI
 png_get_asm_flagmask (int flag_select)
 {
     /* Obsolete, to be removed from libpng-1.4.0 */
-    flag_select=flag_select;
+    UNUSED(flag_select);
     return 0L;
 }
 
@@ -903,7 +903,7 @@ png_uint_32 PNGAPI
 png_get_mmx_flagmask (int flag_select, int *compilerID)
 {
     /* Obsolete, to be removed from libpng-1.4.0 */
-    flag_select=flag_select;
+    UNUSED(flag_select);
     *compilerID = -1;   /* unknown (i.e., no asm/MMX code compiled) */
     return 0L;
 }
diff --git a/pngpread.c b/pngpread.c
index d066944..2ab4907 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1209,7 +1209,7 @@ png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
          png_error(png_ptr, "Out of place tEXt");
-         info_ptr = info_ptr; /* To quiet some compiler warnings */
+         UNUSED(info_ptr); /* To quiet some compiler warnings */
       }
 
 #ifdef PNG_MAX_MALLOC_64K
@@ -1307,7 +1307,7 @@ png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
       {
          png_error(png_ptr, "Out of place zTXt");
-         info_ptr = info_ptr; /* To quiet some compiler warnings */
+         UNUSED(info_ptr); /* To quiet some compiler warnings */
       }
 
 #ifdef PNG_MAX_MALLOC_64K
@@ -1643,7 +1643,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
 #endif
          png_chunk_error(png_ptr, "unknown critical chunk");
 
-      info_ptr = info_ptr; /* To quiet some compiler warnings */
+      UNUSED(info_ptr); /* To quiet some compiler warnings */
    }
 
 #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
diff --git a/pngread.c b/pngread.c
index b301d41..9f1cd74 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1699,8 +1699,8 @@ png_read_png(png_structp png_ptr, png_infop info_ptr,
    /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
    png_read_end(png_ptr, info_ptr);
 
-   transforms = transforms; /* Quiet compiler warnings */
-   params = params;
+   UNUSED(transforms); /* Quiet compiler warnings */
+   UNUSED(params);
 
 }
 #endif /* PNG_INFO_IMAGE_SUPPORTED */
diff --git a/pngrutil.c b/pngrutil.c
index d49c25b..9407fe4 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -692,7 +692,7 @@ png_handle_IEND(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
    png_crc_finish(png_ptr, length);
 
-   info_ptr = info_ptr; /* Quiet compiler warnings about unused info_ptr */
+   UNUSED(info_ptr); /* Quiet compiler warnings about unused info_ptr */
 }
 
 #ifdef PNG_READ_gAMA_SUPPORTED
@@ -3074,6 +3074,8 @@ png_read_filter_row(png_structp png_ptr, png_row_infop row_info, png_bytep row,
          break;
    }
 #endif
+
+   UNUSED(png_ptr);
 }
 
 #ifdef PNG_INDEX_SUPPORTED
diff --git a/pngset.c b/pngset.c
index c9ab8f6..168edb1 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1184,7 +1184,7 @@ png_set_asm_flags (png_structp png_ptr, png_uint_32 asm_flags)
 /* Obsolete as of libpng-1.2.20 and will be removed from libpng-1.4.0 */
     if (png_ptr != NULL)
     png_ptr->asm_flags = 0;
-    asm_flags = asm_flags; /* Quiet the compiler */
+    UNUSED(asm_flags); /* Quiet the compiler */
 }
 
 /* This function was added to libpng 1.2.0 */
@@ -1197,8 +1197,8 @@ png_set_mmx_thresholds (png_structp png_ptr,
     if (png_ptr == NULL)
        return;
     /* Quiet the compiler */
-    mmx_bitdepth_threshold = mmx_bitdepth_threshold;
-    mmx_rowbytes_threshold = mmx_rowbytes_threshold;
+    UNUSED(mmx_bitdepth_threshold);
+    UNUSED(mmx_rowbytes_threshold);
 }
 #endif /* ?PNG_ASSEMBLER_CODE_SUPPORTED */
 
diff --git a/pngwrite.c b/pngwrite.c
index 1d8c53f..646c3d3 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1586,8 +1586,8 @@ png_write_png(png_structp png_ptr, png_infop info_ptr,
    /* It is REQUIRED to call this to finish writing the rest of the file */
    png_write_end(png_ptr, info_ptr);
 
-   transforms = transforms; /* Quiet compiler warnings */
-   params = params;
+   UNUSED(transforms); /* Quiet compiler warnings */
+   UNUSED(params);
 }
 #endif
 #endif /* PNG_WRITE_SUPPORTED */