3 files changed, 23 insertions, 21 deletions
diff --git a/thirdparty/libpng/arm/arm_init.c b/thirdparty/libpng/arm/arm_init.c
index a34ecdbef7..ab22525b38 100644
--- a/thirdparty/libpng/arm/arm_init.c
+++ b/thirdparty/libpng/arm/arm_init.c
@@ -1,7 +1,7 @@
 
 /* arm_init.c - NEON optimised filter functions
  *
- * Copyright (c) 2018 Cosmin Truta
+ * Copyright (c) 2018-2022 Cosmin Truta
  * Copyright (c) 2014,2016 Glenn Randers-Pehrson
  * Written by Mans Rullgard, 2011.
  *
@@ -10,9 +10,7 @@
  * and license in png.h
  */
 
-/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
- * called.
- */
+/* This module requires POSIX 1003.1 functions. */
 #define _POSIX_SOURCE 1
 
 #include "../pngpriv.h"
@@ -33,21 +31,23 @@
  * has partial support is contrib/arm-neon/linux.c - a generic Linux
  * implementation which reads /proc/cpufino.
  */
+#include <signal.h> /* for sig_atomic_t */
+
 #ifndef PNG_ARM_NEON_FILE
-#  ifdef __linux__
-#     define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+#  if defined(__aarch64__) || defined(_M_ARM64)
+     /* ARM Neon is expected to be unconditionally available on ARM64. */
+#    error "PNG_ARM_NEON_CHECK_SUPPORTED must not be defined on this platform"
+#  elif defined(__linux__)
+#    define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+#  else
+#    error "No support for run-time ARM Neon checking; use compile-time options"
 #  endif
 #endif
 
-#ifdef PNG_ARM_NEON_FILE
-
-#include <signal.h> /* for sig_atomic_t */
 static int png_have_neon(png_structp png_ptr);
-#include PNG_ARM_NEON_FILE
-
-#else  /* PNG_ARM_NEON_FILE */
-#  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
-#endif /* PNG_ARM_NEON_FILE */
+#ifdef PNG_ARM_NEON_FILE
+#  include PNG_ARM_NEON_FILE
+#endif
 #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
 
 #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
diff --git a/thirdparty/libpng/arm/filter_neon_intrinsics.c b/thirdparty/libpng/arm/filter_neon_intrinsics.c
index 553c0be21c..4466d48b20 100644
--- a/thirdparty/libpng/arm/filter_neon_intrinsics.c
+++ b/thirdparty/libpng/arm/filter_neon_intrinsics.c
@@ -18,7 +18,7 @@
 /* This code requires -mfpu=neon on the command line: */
 #if PNG_ARM_NEON_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
 
-#if defined(_MSC_VER) && defined(_M_ARM64)
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
 #  include <arm64_neon.h>
 #else
 #  include <arm_neon.h>
diff --git a/thirdparty/libpng/arm/palette_neon_intrinsics.c b/thirdparty/libpng/arm/palette_neon_intrinsics.c
index b4d1fd2abf..92c7d6f9f6 100644
--- a/thirdparty/libpng/arm/palette_neon_intrinsics.c
+++ b/thirdparty/libpng/arm/palette_neon_intrinsics.c
@@ -14,7 +14,7 @@
 
 #if PNG_ARM_NEON_IMPLEMENTATION == 1
 
-#if defined(_MSC_VER) && defined(_M_ARM64)
+#if defined(_MSC_VER) && !defined(__clang__) && defined(_M_ARM64)
 #  include <arm64_neon.h>
 #else
 #  include <arm_neon.h>
@@ -30,8 +30,6 @@ png_riffle_palette_neon(png_structrp png_ptr)
    int num_trans = png_ptr->num_trans;
    int i;
 
-   png_debug(1, "in png_riffle_palette_neon");
-
    /* Initially black, opaque. */
    uint8x16x4_t w = {{
       vdupq_n_u8(0x00),
@@ -40,6 +38,8 @@ png_riffle_palette_neon(png_structrp png_ptr)
       vdupq_n_u8(0xff),
    }};
 
+   png_debug(1, "in png_riffle_palette_neon");
+
    /* First, riffle the RGB colours into an RGBA8 palette.
     * The alpha component is set to opaque for now.
     */
@@ -65,11 +65,12 @@ png_do_expand_palette_rgba8_neon(png_structrp png_ptr, png_row_infop row_info,
    png_uint_32 row_width = row_info->width;
    const png_uint_32 *riffled_palette =
       (const png_uint_32 *)png_ptr->riffled_palette;
-   const png_int_32 pixels_per_chunk = 4;
-   int i;
+   const png_uint_32 pixels_per_chunk = 4;
+   png_uint_32 i;
 
    png_debug(1, "in png_do_expand_palette_rgba8_neon");
 
+   PNG_UNUSED(row)
    if (row_width < pixels_per_chunk)
       return 0;
 
@@ -109,10 +110,11 @@ png_do_expand_palette_rgb8_neon(png_structrp png_ptr, png_row_infop row_info,
    png_uint_32 row_width = row_info->width;
    png_const_bytep palette = (png_const_bytep)png_ptr->palette;
    const png_uint_32 pixels_per_chunk = 8;
-   int i;
+   png_uint_32 i;
 
    png_debug(1, "in png_do_expand_palette_rgb8_neon");
 
+   PNG_UNUSED(row)
    if (row_width <= pixels_per_chunk)
       return 0;