improved static_assert compat

Use static_assert instead of _Static_assert, which is deprecated in c23.

- compat using static_assert macro defined in assert.h since c11 (until 23)
- dismiss for C prior to C11, but just for MSVS <=2015 (otherwise assume
it as an error, eg. missing /std with MSVC)

.clang-format

@@ -9,6 +9,7 @@ BraceWrapping:
 ColumnLimit: 120
 IndentWidth: 4
 PointerAlignment: Left
+IndentPPDirectives: BeforeHash
 ReflowComments: true
 SpacesInParens: Custom
 SpacesInParensOptions:

src/gpujpeg_common_internal.h

@@ -43,10 +43,20 @@
 #include "../libgpujpeg/gpujpeg_type.h"
 #include "gpujpeg_util.h"
 
+// static_assert compat
+#if __STDC_VERSION__ < 202311L
+    #include <assert.h> // static_assert compat macro in C11-C17
+#elif __STDC_VERSION__ < 201112L
+    #if defined _MSC_VER && _MSC_VER <= 1900
+        #define static_assert(cond, msg)
+    #else
+        #error "compiler is not supporting C11 - perhaps an error?"
+    #endif
+#endif
+
 // VS 2015 compat
 #if defined _MSC_VER && _MSC_VER <= 1900
 #define __func__ ""
-#define _Static_assert(cond, msg)
 #endif // VS <=2015
 
 /** Contants */

src/gpujpeg_huffman_cpu_decoder.c

@@ -187,7 +187,7 @@ gpujpeg_huffman_cpu_decoder_value_from_category(int category, int offset)
 #pragma GCC diagnostic ignored "-Wshift-negative-value"
 #pragma GCC diagnostic ignored "-Wpedantic"
 #endif // defined __GNUC_
-    _Static_assert((-1)<<1 == -2, "Implementation defined behavior doesn't work as assumed.");
+    static_assert((-1)<<1 == -2, "Implementation defined behavior doesn't work as assumed.");
     //start[i] is the starting value in this category; surely it is below zero
     // entry n is (-1 << n) + 1
     static const int start[16] = { 

src/gpujpeg_reader.c

@@ -695,7 +695,7 @@ static const char *array_serialize(int comp_count, const uint8_t *comp_id) {
  * checks component ID to determine if JPEG is in YCbCr (component IDs 1, 2, 3) or RGB (component IDs 'R', 'G', 'B')
  */
 static enum gpujpeg_color_space gpujpeg_reader_process_cid(int comp_count, uint8_t *comp_id, enum gpujpeg_color_space header_color_space) {
-    _Static_assert(GPUJPEG_MAX_COMPONENT_COUNT >= 3, "An array of at least 3 components expected");
+    static_assert(GPUJPEG_MAX_COMPONENT_COUNT >= 3, "An array of at least 3 components expected");
     static const uint8_t ycbcr_ids[] = { 1, 2, 3 };
     static const uint8_t rgb_ids[] = { 'R', 'G', 'B' };
     static const uint8_t bg_rgb_ids[] = { 'r', 'g', 'b' }; // big gamut sRGB (see ILG libjpeg - seemingly handled as above)
@@ -1468,7 +1468,7 @@ adjust_pixel_format(struct gpujpeg_parameters * param, struct gpujpeg_image_para
 static void
 adjust_format(struct gpujpeg_parameters* param, struct gpujpeg_image_parameters* param_image)
 {
-    _Static_assert(GPUJPEG_PIXFMT_AUTODETECT < 0, "enum gpujpeg_pixel_format type should be signed");
+    static_assert(GPUJPEG_PIXFMT_AUTODETECT < 0, "enum gpujpeg_pixel_format type should be signed");
     if ( param_image->color_space == GPUJPEG_CS_DEFAULT ) {
         if ( param_image->pixel_format == GPUJPEG_U8 ||
              (param_image->pixel_format <= GPUJPEG_PIXFMT_AUTODETECT && param->comp_count == 1) ) {

src/gpujpeg_table.c

@@ -311,14 +311,14 @@ gpujpeg_table_huffman_encoder_init(struct gpujpeg_table_huffman_encoder* table,
 {
     assert(comp_type == GPUJPEG_COMPONENT_LUMINANCE || comp_type == GPUJPEG_COMPONENT_CHROMINANCE);
     assert(huff_type == GPUJPEG_HUFFMAN_DC || huff_type == GPUJPEG_HUFFMAN_AC);
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_dc_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_dc_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_ac_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_ac_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_dc_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_dc_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_ac_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_ac_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_dc_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_dc_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_ac_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_ac_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_dc_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_dc_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_ac_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_ac_value), "table buffer too small");
 
     if ( comp_type == GPUJPEG_COMPONENT_LUMINANCE ) {
         if ( huff_type == GPUJPEG_HUFFMAN_DC ) {
@@ -348,14 +348,14 @@ gpujpeg_table_huffman_decoder_init(struct gpujpeg_table_huffman_decoder* table,
 {
     assert(comp_type == GPUJPEG_COMPONENT_LUMINANCE || comp_type == GPUJPEG_COMPONENT_CHROMINANCE);
     assert(huff_type == GPUJPEG_HUFFMAN_DC || huff_type == GPUJPEG_HUFFMAN_AC);
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_dc_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_dc_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_ac_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_ac_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_dc_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_dc_value), "table buffer too small");
-    _Static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_ac_bits), "table buffer too small");
-    _Static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_ac_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_dc_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_dc_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_y_ac_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_y_ac_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_dc_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_dc_value), "table buffer too small");
+    static_assert(sizeof(table->bits) >= sizeof(gpujpeg_table_huffman_cbcr_ac_bits), "table buffer too small");
+    static_assert(sizeof(table->huffval) >= sizeof(gpujpeg_table_huffman_cbcr_ac_value), "table buffer too small");
 
     if ( comp_type == GPUJPEG_COMPONENT_LUMINANCE ) {
         if ( huff_type == GPUJPEG_HUFFMAN_DC ) {