Rework how we avoid clang's -Wunused-function

The previous technique to avoid this was to have explicit

(void)(wuffs_foo__bar_baz);

no-op lines of code. However, on MSVC, this triggers warning C4551
"function call missing argument list".

https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4551
says that "A function call must include the open and close parentheses".
But this is not a function call, it is casting the function pointer.
This false positive is a bug in MSVC, but we work around it for Wuffs.

internal/cgen/base/all-impl.c

@@ -30,6 +30,12 @@
 #include <stdint.h>
 #include <string.h>
 
+// GCC does not warn for unused *static inline* functions, but clang does.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -40,9 +46,19 @@ extern "C" {
 }  // extern "C"
 #endif
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
 // WUFFS C HEADER ENDS HERE.
 #ifdef WUFFS_IMPLEMENTATION
 
+// GCC does not warn for unused *static inline* functions, but clang does.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -105,6 +121,10 @@ const uint64_t wuffs_base__low_bits_mask__u64[65] = {
 }  // extern "C"
 #endif
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
 #endif  // WUFFS_IMPLEMENTATION
 
 // !! WUFFS MONOLITHIC RELEASE DISCARDS EVERYTHING BELOW.

internal/cgen/base/core-private.h

@@ -420,56 +420,3 @@ wuffs_base__table_u8__row(wuffs_base__table_u8 t, uint32_t y) {
 // ---------------- Slices and Tables (Utility)
 
 #define wuffs_base__utility__null_slice_u8 wuffs_base__null_slice_u8
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__core_private()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__core_private() {
-  (void)(wuffs_base__ignore_status);
-  (void)(wuffs_base__load_u16be);
-  (void)(wuffs_base__load_u16le);
-  (void)(wuffs_base__load_u24be);
-  (void)(wuffs_base__load_u24le);
-  (void)(wuffs_base__load_u32be);
-  (void)(wuffs_base__load_u32le);
-  (void)(wuffs_base__load_u40be);
-  (void)(wuffs_base__load_u40le);
-  (void)(wuffs_base__load_u48be);
-  (void)(wuffs_base__load_u48le);
-  (void)(wuffs_base__load_u56be);
-  (void)(wuffs_base__load_u56le);
-  (void)(wuffs_base__load_u64be);
-  (void)(wuffs_base__load_u64le);
-  (void)(wuffs_base__load_u8be);
-  (void)(wuffs_base__slice_u8__copy_from_slice);
-  (void)(wuffs_base__slice_u8__prefix);
-  (void)(wuffs_base__slice_u8__suffix);
-  (void)(wuffs_base__store_u16be);
-  (void)(wuffs_base__store_u16le);
-  (void)(wuffs_base__store_u24be);
-  (void)(wuffs_base__store_u24le);
-  (void)(wuffs_base__store_u32be);
-  (void)(wuffs_base__store_u32le);
-  (void)(wuffs_base__store_u40be);
-  (void)(wuffs_base__store_u40le);
-  (void)(wuffs_base__store_u48be);
-  (void)(wuffs_base__store_u48le);
-  (void)(wuffs_base__store_u56be);
-  (void)(wuffs_base__store_u56le);
-  (void)(wuffs_base__store_u64be);
-  (void)(wuffs_base__store_u64le);
-  (void)(wuffs_base__store_u8be);
-  (void)(wuffs_base__table_u8__row);
-  (void)(wuffs_base__u16__sat_add_indirect);
-  (void)(wuffs_base__u16__sat_sub_indirect);
-  (void)(wuffs_base__u32__sat_add_indirect);
-  (void)(wuffs_base__u32__sat_sub_indirect);
-  (void)(wuffs_base__u64__sat_add_indirect);
-  (void)(wuffs_base__u64__sat_sub_indirect);
-  (void)(wuffs_base__u8__sat_add_indirect);
-  (void)(wuffs_base__u8__sat_sub_indirect);
-}

internal/cgen/base/core-public.h

@@ -425,44 +425,3 @@ wuffs_base__slice_u8__subslice_ij(wuffs_base__slice_u8 s,
   }
   return wuffs_base__make_slice_u8(NULL, 0);
 }
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__core_public()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__core_public() {
-  (void)(wuffs_base__make_empty_struct);
-  (void)(wuffs_base__make_slice_u16);
-  (void)(wuffs_base__make_slice_u32);
-  (void)(wuffs_base__make_slice_u64);
-  (void)(wuffs_base__make_slice_u8);
-  (void)(wuffs_base__null_slice_u8);
-  (void)(wuffs_base__null_table_u8);
-  (void)(wuffs_base__slice_u8__subslice_i);
-  (void)(wuffs_base__slice_u8__subslice_ij);
-  (void)(wuffs_base__slice_u8__subslice_j);
-  (void)(wuffs_base__status__is_complete);
-  (void)(wuffs_base__status__is_error);
-  (void)(wuffs_base__status__is_ok);
-  (void)(wuffs_base__status__is_suspension);
-  (void)(wuffs_base__status__is_warning);
-  (void)(wuffs_base__u16__max);
-  (void)(wuffs_base__u16__min);
-  (void)(wuffs_base__u16__sat_add);
-  (void)(wuffs_base__u16__sat_sub);
-  (void)(wuffs_base__u32__max);
-  (void)(wuffs_base__u32__min);
-  (void)(wuffs_base__u32__sat_add);
-  (void)(wuffs_base__u32__sat_sub);
-  (void)(wuffs_base__u64__max);
-  (void)(wuffs_base__u64__min);
-  (void)(wuffs_base__u64__sat_add);
-  (void)(wuffs_base__u64__sat_sub);
-  (void)(wuffs_base__u8__max);
-  (void)(wuffs_base__u8__min);
-  (void)(wuffs_base__u8__sat_add);
-  (void)(wuffs_base__u8__sat_sub);
-}

internal/cgen/base/image-public.h

@@ -1109,56 +1109,3 @@ wuffs_base__pixel_swizzler::swizzle_packed(wuffs_base__slice_u8 dst,
 }
 
 #endif  // __cplusplus
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__image_public()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__image_public() {
-  (void)(wuffs_base__frame_config__blend);
-  (void)(wuffs_base__frame_config__bounds);
-  (void)(wuffs_base__frame_config__disposal);
-  (void)(wuffs_base__frame_config__duration);
-  (void)(wuffs_base__frame_config__height);
-  (void)(wuffs_base__frame_config__index);
-  (void)(wuffs_base__frame_config__io_position);
-  (void)(wuffs_base__frame_config__update);
-  (void)(wuffs_base__frame_config__width);
-  (void)(wuffs_base__image_config__first_frame_io_position);
-  (void)(wuffs_base__image_config__first_frame_is_opaque);
-  (void)(wuffs_base__image_config__invalidate);
-  (void)(wuffs_base__image_config__is_valid);
-  (void)(wuffs_base__image_config__set);
-  (void)(wuffs_base__null_frame_config());
-  (void)(wuffs_base__null_image_config());
-  (void)(wuffs_base__null_pixel_buffer());
-  (void)(wuffs_base__null_pixel_config());
-  (void)(wuffs_base__pixel_buffer__palette);
-  (void)(wuffs_base__pixel_buffer__pixel_format);
-  (void)(wuffs_base__pixel_buffer__plane);
-  (void)(wuffs_base__pixel_buffer__set_from_slice);
-  (void)(wuffs_base__pixel_config__bounds);
-  (void)(wuffs_base__pixel_config__height);
-  (void)(wuffs_base__pixel_config__invalidate);
-  (void)(wuffs_base__pixel_config__is_valid);
-  (void)(wuffs_base__pixel_config__pixbuf_len);
-  (void)(wuffs_base__pixel_config__pixel_format);
-  (void)(wuffs_base__pixel_config__pixel_subsampling);
-  (void)(wuffs_base__pixel_config__set);
-  (void)(wuffs_base__pixel_config__width);
-  (void)(wuffs_base__pixel_format__bits_per_pixel);
-  (void)(wuffs_base__pixel_format__is_indexed);
-  (void)(wuffs_base__pixel_format__is_packed);
-  (void)(wuffs_base__pixel_format__is_planar);
-  (void)(wuffs_base__pixel_format__is_valid);
-  (void)(wuffs_base__pixel_format__num_planes);
-  (void)(wuffs_base__pixel_subsampling__bias_x);
-  (void)(wuffs_base__pixel_subsampling__bias_y);
-  (void)(wuffs_base__pixel_subsampling__shift_x);
-  (void)(wuffs_base__pixel_subsampling__shift_y);
-  (void)(wuffs_base__pixel_swizzler__prepare);
-  (void)(wuffs_base__pixel_swizzler__swizzle_packed);
-}

internal/cgen/base/io-private.h

@@ -279,28 +279,3 @@ wuffs_base__io_writer__set_mark(wuffs_base__io_writer* o, uint8_t* mark) {
 
 #define wuffs_base__utility__null_io_reader wuffs_base__null_io_reader
 #define wuffs_base__utility__null_io_writer wuffs_base__null_io_writer
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__io_private()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__io_private() {
-  (void)(wuffs_base__io_buffer__is_valid);
-  (void)(wuffs_base__io_reader__is_eof);
-  (void)(wuffs_base__io_reader__is_valid);
-  (void)(wuffs_base__io_reader__set);
-  (void)(wuffs_base__io_reader__set_limit);
-  (void)(wuffs_base__io_reader__set_mark);
-  (void)(wuffs_base__io_reader__take);
-  (void)(wuffs_base__io_writer__copy_from_slice);
-  (void)(wuffs_base__io_writer__copy_n_from_history);
-  (void)(wuffs_base__io_writer__copy_n_from_history_fast);
-  (void)(wuffs_base__io_writer__copy_n_from_reader);
-  (void)(wuffs_base__io_writer__copy_n_from_slice);
-  (void)(wuffs_base__io_writer__is_valid);
-  (void)(wuffs_base__io_writer__set);
-  (void)(wuffs_base__io_writer__set_mark);
-}

internal/cgen/base/io-public.h

@@ -205,24 +205,3 @@ wuffs_base__io_buffer__struct::writer_io_position() {
 }
 
 #endif  // __cplusplus
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__io_public()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__io_public() {
-  (void)(wuffs_base__io_buffer__compact);
-  (void)(wuffs_base__io_buffer__reader);
-  (void)(wuffs_base__io_buffer__reader_io_position);
-  (void)(wuffs_base__io_buffer__writer);
-  (void)(wuffs_base__io_buffer__writer_io_position);
-  (void)(wuffs_base__make_io_buffer);
-  (void)(wuffs_base__make_io_buffer_meta);
-  (void)(wuffs_base__null_io_buffer);
-  (void)(wuffs_base__null_io_buffer_meta);
-  (void)(wuffs_base__null_io_reader);
-  (void)(wuffs_base__null_io_writer);
-}

internal/cgen/base/memory-public.h

@@ -72,17 +72,3 @@ wuffs_base__malloc_slice_u64(void* (*malloc_func)(size_t), uint64_t num_u64) {
   }
   return wuffs_base__make_slice_u64(NULL, 0);
 }
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__memory_public()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__memory_public() {
-  (void)(wuffs_base__malloc_slice_u16);
-  (void)(wuffs_base__malloc_slice_u32);
-  (void)(wuffs_base__malloc_slice_u64);
-  (void)(wuffs_base__malloc_slice_u8);
-}

internal/cgen/base/range-private.h

@@ -65,20 +65,3 @@ wuffs_base__range_ie_u64__get_max_excl(const wuffs_base__range_ie_u64* r) {
 #define wuffs_base__utility__make_rect_ii_u32 wuffs_base__make_rect_ii_u32
 #define wuffs_base__utility__make_rect_ie_u32 wuffs_base__make_rect_ie_u32
 
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__range_private()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__range_private() {
-  (void)(wuffs_base__range_ie_u32__get_max_excl);
-  (void)(wuffs_base__range_ie_u32__get_min_incl);
-  (void)(wuffs_base__range_ie_u64__get_max_excl);
-  (void)(wuffs_base__range_ie_u64__get_min_incl);
-  (void)(wuffs_base__range_ii_u32__get_max_incl);
-  (void)(wuffs_base__range_ii_u32__get_min_incl);
-  (void)(wuffs_base__range_ii_u64__get_max_incl);
-  (void)(wuffs_base__range_ii_u64__get_min_incl);
-}

internal/cgen/base/range-public.h

@@ -797,59 +797,3 @@ wuffs_base__rect_ie_u32::height() {
 }
 
 #endif  // __cplusplus
-
-// ---------------- Bureaucracy re -Wunused-function
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__range_public()
-    WUFFS_BASE__POTENTIALLY_UNUSED;
-
-static inline void
-wuffs_base__acknowledge_potentially_unused_functions__range_public() {
-  (void)(wuffs_base__make_range_ie_u32);
-  (void)(wuffs_base__make_range_ie_u64);
-  (void)(wuffs_base__make_range_ii_u32);
-  (void)(wuffs_base__make_range_ii_u64);
-  (void)(wuffs_base__make_rect_ie_u32);
-  (void)(wuffs_base__make_rect_ii_u32);
-  (void)(wuffs_base__range_ie_u32__contains);
-  (void)(wuffs_base__range_ie_u32__contains_range);
-  (void)(wuffs_base__range_ie_u32__equals);
-  (void)(wuffs_base__range_ie_u32__intersect);
-  (void)(wuffs_base__range_ie_u32__is_empty);
-  (void)(wuffs_base__range_ie_u32__length);
-  (void)(wuffs_base__range_ie_u32__unite);
-  (void)(wuffs_base__range_ie_u64__contains);
-  (void)(wuffs_base__range_ie_u64__contains_range);
-  (void)(wuffs_base__range_ie_u64__equals);
-  (void)(wuffs_base__range_ie_u64__intersect);
-  (void)(wuffs_base__range_ie_u64__is_empty);
-  (void)(wuffs_base__range_ie_u64__length);
-  (void)(wuffs_base__range_ie_u64__unite);
-  (void)(wuffs_base__range_ii_u32__contains);
-  (void)(wuffs_base__range_ii_u32__contains_range);
-  (void)(wuffs_base__range_ii_u32__equals);
-  (void)(wuffs_base__range_ii_u32__intersect);
-  (void)(wuffs_base__range_ii_u32__is_empty);
-  (void)(wuffs_base__range_ii_u32__unite);
-  (void)(wuffs_base__range_ii_u64__contains);
-  (void)(wuffs_base__range_ii_u64__contains_range);
-  (void)(wuffs_base__range_ii_u64__equals);
-  (void)(wuffs_base__range_ii_u64__intersect);
-  (void)(wuffs_base__range_ii_u64__is_empty);
-  (void)(wuffs_base__range_ii_u64__unite);
-  (void)(wuffs_base__rect_ie_u32__contains);
-  (void)(wuffs_base__rect_ie_u32__contains_rect);
-  (void)(wuffs_base__rect_ie_u32__equals);
-  (void)(wuffs_base__rect_ie_u32__height);
-  (void)(wuffs_base__rect_ie_u32__intersect);
-  (void)(wuffs_base__rect_ie_u32__is_empty);
-  (void)(wuffs_base__rect_ie_u32__unite);
-  (void)(wuffs_base__rect_ie_u32__width);
-  (void)(wuffs_base__rect_ii_u32__contains);
-  (void)(wuffs_base__rect_ie_u32__contains_rect);
-  (void)(wuffs_base__rect_ii_u32__equals);
-  (void)(wuffs_base__rect_ii_u32__intersect);
-  (void)(wuffs_base__rect_ii_u32__is_empty);
-  (void)(wuffs_base__rect_ii_u32__unite);
-}