Put AVIF_NODISCARD after AVIF_API
It looks more consistent to have AVIF_API at the beginning of a function
declaration. It also looks nicer to have AVIF_NODISCARD right before the
function return type.
diff --git a/include/avif/avif.h b/include/avif/avif.h
index c54dd0d..c896124 100644
--- a/include/avif/avif.h
+++ b/include/avif/avif.h
@@ -11,6 +11,14 @@
extern "C" {
#endif
+// Define the internal macro AVIF_USE_NODISCARD if AVIF_NODISCARD will be defined as [[nodiscard]].
+// In this case, also use the standard [[...]] attribute syntax for GCC's visibility("default")
+// attribute to avoid compilation errors.
+#if defined(AVIF_ENABLE_NODISCARD) || (defined(__cplusplus) && __cplusplus >= 201703L) || \
+ (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
+#define AVIF_USE_NODISCARD 1
+#endif
+
// ---------------------------------------------------------------------------
// Export macros
@@ -31,7 +39,11 @@
#define AVIF_HELPER_EXPORT __declspec(dllexport)
#define AVIF_HELPER_IMPORT __declspec(dllimport)
#elif defined(__GNUC__) && __GNUC__ >= 4
+#if defined(AVIF_USE_NODISCARD)
+#define AVIF_HELPER_EXPORT [[gnu::visibility("default")]]
+#else
#define AVIF_HELPER_EXPORT __attribute__((visibility("default")))
+#endif
#define AVIF_HELPER_IMPORT
#else
#define AVIF_HELPER_EXPORT
@@ -48,8 +60,7 @@
#define AVIF_API
#endif // defined(AVIF_DLL)
-#if defined(AVIF_ENABLE_NODISCARD) || (defined(__cplusplus) && __cplusplus >= 201703L) || \
- (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
+#if defined(AVIF_USE_NODISCARD)
#define AVIF_NODISCARD [[nodiscard]]
#else
// Starting with 3.9, clang allows defining the warn_unused_result attribute for enums.
@@ -510,13 +521,13 @@
// These will return AVIF_FALSE if the resultant values violate any standards, and if so, the output
// values are not guaranteed to be complete or correct and should not be used.
-AVIF_NODISCARD AVIF_API avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
+AVIF_API AVIF_NODISCARD avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
const avifCleanApertureBox * clap,
uint32_t imageW,
uint32_t imageH,
avifPixelFormat yuvFormat,
avifDiagnostics * diag);
-AVIF_NODISCARD AVIF_API avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
+AVIF_API AVIF_NODISCARD avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
const avifCropRect * cropRect,
uint32_t imageW,
uint32_t imageH,
@@ -705,10 +716,10 @@
// Converts a avifGainMapMetadataDouble to avifGainMapMetadata by converting double values
// to the closest uint32_t fractions.
// Returns AVIF_FALSE if some field values are < 0 or > UINT32_MAX.
-AVIF_NODISCARD AVIF_API avifBool avifGainMapMetadataDoubleToFractions(avifGainMapMetadata * dst, const avifGainMapMetadataDouble * src);
+AVIF_API AVIF_NODISCARD avifBool avifGainMapMetadataDoubleToFractions(avifGainMapMetadata * dst, const avifGainMapMetadataDouble * src);
// Converts a avifGainMapMetadata to avifGainMapMetadataDouble by converting fractions to double values.
// Returns AVIF_FALSE if some denominators are zero.
-AVIF_NODISCARD AVIF_API avifBool avifGainMapMetadataFractionsToDouble(avifGainMapMetadataDouble * dst, const avifGainMapMetadata * src);
+AVIF_API AVIF_NODISCARD avifBool avifGainMapMetadataFractionsToDouble(avifGainMapMetadataDouble * dst, const avifGainMapMetadata * src);
#endif // AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP
@@ -819,8 +830,8 @@
} avifImage;
// avifImageCreate() and avifImageCreateEmpty() return NULL if arguments are invalid or if a memory allocation failed.
-AVIF_NODISCARD AVIF_API avifImage * avifImageCreate(uint32_t width, uint32_t height, uint32_t depth, avifPixelFormat yuvFormat);
-AVIF_NODISCARD AVIF_API avifImage * avifImageCreateEmpty(void); // helper for making an image to decode into
+AVIF_API AVIF_NODISCARD avifImage * avifImageCreate(uint32_t width, uint32_t height, uint32_t depth, avifPixelFormat yuvFormat);
+AVIF_API AVIF_NODISCARD avifImage * avifImageCreateEmpty(void); // helper for making an image to decode into
// Performs a deep copy of an image, including all metadata and planes, and the gain map metadata/planes if present
// and if AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP is defined.
AVIF_API avifResult avifImageCopy(avifImage * dstImage, const avifImage * srcImage, avifPlanesFlags planes);
@@ -1366,7 +1377,7 @@
// frameIndex - 0-based, matching avifDecoder->imageIndex, bound by avifDecoder->imageCount
// "nearest" keyframe means the keyframe prior to this frame index (returns frameIndex if it is a keyframe)
// These functions may be used after a successful call (AVIF_RESULT_OK) to avifDecoderParse().
-AVIF_NODISCARD AVIF_API avifBool avifDecoderIsKeyframe(const avifDecoder * decoder, uint32_t frameIndex);
+AVIF_API AVIF_NODISCARD avifBool avifDecoderIsKeyframe(const avifDecoder * decoder, uint32_t frameIndex);
AVIF_API uint32_t avifDecoderNearestKeyframe(const avifDecoder * decoder, uint32_t frameIndex);
// Timing helper - This does not change the current image or invoke the codec (safe to call repeatedly)
@@ -1510,7 +1521,7 @@
} avifEncoder;
// avifEncoderCreate() returns NULL if a memory allocation failed.
-AVIF_NODISCARD AVIF_API avifEncoder * avifEncoderCreate(void);
+AVIF_API AVIF_NODISCARD avifEncoder * avifEncoderCreate(void);
AVIF_API avifResult avifEncoderWrite(avifEncoder * encoder, const avifImage * image, avifRWData * output);
AVIF_API void avifEncoderDestroy(avifEncoder * encoder);
@@ -1575,8 +1586,8 @@
#endif
// Helpers
-AVIF_NODISCARD AVIF_API avifBool avifImageUsesU16(const avifImage * image);
-AVIF_NODISCARD AVIF_API avifBool avifImageIsOpaque(const avifImage * image);
+AVIF_API AVIF_NODISCARD avifBool avifImageUsesU16(const avifImage * image);
+AVIF_API AVIF_NODISCARD avifBool avifImageIsOpaque(const avifImage * image);
// channel can be an avifChannelIndex.
AVIF_API uint8_t * avifImagePlane(const avifImage * image, int channel);
AVIF_API uint32_t avifImagePlaneRowBytes(const avifImage * image, int channel);
@@ -1585,7 +1596,7 @@
// Returns AVIF_TRUE if input begins with a valid FileTypeBox (ftyp) that supports
// either the brand 'avif' or 'avis' (or both), without performing any allocations.
-AVIF_NODISCARD AVIF_API avifBool avifPeekCompatibleFileType(const avifROData * input);
+AVIF_API AVIF_NODISCARD avifBool avifPeekCompatibleFileType(const avifROData * input);
#if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)
// ---------------------------------------------------------------------------
