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Revert "Put AVIF_NODISCARD after AVIF_API" again (#2298)
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This reverts commit da268fb.

I tested this with Visual Studio 2022 Version 17.10.3. It does not work.
I must have made a mistake when I tested this with Visual Studio last
time.

I found two webpages that support my test results:
https://stackoverflow.com/questions/67502217/warning-c5240-nodiscard-attribute-is-ignored-in-this-syntactic-position
microsoft/STL#1702

I think this issue is settled.
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@wantehchang
wantehchang authored Jul 22, 2024
1 parent 6d5341d commit 03acd65
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Showing 2 changed files with 15 additions and 32 deletions.
3 changes: 2 additions & 1 deletion CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,8 @@ The changes are relative to the previous release, unless the baseline is specifi
## [Unreleased]

### Changed since 1.1.0
* In avif.h, fix clang-cl compilation errors of "AVIF_API AVIF_NODISCARD" on
* In avif.h, change "AVIF_API AVIF_NODISCARD" back to "AVIF_NODISCARD AVIF_API"
to fix clang-cl and MSVC compilation errors in the shared library build on
Windows.
* Fix -DAVIF_GTEST=SYSTEM, https://github.com/AOMediaCodec/libavif/issues/2258.
* Fix infe_type and codec_config_type wrongly read as byte-aligned fields in the
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44 changes: 13 additions & 31 deletions include/avif/avif.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,14 +11,6 @@
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 and MSVC's dllexport/dllimport attributes 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

Expand All @@ -36,19 +28,10 @@ extern "C" {
// For static build, AVIF_API is always defined as nothing.

#if defined(_WIN32)
#if defined(AVIF_USE_NODISCARD) && (defined(__GNUC__) || defined(__clang__))
#define AVIF_HELPER_EXPORT [[gnu::dllexport]]
#define AVIF_HELPER_IMPORT [[gnu::dllimport]]
#else
#define AVIF_HELPER_EXPORT __declspec(dllexport)
#define AVIF_HELPER_IMPORT __declspec(dllimport)
#endif
#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
Expand All @@ -65,7 +48,8 @@ extern "C" {
#define AVIF_API
#endif // defined(AVIF_DLL)

#if defined(AVIF_USE_NODISCARD)
#if defined(AVIF_ENABLE_NODISCARD) || (defined(__cplusplus) && __cplusplus >= 201703L) || \
(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
#define AVIF_NODISCARD [[nodiscard]]
#else
// Starting with 3.9, clang allows defining the warn_unused_result attribute for enums.
Expand All @@ -80,8 +64,6 @@ extern "C" {
#endif
#endif

#undef AVIF_USE_NODISCARD

// ---------------------------------------------------------------------------
// Constants

Expand Down Expand Up @@ -528,13 +510,13 @@ typedef struct avifCropRect

// 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_API AVIF_NODISCARD avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
AVIF_NODISCARD AVIF_API avifBool avifCropRectConvertCleanApertureBox(avifCropRect * cropRect,
const avifCleanApertureBox * clap,
uint32_t imageW,
uint32_t imageH,
avifPixelFormat yuvFormat,
avifDiagnostics * diag);
AVIF_API AVIF_NODISCARD avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
AVIF_NODISCARD AVIF_API avifBool avifCleanApertureBoxConvertCropRect(avifCleanApertureBox * clap,
const avifCropRect * cropRect,
uint32_t imageW,
uint32_t imageH,
Expand Down Expand Up @@ -723,10 +705,10 @@ typedef struct avifGainMapMetadataDouble
// 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_API AVIF_NODISCARD avifBool avifGainMapMetadataDoubleToFractions(avifGainMapMetadata * dst, const avifGainMapMetadataDouble * src);
AVIF_NODISCARD AVIF_API 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_API AVIF_NODISCARD avifBool avifGainMapMetadataFractionsToDouble(avifGainMapMetadataDouble * dst, const avifGainMapMetadata * src);
AVIF_NODISCARD AVIF_API avifBool avifGainMapMetadataFractionsToDouble(avifGainMapMetadataDouble * dst, const avifGainMapMetadata * src);

#endif // AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP

Expand Down Expand Up @@ -837,8 +819,8 @@ typedef struct avifImage
} avifImage;

// avifImageCreate() and avifImageCreateEmpty() return NULL if arguments are invalid or if a memory allocation failed.
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
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
// 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);
Expand Down Expand Up @@ -1384,7 +1366,7 @@ AVIF_API avifResult avifDecoderReset(avifDecoder * decoder);
// 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_API AVIF_NODISCARD avifBool avifDecoderIsKeyframe(const avifDecoder * decoder, uint32_t frameIndex);
AVIF_NODISCARD AVIF_API 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)
Expand Down Expand Up @@ -1528,7 +1510,7 @@ typedef struct avifEncoder
} avifEncoder;

// avifEncoderCreate() returns NULL if a memory allocation failed.
AVIF_API AVIF_NODISCARD avifEncoder * avifEncoderCreate(void);
AVIF_NODISCARD AVIF_API avifEncoder * avifEncoderCreate(void);
AVIF_API avifResult avifEncoderWrite(avifEncoder * encoder, const avifImage * image, avifRWData * output);
AVIF_API void avifEncoderDestroy(avifEncoder * encoder);

Expand Down Expand Up @@ -1593,8 +1575,8 @@ AVIF_API size_t avifEncoderGetGainMapSizeBytes(avifEncoder * encoder);
#endif

// Helpers
AVIF_API AVIF_NODISCARD avifBool avifImageUsesU16(const avifImage * image);
AVIF_API AVIF_NODISCARD avifBool avifImageIsOpaque(const avifImage * image);
AVIF_NODISCARD AVIF_API avifBool avifImageUsesU16(const avifImage * image);
AVIF_NODISCARD AVIF_API 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);
Expand All @@ -1603,7 +1585,7 @@ AVIF_API uint32_t avifImagePlaneHeight(const avifImage * image, int channel);

// 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_API AVIF_NODISCARD avifBool avifPeekCompatibleFileType(const avifROData * input);
AVIF_NODISCARD AVIF_API avifBool avifPeekCompatibleFileType(const avifROData * input);

#if defined(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP)
// ---------------------------------------------------------------------------
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