Upload: Fix inaccurate HEIC/HEIF MIME type mapping

[NoumaanAhamed]

Summary

Fixes inaccurate HEIC/HEIF MIME type mappings. Previously, all HEIF-family uploads (.heif, .heics, .heifs) were incorrectly mapped to and renamed as .heic because the $mime_to_ext array collapsed all variants into the heic extension.

Additionally, this PR fixes two related issues:

1. .heics and .heifs were missing from the wp_ext2type() image array, causing them not to be recognized as images in the Media Library.
2. Sub-size generation skipped non-image/heic HEIF variants because of a hardcoded mime type check.

Changes

src/wp-includes/functions.php

• Updated the $mime_to_ext array in wp_check_filetype_and_ext() to map each HEIF MIME type to its proper, distinct extension:
  • image/heif → heif
  • image/heic-sequence → heics
  • image/heif-sequence → heifs
• Added 'heic' to the $heic_images_extensions trigger array.
• Added 'heics' and 'heifs' to the image types array in wp_get_ext_types().
• Removed outdated comments indicating all HEIC/HEIF formats commonly use .heic.

src/wp-admin/includes/image.php

• Replaced the explicit 'image/heic' === $mime_type check in wp_generate_attachment_metadata() with a call to wp_is_heic_image_mime_type(). This ensures all HEIF variants (not just image/heic) correctly trigger sub-size generation.

Testing

Test	Result
Upload .heic file	✅ Remains .heic, sub-sizes generated correctly
Upload .heif file	✅ Remains .heif, sub-sizes generated correctly

Trac ticket: https://core.trac.wordpress.org/ticket/65297

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