Source

File: wp-includes/post-template.php

function wp_get_attachment_link( $id = 0, $size = 'thumbnail', $permalink = false, $icon = false, $text = false, $attr = '' ) {
	$_post = get_post( $id );

	if ( empty( $_post ) || ( 'attachment' !== $_post->post_type ) || ! wp_get_attachment_url( $_post->ID ) ) {
		return __( 'Missing Attachment' );
	}

	$url = wp_get_attachment_url( $_post->ID );

	if ( $permalink ) {
		$url = get_attachment_link( $_post->ID );
	}

	if ( $text ) {
		$link_text = $text;
	} elseif ( $size && 'none' !== $size ) {
		$link_text = wp_get_attachment_image( $_post->ID, $size, $icon, $attr );
	} else {
		$link_text = '';
	}

	if ( '' === trim( $link_text ) ) {
		$link_text = $_post->post_title;
	}

	if ( '' === trim( $link_text ) ) {
		$link_text = esc_html( pathinfo( get_attached_file( $_post->ID ), PATHINFO_FILENAME ) );
	}
	/**
	 * Filters a retrieved attachment page link.
	 *
	 * @since 2.7.0
	 * @since 5.1.0 Added the $attr parameter.
	 *
	 * @param string       $link_html The page link HTML output.
	 * @param int          $id        Post ID.
	 * @param string|array $size      Size of the image. Image size or array of width and height values (in that order).
	 *                                Default 'thumbnail'.
	 * @param bool         $permalink Whether to add permalink to image. Default false.
	 * @param bool         $icon      Whether to include an icon. Default false.
	 * @param string|bool  $text      If string, will be link text. Default false.
	 * @param array|string $attr      Array or string of attributes. Default empty.
	 */
	return apply_filters( 'wp_get_attachment_link', "<a href='" . esc_url( $url ) . "'>$link_text</a>", $id, $size, $permalink, $icon, $text, $attr );
}