Since PHP 7.4, the PHP_SETUP_OPENSSL autoconf macro completely relies on pkg-config and no longer utilizes $PHP_OPENSSL_DIR to search for OpenSSL headers. This change was implemented in php/php-src@fe8fdfa.
Prior to PHPC-888, which introduced support for alternative TLS libraries, we utilized the PHP_SETUP_OPENSSL macro directly. In mongodb/mongo-php-driver@d679bfe, we removed that macro but ported the directory search logic to CheckSSL.m4.
This should be removed so that we can depend on pkg-config as is done in PHP 7.4+.
We might still want to leave the PHP_CHECK_LIBRARY code in place (else condition of PKG_CHECK_MODULES) if that is ultimately necessary for FreeBSD compatibility.
- is related to
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                    PHPC-888 Support additional TLS libraries for bundled libmongoc -         
- Closed
 
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- related to
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                    PHPC-2451 Rely exclusively on pkg-config to detect OpenSSL -         
- Backlog
 
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                    PHPC-2315 Use PKG_CHECK_MODULES for detecting libmongoc, libbson, and libmongocrypt -         
- Closed
 
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                    PHPC-2314 Require OpenSSL 1.0.1+ in CheckSSL.m4 to satisfy libmongoc requirements -         
- Closed
 
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                    PHPC-2452 Warn if deprecated --with-openssl-dir configure option is used -         
- Closed
 
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