Can't link to OpenSSL3 when OpenSSL1.1 is installed

I'm trying to test the new OpenSSL 3.0 code paths that have been added fro Qt 6.5, but I fail to point the build system at my non-standard OpenSSL install in /d/openssl.

(yes, after each attempt CMakeCache.txt was deleted)

I first tried just setting PATH and LD_LIBRARY_PATH, but that didn't change anything.

I then added, in addition, -L /d/openssl/lib64 and -I /d/openssl/include to configure. Nothing.

I then added, instead of -L and -I, -openssl-linked – -DOPENSSL_ROOT_DIR=/d/openssl to configure. This made it detect OpenSSL v3.0, at least as far as config.summary is concerned. It still finds, and insists to use, the libssl.so and libcrypto.so from the system:

-- Found OpenSSL: /usr/lib/x86_64-linux-gnu/libcrypto.so   
-- Found WrapOpenSSLHeaders: /d/openssl/32-dev/include  
-- Performing Test HAVE_opensslv11_headers
-- Performing Test HAVE_opensslv11_headers - Failed
-- Found WrapOpenSSL: /usr/lib/x86_64-linux-gnu/libcrypto.so  
-- Performing Test HAVE_opensslv11
-- Performing Test HAVE_opensslv11 - Failed
-- Performing Test HAVE_opensslv30_headers
-- Performing Test HAVE_opensslv30_headers - Success
-- Performing Test HAVE_opensslv30
-- Performing Test HAVE_opensslv30 - Success

And sure enough, it now compiles (with QT_CONFIG(opensslv30) defined), but fails to link libQt6Core.so with missing symbols, because it continues to pass the system OpenSSL libraries with full path:

~~~ -lm  ~~~  /usr/lib/x86_64-linux-gnu/libssl.so  /usr/lib/x86_64-linux-gnu/libcrypto.so ~~~

I then added -L back in, no change.

My config.opt reads now:

-opensource
-confirm-license
-release
-force-debug-info
-separate-debug-info
-c++std
c++17
-developer-build
-openssl-linked
-L
/d/openssl/lib64
--
-DOPENSSL_ROOT_DIR=/d/openssl

This is probably also in 6.5.