The --no- prefix for non-booleans command line options is silently ignored

[darnir]

I did this

Execute curl with the option --no-http2. E.g.:
$ curl --no-http2 example.com

I expected the following

I expect curl to continue running. However, instead curl returns an error:

curl: (1) Unsupported protocol

My version of curl is built without HTTP/2 support. However, the binary should still support the --no-http2 flag without any issues. The use case for this is usage of curl in a script where one wants to avoid a HTTP/2 connection. Such a script ends up failing on systems where curl is built without HTTP/2 support anyways.

curl/libcurl version

curl 7.54.0 (x86_64-pc-linux-gnu) libcurl/7.54.0 OpenSSL/1.1.0e zlib/1.2.11 libpsl/0.17.0 (+libicu/58.2) libssh2/1.8.0
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp scp sftp smb smbs smtp smtps telnet tftp
Features: AsynchDNS IPv6 Largefile GSS-API Kerberos SPNEGO NTLM NTLM_WB SSL libz TLS-SRP UnixSockets HTTPS-proxy PSL

operating system

Arch Linux

[bagder]

I can see how you want this, but this option is actually not a boolean so there is no "opposite". To get what you want, you can use the - - http1.1 option instead.

We should still improve the parser/error message for this use...

[darnir]

That is an acceptable workaround. Thanks!