Eric Wong [off-list ref] writes:

Thorsten Leemhuis [off-list ref] wrote:

quoted

Just to be sure I'll do what you expect to be done: I assume you want to see
it changed like this?

-	perl -pi -e 's|^Message-Id:\s*<?([^>]+)>?$|Link: https://lore.kernel.org/r/$1|g;' "$1"

...
The entire match should be case-insensitive[1], so I'd add `i'
at the end:

	perl -pi -e 's|^Message-ID:\s*<?([^>]+)>?$|Link: https://lore.kernel.org/r/$1|gi;' "$1"

Fwiw, every mail and HTTP/1.x header parser I've looked at works
case-insensitively.  Also, I'm not sure if `g' is needed, actually...

It is left anchored with "^" so it would be hard to match more than
once on the same line ;-)

I agree that it is the right solution to make the whole thing
case-insensitive by adding 'i' at the end.

FWIW, the RFC first says this:

    1.2.2. Syntactic notation

       This standard uses the Augmented Backus-Naur Form (ABNF) notation
       specified in [RFC2234] for the formal definitions of the syntax of
       messages.  Characters will be specified either by a decimal value
       (e.g., the value %d65 for uppercase A and %d97 for lowercase A) or by
       a case-insensitive literal value enclosed in quotation marks (e.g.,
       "A" for either uppercase or lowercase A).

and then goes on to define how message-id should look like.

    3.6.4. Identification fields

    message-id      =       "Message-ID:" msg-id CRLF


But if you go the "add /i at the end" route, you do not have to
upcase "d" to "D" and that may reduce the patch noise (it only
matters if the patch viewer highlights letter-by-letter changes for
your recipients).

HTH