handle ^ and $ in BRE subexpression start and end as anchors
In BRE, ^ is an anchor at the beginning of an expression, optionally
it may be an anchor at the beginning of a subexpression and must be
treated as a literal otherwise.
Previously musl treated ^ in subexpressions as literal, but at least
glibc and gnu sed treats it as an anchor and that's the more useful
behaviour: it can always be escaped to get back the literal meaning.
Same for $ at the end of a subexpression.
Portable BRE should not rely on this, but there are sed commands in
build scripts which do.
This changes the meaning of the BREs:
\(^a\)
\(a\|^b\)
\(a$\)
\(a$\|b\)
1 file changed