... at call sites that are may be in the hot path.
I do not know how clever the compiler gets at these sites.
My primary concern is to not regress performance and I am confident
that this achieves it the easy way.
When the separator is empty, no difference is observable.
Note that concatStringsSep has centralized definitions. This adds the
required definitions. Alternatively, `strings-inline.hh` could be
included at call sites.
Considering that `value` was probably parsed with tokenizeString
prior, it's unlikely to contain empty strings, and we have no
reason to remove them either.
Empty attributes are probably not well supported, but the least we
could do is leave a hint.
Attribute path rendering and parsing should be done according to
Nix expression syntax in my opinion.
(System) features are unlikely to be empty strings, but when they
come in through structuredAttrs, they probably can.
I don't think this means we should drop them, but most likely they
will be dropped after this because next time they'll be parsed with
tokenizeString.
TODO: We should forbid empty features.
I don't think it's completely impossible, but I can't construct
one easily as derivationStrict seems to (re)tokenize the outputs
attribute, dropping the empty output.
It's not a scenario we have to account for here.
Bug not reported in 6 years, but here you go.
Also it is safe to switch to normal concatStringsSep behavior
because tokenizeString does not produce empty items.
The empty attribute name should not be dropped from attribute paths.
Rendering attribute paths with concatStringsSep is lossy and wrong,
but this is just a first improvement while dealing with the
dropEmptyInitThenConcatStringsSep problem.
Known behavior changes:
- `MemorySourceAccessor`'s comparison operators no longer forget to
compare the `SourceAccessor` base class.
Progress on #10832
What remains for that issue is hopefully much easier!
On some systems, previous usage of `match` may cause a stackoverflow
(presumably due to the large size of the match result). Avoid this by
(ab)using `replaceStrings` to test for containment without using
regexes, thereby avoiding the issue. The causal configuration seems to
be the stack size hard limit, which e.g. Amazon Linux sets, whereas most
Linux distros leave unlimited.
Match the fn name to similar fn in nixpkgs.lib, but different
implementation that does not use `match`. This impl gives perhaps
unexpected results when the needle is `""`, but the scope of this is
narrow and that case is a bit odd anyway.
This makes for some duplication-of-work as we do a different
`replaceStrings` if this one is true, but this only runs during doc
generation at build time so has no runtime impact.
See https://github.com/NixOS/nix/issues/11085 for details.
