Make the evaluator show some suggestions when trying to access an
invalid field from an attrset.
```console
$ nix eval --expr '{ foo = 1; }.foa'
error: attribute 'foa' missing
at «string»:1:1:
1| { foo = 1; }.foa
| ^
Did you mean foo?
```
No real need for keeping a separate header for such a simple class.
This requires changing a bit `OrSuggestions<T>::operator*` to not throw
an `Error` to prevent a cyclic dependency. But since this error is only
thrown on programmer error, we can replace the whole method by a direct
call to `std::get` which will raise its own assertion if needs be.
Refactor the `size == 0` logic into a new helper function that
replaces dupStringWithLen.
The name had to change, because unlike a `dup`-function, it does
not always allocate a new string.
Allows completing `nix build ~/flake#<Tab>`.
We can implement expansion for `~user` later if needed.
Not using wordexp(3) since that expands way too much.
Starts progress on #5729.
The idea is that we should not have these default methods throwing
"unimplemented". This is a small step in that direction.
I kept `addTempRoot` because it is a no-op, rather than failure. Also,
as a practical matter, it is called all over the place, while doing
other tasks, so the downcasting would be annoying.
Maybe in the future I could move the "real" `addTempRoot` to `GcStore`,
and the existing usecases use a `tryAddTempRoot` wrapper to downcast or
do nothing, but I wasn't sure whether that was a good idea so with a
bias to less churn I didn't do it yet.
Setting the `_NIX_FORCE_HTTP` environment variable is supposed to force `file://` store urls to use the `HttpBinaryCacheStore` implementation rather than the `LocalBinaryCacheStore` one (very useful for testing).
However because of a name mismatch, the `LocalBinaryCacheStore` was still registering the `file` scheme when this variable was set, meaning that the actual store implementation picked up on `file://` uris was dependent on the registration order of the stores (itself dependent on the link order of the object files).
Fix this by making the `LocalBinaryCacheStore` gracefully not register the `file` uri scheme when the variable is set.
gives 2-5% performance improvement across a board of tests.
LTO is broken when using clang; some libs link fine while others crash
the linker with a segfault in the llvm linker plugin. 🙁
We now memoize on Bindings / list element vectors rather than Values,
so that e.g. two Values that point to the same Bindings will be
printed only once.
