Remove confusing `use_polonius` flag and do less cloning
The `use_polonius` flag is both redundant and confusing since every function it's propagated to also checks if `all_facts` is `Some`, the true test of whether to generate Polonius facts for Polonius or for external consumers. This PR makes that path clearer by simply doing away with the argument and handling the logic in precisely two places: where facts are populated (check for `Some`), and where `all_facts` are initialised. It also delays some statements until after that check to avoid the miniscule performance penalty of executing them when Polonius is disabled.
This also addresses `@lqd's` concern in #125652 by reducing the size of what is cloned out of Polonius facts to just the facts being added, as opposed to the entire vector of potential inputs, and added descriptive comments.
*Reviewer note*: the comments in `add_extra_drop_facts` should be inspected by a reviewer, in particular the one on [L#259](https://github.com/rust-lang/rust/compare/master...amandasystems:you-dropped-this-again?expand=1#diff-aa727290e6670264df2face84f012897878e11a70e9c8b156543cfcd9619bac3R259) in this PR, which should be trivial for someone with the right background knowledge to address.
I also included some lints I found on the way there that I couldn't help myself from addressing.
The `use_polonius` flag is both redundant and confusing since every
function it's propagated to also checks if `all_facts` is `Some`,
the true test of whether to generate Polonius facts for Polonius
or for external consumers. This PR makes that path clearer by
simply doing away with the argument and handling the logic in
precisely two places: where facts are populated (check for `Some`),
and where `all_facts` are initialised. It also delays some statements
until after that check to avoid the miniscule performance penalty
of executing them when Polonius is disabled.
This also addresses @lqd's concern in #125652 by reducing
the size of what is cloned out of Polonius facts to just the
facts being added, as opposed to the entire vector of potential
inputs, and added descriptive comments.
*Reviewer note*: the comments in [add_extra_drop_facts](85f90a4612/compiler/rustc_borrowck/src/type_check/liveness/trace.rs (L219)) should be inspected by a reviewer,
in particular the one on L#259 in this PR, which should be trivial
for someone with the right background knowledge.
I also included some minor lints I found on the way there that I
couldn't help myself from addressing.
Invert diagnostic lints.
That is, change `diagnostic_outside_of_impl` and `untranslatable_diagnostic` from `allow` to `deny`, because more than half of the compiler has been converted to use translated diagnostics.
This commit removes more `deny` attributes than it adds `allow` attributes, which proves that this change is warranted.
r? ````@davidtwco````
Remove unused args from functions
`#[instrument]` suppresses the unused arguments from a function, *and* suppresses unused methods too! This PR removes things which are only used via `#[instrument]` calls, and fixes some other errors (privacy?) that I will comment inline.
It's possible that some of these arguments were being passed in for the purposes of being instrumented, but I am unconvinced by most of them.
That is, change `diagnostic_outside_of_impl` and
`untranslatable_diagnostic` from `allow` to `deny`, because more than
half of the compiler has be converted to use translated diagnostics.
This commit removes more `deny` attributes than it adds `allow`
attributes, which proves that this change is warranted.
Liveness data is pushed from multiple parts of NLL. Instead of changing
the call sites to maintain live loans, move the latter to `LivenessValues` where
this liveness data is pushed to, and maintain live loans there.
This fixes the differences in polonius scopes on some CFGs where a
variable was dead in tracing but as a MIR terminator its regions were marked
live from "constraint generation"
Refactor NLL constraint generation and most of polonius fact generation
As discussed in #118175, NLL "constraint generation" is only about liveness, but currently also contains legacy polonius fact generation. The latter is quite messy, and this PR cleans this up to prepare for its future removal:
- splits polonius fact generation out of NLL constraint generation
- merges NLL constraint generation to its more natural place, liveness
- extracts all of the polonius fact generation from NLLs apart from MIR typeck (as fact generation is somewhat in a single place there already, but should be cleaned up) into its own explicit module, with a single entry point instead of many.
There should be no behavior changes, and tests seem to behave the same as master: without polonius, with legacy polonius, with the in-tree polonius.
I've split everything into smaller logical commits for easier review, as it required quite a bit of code to be split and moved around, but it should all be trivial changes.
r? `@matthewjasper`
to help review, this duplicates the existing NLL + polonius constraint
generation component, before splitting them up to only do what they
individually need.
The `Debug` impl for `Ty` just calls the `Display` impl for `Ty`. This
is surprising and annoying. In particular, it means `Debug` doesn't show
as much information as `Debug` for `TyKind` does. And `Debug` is used in
some user-facing error messages, which seems bad.
This commit changes the `Debug` impl for `Ty` to call the `Debug` impl
for `TyKind`. It also does a number of follow-up changes to preserve
existing output, many of which involve inserting
`with_no_trimmed_paths!` calls. It also adds `Display` impls for
`UserType` and `Canonical`.
Some tests have changes to expected output:
- Those that use the `rustc_abi(debug)` attribute.
- Those that use the `EMIT_MIR` annotation.
In each case the output is slightly uglier than before. This isn't
ideal, but it's pretty weird (particularly for the attribute) that the
output is using `Debug` in the first place. They're fairly obscure
attributes (I hadn't heard of them) so I'm not worried by this.
For `async-is-unwindsafe.stderr`, there is one line that now lacks a
full path. This is a consistency improvement, because all the other
mentions of `Context` in this test lack a path.
Error message all end up passing into a function as an `impl
Into<{D,Subd}iagnosticMessage>`. If an error message is creatd as
`&format("...")` that means we allocate a string (in the `format!`
call), then take a reference, and then clone (allocating again) the
reference to produce the `{D,Subd}iagnosticMessage`, which is silly.
This commit removes the leading `&` from a lot of these cases. This
means the original `String` is moved into the
`{D,Subd}iagnosticMessage`, avoiding the double allocations. This
requires changing some function argument types from `&str` to `String`
(when all arguments are `String`) or `impl
Into<{D,Subd}iagnosticMessage>` (when some arguments are `String` and
some are `&str`).
Currently a `{D,Subd}iagnosticMessage` can be created from any type that
impls `Into<String>`. That includes `&str`, `String`, and `Cow<'static,
str>`, which are reasonable. It also includes `&String`, which is pretty
weird, and results in many places making unnecessary allocations for
patterns like this:
```
self.fatal(&format!(...))
```
This creates a string with `format!`, takes a reference, passes the
reference to `fatal`, which does an `into()`, which clones the
reference, doing a second allocation. Two allocations for a single
string, bleh.
This commit changes the `From` impls so that you can only create a
`{D,Subd}iagnosticMessage` from `&str`, `String`, or `Cow<'static,
str>`. This requires changing all the places that currently create one
from a `&String`. Most of these are of the `&format!(...)` form
described above; each one removes an unnecessary static `&`, plus an
allocation when executed. There are also a few places where the existing
use of `&String` was more reasonable; these now just use `clone()` at
the call site.
As well as making the code nicer and more efficient, this is a step
towards possibly using `Cow<'static, str>` in
`{D,Subd}iagnosticMessage::{Str,Eager}`. That would require changing
the `From<&'a str>` impls to `From<&'static str>`, which is doable, but
I'm not yet sure if it's worthwhile.
Clone region var origins instead of taking them in borrowck
Fixes an issue with the new solver where reporting a borrow-checker error ICEs because it calls `InferCtxt::evaluate_obligation`.
This also removes a handful of unnecessary `tcx.infer_ctxt().build()` calls that are only there to mitigate this same exact issue, but with the old solver.
Fixescompiler-errors/next-solver-hir-issues#12.
----
This implements `@aliemjay's` solution where we just don't *take* the region constraints, but clone them. This potentially makes it easier to write a bug about taking region constraints twice or never at all, but again, not many folks are touching this code.
