Add debug flag `-Z print-type-sizes` for instrumention type/variant sizes
Add debug flag `-Z print-type-sizes` for instrumention type/variant sizes
This is meant to help with things like #36799 in a very local way; namely, once you have a hypothesis as to which types have a large population or are "too large", you can use `-Z print-type-sizes` to learn how large each type is, and how much each variant in an enum contributes to the size of that overall enum.
Note that the tests have been updated to initialize the local
variables; originally it was enough just to declare them.
Back when I started this, the `layout_cache` contained entries even
just for types that had been declared but not initialized. Apparently
things have changed in the interim so that if I want one of those
layouts to be computed, I need to actually initialize the value.
(Incidentally, this shows a weakness in the strategy of just walking
the `layout_cache`; the original strategy of using a MIR visitor would
probably have exhibited more robustness in terms of consistent output,
but it had other weaknesses so I chose not to reimplement it. At
least, not yet.)
----
Also, I have updated tests to avoid target-specific alignments.
Biggest change: Revised print-type-sizes output to include breakdown
of layout.
Includes info about field sizes (and alignment + padding when padding
is injected; the injected padding is derived from the offsets computed
by layout module).
Output format is illustrated in commit that has the ui tests.
Note: there exists (at least) one case of variant w/o name: empty
enums. Namely, empty enums use anonymous univariant repr. So for such
cases, print the number of the variant instead of the name.
----
Also, eddyb suggested of reading from `layout_cache` post-trans.
(For casual readers: the compiler source often uses the word "cache"
for tables that are in fact not periodically purged, and thus are
useful as the basis for data like this.)
Some types that were previously not printed are now included in the
output. (See e.g. the tests `print_type_sizes/generics.rs` and
`print_type_sizes/variants.rs`)
----
Other review feedback:
switch to an exhaustive match when filtering in just structural types.
switch to hashset for layout info and move sort into print method.
----
Driveby change: Factored session::code_stats into its own module
----
incorporate njn feedback re output formatting.
rustdoc: separate test collection from the main "clean"-ing pipeline.
While reusing the documentation "clean"-ing infrastructure for collecting code examples to test may have seemed appealing at some point, doing the same through a HIR visitor is barely any harder.
At the same time, supporting both "regular documentation" and "test collection" modes in `rustdoc::clean` has its cost, requiring any use of a `TyCtxt` to be speculative, and provide some sort of fallback.
This simplification is the first step towards bringing rustdoc closer to the compiler, and perhaps even unifying the "local crate" (based on the HIR AST) and "inlinined across crates" (based on crate metadata and typesystem information) implementations of rustdoc.
Sadly, not all possible changes to rustdoc will be uncontroversial, so I'm starting small with this patch.
with this feature disabled, you can (Cargo) compile std with
"panic=abort"
rustbuild will build std with this feature enabled, to maintain the
status quo
fixes#37252
rustc_metadata: don't break the version check when CrateRoot changes.
In #36551 I made `rustc_version` a field of `CrateRoot`, but despite it being the first field, one could still break the version check by changing `CrateRoot` so older compilers couldn't fully decode it (e.g. #37463).
This PR fixes#37803 by moving the version string back at the beginning of metadata, right after the 32-bit big-endian absolute position of `CrateRoot`, and by incrementing `METADATA_VERSION`.
Expand is_uninhabited
This allows code such as this to compile:
``` rust
let x: ! = ...;
match x {};
let y: (u32, !) = ...;
match y {};
```
@eddyb You were worried about making this change. Do you have any idea about what could break? Are there any special tests that need to be written for it?
Add some internal docs links for Args/ArgsOs
In many places the docs link to other sections and I noticed it was lacking here. Not sure if there is a standard for if inter-linking is appropriate.
Clarify the reference's status.
The former wording only gave part of the picture, we want to be crystal
clear about this.
/cc @petrochenkov, who had concerns about https://github.com/rust-lang/rust/pull/37820
Type walker small vector
These two changes avoid allocations on some hot paths and speed up a few workloads (some from rustc-benchmarks, as well as the workload from #36799) by 1--2%.
Provide hint when cast needs a dereference
For a given code:
``` rust
vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
```
display:
``` nocode
error: casting `&f64` as `i16` is invalid
--> file3.rs:2:35
|
2 | vec![0.0].iter().map(|s| s as i16).collect::<Vec<i16>>();
| - ^^^
| |
| did you mean `*s`?
```
instead of:
``` nocode
error: casting `&f64` as `i16` is invalid
--> <anon>:2:30
|
2 | vec![0.0].iter().map(|s| s as i16).collect();
| ^^^^^^^^
|
= help: cast through a raw pointer first
```
Fixes#37338.
Add a method for setting permissions directly on an open file.
On unix like systems, the underlying file corresponding to any given path may change at any time. This function makes it possible to set the permissions of the a file corresponding to a `File` object even if its path changes.
@retep998, what's the best way to do this on Windows? I looked into `SetFileInformationByHandle` but couldn't find a way to do it atomically risking clobbering access time information.
This is a first step towards fixing #37885. This function doesn't *have* to be public but this is useful functionality that should probably be exposed.
Implement the `loop_break_value` feature.
This implements RFC 1624, tracking issue #37339.
- `FnCtxt` (in typeck) gets a stack of `LoopCtxt`s, which store the
currently deduced type of that loop, the desired type, and a list of
break expressions currently seen. `loop` loops get a fresh type
variable as their initial type (this logic is stolen from that for
arrays). `while` loops get `()`.
- `break {expr}` looks up the broken loop, and unifies the type of
`expr` with the type of the loop.
- `break` with no expr unifies the loop's type with `()`.
- When building MIR, loops no longer construct a `()` value at
termination of the loop; rather, the `break` expression assigns the
result of the loop.
- ~~I have also changed the loop scoping in MIR-building so that the test
of a while loop is not considered to be part of that loop. This makes
the rules consistent with #37360. The new loop scopes in typeck also
follow this rule. That means that `loop { while (break) {} }` now
terminates instead of looping forever. This is technically a breaking
change.~~
- ~~On that note, expressions like `while break {}` and `if break {}` no
longer parse because `{}` is interpreted as an expression argument to
`break`. But no code except compiler test cases should do that anyway
because it makes no sense.~~
- The RFC did not make it clear, but I chose to make `break ()` inside
of a `while` loop illegal, just in case we wanted to do anything with
that design space in the future.
This is my first time dealing with this part of rustc so I'm sure
there's plenty of problems to pick on here ^_^
