Ignore ZST offsets when deciding whether to use Scalar/ScalarPair layout
This is important because Scalar/ScalarPair layout previously would not be used if any ZST had nonzero offset.
For example, before this change, only `((), u128)` would be laid out like `u128`, not `(u128, ())`.
Fixes#63244
The main use case of TrustedLen is allowing APIs to specialize on it,
but no use of it uses that specialization. Instead, only the .len()
function provided by ExactSizeIterator is used, which is already
required to be accurate.
Thus, the TrustedLen requirement on BuilderMethods::switch is redundant.
Remove DeclareMethods
Most of the `DeclareMethods` API was only used internally by rustc_codegen_llvm. As such, it makes no sense to require other backends to implement them.
(`get_declared_value` and `declare_cfn` were used, in one place, specific to the `main` symbol, which I've replaced with a more specialized function to allow more flexibility in implementation - the intent is that `declare_c_main` can go away once we do something more clever, e.g. @eddyb has ideas around having a MIR shim or somesuch we can explore in a follow-up PR)
Rollup of 15 pull requests
Successful merges:
- #76722 (Test and fix Send and Sync traits of BTreeMap artefacts)
- #76766 (Extract some intrinsics out of rustc_codegen_llvm)
- #76800 (Don't generate bootstrap usage unless it's needed)
- #76809 (simplfy condition in ItemLowerer::with_trait_impl_ref())
- #76815 (Fix wording in mir doc)
- #76818 (Don't compile regex at every function call.)
- #76821 (Remove redundant nightly features)
- #76823 (black_box: silence unused_mut warning when building with cfg(miri))
- #76825 (use `array_windows` instead of `windows` in the compiler)
- #76827 (fix array_windows docs)
- #76828 (use strip_prefix over starts_with and manual slicing based on pattern length (clippy::manual_strip))
- #76840 (Move to intra doc links in core/src/future)
- #76845 (Use intra docs links in core::{ascii, option, str, pattern, hash::map})
- #76853 (Use intra-doc links in library/core/src/task/wake.rs)
- #76871 (support panic=abort in Miri)
Failed merges:
r? `@ghost`
Remove redundant nightly features
Removes a bunch of redundant/outdated nightly features. The first commit removes a `core_intrinsics` use for which a stable wrapper has been provided since. The second commit replaces the `const_generics` feature with `min_const_generics` which might get stabilized this year. The third commit is the result of a trial/error run of removing every single feature and then adding it back if compile failed. A bunch of unused features are the result that the third commit removes.
As a side effect, we now represent most promoteds as `ConstValue::Scalar` again. This is useful because all implict promoteds are just references anyway and most explicit promoteds are numeric arguments to `asm!` or SIMD instructions.
A significant amount of intrinsics do not actually need backend-specific
behaviors to be implemented, instead relying on methods already in
rustc_codegen_ssa. So, extract those methods out to rustc_codegen_ssa,
so that each backend doesn't need to reimplement the same code.
diagnostics: shorten paths of unique symbols
This is a step towards implementing a fix for #50310, and continuation of the discussion in [Pre-RFC: Nicer Types In Diagnostics - compiler - Rust Internals](https://internals.rust-lang.org/t/pre-rfc-nicer-types-in-diagnostics/11139). Impressed upon me from previous discussion in #21934 that an RFC for this is not needed, and I should just come up with code.
The recent improvements to `use` suggestions that I've contributed have given rise to this implementation. Contrary to previous suggestions, it's rather simple logic, and I believe it only reduces the amount of cognitive load that a developer would need when reading type errors.
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If a symbol name can only be imported from one place, and as long as it was not glob-imported anywhere in the current crate, we can trim its printed path to the last component.
This has wide implications on error messages with types, for example, shortening `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable from anywhere.
If a symbol name can only be imported from one place for a type, and
as long as it was not glob-imported anywhere in the current crate, we
can trim its printed path and print only the name.
This has wide implications on error messages with types, for example,
shortening `std::vec::Vec` to just `Vec`, as long as there is no other
`Vec` importable anywhere.
This adds a new '-Z trim-diagnostic-paths=false' option to control this
feature.
On the good path, with no diagnosis printed, we should try to avoid
issuing this query, so we need to prevent trimmed_def_paths query on
several cases.
This change also relies on a previous commit that differentiates
between `Debug` and `Display` on various rustc types, where the latter
is trimmed and presented to the user and the former is not.
Eliminate some other bound checks when index comes from an enum
#36962 introduced an assumption for the upper limit of the enum's value. This PR adds an assumption to the lower value as well.
I've modified the original codegen test to show that derived (in that case, adding 1) values also don't generate bounds checks.
However, this test is actually carefully crafted to not hit a bug: if the enum's variants are modified to 1 and 2 instead of 2 and 3, the test fails by adding a bounds check. I suppose this is an LLVM issue and #75525, while not exactly in this context should be tracking it.
I'm not at all confident if this patch can be accepted, or even if it _should_ be accepted in this state. But I'm curious about what others think :)
~Improves~ Should improve #13926 but does not close it because it's not exactly predictable, where bounds checks may pop up against the assumptions.
Make to_immediate/from_immediate configurable by backends
`librustc_codegen_ssa` has the concept of an immediate vs. memory type, and `librustc_codegen_llvm` uses this distinction to implement `bool`s being `i8` in memory, and `i1` in immediate contexts. However, some of that implementation leaked into `codegen_ssa` when converting to/from immediate values. So, move those methods into builder traits, so that behavior can be configured by backends.
This is useful if a backend is able to keep bools as bools, or, needs to do more trickery than just bools to bytes.
(Note that there's already a large amount of things abstracted with "immediate types" - this is just bringing this particular thing in line to be abstracted as well)
---
Pinging @eddyb since that's who I was talking about this change with when they suggested I submit a PR.
Fix `-Z instrument-coverage` on MSVC
Found that `-C link-dead-code` (which was enabled automatically
under `-Z instrument-coverage`) was causing the linking error that
resulted in segmentation faults in coverage instrumented binaries. Link
dead code is now disabled under MSVC, allowing `-Z instrument-coverage`
to be enabled under MSVC for the first time.
More details are included in Issue #76038 .
Note this PR makes it possible to support `Z instrument-coverage` but
does not enable instrument coverage for MSVC in existing tests. It will be
enabled in another PR to follow this one (both PRs coming from original
PR #75828).
r? @tmandry
FYI: @wesleywiser
Found that -C link-dead-code (which was enabled automatically
under -Z instrument-coverage) was causing the linking error that
resulted in segmentation faults in coverage instrumented binaries. Link
dead code is now disabled under MSVC, allowing `-Z instrument-coverage`
to be enabled under MSVC for the first time.
More details are included in Issue #76038.
(This PR was broken out from PR #75828)
This commit removes the obsolete printer and replaces all uses of it
with `FmtPrinter`. Of the replaced uses, all but one use was in `debug!`
logging, two cases were notable:
- `MonoItem::to_string` is used in `-Z print-mono-items` and therefore
affects the output of all codegen-units tests.
- `DefPathBasedNames` was used in `librustc_codegen_llvm/type_of.rs`
with `LLVMStructCreateNamed` and that'll now get different values, but
this should result in no functional change.
Signed-off-by: David Wood <david@davidtw.co>
