Expand the "givens" set to cover transitive relations. The givens array
stores relationships like `'c <= '0` (where `'c` is a free region and
`'0` is an inference variable) that are derived from closure
arguments. These are (rather hackily) ignored for purposes of inference,
preventing spurious errors. The current code did not handle transitive
cases like `'c <= '0` and `'0 <= '1`. Fixes#24085.
r? @pnkfelix
cc @bkoropoff
*But* I am not sure whether this fix will have a compile-time hit. I'd like to push to try branch observe cycle times.
Pre-requisite for splitting the type context into global and local parts.
The `Repr` and `UserString` traits were also replaced by `Debug` and `Display`.
stores relationships like `'c <= '0` (where `'c` is a free region and
`'0` is an inference variable) that are derived from closure
arguments. These are (rather hackily) ignored for purposes of inference,
preventing spurious errors. The current code did not handle transitive
cases like `'c <= '0` and `'0 <= '1`. Fixes#24085.
This commit shards the all-encompassing `core`, `std_misc`, `collections`, and `alloc` features into finer-grained components that are much more easily opted into and tracked. This reflects the effort to push forward current unstable APIs to either stabilization or removal. Keeping track of unstable features on a much more fine-grained basis will enable the library subteam to quickly analyze a feature and help prioritize internally about what APIs should be stabilized.
A few assorted APIs were deprecated along the way, but otherwise this change is just changing the feature name associated with each API. Soon we will have a dashboard for keeping track of all the unstable APIs in the standard library, and I'll also start making issues for each unstable API after performing a first-pass for stabilization.
Currently in the E0252 message, traits and modules are all called types (as in "a type named `Foo` has already been imported", even when `Foo` was a trait or module). This commit changes that to additionally detect when the import in question is a trait or module and report it accordingly.
Fixes#25396.
This makes them compliant with the new version of RFC 401 (i.e.
RFC 1052).
Fixes#26391. I *hope* the tests I have are enough.
This is a [breaking-change]
Previously, it said "import `Foo` conflicts with existing submodule" even
when it was a type alias, enum, or trait. The message now says the conflict
is with "type in this module" in the case of the first two, and "trait in
this module" for the last one.
Fixes#24081.
Unlike coercing from reference to unsafe pointer, coercing between two
unsafe pointers doesn't need an AutoDerefRef, because there is no region
that regionck would need to know about.
In unoptimized libcore, this reduces the number of "auto_deref" allocas
from 174 to 4.
Currently in the E0252 message, traits and modules are all called types
(as in "a type named `Foo` has already been imported", even when `Foo` was
a trait or module). This commit changes that to additionally detect when
the import in question is a trait or module and report it accordingly.
Fixes#25396.
When we successfully resolve a trait reference with no type/lifetime parameters, like `i32: Foo` or `Box<u32>: Sized`, this is in fact globally true. This patch adds a simple global to the tcx to cache such cases. The main advantage of this is really about caching things like `Box<Vec<Foo>>: Sized`. It also points to the need to revamp our caching infrastructure -- the current caches make selection cost cheaper, but we still wind up paying a high cost in the confirmation process, and in particular unrolling out dependent obligations. Moreover, we should probably do caching more uniformly and with a key that takes the where-clauses into account. But that's for later.
For me, this shows up as a reasonably nice win (20%) on Servo's script crate (when built in dev mode). This is not as big as my initial measurements suggested, I think because I was building my rustc with more debugging enabled at the time. I've not yet done follow-up profiling and so forth to see where the new hot spots are. Bootstrap times seem to be largely unaffected.
cc @pcwalton
This is technically a [breaking-change] in that functions with unsatisfiable where-clauses may now yield errors where before they may have been accepted. Even before, these functions could never have been *called* by actual code. In the future, such functions will probably become illegal altogether, but in this commit they are still accepted, so long as they do not rely on the unsatisfiable where-clauses. As before, the functions still cannot be called in any case.
This addresses an item in #22709. SizeHint in libcore/iter.rs also implements Iterator, but it's implementation is not accessible and is only used to send size hints to extend (it appears to be a performance improvement to avoid unnecessary memory reallocations). The is the only implementation of Iterator within libcore/iter.rs that is not/cannot be tested in this PR.
This commit updates the LLVM submodule in use to the current HEAD of the LLVM
repository. This is primarily being done to start picking up unwinding support
for MSVC, which is currently unimplemented in the revision of LLVM we are using.
Along the way a few changes had to be made:
* As usual, lots of C++ debuginfo bindings in LLVM changed, so there were some
significant changes to our RustWrapper.cpp
* As usual, some pass management changed in LLVM, so clang was re-scrutinized to
ensure that we're doing the same thing as clang.
* Some optimization options are now passed directly into the
`PassManagerBuilder` instead of through CLI switches to LLVM.
* The `NoFramePointerElim` option was removed from LLVM, favoring instead the
`no-frame-pointer-elim` function attribute instead.
* The `LoopVectorize` option of the LLVM optimization passes has been disabled
as it causes a divide-by-zero exception to happen in LLVM for zero-sized
types. This is reported as https://llvm.org/bugs/show_bug.cgi?id=23763
Additionally, LLVM has picked up some new optimizations which required fixing an
existing soundness hole in the IR we generate. It appears that the current LLVM
we use does not expose this hole. When an enum is moved, the previous slot in
memory is overwritten with a bit pattern corresponding to "dropped". When the
drop glue for this slot is run, however, the switch on the discriminant can
often start executing the `unreachable` block of the switch due to the
discriminant now being outside the normal range. This was patched over locally
for now by having the `unreachable` block just change to a `ret void`.
This commit updates the LLVM submodule in use to the current HEAD of the LLVM
repository. This is primarily being done to start picking up unwinding support
for MSVC, which is currently unimplemented in the revision of LLVM we are using.
Along the way a few changes had to be made:
* As usual, lots of C++ debuginfo bindings in LLVM changed, so there were some
significant changes to our RustWrapper.cpp
* As usual, some pass management changed in LLVM, so clang was re-scrutinized to
ensure that we're doing the same thing as clang.
* Some optimization options are now passed directly into the
`PassManagerBuilder` instead of through CLI switches to LLVM.
* The `NoFramePointerElim` option was removed from LLVM, favoring instead the
`no-frame-pointer-elim` function attribute instead.
Additionally, LLVM has picked up some new optimizations which required fixing an
existing soundness hole in the IR we generate. It appears that the current LLVM
we use does not expose this hole. When an enum is moved, the previous slot in
memory is overwritten with a bit pattern corresponding to "dropped". When the
drop glue for this slot is run, however, the switch on the discriminant can
often start executing the `unreachable` block of the switch due to the
discriminant now being outside the normal range. This was patched over locally
for now by having the `unreachable` block just change to a `ret void`.
Previously, it said "import `Foo` conflicts with existing submodule" even
when it was a type alias, enum, or trait. The message now says the conflict
is with "type in this module" in the case of the first two, and "trait in
this module" for the last one.
Fixes#24081.
Unlike coercing from reference to unsafe pointer, coercing between two
unsafe pointers doesn't need an AutoDerefRef, because there is no region
that regionck would need to know about.
In unoptimized libcore, this reduces the number of "auto_deref" allocas
from 174 to 4.
