Two minor improvements that have been on my TODO list for a while:
* Clang uses a size of `-1` for arrays of unknown size and we should do that too as it will tell LLVM to omit the size information in debuginfo.
* There was no LLDB test case for handling the optimized enum representation introduced by @luqmana. This PR finally adds one.
E.g. `fn foo() { foo() }`, or, more subtlely
impl Foo for Box<Foo+'static> {
fn bar(&self) {
self.bar();
}
}
The compiler will warn and point out the points where recursion occurs,
if it determines that the function cannot return without calling itself.
Closes#17899.
---
This is highly non-perfect, in particular, my wording above is quite precise, and I have some unresolved questions: This currently will warn about
```rust
fn foo() {
if bar { loop {} }
foo()
}
```
even though `foo` may never be called (i.e. our apparent "unconditional" recursion is actually conditional). I don't know if we should handle this case, and ones like it with `panic!()` instead of `loop` (or anything else that "returns" `!`).
However, strictly speaking, it seems to me that changing the above to not warn will require changing
```rust
fn foo() {
while bar {}
foo()
}
```
to also not warn since it could be that the `while` is an infinite loop and doesn't ever hit the `foo`.
I'm inclined to think we let these cases warn since true edge cases like the first one seem rare, and if they do occur they seem like they would usually be typos in the function call. (I could imagine someone accidentally having code like `fn foo() { assert!(bar()); foo() /* meant to be boo() */ }` which won't warn if the `loop` case is "fixed".)
(Part of the reason this is unresolved is wanting feedback, part of the reason is I couldn't devise a strategy that worked in all cases.)
---
The name `unconditional_self_calls` is kinda clunky; and this reconstructs the CFG for each function that is linted which may or may not be very expensive, I don't know.
This allows one to look at an `ExprMethodCall` `foo.bar()` where `bar`
is a method in some trait and (sometimes) extract the `impl` that `bar`
is defined in, e.g.
trait Foo {
fn bar(&self);
}
impl Foo for uint { // <A>
fn bar(&self) {}
}
fn main() {
1u.bar(); // impl_def_id == Some(<A>)
}
This definitely doesn't handle all cases, but is correct when it is
known, meaning it should only be used for certain linting/heuristic
purposes; no safety analysis.
This should fix issue #20797 (but I don't want to close it automatically).
As the actual fix is very small this would be a perfect candidate for a rollup.
So far, the source location an LLVM instruction was linked to was controlled by
`debuginfo::set_source_location()` and `debuginfo::clear_source_location()`.
This interface mimicked how LLVM's `IRBuilder` handles debug location
assignment. While this interface has some theoretical performance benefits, it
also makes things terribly unstable: One sets some quasi-global state and then
hopes that it is still correct when a given instruction is emitted---an
assumption that has been proven to not hold a bit too often.
This patch requires the debug source location to be passed to the actual
instruction emitting function. This makes source location assignment explicit
and will prevent future changes to `trans` from accidentally breaking things in
the majority of cases.
This patch does not yet implement the new principle for all instruction kinds
but the stepping experience should have improved significantly nonetheless
already.
This commit is an implementation of [RFC 565][rfc] which is a stabilization of
the `std::fmt` module and the implementations of various formatting traits.
Specifically, the following changes were performed:
[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/0565-show-string-guidelines.md
* The `Show` trait is now deprecated, it was renamed to `Debug`
* The `String` trait is now deprecated, it was renamed to `Display`
* Many `Debug` and `Display` implementations were audited in accordance with the
RFC and audited implementations now have the `#[stable]` attribute
* Integers and floats no longer print a suffix
* Smart pointers no longer print details that they are a smart pointer
* Paths with `Debug` are now quoted and escape characters
* The `unwrap` methods on `Result` now require `Display` instead of `Debug`
* The `Error` trait no longer has a `detail` method and now requires that
`Display` must be implemented. With the loss of `String`, this has moved into
libcore.
* `impl<E: Error> FromError<E> for Box<Error>` now exists
* `derive(Show)` has been renamed to `derive(Debug)`. This is not currently
warned about due to warnings being emitted on stage1+
While backwards compatibility is attempted to be maintained with a blanket
implementation of `Display` for the old `String` trait (and the same for
`Show`/`Debug`) this is still a breaking change due to primitives no longer
implementing `String` as well as modifications such as `unwrap` and the `Error`
trait. Most code is fairly straightforward to update with a rename or tweaks of
method calls.
[breaking-change]
Closes#21436
After PR #19766 added implicit coersions `*mut T -> *const T`, the explicit casts can be removed.
(The number of such casts turned out to be relatively small).
This commit aims to stabilize the `TypeId` abstraction by moving it out of the
`intrinsics` module into the `any` module of the standard library. Specifically,
* `TypeId` is now defined at `std::any::TypeId`
* `TypeId::hash` has been removed in favor of an implementation of `Hash`.
This commit also performs a final pass over the `any` module, confirming the
following:
* `Any::get_type_id` remains unstable as *usage* of the `Any` trait will likely
never require this, and the `Any` trait does not need to be implemented for
any other types. As a result, this implementation detail can remain unstable
until associated statics are implemented.
* `Any::downcast_ref` is now stable
* `Any::downcast_mut` is now stable
* `BoxAny` remains unstable. While a direct impl on `Box<Any>` is allowed today
it does not allow downcasting of trait objects like `Box<Any + Send>` (those
returned from `Thread::join`). This is covered by #18737.
* `BoxAny::downcast` is now stable.
This commit modifies resolve to prevent conflicts with typedef names in the same
method that conflits are prevented with enum names. This is a breaking change
due to the differing semantics in resolve, and any errors generated on behalf of
this change require that a conflicting typedef, module, or structure to be
renamed so they do not conflict.
[breaking-change]
Closes#6936
LLVM gets overwhelmed when presented with a zeroinitializer for a large
type. In unoptimised builds, it generates a long sequence of stores to
memory. In optmised builds, it manages to generate a standard memset of
zero values, but takes a long time doing so.
Call out to the `llvm.memset` function to zero out the memory instead.
Fixes#21264
This commit aims to stabilize the `TypeId` abstraction by moving it out of the
`intrinsics` module into the `any` module of the standard library. Specifically,
* `TypeId` is now defined at `std::any::TypeId`
* `TypeId::hash` has been removed in favor of an implementation of `Hash`.
This commit also performs a final pass over the `any` module, confirming the
following:
* `Any::get_type_id` remains unstable as *usage* of the `Any` trait will likely
never require this, and the `Any` trait does not need to be implemented for
any other types. As a result, this implementation detail can remain unstable
until associated statics are implemented.
* `Any::downcast_ref` is now stable
* `Any::downcast_mut` is now stable
* `BoxAny` remains unstable. While a direct impl on `Box<Any>` is allowed today
it does not allow downcasting of trait objects like `Box<Any + Send>` (those
returned from `Thread::join`). This is covered by #18737.
* `BoxAny::downcast` is now stable.
LLVM gets overwhelmed when presented with a zeroinitializer for a large
type. In unoptimised builds, it generates a long sequence of stores to
memory. In optmised builds, it manages to generate a standard memset of
zero values, but takes a long time doing so.
Call out to the `llvm.memset` function to zero out the memory instead.
This stops the compiler ICEing on the use of SIMD types in FFI signatures. It emits correct code for LLVM intrinsics, but I am quite unsure about the ABI handling in general so I've added a new feature gate `simd_ffi` to try to ensure people don't use it without realising there's a non-trivial risk of codegen brokenness.
Closes#20043.
I don't know if this handling of SIMD types is correct for the C ABI on
all platforms, so lets add an even finer feature gate than just the
`simd` one.
The `simd` one can be used with (relatively) little risk of complete
nonsense, the reason for it is that it is likely that things will
change. Using the types in FFI with an incorrect ABI will at best give
absolute nonsense results, but possibly cause serious breakage too, so
this is a step up in badness, hence a new feature gate.
This seems to match what clang does on arm, but I cannot do any
experimentation with mips, but it matches how the LLVM intrinsics are
defined in any case...
Unlike the intrinics in C, this types the SSE values base on integer
size. This matches the LLVM intrinsics which have concrete vector types
(`<4 x i32>` etc.), and is no loss of expressivity: if one is using a C
function that really takes an untyped integral SSE value, just give it
whatever Rust type makes most sense.
While it's unstable and will probably be replaced or "reformed" at some point, it's useful in the mean time to be able to introspect the type system when debugging, and not be limited to sized types.
Fixes#21058
There are two places left where we used to only know the byte
size of/offset into an array and had to cast to i8 and back to get the
right addresses. But by now, we always know the sizes in terms of the
number of elements in the array. In fact we have to add an extra Mul
instruction so we can use the weird cast-to-u8 code. So we should really
just embrace our new knowledge and use simple GEPs to do the address
calculations.
Fixes#3729
Originally, this was going to be discussed and revisted, however I've been working on this for months, and a rebase on top of master was about 1 flight's worth of work so I just went ahead and did it.
This gets you as far as being able to target powerpc with, eg:
LD_LIBRARY_PATH=./x86_64-unknown-linux-gnu/stage2/lib/ x86_64-unknown-linux-gnu/stage2/bin/rustc -C linker=powerpc-linux-gnu-gcc --target powerpc-unknown-linux-gnu hello.rs
Would really love to get this out before 1.0. r? @alexcrichton
