Never return uninhabited values at all
Functions with uninhabited return values are already marked `noreturn`,
but we were still generating return instructions for this. When running
with `-C passes=lint`, LLVM prints:
Unusual: Return statement in function with noreturn attribute
The LLVM manual makes a stronger statement about `noreturn` though:
> This produces undefined behavior at runtime if the function ever does
dynamically return.
We now emit an `abort` anywhere that would have tried to return an
uninhabited value.
Fixes#48227
cc #7463#48229
r? @eddyb
Functions with uninhabited return values are already marked `noreturn`,
but we were still generating return instructions for this. When running
with `-C passes=lint`, LLVM prints:
Unusual: Return statement in function with noreturn attribute
The LLVM manual makes a stronger statement about `noreturn` though:
> This produces undefined behavior at runtime if the function ever does
dynamically return.
We now emit an `abort` anywhere that would have tried to return an
uninhabited value.
Fix stack overflow when generating debuginfo for 'recursive' type
By using 'impl trait', it's possible to create a self-referential
type as follows:
fn foo() -> impl Copy { foo }
This is a function which returns itself.
Normally, the signature of this function would be impossible
to write - it would look like 'fn foo() -> fn() -> fn() ...'
e.g. a function which returns a function, which returns a function...
Using 'impl trait' allows us to avoid writing this infinitely long
type. While it's useless for practical purposes, it does compile and run
However, issues arise when we try to generate llvm debuginfo for such a
type. All 'impl trait' types (e.g. ty::Opaque) are resolved when we
generate debuginfo, which can lead to us recursing back to the original
'fn' type when we try to process its return type.
To resolve this, I've modified debuginfo generation to account for these
kinds of weird types. Unfortunately, there's no 'correct' debuginfo that
we can generate - 'impl trait' does not exist in debuginfo, and this
kind of recursive type is impossible to directly represent.
To ensure that we emit *something*, this commit emits dummy
debuginfo/type names whenever it encounters a self-reference. In
practice, this should never happen - it's just to ensure that we can
emit some kind of debuginfo, even if it's not particularly meaningful
Fixes#58463
resolve: collect trait aliases along with traits
It seems trait aliases weren't being collected as `TraitCandidates` in resolve, this should change that. (I can't compile the full compiler locally, so relying on CI...)
Fixes https://github.com/rust-lang/rust/issues/56485
r? @alexreg
async fn now lowers directly to an existential type declaration
rather than reusing the `impl Trait` return type lowering.
As part of this, it lowers all argument-position elided lifetimes
using the in-band-lifetimes machinery, creating fresh parameter
names for each of them, using each lifetime parameter as a generic
argument to the generated existential type.
This doesn't currently successfully allow multiple
argument-position elided lifetimes since `existential type`
doesn't yet support multiple lifetimes where neither outlive
the other. This requires a separate fix.
By using 'impl trait', it's possible to create a self-referential
type as follows:
fn foo() -> impl Copy { foo }
This is a function which returns itself.
Normally, the signature of this function would be impossible
to write - it would look like 'fn foo() -> fn() -> fn() ...'
e.g. a function which returns a function, which returns a function...
Using 'impl trait' allows us to avoid writing this infinitely long
type. While it's useless for practical purposes, it does compile and run
However, issues arise when we try to generate llvm debuginfo for such a
type. All 'impl trait' types (e.g. ty::Opaque) are resolved when we
generate debuginfo, which can lead to us recursing back to the original
'fn' type when we try to process its return type.
To resolve this, I've modified debuginfo generation to account for these
kinds of weird types. Unfortunately, there's no 'correct' debuginfo that
we can generate - 'impl trait' does not exist in debuginfo, and this
kind of recursive type is impossible to directly represent.
To ensure that we emit *something*, this commit emits dummy
debuginfo/type names whenever it encounters a self-reference. In
practice, this should never happen - it's just to ensure that we can
emit some kind of debuginfo, even if it's not particularly meaningful
Fixes#58463
Fix LLVM IR generated for C-variadic arguments
It is possible to create malformed LLVM IR given variadic arguments that
are aggregate types. This occurs due to improper tracking of the current
argument in the functions list of arguments.
Fixes: #58881
It is possible to create malformed LLVM IR given variadic arguments that
are aggregate types. This occurs due to improper tracking of the current
argument in the functions list of arguments.
Fallback to `static_impl_trait` for nice error message by peeking at the
return type and the lifetime type. Point at the return type instead of
the return expr/stmt in NLL mode.
skip dyn keyword lint under macros
This PR is following my own intuition that `rustfix` should never inject bugs into working code (even if that comes at the expense of it failing to fix things that will become bugs).
Fix#56327
Fix invalid DWARF for enums when using ThinLTO
We were setting the same identifier for both the DW_TAG_structure_type
and the DW_TAG_variant_part. This becomes a problem when using ThinLTO
becauses it uses the identifier as a key for a map of types that is used
to delete duplicates based on the ODR, so one of them is deleted as a
duplicate, resulting in invalid DWARF.
The DW_TAG_variant_part isn't a standalone type, so it doesn't need
an identifier. Fix by omitting its identifier.
ODR uniquing is [enabled here](f21dee2c61/src/rustllvm/PassWrapper.cpp (L1101)).
