Reattach all grandchildren when constructing specialization graph.
Specialization graphs are constructed by incrementally adding impls in the order of declaration. If the impl being added has its specializations in the graph already, they should be reattached under the impl. However, the current implementation only reattaches the one found first. Therefore, in the following specialization graph,
```
Tr1
|
I3
/ \
I1 I2
```
If `I1`, `I2`, and `I3` are declared in this order, the compiler mistakenly constructs the following graph:
```
Tr1
/ \
I3 I2
|
I1
```
This patch fixes the reattach procedure to include all specializing grandchildren-to-be.
Fixes#50452.
This commit, after reverting #55359, applies a different fix for #46775
while also fixing #55775. The basic idea was to go back to pre-#55359
libstd, and then fix#46775 in a way that doesn't expose #55775.
The issue described in #46775 boils down to two problems:
* First, the global environment is reset during `exec` but, but if the
`exec` call fails then the global environment was a dangling pointer
into free'd memory as the block of memory was deallocated when
`Command` is dropped. This is fixed in this commit by installing a
`Drop` stack object which ensures that the `environ` pointer is
preserved on a failing `exec`.
* Second, the global environment was accessed in an unsynchronized
fashion during `exec`. This was fixed by ensuring that the
Rust-specific environment lock is acquired for these system-level
operations.
Thanks to Alex Gaynor for pioneering the solution here!
Closes#55775
Co-authored-by: Alex Gaynor <alex.gaynor@gmail.com>
Check for negative impls when finding auto traits
Fixes#55321
When AutoTraitFinder begins examining a type, it checks for an explicit
negative impl. However, it wasn't checking for negative impls found when
calling 'select' on predicates found from nested obligations.
This commit makes AutoTraitFinder check for negative impls whenever it
makes a call to 'select'. If a negative impl is found, it immediately
bails out.
Normal users of SelectioContext don't need to worry about this, since
they stop as soon as an Unimplemented error is encountered. However, we
add predicates to our ParamEnv when we encounter this error, so we need
to handle negative impls specially (so that we don't try adding them to
our ParamEnv).
Make PhantomData #[structural_match]
fixes https://github.com/rust-lang/rust/issues/55028
This makes `PhantomData<T>` structurally matchable, irrespective of whether `T` is, per the discussion on this week's language team meeting (the general consensus was that this was a bug-fix).
All types containing `PhantomData<T>` and which used `#[derive(PartialEq, Eq)]` and were previously not `#[structural_match]` only because of `PhantomData<T>` will now be `#[structural_match]`.
r? @nikomatsakis
rustdoc: don't inline `pub use some_crate` unless directly asked to
cc https://github.com/rust-lang/rust/issues/52509 (fixes it? i'm not sure about my comment summoning the docs team)
When rustdoc encounters a `pub use` statement for an item from another crate, it will eagerly inline its contents into your crate. This somewhat clashes with the new paths behavior in Rust 2018, in which crates are implicitly linked and re-exported with `pub use` instead of `pub extern crate`. In rust 2015, `pub extern crate` would only create a single line for its re-export in the docs, so i'm making it do the same with `pub use some_crate;`.
The exact new behavior is like this: *If rustdoc sees a `pub use` statement, and the item being imported is the root of another crate, it will only inline it if `#[doc(inline)]` is provided.* I made it only avoid crate roots because otherwise it would stop inlining any module, which may or may not be what people want.
Fix emission of niche-filling discriminant values
Bug #55606 points out a regression introduced by #54004; namely that
an assertion can erroneously fire when a niche-filling discriminant
value is emitted.
This fixes the bug by removing the assertion, and furthermore by
arranging for the discriminant value to be masked according to the
size of the niche. This makes handling the discriminant a bit simpler
for debuggers.
The test case is from Jonathan Turner.
Closes#55606
NLL Diagnostic Review 3: Unions not reinitialized after assignment into field
Fixes#55651, #55652.
This PR makes two changes:
First, it updates the dataflow builder to add an init for the place
containing a union if there is an assignment into the field of
that union.
Second, it stops a "use of uninitialized" error occuring when there is an
assignment into the field of an uninitialized union that was previously
initialized. Making this assignment would re-initialize the union, as
tested in `src/test/ui/borrowck/borrowck-union-move-assign.nll.stderr`.
The check for previous initialization ensures that we do not start
supporting partial initialization yet (cc #21232, #54499, #54986).
This PR also fixes#55652 which was marked as requiring investigation
as the changes in this PR add an error that was previously missing
(and mentioned in the review comments) and confirms that the error
that was present is correct and a result of earlier partial
initialization changes in NLL.
r? @pnkfelix (due to earlier work with partial initialization)
cc @nikomatsakis
resolve: Filter away macro prelude in modules with `#[no_implicit_prelude]` on 2018 edition
This is a tiny thing.
For historical reasons macro prelude (macros from `#[macro_use] extern crate ...`, including `extern crate std`) is still available in modules with `#[no_implicit_prelude]`.
This PR provides proper isolation and removes those names from scope.
`#[no_implicit_prelude]` modules still have built-in types (`u8`), built-in attributes (`#[inline]`) and built-in macros (`env!("PATH")`) in scope. We can introduce some `#[no_implicit_prelude_at_all]` to remove those as well, but that's a separate issue.
The change is done only on 2018 edition for backward compatibility.
I'm pretty sure this can be done on 2015 as well because `#[no_implicit_prelude]` is rarely used, but I don't want to go through the crater/deprecation process right now, maybe later.
cc https://github.com/rust-lang/rust/issues/53977
r? @ghost
ICE with #![feature(nll)] and elided lifetimes
Fixes#55394.
This commit fixes an ICE and determines the correct return span in cases
with a method implemented on a struct with an an elided lifetime.
r? @pnkfelix
Don't inline virtual calls (take 2)
When I fixed the previous mis-optimizations, I didn't realize there were
actually two different places where we mutate `callsites` and both of
them should have the same behavior.
As a result, if a function was inlined and that function contained
virtual function calls, they were incorrectly being inlined. I also
added a test case which covers this.
NLL: Update box insensitivity test
This is just keeping one of our tests honest with respect to NLL, in two ways:
1. Adds uses of borrows that would otherwise be too short to observe the error that we would have expected to see...
2. ... I say "would have expected" because all of the errors in this file are part of the reversion of rust-lang/rfcs#130 that is attached to NLL (you can see more discussion of this here https://github.com/rust-lang/rust/issues/43234#issuecomment-411017768 )
Removed unneeded instance of `// revisions` from a lint test
Removed an unneeded instance of `// revisions`; the compare-mode=nll shows the output is identical now.
cc #54528
Take supertraits into account when calculating associated types
Fixes#24010 and #23856. Applies to trait aliases too.
As a by-product, this PR also makes repeated bindings of the same associated item in the same definition a hard error. This was previously a warning with a note about it becoming a hard error in the future. See #50589 for more info.
I talked about this with @nikomatsakis recently, but only very superficially, so this shouldn't stop anyone from assigning it to themself to review and r+.
N.B. The "WIP" commits represent imperfect attempts to solve the problem just for trait objects, but I've left them in for reference for the sake of whomever is reviewing this.
CC @carllerche @theemathas @durka @mbrubeck
Do not attempt to ascribe projections out of a ty var
If we encounter `_` ascribed to structural pattern like `(a, b)`, just skip relate_types.
Fix#55552
Bubble up an overflow error so that rustdoc can ignore it
fixes#54524
Idk how to write a test for this, other than trying to minimize the entire diesel crate. If desirable I will do that.
Note that there are many other such overflow errors hiding out there. Should we try to proactively eliminate them or do we just whack-a-mole them?
cc @GuillaumeGomez
r? @nikomatsakis
When I fixed the previous mis-optimizations, I didn't realize there were
actually two different places where we mutate `callsites` and both of
them should have the same behavior.
As a result, if a function was inlined and that function contained
virtual function calls, they were incorrectly being inlined. I also
added a test case which covers this.
Update emscripten
This updates emscripten to 1.38.15, which is based on LLVM 6.0.1 and would allow us to drop code for handling LLVM 4.
The main issue I ran into is that exporting statics through `EXPORTED_FUNCTIONS` no longer works. As far as I understand exporting non-functions doesn't really make sense under emscripten anyway, so I've modified the symbol export code to not even try.
Closes#52323.
