rust: Add a `-C default-linker-libraries` option
This commit adds a new codegen option for the compiler which disables
rustc's passing of `-nodefaultlibs` by default on relevant platforms.
Sometimes Rust is linked with C code which fails to link with
`-nodefaultlibs` and is unnecessarily onerous to get linking correctly
with `-nodefaultlibs`.
An example of this is that when you compile C code with sanitizers and
then pass `-fsanitize=address` to the linker, it's incompatible with
`-nodefaultlibs` also being passed to the linker.
In these situations it's easiest to turn off Rust's default passing of
`-nodefaultlibs`, which was more ideological to start with than
anything! Preserving the default is somewhat important but having this
be opt-in shouldn't cause any breakage.
Closes#54237
Fix Once perf regression
Because `call_once` is generic, but `is_completed` is not, we need
`#[inline]` annotation to allow LLVM to inline `is_completed` into
`call_once` in downstream crates.
cc https://github.com/rust-lang/rust/pull/53027/files#r221418859
Don't lint non-extern-prelude extern crate's in Rust 2018.
Fixes#54381 by silencing the lint telling users to remove `extern crate` when `use` doesn't work.
r? @alexcrichton cc @petrochenkov @nikomatsakis @Centril
Add a per-tree error cache to the obligation forest
This implements part of what @nikomatsakis mentioned in https://github.com/rust-lang/rust/pull/30533#issuecomment-170705871:
> 1. If you find that a new obligation is a duplicate of one already in the tree, the proper processing is:
> * if that other location is your parent, you should abort with a cycle error (or accept it, if coinductive)
> * if that other location is not an ancestor, you can safely ignore the new obligation
In particular it implements the "if that other location is your parent accept it, if coinductive" part. This fixes#40827.
I have to say that I'm not 100% confident that this is rock solid. This is my first pull request 🎉, and I didn't know anything about the trait resolver before this. In particular I'm not totally sure that comparing predicates is enough (for instance, do we need to compare `param_env` as well?). Also, I'm not sure what @nikomatsakis mentions [here](https://github.com/rust-lang/rust/issues/30977#issue-127091096), but it might be something that affects this PR:
> In particular, I am wary of getting things wrong around inference variables! We can always add things to the set in their current state, and if unifications occur then the obligation is just kind of out-of-date, but I want to be sure we don't accidentally fail to notice that something is our ancestor. I decided this was subtle enough to merit its own PR.
Anyway, go ahead and review 🙂.
Ref #30977.
# Performance
We are now copying vectors around, so I decided to do some benchmarking. A simple benchmark shows that this does not seem to affect performance in a measurable way:
I ran `cargo clean && cargo build` 20 times on actix-web (84b27db) and these are the results:
```text
rustc master:
Mean Std.Dev. Min Median Max
real 66.637 2.996 57.220 67.714 69.314
user 307.293 14.741 258.093 312.209 320.702
sys 12.524 0.653 10.499 12.726 13.193
rustc fix-bug-overflow-send:
Mean Std.Dev. Min Median Max
real 66.297 4.310 53.532 67.516 70.348
user 306.812 22.371 236.917 314.748 326.229
sys 12.757 0.952 9.671 13.125 13.544
```
I will do a more comprehensive benchmark (compiling rustc stage1) and post the results.
r? @nikomatsakis, @nnethercote
PS: It is better to review this commit-by-commit.
Enable NLL compare mode for more tests
Most of these tests were disabled due to NLL bugs that have since been fixed. A few needed updating for NLL.
r? @nikomatsakis
don't elide lifetimes in paths in librustc/
In light of the "Apply to rustc" checkbox on #44524 and @nikomatsakis's [recent comment about regularly wanting visual indication of elided lifetimes in types](https://github.com/rust-lang/rust/issues/44524#issuecomment-414663773), I was curious to see what it would look like if we turned the `elided_lifetimes_in_path` lint on in at least one crate in the codebase (I chose librustc). Given that I couldn't figure out how to get `cargo fix` work with the build system, this arguably wasn't a very efficient use of my time, but once I started, the conjunction of moral law and the sunk cost fallacy forced me to continue.
This is mostly applying the `<'_>` suggestions issued by the lint, but there were a few places where I named the lifetimes (_e.g._, `<'a, 'gcx, 'tcx>` on `TyCtxt`) in order to match style with surrounding code.
r? @nikomatsakis
Do not put noalias annotations by default
This will be re-enabled sooner or later depending on results of further
investigation.
Fixes#54462
Beta backport is: #54640
r? @nikomatsakis
This seemed like a good way to kick the tires on the
elided-lifetimes-in-paths lint (#52069)—seems to work! This was also
pretty tedious—it sure would be nice if `cargo fix` worked on this
codebase (#53896)!
A few cleanups and minor improvements to typeck
This PR complements https://github.com/rust-lang/rust/pull/54533, which was limited to `check`.
- change a few `push` loops to `extend`s
- prefer `to_owned` to `to_string` for string literals
- prefer `if let` to `match` where only one branch matters
- a few other minor improvements
- whitespace fixes
This commit adds a new codegen option for the compiler which disables
rustc's passing of `-nodefaultlibs` by default on relevant platforms.
Sometimes Rust is linked with C code which fails to link with
`-nodefaultlibs` and is unnecessarily onerous to get linking correctly
with `-nodefaultlibs`.
An example of this is that when you compile C code with sanitizers and
then pass `-fsanitize=address` to the linker, it's incompatible with
`-nodefaultlibs` also being passed to the linker.
In these situations it's easiest to turn off Rust's default passing of
`-nodefaultlibs`, which was more ideological to start with than
anything! Preserving the default is somewhat important but having this
be opt-in shouldn't cause any breakage.
Closes#54237
use closure def-id in returns, but base def-id in locals
The refactorings to handle `let x: impl Trait` wound up breaking `impl Trait` in closure return types. I think there are some deeper problems with the code in question, but this a least should make @eddyb's example work.
Fixes#54593
r? @eddyb
Rollup of 8 pull requests
Successful merges:
- #54564 (Add 1.29.1 release notes)
- #54567 (Include path in stamp hash for debuginfo tests)
- #54577 (rustdoc: give proc-macros their own pages)
- #54590 (std: Don't let `rust_panic` get inlined)
- #54598 (Remove useless lifetimes from `Pin` `impl`s.)
- #54604 (Added help message for `self_in_typedefs` feature gate)
- #54635 (Improve docs for std::io::Seek)
- #54645 (Compute Android gdb version in compiletest)
Revert most of MaybeUninit, except for the new API itself
This reverts most of https://github.com/rust-lang/rust/pull/53508/ for perf reasons (first commit reverts that entire PR), except for the new API itself (added back in 2nd commit).
rustdoc: give proc-macros their own pages
related to https://github.com/rust-lang/rust/issues/49553 but i don't think it'll fix it
Currently, rustdoc doesn't expose proc-macros all that well. In the source crate, only their definition function is exposed, but when re-exported, they're treated as a macro! This is an awkward situation in all accounts. This PR checks functions to see whether they have any of `#[proc_macro]`, `#[proc_macro_attribute]`, or `#[proc_macro_derive]`, and exposes them as macros instead. In addition, attributes and derives are exposed differently than other macros, getting their own item-type, CSS class, and module heading.
Function-like proc-macros are lumped in with `macro_rules!` macros, but they get a different declaration block (i'm open to tweaking this, it's just what i thought of given how function-proc-macros operate):
Proc-macro attributes and derives get their own pages, with a representative declaration block. Derive macros also show off their helper attributes:
There's one wrinkle which this PR doesn't address, which is why i didn't mark this as fixing the linked issue. Currently, proc-macros don't expose their attributes or source span across crates, so while rustdoc knows they exist, that's about all the information it gets. This leads to an "inlined" macro that has absolutely no docs on it, and no `[src]` link to show you where it was declared.
The way i got around it was to keep proc-macro re-export disabled, since we do get enough information across crates to properly link to the source page:
Until we can get a proc-macro's docs (and ideally also its source span) across crates, i believe this is the best way forward.
Compute Android gdb version in compiletest
compiletest has special code for running gdb for Android targets. In
particular it computes a different path to gdb. However, this gdb is
not used for the version test, which results in some tests being run
when they should not be. You can see this in #54004.
This patch moves the special case to analyze_gdb and a new helper
function to decide whether the case applies. This causes the version
check to work properly.
Note that the bulk of the runtest.rs change is just reindentation
caused by moving from a "match" to an "if" -- but there is a (small)
change buried in there.
std: Don't let `rust_panic` get inlined
It's meant for breakpoints, so if it gets inlined we can't set a
breakpoint on it easily!
Will hopefully help fix at least one aspect of https://github.com/rust-lang/rust/issues/49013
Because `call_once` is generic, but `is_completed` is not, we need
`#[inline]` annotation to allow LLVM to inline `is_completed` into
`call_once` in downstream crates.
ignore {std,fast,vector,this}call on non-x86 windows
MSVC ignores these keywords for C/C++ and uses the standard system
calling convention. Rust should do so as well.
Fixes#54569.
Include path in stamp hash for debuginfo tests
The debuginfo tests are exposed to the environment in a couple of
ways: the path to the gdb executable matters, as does the Python path
used when loading lldb.
This patch incorporates these paths into the hash that is written to
the stamp file, so that changing the path will cause the tests to be
re-run.
rustc: keep a Span for each predicate in ty::GenericPredicates.
This should allow finer-grained diagnostics, including migration suggestions for #54090.
(Note that I haven't changed most of the users of `predicates_of` to use the new spans)
r? @nikomatsakis
compiletest has special code for running gdb for Android targets. In
particular it computes a different path to gdb. However, this gdb is
not used for the version test, which results in some tests being run
when they should not be. You can see this in #54004.
This patch moves the special case to analyze_gdb and a new helper
function to decide whether the case applies. This causes the version
check to work properly.
Note that the bulk of the runtest.rs change is just reindentation
caused by moving from a "match" to an "if" -- but there is a (small)
change buried in there.
Emit used rustc invocation in the save-analysis file
Blocked on https://github.com/nrc/rls-data/pull/19. (I'm guessing it won't pass CI due to an out-of-tree git dependency)
This should allow RLS to recreate a Rust compilation build plan from the save-analysis files alone, which should be useful when fetching those from external build systems, most notably Buck now.
Also this includes some more potentially useful compilation-specific options (e.g. sysroot or the actual path to extern crates) but that's not required for the build plan bits.
cc @jsgf @alexcrichton
r? @nrc
