This patch adds a `-Z linker-flavor` flag to rustc which can be used to invoke
the linker using a different interface.
For example, by default rustc assumes that all the Linux targets will be linked
using GCC. This makes it impossible to use LLD as a linker using just `-C
linker=ld.lld` because that will invoke LLD with invalid command line
arguments. (e.g. rustc will pass -Wl,--gc-sections to LLD but LLD doesn't
understand that; --gc-sections would be the right argument)
With this patch one can pass `-Z linker-flavor=ld` to rustc to invoke the linker
using a LD-like interface. This way, `rustc -C linker=ld.lld -Z
linker-flavor=ld` will invoke LLD with the right arguments.
`-Z linker-flavor` accepts 4 different arguments: `em` (emcc), `ld`,
`gcc`, `msvc` (link.exe). `em`, `gnu` and `msvc` cover all the existing linker
interfaces. `ld` is a new flavor for interfacing GNU's ld and LLD.
This patch also changes target specifications. `linker-flavor` is now a
mandatory field that specifies the *default* linker flavor that the target will
use. This change also makes the linker interface *explicit*; before, it used to
be derived from other fields like linker-is-gnu, is-like-msvc,
is-like-emscripten, etc.
Another change to target specifications is that the fields `pre-link-args`,
`post-link-args` and `late-link-args` now expect a map from flavor to linker
arguments.
``` diff
- "pre-link-args": ["-Wl,--as-needed", "-Wl,-z,-noexecstack"],
+ "pre-link-args": {
+ "gcc": ["-Wl,--as-needed", "-Wl,-z,-noexecstack"],
+ "ld": ["--as-needed", "-z,-noexecstack"],
+ },
```
[breaking-change] for users of custom targets specifications
In addition to defining and handling the new option, we also add a
method on librustc::Session for determining the necessity of overflow
checks. This method provides a single point to sort out the three (!)
different ways for turning on overflow checks: -C debug-assertions, -C
overflow-checks, and -Z force-overflow-checks.
Fixes#33134.
Biggest change: Revised print-type-sizes output to include breakdown
of layout.
Includes info about field sizes (and alignment + padding when padding
is injected; the injected padding is derived from the offsets computed
by layout module).
Output format is illustrated in commit that has the ui tests.
Note: there exists (at least) one case of variant w/o name: empty
enums. Namely, empty enums use anonymous univariant repr. So for such
cases, print the number of the variant instead of the name.
----
Also, eddyb suggested of reading from `layout_cache` post-trans.
(For casual readers: the compiler source often uses the word "cache"
for tables that are in fact not periodically purged, and thus are
useful as the basis for data like this.)
Some types that were previously not printed are now included in the
output. (See e.g. the tests `print_type_sizes/generics.rs` and
`print_type_sizes/variants.rs`)
----
Other review feedback:
switch to an exhaustive match when filtering in just structural types.
switch to hashset for layout info and move sort into print method.
----
Driveby change: Factored session::code_stats into its own module
----
incorporate njn feedback re output formatting.
Group unused import warnings per import list
Given a file
``` rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
``` nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> file2.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Fixes#16132.
Given a file
```rust
use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
fn main() {}
```
Show a single warning, instead of three for each unused import:
```nocode
warning: unused imports, #[warn(unused_imports)] on by default
--> foo.rs:1:24
|
1 | use std::collections::{BinaryHeap, BTreeMap, BTreeSet};
| ^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
```
Include support for lints pointing at `MultilineSpan`s, instead of just
`Span`s.
Most of the Rust community agrees that the vec! macro is clearer when
called using square brackets [] instead of regular brackets (). Most of
these ocurrences are from before macros allowed using different types of
brackets.
There is one left unchanged in a pretty-print test, as the pretty
printer still wants it to have regular brackets.
Some lint-level attributes (like `bad-style`, or, more dramatically,
`warnings`) can affect more than one lint; it seems fairer to point out
the attribute once for each distinct lint affected. Also, a UI test is
added. This remains in the matter of #24690.
Jonathan D. Turner pointed out that we don't want to dedup in JSON
mode. Since the compile-test runner uses JSON output, we regrettably
need to revert the edits to existing tests; one imagines that testing
for one-time diagnosticity for humans will have to be added as a UI
test.
This remains in the matter of #24690.
We introduce a new `one_time_diagnostics` field on
`rustc::session::Session` to hold a hashset of diagnostic messages we've
set once but don't want to see again (as uniquified by span and message
text), "lint level defined here" being the motivating example dealt with
here.
This is in the matter of #24690.
add a panic-strategy field to the target specification
Now a target can define its panic strategy in its specification. If a
user doesn't specify a panic strategy via the command line, i.e. '-C
panic', then the compiler will use the panic strategy defined by the
target specification.
Custom targets can pick their panic strategy via the "panic-strategy"
field of their target specification JSON file. If omitted in the
specification, the strategy defaults to "unwind".
closes#36647
---
I checked that compiling an executable for a custom target with "panic-strategy" set to "abort" doesn't need the "eh_personality" lang item and also that standard crates compiled for that custom target didn't contained undefined symbols to _Unwind_Resume. But this needs an actual unit test, any suggestion on how to test this?
Most of the noise in the diff is due to moving `PanicStrategy` from the `rustc` to the `rustc_back` crate.
r? @alexcrichton
cc @phil-opp
Now a target can define its panic strategy in its specification. If a
user doesn't specify a panic strategy via the command line, i.e. '-C
panic', then the compiler will use the panic strategy defined by the
target specification.
Custom targets can pick their panic strategy via the "panic-strategy"
field of their target specification JSON file. If omitted in the
specification, the strategy defaults to "unwind".
closes#36647
incr. comp.: Take spans into account for ICH
This PR makes the ICH (incr. comp. hash) take spans into account when debuginfo is enabled.
A side-effect of this is that the SVH (which is based on the ICHs of all items in the crate) becomes sensitive to the tiniest change in a code base if debuginfo is enabled. Since we are not trying to model ABI compatibility via the SVH anymore (this is done via the crate disambiguator now), this should be not be a problem.
Fixes#33888.
Fixes#32753.
This commit is an implementation of [RFC 1681] which adds support to the
compiler for first-class user-define custom `#[derive]` modes with a far more
stable API than plugins have today.
[RFC 1681]: https://github.com/rust-lang/rfcs/blob/master/text/1681-macros-1.1.md
The main features added by this commit are:
* A new `rustc-macro` crate-type. This crate type represents one which will
provide custom `derive` implementations and perhaps eventually flower into the
implementation of macros 2.0 as well.
* A new `rustc_macro` crate in the standard distribution. This crate will
provide the runtime interface between macro crates and the compiler. The API
here is particularly conservative right now but has quite a bit of room to
expand into any manner of APIs required by macro authors.
* The ability to load new derive modes through the `#[macro_use]` annotations on
other crates.
All support added here is gated behind the `rustc_macro` feature gate, both for
the library support (the `rustc_macro` crate) as well as the language features.
There are a few minor differences from the implementation outlined in the RFC,
such as the `rustc_macro` crate being available as a dylib and all symbols are
`dlsym`'d directly instead of having a shim compiled. These should only affect
the implementation, however, not the public interface.
This commit also ended up touching a lot of code related to `#[derive]`, making
a few notable changes:
* Recognized derive attributes are no longer desugared to `derive_Foo`. Wasn't
sure how to keep this behavior and *not* expose it to custom derive.
* Derive attributes no longer have access to unstable features by default, they
have to opt in on a granular level.
* The `derive(Copy,Clone)` optimization is now done through another "obscure
attribute" which is just intended to ferry along in the compiler that such an
optimization is possible. The `derive(PartialEq,Eq)` optimization was also
updated to do something similar.
---
One part of this PR which needs to be improved before stabilizing are the errors
and exact interfaces here. The error messages are relatively poor quality and
there are surprising spects of this such as `#[derive(PartialEq, Eq, MyTrait)]`
not working by default. The custom attributes added by the compiler end up
becoming unstable again when going through a custom impl.
Hopefully though this is enough to start allowing experimentation on crates.io!
syntax-[breaking-change]
Commandline arguments influence whether incremental compilation
can use its compilation cache and thus their changes relative to
previous compilation sessions need to be taking into account. This
commit makes sure that one has to specify for every commandline
argument whether it influences incremental compilation or not.
We used to use `Name`, but the session outlives the tokenizer, which
means that attempts to read this field after trans has complete
otherwise panic. All reads want an `InternedString` anyhow.
This is a spiritual succesor to #34268/8531d581, in which we replaced a
number of matches of None to the unit value with `if let` conditionals
where it was judged that this made for clearer/simpler code (as would be
recommended by Manishearth/rust-clippy's `single_match` lint). The same
rationale applies to matches of None to the empty block.
This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.
[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md
Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.
With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.
Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).
Major changes:
- Remove old snippet rendering code and use the new stuff.
- Introduce `span_label` method to add a label
- Remove EndSpan mode and replace with a fn to get the last
character of a span.
- Stop using `Option<MultiSpan>` and just use an empty `MultiSpan`
- and probably a bunch of other stuff :)
