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Auto merge of #71916 - Dylan-DPC:rollup-luj7zx3, r=Dylan-DPC
Rollup of 4 pull requests Successful merges: - #69984 (Add Option to Force Unwind Tables) - #71830 (Remove clippy from some leftover lists of "possibly failing" tools) - #71894 (Suggest removing semicolon in last expression only if it's type is known) - #71897 (Improve docs for embed-bitcode and linker-plugin-lto) Failed merges: r? @ghost
2 parents de27cd7 + 3efcba6 commit f8d394e

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-24
lines changed

16 files changed

+156
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lines changed

‎src/bootstrap/test.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -528,7 +528,7 @@ impl Step for Clippy {
528528
host,
529529
"test",
530530
"src/tools/clippy",
531-
SourceType::Submodule,
531+
SourceType::InTree,
532532
&[],
533533
);
534534

‎src/bootstrap/toolstate.rs

-1
Original file line numberDiff line numberDiff line change
@@ -78,7 +78,6 @@ static STABLE_TOOLS: &[(&str, &str)] = &[
7878
("edition-guide", "src/doc/edition-guide"),
7979
("rls", "src/tools/rls"),
8080
("rustfmt", "src/tools/rustfmt"),
81-
("clippy-driver", "src/tools/clippy"),
8281
];
8382

8483
// These tools are permitted to not build on the beta/stable channels.

‎src/doc/rustc/src/codegen-options/index.md

+48-8
Original file line numberDiff line numberDiff line change
@@ -62,24 +62,40 @@ the linker.
6262

6363
## embed-bitcode
6464

65-
This flag controls whether or not the compiler puts LLVM bitcode into generated
66-
rlibs. It takes one of the following values:
65+
This flag controls whether or not the compiler embeds LLVM bitcode into object
66+
files. It takes one of the following values:
6767

6868
* `y`, `yes`, `on`, or no value: put bitcode in rlibs (the default).
6969
* `n`, `no`, or `off`: omit bitcode from rlibs.
7070

71-
LLVM bitcode is only needed when link-time optimization (LTO) is being
72-
performed, but it is enabled by default for backwards compatibility reasons.
71+
LLVM bitcode is required when rustc is performing link-time optimization (LTO).
72+
It is also required on some targets like iOS ones where vendors look for LLVM
73+
bitcode. Embedded bitcode will appear in rustc-generated object files inside of
74+
a section whose name is defined by the target platform. Most of the time this is
75+
`.llvmbc`.
7376

7477
The use of `-C embed-bitcode=no` can significantly improve compile times and
75-
reduce generated file sizes. For these reasons, Cargo uses `-C
76-
embed-bitcode=no` whenever possible. Likewise, if you are building directly
77-
with `rustc` we recommend using `-C embed-bitcode=no` whenever you are not
78-
using LTO.
78+
reduce generated file sizes if your compilation does not actually need bitcode
79+
(e.g. if you're not compiling for iOS or you're not performing LTO). For these
80+
reasons, Cargo uses `-C embed-bitcode=no` whenever possible. Likewise, if you
81+
are building directly with `rustc` we recommend using `-C embed-bitcode=no`
82+
whenever you are not using LTO.
7983

8084
If combined with `-C lto`, `-C embed-bitcode=no` will cause `rustc` to abort
8185
at start-up, because the combination is invalid.
8286

87+
> **Note**: if you're building Rust code with LTO then you probably don't even
88+
> need the `embed-bitcode` option turned on. You'll likely want to use
89+
> `-Clinker-plugin-lto` instead which skips generating object files entirely and
90+
> simply replaces object files with LLVM bitcode. The only purpose for
91+
> `-Cembed-bitcode` is when you're generating an rlib that is both being used
92+
> with and without LTO. For example Rust's standard library ships with embedded
93+
> bitcode since users link to it both with and without LTO.
94+
>
95+
> This also may make you wonder why the default is `yes` for this option. The
96+
> reason for that is that it's how it was for rustc 1.44 and prior. In 1.45 this
97+
> option was added to turn off what had always been the default.
98+
8399
## extra-filename
84100

85101
This option allows you to put extra data in each output filename. It takes a
@@ -98,6 +114,18 @@ values:
98114
The default behaviour, if frame pointers are not force-enabled, depends on the
99115
target.
100116

117+
## force-unwind-tables
118+
119+
This flag forces the generation of unwind tables. It takes one of the following
120+
values:
121+
122+
* `y`, `yes`, `on`, or no value: Unwind tables are forced to be generated.
123+
* `n`, `no`, or `off`: Unwind tables are not forced to be generated. If unwind
124+
tables are required by the target or `-C panic=unwind`, an error will be
125+
emitted.
126+
127+
The default if not specified depends on the target.
128+
101129
## incremental
102130

103131
This flag allows you to enable incremental compilation, which allows `rustc`
@@ -187,6 +215,18 @@ the following values:
187215
* `n`, `no`, or `off`: disable linker plugin LTO (the default).
188216
* A path to the linker plugin.
189217

218+
More specifically this flag will cause the compiler to replace its typical
219+
object file output with LLVM bitcode files. For example an rlib produced with
220+
`-Clinker-plugin-lto` will still have `*.o` files in it, but they'll all be LLVM
221+
bitcode instead of actual machine code. It is expected that the native platform
222+
linker is capable of loading these LLVM bitcode files and generating code at
223+
link time (typically after performing optimizations).
224+
225+
Note that rustc can also read its own object files produced with
226+
`-Clinker-plugin-lto`. If an rlib is only ever going to get used later with a
227+
`-Clto` compilation then you can pass `-Clinker-plugin-lto` to speed up
228+
compilation and avoid generating object files that aren't used.
229+
190230
## llvm-args
191231

192232
This flag can be used to pass a list of arguments directly to LLVM.

‎src/librustc_codegen_llvm/allocator.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -54,7 +54,7 @@ pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut ModuleLlvm, kind: Alloc
5454
if tcx.sess.target.target.options.default_hidden_visibility {
5555
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
5656
}
57-
if tcx.sess.target.target.options.requires_uwtable {
57+
if tcx.sess.must_emit_unwind_tables() {
5858
attributes::emit_uwtable(llfn, true);
5959
}
6060

‎src/librustc_codegen_llvm/attributes.rs

+1-4
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,6 @@ use rustc_middle::ty::query::Providers;
1313
use rustc_middle::ty::{self, TyCtxt};
1414
use rustc_session::config::{OptLevel, Sanitizer};
1515
use rustc_session::Session;
16-
use rustc_target::spec::PanicStrategy;
1716

1817
use crate::attributes;
1918
use crate::llvm::AttributePlace::Function;
@@ -271,9 +270,7 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
271270
//
272271
// You can also find more info on why Windows is whitelisted here in:
273272
// https://bugzilla.mozilla.org/show_bug.cgi?id=1302078
274-
if cx.sess().panic_strategy() == PanicStrategy::Unwind
275-
|| cx.sess().target.target.options.requires_uwtable
276-
{
273+
if cx.sess().must_emit_unwind_tables() {
277274
attributes::emit_uwtable(llfn, true);
278275
}
279276

‎src/librustc_interface/tests.rs

+1
Original file line numberDiff line numberDiff line change
@@ -415,6 +415,7 @@ fn test_codegen_options_tracking_hash() {
415415
tracked!(debuginfo, 0xdeadbeef);
416416
tracked!(embed_bitcode, false);
417417
tracked!(force_frame_pointers, Some(false));
418+
tracked!(force_unwind_tables, Some(true));
418419
tracked!(inline_threshold, Some(0xf007ba11));
419420
tracked!(linker_plugin_lto, LinkerPluginLto::LinkerPluginAuto);
420421
tracked!(llvm_args, vec![String::from("1"), String::from("2")]);

‎src/librustc_session/options.rs

+2
Original file line numberDiff line numberDiff line change
@@ -668,6 +668,8 @@ options! {CodegenOptions, CodegenSetter, basic_codegen_options,
668668
"extra data to put in each output filename"),
669669
force_frame_pointers: Option<bool> = (None, parse_opt_bool, [TRACKED],
670670
"force use of the frame pointers"),
671+
force_unwind_tables: Option<bool> = (None, parse_opt_bool, [TRACKED],
672+
"force use of unwind tables"),
671673
incremental: Option<String> = (None, parse_opt_string, [UNTRACKED],
672674
"enable incremental compilation"),
673675
inline_threshold: Option<usize> = (None, parse_opt_uint, [TRACKED],

‎src/librustc_session/session.rs

+44
Original file line numberDiff line numberDiff line change
@@ -646,6 +646,33 @@ impl Session {
646646
}
647647
}
648648

649+
pub fn must_emit_unwind_tables(&self) -> bool {
650+
// This is used to control the emission of the `uwtable` attribute on
651+
// LLVM functions.
652+
//
653+
// At the very least, unwind tables are needed when compiling with
654+
// `-C panic=unwind`.
655+
//
656+
// On some targets (including windows), however, exceptions include
657+
// other events such as illegal instructions, segfaults, etc. This means
658+
// that on Windows we end up still needing unwind tables even if the `-C
659+
// panic=abort` flag is passed.
660+
//
661+
// You can also find more info on why Windows needs unwind tables in:
662+
// https://bugzilla.mozilla.org/show_bug.cgi?id=1302078
663+
//
664+
// If a target requires unwind tables, then they must be emitted.
665+
// Otherwise, we can defer to the `-C force-unwind-tables=<yes/no>`
666+
// value, if it is provided, or disable them, if not.
667+
if self.panic_strategy() == PanicStrategy::Unwind {
668+
true
669+
} else if self.target.target.options.requires_uwtable {
670+
true
671+
} else {
672+
self.opts.cg.force_unwind_tables.unwrap_or(false)
673+
}
674+
}
675+
649676
/// Returns the symbol name for the registrar function,
650677
/// given the crate `Svh` and the function `DefIndex`.
651678
pub fn generate_plugin_registrar_symbol(&self, disambiguator: CrateDisambiguator) -> String {
@@ -1224,6 +1251,23 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
12241251
}
12251252
}
12261253

1254+
// Unwind tables cannot be disabled if the target requires them.
1255+
if let Some(include_uwtables) = sess.opts.cg.force_unwind_tables {
1256+
if sess.panic_strategy() == PanicStrategy::Unwind && !include_uwtables {
1257+
sess.err(
1258+
"panic=unwind requires unwind tables, they cannot be disabled \
1259+
with `-C force-unwind-tables=no`.",
1260+
);
1261+
}
1262+
1263+
if sess.target.target.options.requires_uwtable && !include_uwtables {
1264+
sess.err(
1265+
"target requires unwind tables, they cannot be disabled with \
1266+
`-C force-unwind-tables=no`.",
1267+
);
1268+
}
1269+
}
1270+
12271271
// PGO does not work reliably with panic=unwind on Windows. Let's make it
12281272
// an error to combine the two for now. It always runs into an assertions
12291273
// if LLVM is built with assertions, but without assertions it sometimes

‎src/librustc_typeck/check/mod.rs

+3-1
Original file line numberDiff line numberDiff line change
@@ -5387,7 +5387,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
53875387
_ => return None,
53885388
};
53895389
let last_expr_ty = self.node_ty(last_expr.hir_id);
5390-
if self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err() {
5390+
if matches!(last_expr_ty.kind, ty::Error)
5391+
|| self.can_sub(self.param_env, last_expr_ty, expected_ty).is_err()
5392+
{
53915393
return None;
53925394
}
53935395
let original_span = original_sp(last_stmt.span, blk.span);

‎src/test/codegen/force-unwind-tables.rs

+7
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,7 @@
1+
// min-llvm-version 8.0
2+
// compile-flags: -C no-prepopulate-passes -C force-unwind-tables=y
3+
4+
#![crate_type="lib"]
5+
6+
// CHECK: attributes #{{.*}} uwtable
7+
pub fn foo() {}

‎src/test/compile-fail/unwind-tables-panic-required.rs

+10
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
1+
// Tests that the compiler errors if the user tries to turn off unwind tables
2+
// when they are required.
3+
//
4+
// compile-flags: -C panic=unwind -C force-unwind-tables=no
5+
// ignore-tidy-linelength
6+
//
7+
// error-pattern: panic=unwind requires unwind tables, they cannot be disabled with `-C force-unwind-tables=no`.
8+
9+
pub fn main() {
10+
}

‎src/test/compile-fail/unwind-tables-target-required.rs

+11
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
// Tests that the compiler errors if the user tries to turn off unwind tables
2+
// when they are required.
3+
//
4+
// only-x86_64-windows-msvc
5+
// compile-flags: -C force-unwind-tables=no
6+
// ignore-tidy-linelength
7+
//
8+
// error-pattern: target requires unwind tables, they cannot be disabled with `-C force-unwind-tables=no`.
9+
10+
pub fn main() {
11+
}

‎src/test/ui/issues/issue-43162.stderr

-3
Original file line numberDiff line numberDiff line change
@@ -17,9 +17,6 @@ LL | fn foo() -> bool {
1717
| --- ^^^^ expected `bool`, found `()`
1818
| |
1919
| implicitly returns `()` as its body has no tail or `return` expression
20-
LL |
21-
LL | break true;
22-
| - help: consider removing this semicolon
2320

2421
error: aborting due to 3 previous errors
2522

‎src/test/ui/typeck/issue-67971.rs

+9
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,9 @@
1+
struct S {}
2+
3+
fn foo(ctx: &mut S) -> String { //~ ERROR mismatched types
4+
// Don't suggest to remove semicolon as it won't fix anything
5+
ctx.sleep = 0;
6+
//~^ ERROR no field `sleep` on type `&mut S`
7+
}
8+
9+
fn main() {}

‎src/test/ui/typeck/issue-67971.stderr

+18
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
error[E0609]: no field `sleep` on type `&mut S`
2+
--> $DIR/issue-67971.rs:5:9
3+
|
4+
LL | ctx.sleep = 0;
5+
| ^^^^^ unknown field
6+
7+
error[E0308]: mismatched types
8+
--> $DIR/issue-67971.rs:3:24
9+
|
10+
LL | fn foo(ctx: &mut S) -> String {
11+
| --- ^^^^^^ expected struct `std::string::String`, found `()`
12+
| |
13+
| implicitly returns `()` as its body has no tail or `return` expression
14+
15+
error: aborting due to 2 previous errors
16+
17+
Some errors have detailed explanations: E0308, E0609.
18+
For more information about an error, try `rustc --explain E0308`.

‎src/tools/publish_toolstate.py

-5
Original file line numberDiff line numberDiff line change
@@ -25,10 +25,6 @@
2525
# read privileges on it). CI will fail otherwise.
2626
MAINTAINERS = {
2727
'miri': {'oli-obk', 'RalfJung', 'eddyb'},
28-
'clippy-driver': {
29-
'Manishearth', 'llogiq', 'mcarton', 'oli-obk', 'phansch', 'flip1995',
30-
'yaahc',
31-
},
3228
'rls': {'Xanewok'},
3329
'rustfmt': {'topecongiro'},
3430
'book': {'carols10cents', 'steveklabnik'},
@@ -45,7 +41,6 @@
4541

4642
REPOS = {
4743
'miri': 'https://github.com/rust-lang/miri',
48-
'clippy-driver': 'https://github.com/rust-lang/rust-clippy',
4944
'rls': 'https://github.com/rust-lang/rls',
5045
'rustfmt': 'https://github.com/rust-lang/rustfmt',
5146
'book': 'https://github.com/rust-lang/book',

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