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Auto merge of #86231 - nagisa:nagisa/abi-allowlist, r=petrochenkov
Replace per-target ABI denylist with an allowlist It makes very little sense to maintain denylists of ABIs when, as far as non-generic ABIs are concerned, targets usually only support a small subset of the available ABIs. This has historically been a cause of bugs such as us allowing use of the platform-specific ABIs on x86 targets – these in turn would cause LLVM errors or assertions to fire. In this PR we got rid of the per-target ABI denylists, and instead compute which ABIs are supported with a simple match based on, mostly, the `Target::arch` field. Among other things, this makes it impossible to forget to consider this problem (in either direction) and forces one to consider what the ABI support looks like when adding an ABI (rarely) rather than target (often), which should hopefully also reduce the cognitive load on both contributors as well as reviewers. Fixes #57182 Sponsored by: standard.ai --- ## Summary for teams One significant user-facing change after this PR is that there's now a future compat warning when building… * `stdcall`, `fastcall`, `thiscall` using code with targets other than 32-bit x86 (i386...i686) or *-windows-*; * `vectorcall` using code when building for targets other than x86 (either 32 or 64 bit) or *-windows-*. Previously these ABIs have been accepted much more broadly, even for architectures and targets where this made no sense (e.g. on wasm32) and would fall back to the C ABI. In practice this doesn't seem to be used too widely and the [breakages in crater](#86231 (comment)) that we see are mostly about Windows-specific code that was missing relevant `cfg`s and just happened to successfully `check` on Linux for one reason or another. The intention is that this warning becomes a hard error after some time.
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‎compiler/rustc_lint_defs/src/builtin.rs

+47
Original file line numberDiff line numberDiff line change
@@ -2974,6 +2974,7 @@ declare_lint_pass! {
29742974
LARGE_ASSIGNMENTS,
29752975
FUTURE_PRELUDE_COLLISION,
29762976
RESERVED_PREFIX,
2977+
UNSUPPORTED_CALLING_CONVENTIONS,
29772978
]
29782979
}
29792980

@@ -3303,3 +3304,49 @@ declare_lint! {
33033304
};
33043305
crate_level_only
33053306
}
3307+
3308+
declare_lint! {
3309+
/// The `unsupported_calling_conventions` lint is output whenever there is an use of the
3310+
/// `stdcall`, `fastcall`, `thiscall`, `vectorcall` calling conventions (or their unwind
3311+
/// variants) on targets that cannot meaningfully be supported for the requested target.
3312+
///
3313+
/// For example `stdcall` does not make much sense for a x86_64 or, more apparently, powerpc
3314+
/// code, because this calling convention was never specified for those targets.
3315+
///
3316+
/// Historically MSVC toolchains have fallen back to the regular C calling convention for
3317+
/// targets other than x86, but Rust doesn't really see a similar need to introduce a similar
3318+
/// hack across many more targets.
3319+
///
3320+
/// ### Example
3321+
///
3322+
/// ```rust,ignore (needs specific targets)
3323+
/// extern "stdcall" fn stdcall() {}
3324+
/// ```
3325+
///
3326+
/// This will produce:
3327+
///
3328+
/// ```text
3329+
/// warning: use of calling convention not supported on this target
3330+
/// --> $DIR/unsupported.rs:39:1
3331+
/// |
3332+
/// LL | extern "stdcall" fn stdcall() {}
3333+
/// | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
3334+
/// |
3335+
/// = note: `#[warn(unsupported_calling_conventions)]` on by default
3336+
/// = warning: this was previously accepted by the compiler but is being phased out;
3337+
/// it will become a hard error in a future release!
3338+
/// = note: for more information, see issue ...
3339+
/// ```
3340+
///
3341+
/// ### Explanation
3342+
///
3343+
/// On most of the targets the behaviour of `stdcall` and similar calling conventions is not
3344+
/// defined at all, but was previously accepted due to a bug in the implementation of the
3345+
/// compiler.
3346+
pub UNSUPPORTED_CALLING_CONVENTIONS,
3347+
Warn,
3348+
"use of unsupported calling convention",
3349+
@future_incompatible = FutureIncompatibleInfo {
3350+
reference: "issue #00000 <https://github.com/rust-lang/rust/issues/00000>",
3351+
};
3352+
}

‎compiler/rustc_target/src/spec/aarch64_apple_ios.rs

+1-3
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,6 @@ use super::apple_sdk_base::{opts, Arch};
22
use crate::spec::{FramePointer, Target, TargetOptions};
33

44
pub fn target() -> Target {
5-
let base = opts("ios", Arch::Arm64);
65
Target {
76
llvm_target: "arm64-apple-ios".to_string(),
87
pointer_width: 64,
@@ -11,7 +10,6 @@ pub fn target() -> Target {
1110
options: TargetOptions {
1211
features: "+neon,+fp-armv8,+apple-a7".to_string(),
1312
max_atomic_width: Some(128),
14-
unsupported_abis: super::arm_base::unsupported_abis(),
1513
forces_embed_bitcode: true,
1614
frame_pointer: FramePointer::NonLeaf,
1715
// Taken from a clang build on Xcode 11.4.1.
@@ -25,7 +23,7 @@ pub fn target() -> Target {
2523
darwinpcs\0\
2624
-Os\0"
2725
.to_string(),
28-
..base
26+
..opts("ios", Arch::Arm64)
2927
},
3028
}
3129
}

‎compiler/rustc_target/src/spec/aarch64_apple_ios_macabi.rs

+1-3
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,6 @@ use super::apple_sdk_base::{opts, Arch};
22
use crate::spec::{FramePointer, Target, TargetOptions};
33

44
pub fn target() -> Target {
5-
let base = opts("ios", Arch::Arm64_macabi);
65
Target {
76
llvm_target: "arm64-apple-ios14.0-macabi".to_string(),
87
pointer_width: 64,
@@ -11,7 +10,6 @@ pub fn target() -> Target {
1110
options: TargetOptions {
1211
features: "+neon,+fp-armv8,+apple-a12".to_string(),
1312
max_atomic_width: Some(128),
14-
unsupported_abis: super::arm_base::unsupported_abis(),
1513
forces_embed_bitcode: true,
1614
frame_pointer: FramePointer::NonLeaf,
1715
// Taken from a clang build on Xcode 11.4.1.
@@ -23,7 +21,7 @@ pub fn target() -> Target {
2321
-disable-llvm-passes\0\
2422
-Os\0"
2523
.to_string(),
26-
..base
24+
..opts("ios", Arch::Arm64_macabi)
2725
},
2826
}
2927
}

‎compiler/rustc_target/src/spec/aarch64_apple_ios_sim.rs

-1
Original file line numberDiff line numberDiff line change
@@ -19,7 +19,6 @@ pub fn target() -> Target {
1919
options: TargetOptions {
2020
features: "+neon,+fp-armv8,+apple-a7".to_string(),
2121
max_atomic_width: Some(128),
22-
unsupported_abis: super::arm_base::unsupported_abis(),
2322
forces_embed_bitcode: true,
2423
frame_pointer: FramePointer::NonLeaf,
2524
// Taken from a clang build on Xcode 11.4.1.

‎compiler/rustc_target/src/spec/aarch64_apple_tvos.rs

+1-3
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,6 @@ use super::apple_sdk_base::{opts, Arch};
22
use crate::spec::{FramePointer, Target, TargetOptions};
33

44
pub fn target() -> Target {
5-
let base = opts("tvos", Arch::Arm64);
65
Target {
76
llvm_target: "arm64-apple-tvos".to_string(),
87
pointer_width: 64,
@@ -11,10 +10,9 @@ pub fn target() -> Target {
1110
options: TargetOptions {
1211
features: "+neon,+fp-armv8,+apple-a7".to_string(),
1312
max_atomic_width: Some(128),
14-
unsupported_abis: super::arm_base::unsupported_abis(),
1513
forces_embed_bitcode: true,
1614
frame_pointer: FramePointer::NonLeaf,
17-
..base
15+
..opts("tvos", Arch::Arm64)
1816
},
1917
}
2018
}

‎compiler/rustc_target/src/spec/aarch64_be_unknown_linux_gnu.rs

+2-5
Original file line numberDiff line numberDiff line change
@@ -2,19 +2,16 @@ use crate::abi::Endian;
22
use crate::spec::{Target, TargetOptions};
33

44
pub fn target() -> Target {
5-
let mut base = super::linux_gnu_base::opts();
6-
base.max_atomic_width = Some(128);
7-
85
Target {
96
llvm_target: "aarch64_be-unknown-linux-gnu".to_string(),
107
pointer_width: 64,
118
data_layout: "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
129
arch: "aarch64".to_string(),
1310
options: TargetOptions {
14-
unsupported_abis: super::arm_base::unsupported_abis(),
11+
max_atomic_width: Some(128),
1512
mcount: "\u{1}_mcount".to_string(),
1613
endian: Endian::Big,
17-
..base
14+
..super::linux_gnu_base::opts()
1815
},
1916
}
2017
}

‎compiler/rustc_target/src/spec/aarch64_be_unknown_linux_gnu_ilp32.rs

+1-6
Original file line numberDiff line numberDiff line change
@@ -10,11 +10,6 @@ pub fn target() -> Target {
1010
pointer_width: 32,
1111
data_layout: "E-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
1212
arch: "aarch64".to_string(),
13-
options: TargetOptions {
14-
unsupported_abis: super::arm_base::unsupported_abis(),
15-
mcount: "\u{1}_mcount".to_string(),
16-
endian: Endian::Big,
17-
..base
18-
},
13+
options: TargetOptions { mcount: "\u{1}_mcount".to_string(), endian: Endian::Big, ..base },
1914
}
2015
}

‎compiler/rustc_target/src/spec/aarch64_fuchsia.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,15 @@
11
use crate::spec::{SanitizerSet, Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::fuchsia_base::opts();
5-
base.max_atomic_width = Some(128);
6-
base.supported_sanitizers = SanitizerSet::ADDRESS;
7-
84
Target {
95
llvm_target: "aarch64-fuchsia".to_string(),
106
pointer_width: 64,
117
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
128
arch: "aarch64".to_string(),
13-
options: TargetOptions { unsupported_abis: super::arm_base::unsupported_abis(), ..base },
9+
options: TargetOptions {
10+
max_atomic_width: Some(128),
11+
supported_sanitizers: SanitizerSet::ADDRESS,
12+
..super::fuchsia_base::opts()
13+
},
1414
}
1515
}

‎compiler/rustc_target/src/spec/aarch64_linux_android.rs

+8-7
Original file line numberDiff line numberDiff line change
@@ -4,17 +4,18 @@ use crate::spec::{SanitizerSet, Target, TargetOptions};
44
// for target ABI requirements.
55

66
pub fn target() -> Target {
7-
let mut base = super::android_base::opts();
8-
base.max_atomic_width = Some(128);
9-
// As documented in https://developer.android.com/ndk/guides/cpu-features.html
10-
// the neon (ASIMD) and FP must exist on all android aarch64 targets.
11-
base.features = "+neon,+fp-armv8".to_string();
12-
base.supported_sanitizers = SanitizerSet::HWADDRESS;
137
Target {
148
llvm_target: "aarch64-linux-android".to_string(),
159
pointer_width: 64,
1610
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
1711
arch: "aarch64".to_string(),
18-
options: TargetOptions { unsupported_abis: super::arm_base::unsupported_abis(), ..base },
12+
options: TargetOptions {
13+
max_atomic_width: Some(128),
14+
// As documented in https://developer.android.com/ndk/guides/cpu-features.html
15+
// the neon (ASIMD) and FP must exist on all android aarch64 targets.
16+
features: "+neon,+fp-armv8".to_string(),
17+
supported_sanitizers: SanitizerSet::HWADDRESS,
18+
..super::android_base::opts()
19+
},
1920
}
2021
}

‎compiler/rustc_target/src/spec/aarch64_unknown_freebsd.rs

+1-4
Original file line numberDiff line numberDiff line change
@@ -1,14 +1,11 @@
11
use crate::spec::{Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::freebsd_base::opts();
5-
base.max_atomic_width = Some(128);
6-
74
Target {
85
llvm_target: "aarch64-unknown-freebsd".to_string(),
96
pointer_width: 64,
107
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
118
arch: "aarch64".to_string(),
12-
options: TargetOptions { unsupported_abis: super::arm_base::unsupported_abis(), ..base },
9+
options: TargetOptions { max_atomic_width: Some(128), ..super::freebsd_base::opts() },
1310
}
1411
}

‎compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu.rs

+7-10
Original file line numberDiff line numberDiff line change
@@ -1,23 +1,20 @@
11
use crate::spec::{SanitizerSet, Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::linux_gnu_base::opts();
5-
base.max_atomic_width = Some(128);
6-
base.supported_sanitizers = SanitizerSet::ADDRESS
7-
| SanitizerSet::LEAK
8-
| SanitizerSet::MEMORY
9-
| SanitizerSet::THREAD
10-
| SanitizerSet::HWADDRESS;
11-
124
Target {
135
llvm_target: "aarch64-unknown-linux-gnu".to_string(),
146
pointer_width: 64,
157
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
168
arch: "aarch64".to_string(),
179
options: TargetOptions {
18-
unsupported_abis: super::arm_base::unsupported_abis(),
1910
mcount: "\u{1}_mcount".to_string(),
20-
..base
11+
max_atomic_width: Some(128),
12+
supported_sanitizers: SanitizerSet::ADDRESS
13+
| SanitizerSet::LEAK
14+
| SanitizerSet::MEMORY
15+
| SanitizerSet::THREAD
16+
| SanitizerSet::HWADDRESS,
17+
..super::linux_gnu_base::opts()
2118
},
2219
}
2320
}

‎compiler/rustc_target/src/spec/aarch64_unknown_linux_gnu_ilp32.rs

+2-5
Original file line numberDiff line numberDiff line change
@@ -1,18 +1,15 @@
11
use crate::spec::{Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::linux_gnu_base::opts();
5-
base.max_atomic_width = Some(128);
6-
74
Target {
85
llvm_target: "aarch64-unknown-linux-gnu_ilp32".to_string(),
96
pointer_width: 32,
107
data_layout: "e-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
118
arch: "aarch64".to_string(),
129
options: TargetOptions {
13-
unsupported_abis: super::arm_base::unsupported_abis(),
10+
max_atomic_width: Some(128),
1411
mcount: "\u{1}_mcount".to_string(),
15-
..base
12+
..super::linux_gnu_base::opts()
1613
},
1714
}
1815
}

‎compiler/rustc_target/src/spec/aarch64_unknown_linux_musl.rs

+1-5
Original file line numberDiff line numberDiff line change
@@ -9,10 +9,6 @@ pub fn target() -> Target {
99
pointer_width: 64,
1010
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
1111
arch: "aarch64".to_string(),
12-
options: TargetOptions {
13-
unsupported_abis: super::arm_base::unsupported_abis(),
14-
mcount: "\u{1}_mcount".to_string(),
15-
..base
16-
},
12+
options: TargetOptions { mcount: "\u{1}_mcount".to_string(), ..base },
1713
}
1814
}

‎compiler/rustc_target/src/spec/aarch64_unknown_netbsd.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,15 @@
11
use crate::spec::{Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::netbsd_base::opts();
5-
base.max_atomic_width = Some(128);
6-
base.unsupported_abis = super::arm_base::unsupported_abis();
7-
84
Target {
95
llvm_target: "aarch64-unknown-netbsd".to_string(),
106
pointer_width: 64,
117
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
128
arch: "aarch64".to_string(),
13-
options: TargetOptions { mcount: "__mcount".to_string(), ..base },
9+
options: TargetOptions {
10+
mcount: "__mcount".to_string(),
11+
max_atomic_width: Some(128),
12+
..super::netbsd_base::opts()
13+
},
1414
}
1515
}

‎compiler/rustc_target/src/spec/aarch64_unknown_none.rs

-1
Original file line numberDiff line numberDiff line change
@@ -18,7 +18,6 @@ pub fn target() -> Target {
1818
disable_redzone: true,
1919
max_atomic_width: Some(128),
2020
panic_strategy: PanicStrategy::Abort,
21-
unsupported_abis: super::arm_base::unsupported_abis(),
2221
..Default::default()
2322
};
2423
Target {

‎compiler/rustc_target/src/spec/aarch64_unknown_none_softfloat.rs

-1
Original file line numberDiff line numberDiff line change
@@ -18,7 +18,6 @@ pub fn target() -> Target {
1818
disable_redzone: true,
1919
max_atomic_width: Some(128),
2020
panic_strategy: PanicStrategy::Abort,
21-
unsupported_abis: super::arm_base::unsupported_abis(),
2221
..Default::default()
2322
};
2423
Target {

‎compiler/rustc_target/src/spec/aarch64_unknown_openbsd.rs

+2-6
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,11 @@
1-
use crate::spec::Target;
1+
use crate::spec::{Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::openbsd_base::opts();
5-
base.max_atomic_width = Some(128);
6-
base.unsupported_abis = super::arm_base::unsupported_abis();
7-
84
Target {
95
llvm_target: "aarch64-unknown-openbsd".to_string(),
106
pointer_width: 64,
117
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
128
arch: "aarch64".to_string(),
13-
options: base,
9+
options: TargetOptions { max_atomic_width: Some(128), ..super::openbsd_base::opts() },
1410
}
1511
}

‎compiler/rustc_target/src/spec/aarch64_wrs_vxworks.rs

+1-4
Original file line numberDiff line numberDiff line change
@@ -1,14 +1,11 @@
11
use crate::spec::{Target, TargetOptions};
22

33
pub fn target() -> Target {
4-
let mut base = super::vxworks_base::opts();
5-
base.max_atomic_width = Some(128);
6-
74
Target {
85
llvm_target: "aarch64-unknown-linux-gnu".to_string(),
96
pointer_width: 64,
107
data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".to_string(),
118
arch: "aarch64".to_string(),
12-
options: TargetOptions { unsupported_abis: super::arm_base::unsupported_abis(), ..base },
9+
options: TargetOptions { max_atomic_width: Some(128), ..super::vxworks_base::opts() },
1310
}
1411
}

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