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Disallow setting built-in cfgs via set the command-line
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41 files changed

+436
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‎compiler/rustc_lint/messages.ftl

+4
Original file line numberDiff line numberDiff line change
@@ -775,6 +775,10 @@ lint_undropped_manually_drops = calls to `std::mem::drop` with `std::mem::Manual
775775
.label = argument has type `{$arg_ty}`
776776
.suggestion = use `std::mem::ManuallyDrop::into_inner` to get the inner value
777777
778+
lint_unexpected_builtin_cfg = unexpected `--cfg {$cfg}` flag
779+
.controlled_by = config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`
780+
.incoherent = manually setting a built-in cfg can and does create incoherent behaviors
781+
778782
lint_unexpected_cfg_add_build_rs_println = or consider adding `{$build_rs_println}` to the top of the `build.rs`
779783
lint_unexpected_cfg_add_cargo_feature = consider using a Cargo feature instead
780784
lint_unexpected_cfg_add_cargo_toml_lint_cfg = or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:{$cargo_toml_lint_cfg}

‎compiler/rustc_lint/src/context/diagnostics.rs

+3
Original file line numberDiff line numberDiff line change
@@ -438,5 +438,8 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
438438
BuiltinLintDiag::OutOfScopeMacroCalls { path } => {
439439
lints::OutOfScopeMacroCalls { path }.decorate_lint(diag)
440440
}
441+
BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by } => {
442+
lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
443+
}
441444
}
442445
}

‎compiler/rustc_lint/src/lints.rs

+10
Original file line numberDiff line numberDiff line change
@@ -2379,6 +2379,16 @@ pub mod unexpected_cfg_value {
23792379
}
23802380
}
23812381

2382+
#[derive(LintDiagnostic)]
2383+
#[diag(lint_unexpected_builtin_cfg)]
2384+
#[note(lint_controlled_by)]
2385+
#[note(lint_incoherent)]
2386+
pub struct UnexpectedBuiltinCfg {
2387+
pub(crate) cfg: String,
2388+
pub(crate) cfg_name: Symbol,
2389+
pub(crate) controlled_by: &'static str,
2390+
}
2391+
23822392
#[derive(LintDiagnostic)]
23832393
#[diag(lint_macro_use_deprecated)]
23842394
#[help]

‎compiler/rustc_lint_defs/src/builtin.rs

+34
Original file line numberDiff line numberDiff line change
@@ -42,6 +42,7 @@ declare_lint_pass! {
4242
DUPLICATE_MACRO_ATTRIBUTES,
4343
ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
4444
ELIDED_LIFETIMES_IN_PATHS,
45+
EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
4546
EXPORTED_PRIVATE_DEPENDENCIES,
4647
FFI_UNWIND_CALLS,
4748
FORBIDDEN_LINT_GROUPS,
@@ -3288,6 +3289,39 @@ declare_lint! {
32883289
"detects unexpected names and values in `#[cfg]` conditions",
32893290
}
32903291

3292+
declare_lint! {
3293+
/// The `explicit_builtin_cfgs_in_flags` lint detects builtin cfgs set via the `--cfg` flag.
3294+
///
3295+
/// ### Example
3296+
///
3297+
/// ```text
3298+
/// rustc --cfg unix
3299+
/// ```
3300+
///
3301+
/// ```rust,ignore (needs command line option)
3302+
/// fn main() {}
3303+
/// ```
3304+
///
3305+
/// This will produce:
3306+
///
3307+
/// ```text
3308+
/// error: unexpected `--cfg unix` flag
3309+
/// |
3310+
/// = note: config `unix` is only supposed to be controlled by `--target`
3311+
/// = note: manually setting a built-in cfg can and does create incoherent behaviors
3312+
/// = note: `#[deny(explicit_builtin_cfgs_in_flags)]` on by default
3313+
/// ```
3314+
///
3315+
/// ### Explanation
3316+
///
3317+
/// Setting builtin cfgs can and does produce incoherent behavior, it's better to the use
3318+
/// the appropriate `rustc` flag that controls the config. For example setting the `windows`
3319+
/// cfg but on Linux based target.
3320+
pub EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
3321+
Deny,
3322+
"detects builtin cfgs set via the `--cfg`"
3323+
}
3324+
32913325
declare_lint! {
32923326
/// The `repr_transparent_external_private_fields` lint
32933327
/// detects types marked `#[repr(transparent)]` that (transitively)

‎compiler/rustc_lint_defs/src/lib.rs

+5
Original file line numberDiff line numberDiff line change
@@ -746,6 +746,11 @@ pub enum BuiltinLintDiag {
746746
OutOfScopeMacroCalls {
747747
path: String,
748748
},
749+
UnexpectedBuiltinCfg {
750+
cfg: String,
751+
cfg_name: Symbol,
752+
controlled_by: &'static str,
753+
},
749754
}
750755

751756
/// Lints that are buffered up early on in the `Session` before the

‎compiler/rustc_session/src/config.rs

+4-1
Original file line numberDiff line numberDiff line change
@@ -1304,7 +1304,10 @@ pub(crate) const fn default_lib_output() -> CrateType {
13041304
}
13051305

13061306
pub fn build_configuration(sess: &Session, mut user_cfg: Cfg) -> Cfg {
1307-
// Combine the configuration requested by the session (command line) with
1307+
// First disallow some configuration given on the command line
1308+
cfg::disallow_cfgs(sess, &user_cfg);
1309+
1310+
// Then combine the configuration requested by the session (command line) with
13081311
// some default and generated configuration items.
13091312
user_cfg.extend(cfg::default_configuration(sess));
13101313
user_cfg

‎compiler/rustc_session/src/config/cfg.rs

+65
Original file line numberDiff line numberDiff line change
@@ -17,12 +17,16 @@
1717
//! - Add the activation logic in [`default_configuration`]
1818
//! - Add the cfg to [`CheckCfg::fill_well_known`] (and related files),
1919
//! so that the compiler can know the cfg is expected
20+
//! - Add the cfg in [`disallow_cfgs`] to disallow users from setting it via `--cfg`
2021
//! - Add the feature gating in `compiler/rustc_feature/src/builtin_attrs.rs`
2122
2223
use std::hash::Hash;
2324
use std::iter;
2425

26+
use rustc_ast::ast;
2527
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
28+
use rustc_lint_defs::builtin::EXPLICIT_BUILTIN_CFGS_IN_FLAGS;
29+
use rustc_lint_defs::BuiltinLintDiag;
2630
use rustc_span::symbol::{sym, Symbol};
2731
use rustc_target::abi::Align;
2832
use rustc_target::spec::{PanicStrategy, RelocModel, SanitizerSet, Target, TargetTriple, TARGETS};
@@ -82,6 +86,67 @@ impl<'a, T: Eq + Hash + Copy + 'a> Extend<&'a T> for ExpectedValues<T> {
8286
}
8387
}
8488

89+
/// Disallow builtin cfgs from the CLI.
90+
pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) {
91+
let disallow = |cfg: &(Symbol, Option<Symbol>), controlled_by| {
92+
let cfg_name = cfg.0;
93+
let cfg = if let Some(value) = cfg.1 {
94+
format!(r#"{}="{}""#, cfg_name, value)
95+
} else {
96+
format!("{}", cfg_name)
97+
};
98+
sess.psess.opt_span_buffer_lint(
99+
EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
100+
None,
101+
ast::CRATE_NODE_ID,
102+
BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by },
103+
)
104+
};
105+
106+
// We want to restrict setting builtin cfgs that will produce incoherent behavior
107+
// between the cfg and the rustc cli flag that sets it.
108+
//
109+
// The tests are in tests/ui/cfg/disallowed-cli-cfgs.rs.
110+
111+
// By-default all builtin cfgs are disallowed, only those are allowed:
112+
// - test: as it makes sense to the have the `test` cfg active without the builtin
113+
// test harness. See Cargo `harness = false` config.
114+
//
115+
// Cargo `--cfg test`: https://github.com/rust-lang/cargo/blob/bc89bffa5987d4af8f71011c7557119b39e44a65/src/cargo/core/compiler/mod.rs#L1124
116+
117+
for cfg in user_cfgs {
118+
match cfg {
119+
(sym::overflow_checks, None) => disallow(cfg, "-C overflow-checks"),
120+
(sym::debug_assertions, None) => disallow(cfg, "-C debug-assertions"),
121+
(sym::ub_checks, None) => disallow(cfg, "-Z ub-checks"),
122+
(sym::sanitize, None | Some(_)) => disallow(cfg, "-Z sanitizer"),
123+
(
124+
sym::sanitizer_cfi_generalize_pointers | sym::sanitizer_cfi_normalize_integers,
125+
None | Some(_),
126+
) => disallow(cfg, "-Z sanitizer=cfi"),
127+
(sym::proc_macro, None) => disallow(cfg, "--crate-type proc-macro"),
128+
(sym::panic, Some(sym::abort | sym::unwind)) => disallow(cfg, "-C panic"),
129+
(sym::target_feature, Some(_)) => disallow(cfg, "-C target-feature"),
130+
(sym::unix, None)
131+
| (sym::windows, None)
132+
| (sym::relocation_model, Some(_))
133+
| (sym::target_abi, None | Some(_))
134+
| (sym::target_arch, Some(_))
135+
| (sym::target_endian, Some(_))
136+
| (sym::target_env, None | Some(_))
137+
| (sym::target_family, Some(_))
138+
| (sym::target_os, Some(_))
139+
| (sym::target_pointer_width, Some(_))
140+
| (sym::target_vendor, None | Some(_))
141+
| (sym::target_has_atomic, Some(_))
142+
| (sym::target_has_atomic_equal_alignment, Some(_))
143+
| (sym::target_has_atomic_load_store, Some(_))
144+
| (sym::target_thread_local, None) => disallow(cfg, "--target"),
145+
_ => {}
146+
}
147+
}
148+
}
149+
85150
/// Generate the default configs for a given session
86151
pub(crate) fn default_configuration(sess: &Session) -> Cfg {
87152
let mut ret = Cfg::default();

‎tests/assembly/x86-return-float.rs

+27-27
Original file line numberDiff line numberDiff line change
@@ -8,9 +8,9 @@
88
// Force frame pointers to make ASM more consistent between targets
99
//@ compile-flags: -O -C force-frame-pointers
1010
//@ filecheck-flags: --implicit-check-not fld --implicit-check-not fst
11-
//@ revisions: unix windows
12-
//@[unix] ignore-windows
13-
//@[windows] only-windows
11+
//@ revisions: normal win
12+
//@[normal] ignore-windows
13+
//@[win] only-windows
1414

1515
#![crate_type = "lib"]
1616
#![feature(f16, f128)]
@@ -190,10 +190,10 @@ pub unsafe fn call_f64_f64(x: &mut (f64, f64)) {
190190
}
191191
// CHECK: movl {{.*}}(%ebp), %[[PTR:.*]]
192192
// CHECK: calll {{()|_}}get_f64_f64
193-
// unix: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
194-
// unix-NEXT: movsd [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
195-
// windows: movsd (%esp), %[[VAL1:.*]]
196-
// windows-NEXT: movsd 8(%esp), %[[VAL2:.*]]
193+
// normal: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
194+
// normal-NEXT: movsd [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
195+
// win: movsd (%esp), %[[VAL1:.*]]
196+
// win-NEXT: movsd 8(%esp), %[[VAL2:.*]]
197197
// CHECK-NEXT: movsd %[[VAL1]], (%[[PTR]])
198198
// CHECK-NEXT: movsd %[[VAL2]], 8(%[[PTR]])
199199
*x = get_f64_f64();
@@ -207,13 +207,13 @@ pub unsafe fn call_f32_f64(x: &mut (f32, f64)) {
207207
}
208208
// CHECK: movl {{.*}}(%ebp), %[[PTR:.*]]
209209
// CHECK: calll {{()|_}}get_f32_f64
210-
// unix: movss [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
211-
// unix-NEXT: movsd [[#%d,OFFSET+4]](%ebp), %[[VAL2:.*]]
212-
// windows: movss (%esp), %[[VAL1:.*]]
213-
// windows-NEXT: movsd 8(%esp), %[[VAL2:.*]]
210+
// normal: movss [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
211+
// normal-NEXT: movsd [[#%d,OFFSET+4]](%ebp), %[[VAL2:.*]]
212+
// win: movss (%esp), %[[VAL1:.*]]
213+
// win-NEXT: movsd 8(%esp), %[[VAL2:.*]]
214214
// CHECK-NEXT: movss %[[VAL1]], (%[[PTR]])
215-
// unix-NEXT: movsd %[[VAL2]], 4(%[[PTR]])
216-
// windows-NEXT: movsd %[[VAL2]], 8(%[[PTR]])
215+
// normal-NEXT: movsd %[[VAL2]], 4(%[[PTR]])
216+
// win-NEXT: movsd %[[VAL2]], 8(%[[PTR]])
217217
*x = get_f32_f64();
218218
}
219219

@@ -225,10 +225,10 @@ pub unsafe fn call_f64_f32(x: &mut (f64, f32)) {
225225
}
226226
// CHECK: movl {{.*}}(%ebp), %[[PTR:.*]]
227227
// CHECK: calll {{()|_}}get_f64_f32
228-
// unix: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
229-
// unix-NEXT: movss [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
230-
// windows: movsd (%esp), %[[VAL1:.*]]
231-
// windows-NEXT: movss 8(%esp), %[[VAL2:.*]]
228+
// normal: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
229+
// normal-NEXT: movss [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
230+
// win: movsd (%esp), %[[VAL1:.*]]
231+
// win-NEXT: movss 8(%esp), %[[VAL2:.*]]
232232
// CHECK-NEXT: movsd %[[VAL1]], (%[[PTR]])
233233
// CHECK-NEXT: movss %[[VAL2]], 8(%[[PTR]])
234234
*x = get_f64_f32();
@@ -257,10 +257,10 @@ pub unsafe fn call_f64_other(x: &mut (f64, usize)) {
257257
}
258258
// CHECK: movl {{.*}}(%ebp), %[[PTR:.*]]
259259
// CHECK: calll {{()|_}}get_f64_other
260-
// unix: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
261-
// unix-NEXT: movl [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
262-
// windows: movsd (%esp), %[[VAL1:.*]]
263-
// windows-NEXT: movl 8(%esp), %[[VAL2:.*]]
260+
// normal: movsd [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
261+
// normal-NEXT: movl [[#%d,OFFSET+8]](%ebp), %[[VAL2:.*]]
262+
// win: movsd (%esp), %[[VAL1:.*]]
263+
// win-NEXT: movl 8(%esp), %[[VAL2:.*]]
264264
// CHECK-NEXT: movsd %[[VAL1]], (%[[PTR]])
265265
// CHECK-NEXT: movl %[[VAL2]], 8(%[[PTR]])
266266
*x = get_f64_other();
@@ -289,13 +289,13 @@ pub unsafe fn call_other_f64(x: &mut (usize, f64)) {
289289
}
290290
// CHECK: movl {{.*}}(%ebp), %[[PTR:.*]]
291291
// CHECK: calll {{()|_}}get_other_f64
292-
// unix: movl [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
293-
// unix-NEXT: movsd [[#%d,OFFSET+4]](%ebp), %[[VAL2:.*]]
294-
// windows: movl (%esp), %[[VAL1:.*]]
295-
// windows-NEXT: movsd 8(%esp), %[[VAL2:.*]]
292+
// normal: movl [[#%d,OFFSET:]](%ebp), %[[VAL1:.*]]
293+
// normal-NEXT: movsd [[#%d,OFFSET+4]](%ebp), %[[VAL2:.*]]
294+
// win: movl (%esp), %[[VAL1:.*]]
295+
// win-NEXT: movsd 8(%esp), %[[VAL2:.*]]
296296
// CHECK-NEXT: movl %[[VAL1]], (%[[PTR]])
297-
// unix-NEXT: movsd %[[VAL2]], 4(%[[PTR]])
298-
// windows-NEXT: movsd %[[VAL2]], 8(%[[PTR]])
297+
// normal-NEXT: movsd %[[VAL2]], 4(%[[PTR]])
298+
// win-NEXT: movsd %[[VAL2]], 8(%[[PTR]])
299299
*x = get_other_f64();
300300
}
301301

‎tests/codegen/aarch64-struct-align-128.rs

+15-15
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,12 @@
11
// Test that structs aligned to 128 bits are passed with the correct ABI on aarch64.
22

3-
//@ revisions:linux darwin windows
3+
//@ revisions: linux darwin win
44
//@[linux] compile-flags: --target aarch64-unknown-linux-gnu
55
//@[darwin] compile-flags: --target aarch64-apple-darwin
6-
//@[windows] compile-flags: --target aarch64-pc-windows-msvc
6+
//@[win] compile-flags: --target aarch64-pc-windows-msvc
77
//@[linux] needs-llvm-components: aarch64
88
//@[darwin] needs-llvm-components: aarch64
9-
//@[windows] needs-llvm-components: aarch64
9+
//@[win] needs-llvm-components: aarch64
1010

1111
#![feature(no_core, lang_items)]
1212
#![crate_type = "lib"]
@@ -39,9 +39,9 @@ pub struct Wrapped8 {
3939
}
4040

4141
extern "C" {
42-
// linux: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
43-
// darwin: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
44-
// windows: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
42+
// linux: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
43+
// darwin: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
44+
// win: declare void @test_8([2 x i64], [2 x i64], [2 x i64])
4545
fn test_8(a: Align8, b: Transparent8, c: Wrapped8);
4646
}
4747

@@ -69,9 +69,9 @@ pub struct Wrapped16 {
6969
}
7070

7171
extern "C" {
72-
// linux: declare void @test_16([2 x i64], [2 x i64], i128)
73-
// darwin: declare void @test_16(i128, i128, i128)
74-
// windows: declare void @test_16(i128, i128, i128)
72+
// linux: declare void @test_16([2 x i64], [2 x i64], i128)
73+
// darwin: declare void @test_16(i128, i128, i128)
74+
// win: declare void @test_16(i128, i128, i128)
7575
fn test_16(a: Align16, b: Transparent16, c: Wrapped16);
7676
}
7777

@@ -94,9 +94,9 @@ pub struct WrappedI128 {
9494
}
9595

9696
extern "C" {
97-
// linux: declare void @test_i128(i128, i128, i128)
98-
// darwin: declare void @test_i128(i128, i128, i128)
99-
// windows: declare void @test_i128(i128, i128, i128)
97+
// linux: declare void @test_i128(i128, i128, i128)
98+
// darwin: declare void @test_i128(i128, i128, i128)
99+
// win: declare void @test_i128(i128, i128, i128)
100100
fn test_i128(a: I128, b: TransparentI128, c: WrappedI128);
101101
}
102102

@@ -121,9 +121,9 @@ pub struct WrappedPacked {
121121
}
122122

123123
extern "C" {
124-
// linux: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
125-
// darwin: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
126-
// windows: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
124+
// linux: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
125+
// darwin: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
126+
// win: declare void @test_packed([2 x i64], [2 x i64], [2 x i64])
127127
fn test_packed(a: Packed, b: TransparentPacked, c: WrappedPacked);
128128
}
129129

‎tests/codegen/cold-call-declare-and-call.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -1,8 +1,8 @@
1-
//@ revisions: NORMAL WINDOWS
1+
//@ revisions: NORMAL WIN
22
//@ compile-flags: -C no-prepopulate-passes
33
//@[NORMAL] ignore-windows
4-
//@[WINDOWS] only-windows
5-
//@[WINDOWS] only-x86_64
4+
//@[WIN] only-windows
5+
//@[WIN] only-x86_64
66

77
#![crate_type = "lib"]
88
#![feature(rust_cold_cc)]
@@ -14,8 +14,8 @@
1414

1515
// See the comment in `Target::adjust_abi` for why this differs
1616

17-
// WINDOWS: define void @this_should_never_happen(i16
18-
// WINDOWS: call void @this_should_never_happen(i16
17+
// WIN: define void @this_should_never_happen(i16
18+
// WIN: call void @this_should_never_happen(i16
1919

2020
#[no_mangle]
2121
pub extern "rust-cold" fn this_should_never_happen(x: u16) {}

‎tests/codegen/default-requires-uwtable.rs

+5-5
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
1-
//@ revisions: WINDOWS ANDROID
1+
//@ revisions: WINDOWS_ ANDROID_
22
//@ compile-flags: -C panic=abort -Copt-level=0
3-
//@ [WINDOWS] compile-flags: --target=x86_64-pc-windows-msvc
4-
//@ [WINDOWS] needs-llvm-components: x86
5-
//@ [ANDROID] compile-flags: --target=armv7-linux-androideabi
6-
//@ [ANDROID] needs-llvm-components: arm
3+
//@ [WINDOWS_] compile-flags: --target=x86_64-pc-windows-msvc
4+
//@ [WINDOWS_] needs-llvm-components: x86
5+
//@ [ANDROID_] compile-flags: --target=armv7-linux-androideabi
6+
//@ [ANDROID_] needs-llvm-components: arm
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#![feature(no_core, lang_items)]
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#![crate_type = "lib"]

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