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Auto merge of #10539 - Urgau:check-cfg-build-script, r=ehuss
Add unstable `rustc-check-cfg` build script output This PR adds a new build script output as unstable behind `-Zcheck-cfg=output`: `rustc-check-cfg`. ### What does this PR try to resolve? This PR add a way to add to use the unstable `--check-cfg` command line option of `rustc` and `rustdoc`. It was discover in [Bump bootstrap compiler to 1.61.0 beta](rust-lang/rust#95678 (comment)) that `rustc_llvm` sets some custom `cfg` from a build script and because `--check-cfg=values()` is globally enable in the Rust codebase that cause the compilation to fail. For now no values are checked in stage 0 for the entire codebase which is a shame and should be fixed with the addition of this feature. ### How should we test and review this PR? Commits are separated in: implementation, tests and doc. Testing should simply be done by adding a valid `cargo:rustc-check-cfg` in a build script. Watch the added tests or doc to have an example. ### Additional information This PR is also the logical next step after `-Zcheck-cfg-features`.
2 parents a4c1cd0 + f2a1e43 commit c8c6e33

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7 files changed

+289
-36
lines changed

7 files changed

+289
-36
lines changed

‎src/cargo/core/compiler/context/mod.rs

+8
Original file line numberDiff line numberDiff line change
@@ -235,6 +235,14 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
235235
args.push(cfg.into());
236236
}
237237

238+
if !output.check_cfgs.is_empty() {
239+
args.push("-Zunstable-options".into());
240+
for check_cfg in &output.check_cfgs {
241+
args.push("--check-cfg".into());
242+
args.push(check_cfg.into());
243+
}
244+
}
245+
238246
for (lt, arg) in &output.linker_args {
239247
if lt.applies_to(&unit.target) {
240248
args.push("-C".into());

‎src/cargo/core/compiler/custom_build.rs

+24
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,8 @@ pub struct BuildOutput {
2929
pub linker_args: Vec<(LinkType, String)>,
3030
/// Various `--cfg` flags to pass to the compiler.
3131
pub cfgs: Vec<String>,
32+
/// Various `--check-cfg` flags to pass to the compiler.
33+
pub check_cfgs: Vec<String>,
3234
/// Additional environment variables to run the compiler with.
3335
pub env: Vec<(String, String)>,
3436
/// Metadata to pass to the immediate dependencies.
@@ -322,6 +324,10 @@ fn build_work(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Job> {
322324
paths::create_dir_all(&script_out_dir)?;
323325

324326
let nightly_features_allowed = cx.bcx.config.nightly_features_allowed;
327+
let extra_check_cfg = match cx.bcx.config.cli_unstable().check_cfg {
328+
Some((_, _, _, output)) => output,
329+
None => false,
330+
};
325331
let targets: Vec<Target> = unit.pkg.targets().to_vec();
326332
// Need a separate copy for the fresh closure.
327333
let targets_fresh = targets.clone();
@@ -432,6 +438,7 @@ fn build_work(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Job> {
432438
&pkg_descr,
433439
&script_out_dir,
434440
&script_out_dir,
441+
extra_check_cfg,
435442
nightly_features_allowed,
436443
&targets,
437444
)?;
@@ -459,6 +466,7 @@ fn build_work(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Job> {
459466
&pkg_descr,
460467
&prev_script_out_dir,
461468
&script_out_dir,
469+
extra_check_cfg,
462470
nightly_features_allowed,
463471
&targets_fresh,
464472
)?,
@@ -511,6 +519,7 @@ impl BuildOutput {
511519
pkg_descr: &str,
512520
script_out_dir_when_generated: &Path,
513521
script_out_dir: &Path,
522+
extra_check_cfg: bool,
514523
nightly_features_allowed: bool,
515524
targets: &[Target],
516525
) -> CargoResult<BuildOutput> {
@@ -521,6 +530,7 @@ impl BuildOutput {
521530
pkg_descr,
522531
script_out_dir_when_generated,
523532
script_out_dir,
533+
extra_check_cfg,
524534
nightly_features_allowed,
525535
targets,
526536
)
@@ -536,13 +546,15 @@ impl BuildOutput {
536546
pkg_descr: &str,
537547
script_out_dir_when_generated: &Path,
538548
script_out_dir: &Path,
549+
extra_check_cfg: bool,
539550
nightly_features_allowed: bool,
540551
targets: &[Target],
541552
) -> CargoResult<BuildOutput> {
542553
let mut library_paths = Vec::new();
543554
let mut library_links = Vec::new();
544555
let mut linker_args = Vec::new();
545556
let mut cfgs = Vec::new();
557+
let mut check_cfgs = Vec::new();
546558
let mut env = Vec::new();
547559
let mut metadata = Vec::new();
548560
let mut rerun_if_changed = Vec::new();
@@ -669,6 +681,13 @@ impl BuildOutput {
669681
linker_args.push((LinkType::All, value));
670682
}
671683
"rustc-cfg" => cfgs.push(value.to_string()),
684+
"rustc-check-cfg" => {
685+
if extra_check_cfg {
686+
check_cfgs.push(value.to_string());
687+
} else {
688+
warnings.push(format!("cargo:{} requires -Zcheck-cfg=output flag", key));
689+
}
690+
}
672691
"rustc-env" => {
673692
let (key, val) = BuildOutput::parse_rustc_env(&value, &whence)?;
674693
// Build scripts aren't allowed to set RUSTC_BOOTSTRAP.
@@ -728,6 +747,7 @@ impl BuildOutput {
728747
library_links,
729748
linker_args,
730749
cfgs,
750+
check_cfgs,
731751
env,
732752
metadata,
733753
rerun_if_changed,
@@ -968,6 +988,10 @@ fn prev_build_output(cx: &mut Context<'_, '_>, unit: &Unit) -> (Option<BuildOutp
968988
&unit.pkg.to_string(),
969989
&prev_script_out_dir,
970990
&script_out_dir,
991+
match cx.bcx.config.cli_unstable().check_cfg {
992+
Some((_, _, _, output)) => output,
993+
None => false,
994+
},
971995
cx.bcx.config.nightly_features_allowed,
972996
unit.pkg.targets(),
973997
)

‎src/cargo/core/compiler/mod.rs

+33-31
Original file line numberDiff line numberDiff line change
@@ -292,7 +292,7 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
292292
)?;
293293
add_plugin_deps(&mut rustc, &script_outputs, &build_scripts, &root_output)?;
294294
}
295-
add_custom_env(&mut rustc, &script_outputs, script_metadata);
295+
add_custom_flags(&mut rustc, &script_outputs, script_metadata)?;
296296
}
297297

298298
for output in outputs.iter() {
@@ -408,9 +408,6 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
408408
}
409409

410410
if key.0 == current_id {
411-
for cfg in &output.cfgs {
412-
rustc.arg("--cfg").arg(cfg);
413-
}
414411
if pass_l_flag {
415412
for name in output.library_links.iter() {
416413
rustc.arg("-l").arg(name);
@@ -431,22 +428,6 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
431428
}
432429
Ok(())
433430
}
434-
435-
// Add all custom environment variables present in `state` (after they've
436-
// been put there by one of the `build_scripts`) to the command provided.
437-
fn add_custom_env(
438-
rustc: &mut ProcessBuilder,
439-
build_script_outputs: &BuildScriptOutputs,
440-
metadata: Option<Metadata>,
441-
) {
442-
if let Some(metadata) = metadata {
443-
if let Some(output) = build_script_outputs.get(metadata) {
444-
for &(ref name, ref value) in output.env.iter() {
445-
rustc.env(name, value);
446-
}
447-
}
448-
}
449-
}
450431
}
451432

452433
/// Link the compiled target (often of form `foo-{metadata_hash}`) to the
@@ -713,16 +694,11 @@ fn rustdoc(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Work> {
713694
let mut output_options = OutputOptions::new(cx, unit);
714695
let script_metadata = cx.find_build_script_metadata(unit);
715696
Ok(Work::new(move |state| {
716-
if let Some(script_metadata) = script_metadata {
717-
if let Some(output) = build_script_outputs.lock().unwrap().get(script_metadata) {
718-
for cfg in output.cfgs.iter() {
719-
rustdoc.arg("--cfg").arg(cfg);
720-
}
721-
for &(ref name, ref value) in output.env.iter() {
722-
rustdoc.env(name, value);
723-
}
724-
}
725-
}
697+
add_custom_flags(
698+
&mut rustdoc,
699+
&build_script_outputs.lock().unwrap(),
700+
script_metadata,
701+
)?;
726702
let crate_dir = doc_dir.join(&crate_name);
727703
if crate_dir.exists() {
728704
// Remove output from a previous build. This ensures that stale
@@ -1055,7 +1031,7 @@ fn features_args(unit: &Unit) -> Vec<OsString> {
10551031

10561032
/// Generate the --check-cfg arguments for the unit
10571033
fn check_cfg_args(cx: &Context<'_, '_>, unit: &Unit) -> Vec<OsString> {
1058-
if let Some((features, well_known_names, well_known_values)) =
1034+
if let Some((features, well_known_names, well_known_values, _output)) =
10591035
cx.bcx.config.cli_unstable().check_cfg
10601036
{
10611037
let mut args = Vec::with_capacity(unit.pkg.summary().features().len() * 2 + 4);
@@ -1184,6 +1160,32 @@ fn build_deps_args(
11841160
Ok(())
11851161
}
11861162

1163+
/// Add custom flags from the output a of build-script to a `ProcessBuilder`
1164+
fn add_custom_flags(
1165+
cmd: &mut ProcessBuilder,
1166+
build_script_outputs: &BuildScriptOutputs,
1167+
metadata: Option<Metadata>,
1168+
) -> CargoResult<()> {
1169+
if let Some(metadata) = metadata {
1170+
if let Some(output) = build_script_outputs.get(metadata) {
1171+
for cfg in output.cfgs.iter() {
1172+
cmd.arg("--cfg").arg(cfg);
1173+
}
1174+
if !output.check_cfgs.is_empty() {
1175+
cmd.arg("-Zunstable-options");
1176+
for check_cfg in &output.check_cfgs {
1177+
cmd.arg("--check-cfg").arg(check_cfg);
1178+
}
1179+
}
1180+
for &(ref name, ref value) in output.env.iter() {
1181+
cmd.env(name, value);
1182+
}
1183+
}
1184+
}
1185+
1186+
Ok(())
1187+
}
1188+
11871189
/// Generates a list of `--extern` arguments.
11881190
pub fn extern_args(
11891191
cx: &Context<'_, '_>,

‎src/cargo/core/features.rs

+11-4
Original file line numberDiff line numberDiff line change
@@ -641,7 +641,7 @@ unstable_cli_options!(
641641
build_std_features: Option<Vec<String>> = ("Configure features enabled for the standard library itself when building the standard library"),
642642
config_include: bool = ("Enable the `include` key in config files"),
643643
credential_process: bool = ("Add a config setting to fetch registry authentication tokens by calling an external process"),
644-
check_cfg: Option<(/*features:*/ bool, /*well_known_names:*/ bool, /*well_known_values:*/ bool)> = ("Specify scope of compile-time checking of `cfg` names/values"),
644+
check_cfg: Option<(/*features:*/ bool, /*well_known_names:*/ bool, /*well_known_values:*/ bool, /*output:*/ bool)> = ("Specify scope of compile-time checking of `cfg` names/values"),
645645
doctest_in_workspace: bool = ("Compile doctests with paths relative to the workspace root"),
646646
doctest_xcompile: bool = ("Compile and run doctests for non-host target using runner config"),
647647
dual_proc_macros: bool = ("Build proc-macros for both the host and the target"),
@@ -783,22 +783,29 @@ impl CliUnstable {
783783
}
784784
}
785785

786-
fn parse_check_cfg(value: Option<&str>) -> CargoResult<Option<(bool, bool, bool)>> {
786+
fn parse_check_cfg(value: Option<&str>) -> CargoResult<Option<(bool, bool, bool, bool)>> {
787787
if let Some(value) = value {
788788
let mut features = false;
789789
let mut well_known_names = false;
790790
let mut well_known_values = false;
791+
let mut output = false;
791792

792793
for e in value.split(',') {
793794
match e {
794795
"features" => features = true,
795796
"names" => well_known_names = true,
796797
"values" => well_known_values = true,
797-
_ => bail!("flag -Zcheck-cfg only takes `features`, `names` or `values` as valid inputs"),
798+
"output" => output = true,
799+
_ => bail!("flag -Zcheck-cfg only takes `features`, `names`, `values` or `output` as valid inputs"),
798800
}
799801
}
800802

801-
Ok(Some((features, well_known_names, well_known_values)))
803+
Ok(Some((
804+
features,
805+
well_known_names,
806+
well_known_values,
807+
output,
808+
)))
802809
} else {
803810
Ok(None)
804811
}

‎src/cargo/util/config/target.rs

+18-1
Original file line numberDiff line numberDiff line change
@@ -120,7 +120,7 @@ fn load_config_table(config: &Config, prefix: &str) -> CargoResult<TargetConfig>
120120
// Links do not support environment variables.
121121
let target_key = ConfigKey::from_str(prefix);
122122
let links_overrides = match config.get_table(&target_key)? {
123-
Some(links) => parse_links_overrides(&target_key, links.val)?,
123+
Some(links) => parse_links_overrides(&target_key, links.val, config)?,
124124
None => BTreeMap::new(),
125125
};
126126
Ok(TargetConfig {
@@ -134,8 +134,14 @@ fn load_config_table(config: &Config, prefix: &str) -> CargoResult<TargetConfig>
134134
fn parse_links_overrides(
135135
target_key: &ConfigKey,
136136
links: HashMap<String, CV>,
137+
config: &Config,
137138
) -> CargoResult<BTreeMap<String, BuildOutput>> {
138139
let mut links_overrides = BTreeMap::new();
140+
let extra_check_cfg = match config.cli_unstable().check_cfg {
141+
Some((_, _, _, output)) => output,
142+
None => false,
143+
};
144+
139145
for (lib_name, value) in links {
140146
// Skip these keys, it shares the namespace with `TargetConfig`.
141147
match lib_name.as_str() {
@@ -200,6 +206,17 @@ fn parse_links_overrides(
200206
let list = value.list(key)?;
201207
output.cfgs.extend(list.iter().map(|v| v.0.clone()));
202208
}
209+
"rustc-check-cfg" => {
210+
if extra_check_cfg {
211+
let list = value.list(key)?;
212+
output.check_cfgs.extend(list.iter().map(|v| v.0.clone()));
213+
} else {
214+
config.shell().warn(format!(
215+
"target config `{}.{}` requires -Zcheck-cfg=output flag",
216+
target_key, key
217+
))?;
218+
}
219+
}
203220
"rustc-env" => {
204221
for (name, val) in value.table(key)?.0 {
205222
let val = val.string(name)?.0;

‎src/doc/src/reference/unstable.md

+24
Original file line numberDiff line numberDiff line change
@@ -1201,6 +1201,7 @@ It's values are:
12011201
Note than this command line options will probably become the default when stabilizing.
12021202
- `names`: enables well known names checking via `--check-cfg=names()`.
12031203
- `values`: enables well known values checking via `--check-cfg=values()`.
1204+
- `output`: enable the use of `rustc-check-cfg` in build script.
12041205

12051206
For instance:
12061207

@@ -1211,6 +1212,29 @@ cargo check -Z unstable-options -Z check-cfg=values
12111212
cargo check -Z unstable-options -Z check-cfg=features,names,values
12121213
```
12131214

1215+
Or for `output`:
1216+
1217+
```rust,no_run
1218+
// build.rs
1219+
println!("cargo:rustc-check-cfg=names(foo, bar)");
1220+
```
1221+
1222+
```
1223+
cargo check -Z unstable-options -Z check-cfg=output
1224+
```
1225+
1226+
### `cargo:rustc-check-cfg=CHECK_CFG`
1227+
1228+
The `rustc-check-cfg` instruction tells Cargo to pass the given value to the
1229+
`--check-cfg` flag to the compiler. This may be used for compile-time
1230+
detection of unexpected conditional compilation name and/or values.
1231+
1232+
This can only be used in combination with `-Zcheck-cfg=output` otherwise it is ignored
1233+
with a warning.
1234+
1235+
If you want to integrate with Cargo features, use `-Zcheck-cfg=features` instead of
1236+
trying to do it manually with this option.
1237+
12141238
### workspace-inheritance
12151239

12161240
* RFC: [#2906](https://github.com/rust-lang/rfcs/blob/master/text/2906-cargo-workspace-deduplicate.md)

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