Gate unexpected target cfgs check behind -Zcheck-target-cfgs

Author: Urgau

src/cargo/core/compiler/build_context/target_info.rs

@@ -946,7 +946,7 @@ pub struct RustcTargetData<'gctx> {
     target_info: HashMap<CompileTarget, TargetInfo>,
 
     /// `--print=cfg`
-    check_cfg: CheckCfg,
+    check_cfg: Option<CheckCfg>,
 }
 
 impl<'gctx> RustcTargetData<'gctx> {
@@ -993,7 +993,7 @@ impl<'gctx> RustcTargetData<'gctx> {
             }
         };
 
-        let check_cfg = {
+        let check_cfg = if gctx.cli_unstable().check_target_cfgs {
             let mut process = rustc.workspace_process();
 
             apply_env_config(gctx, &mut process)?;
@@ -1016,10 +1016,12 @@ impl<'gctx> RustcTargetData<'gctx> {
 
             let lines = output.lines();
 
-            lines.fold(CheckCfg::default(), |mut check_cfg, line| {
+            Some(lines.fold(CheckCfg::default(), |mut check_cfg, line| {
                 check_cfg.process_line(line);
                 check_cfg
-            })
+            }))
+        } else {
+            None
         };
 
         let mut res = RustcTargetData {
@@ -1108,7 +1110,7 @@ impl<'gctx> RustcTargetData<'gctx> {
     }
 
     /// Gets the list of check-cfg
-    pub fn check_cfg(&self) -> &CheckCfg {
+    pub fn check_cfg(&self) -> &Option<CheckCfg> {
         &self.check_cfg
     }
 

src/cargo/core/features.rs

@@ -760,6 +760,7 @@ unstable_cli_options!(
     build_std: Option<Vec<String>>  = ("Enable Cargo to compile the standard library itself as part of a crate graph compilation"),
     build_std_features: Option<Vec<String>>  = ("Configure features enabled for the standard library itself when building the standard library"),
     cargo_lints: bool = ("Enable the `[lints.cargo]` table"),
+    check_target_cfgs: bool = ("Enable unexpected cfgs checking in `[target.'cfg(...)']` tables"),
     codegen_backend: bool = ("Enable the `codegen-backend` option in profiles in .cargo/config.toml file"),
     config_include: bool = ("Enable the `include` key in config files"),
     direct_minimal_versions: bool = ("Resolve minimal dependency versions instead of maximum (direct dependencies only)"),
@@ -1255,6 +1256,7 @@ impl CliUnstable {
             }
             "build-std-features" => self.build_std_features = Some(parse_features(v)),
             "cargo-lints" => self.cargo_lints = parse_empty(k, v)?,
+            "check-target-cfgs" => self.check_target_cfgs = parse_empty(k, v)?,
             "codegen-backend" => self.codegen_backend = parse_empty(k, v)?,
             "config-include" => self.config_include = parse_empty(k, v)?,
             "direct-minimal-versions" => self.direct_minimal_versions = parse_empty(k, v)?,

src/cargo/ops/cargo_compile/mod.rs

@@ -480,9 +480,7 @@ pub fn create_bcx<'a, 'gctx>(
             .extend(args);
     }
 
-    {
-        let check_cfg = target_data.check_cfg();
-
+    if let Some(check_cfg) = target_data.check_cfg() {
         if check_cfg.exhaustive {
             let target_cfgs = gctx.target_cfgs()?;
             for (key, _fields) in target_cfgs {

tests/testsuite/cargo/z_help/stdout.term.svg

@@ -515,16 +515,14 @@ fn exclusive_dep_kinds() {
         .with_status(101)
         // can't find crate for `bar`
         .with_stderr_data(str![[r#"
-[WARNING] [ROOT]/foo/Cargo.toml: unexpected `cfg` condition name: `abc` in `[target.'cfg(abc)'.dependencies]`
-[WARNING] [ROOT]/foo/Cargo.toml: unexpected `cfg` condition name: `abc` in `[target.'cfg(not(abc))'.dependencies]`
 [COMPILING] foo v0.1.0 ([ROOT]/foo)
 error[E0463]: can't find crate for `bar`
 ...
 "#]])
         .run();
 }
 
-#[cargo_test]
+#[cargo_test(nightly, reason = "--print=check-cfg is unstable in rustc")]
 fn unexpected_cfgs_target() {
     let p = project()
         .file(
@@ -566,7 +564,8 @@ fn unexpected_cfgs_target() {
         .file("c/src/lib.rs", "")
         .build();
 
-    p.cargo("check")
+    p.cargo("check -Zcheck-target-cfgs")
+        .masquerade_as_nightly_cargo(&["requires -Zcheck-target-cfgs"])
         .with_stderr_data(str![[r#"
 [LOCKING] 2 packages to latest compatible versions
 [WARNING] unexpected `cfg` condition name: `foo` in `[target.'cfg(any(foo, all(bar)))']`
@@ -585,3 +584,45 @@ fn unexpected_cfgs_target() {
 "#]])
         .run();
 }
+
+#[cargo_test]
+fn no_unexpected_cfgs_target() {
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "a"
+                version = "0.0.1"
+                edition = "2015"
+                authors = []
+
+                [target."cfg(any(windows, unix))".dependencies]
+                b = { path = 'b' }
+                
+                [target.'cfg(unix = "zoo")'.dependencies]
+                b = { path = 'b' }
+            "#,
+        )
+        .file(
+            ".cargo/config.toml",
+            r#"
+                [target."cfg(any(windows, unix))"]
+                [target.'cfg(unix = "zoo")']
+            "#,
+        )
+        .file("src/lib.rs", "extern crate b;")
+        .file("b/Cargo.toml", &basic_manifest("b", "0.0.1"))
+        .file("b/src/lib.rs", "")
+        .build();
+
+    p.cargo("check")
+        .with_stderr_data(str![[r#"
+[LOCKING] 1 package to latest compatible version
+[CHECKING] b v0.0.1 ([ROOT]/foo/b)
+[CHECKING] a v0.0.1 ([ROOT]/foo)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+
+"#]])
+        .run();
+}

tests/testsuite/cfg.rs

@@ -479,8 +479,6 @@ fn cfg_ignored_fields() {
 [WARNING] unused key `ar` in [target] config table `cfg(not(target_os = "none"))`
 [WARNING] unused key `foo` in [target] config table `cfg(not(target_os = "none"))`
 [WARNING] unused key `invalid` in [target] config table `cfg(not(target_os = "none"))`
-[WARNING] unexpected `cfg` condition name: `bar` in `[target.'cfg(not(bar))']`
-[WARNING] unexpected `cfg` condition name: `foo` in `[target.'cfg(not(foo))']`
 [CHECKING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s