Pass rustdocflags like rustflags

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

@@ -134,19 +134,6 @@ impl<'a, 'gctx> BuildContext<'a, 'gctx> {
         self.build_config.jobs
     }
 
-    /// Extra compiler flags to pass to `rustdoc` for a given unit.
-    ///
-    /// Although it depends on the caller, in the current Cargo implementation,
-    /// these flags take precedence over those from [`BuildContext::extra_args_for`].
-    ///
-    /// As of now, these flags come from environment variables and configurations.
-    /// See [`TargetInfo.rustdocflags`] for more on how Cargo collects them.
-    ///
-    /// [`TargetInfo.rustdocflags`]: TargetInfo::rustdocflags
-    pub fn rustdocflags_args(&self, unit: &Unit) -> &[String] {
-        &self.target_data.info(unit.kind).rustdocflags
-    }
-
     /// Extra compiler args for either `rustc` or `rustdoc`.
     ///
     /// As of now, these flags come from the trailing args of either

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

@@ -55,7 +55,7 @@ pub struct TargetInfo {
     /// Extra flags to pass to `rustc`, see [`extra_args`].
     pub rustflags: Arc<[String]>,
     /// Extra flags to pass to `rustdoc`, see [`extra_args`].
-    pub rustdocflags: Vec<String>,
+    pub rustdocflags: Arc<[String]>,
     /// Whether or not rustc (stably) supports the `--check-cfg` flag.
     ///
     /// Can be removed once the minimum supported rustc version of Cargo is
@@ -321,7 +321,8 @@ impl TargetInfo {
                     Some(&cfg),
                     kind,
                     Flags::Rustdoc,
-                )?,
+                )?
+                .into(),
                 cfg,
                 support_split_debuginfo,
                 support_check_cfg,

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

@@ -269,7 +269,7 @@ impl<'a, 'gctx> BuildRunner<'a, 'gctx> {
                         }
                     }
                 }
-                args.extend(self.bcx.rustdocflags_args(unit).iter().map(Into::into));
+                args.extend(unit.rustdocflags.iter().map(Into::into));
 
                 use super::MessageFormat;
                 let format = match self.bcx.build_config.message_format {

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

@@ -1415,7 +1415,7 @@ fn calculate_normal(
     // hashed to take up less space on disk as we just need to know when things
     // change.
     let extra_flags = if unit.mode.is_doc() || unit.mode.is_doc_scrape() {
-        build_runner.bcx.rustdocflags_args(unit)
+        &unit.rustdocflags
     } else {
         &unit.rustflags
     }

src/cargo/core/compiler/mod.rs

@@ -780,7 +780,7 @@ fn prepare_rustdoc(build_runner: &BuildRunner<'_, '_>, unit: &Unit) -> CargoResu
 
     rustdoc::add_output_format(build_runner, unit, &mut rustdoc)?;
 
-    rustdoc.args(bcx.rustdocflags_args(unit));
+    rustdoc.args(&unit.rustdocflags);
 
     if !crate_version_flag_already_present(&rustdoc) {
         append_crate_version_flag(unit, &mut rustdoc);

src/cargo/core/compiler/standard_lib.rs

@@ -218,6 +218,7 @@ pub fn generate_std_roots(
                 mode,
                 features.clone(),
                 target_data.info(*kind).rustflags.clone(),
+                target_data.info(*kind).rustdocflags.clone(),
                 /*is_std*/ true,
                 /*dep_hash*/ 0,
                 IsArtifact::No,

src/cargo/core/compiler/unit.rs

@@ -71,6 +71,17 @@ pub struct UnitInner {
     /// [`BuildContext::extra_args_for`]: crate::core::compiler::build_context::BuildContext::extra_args_for
     /// [`TargetInfo.rustflags`]: crate::core::compiler::build_context::TargetInfo::rustflags
     pub rustflags: Arc<[String]>,
+    /// Extra compiler flags to pass to `rustdoc` for a given unit.
+    ///
+    /// Although it depends on the caller, in the current Cargo implementation,
+    /// these flags take precedence over those from [`BuildContext::extra_args_for`].
+    ///
+    /// As of now, these flags come from environment variables and configurations.
+    /// See [`TargetInfo.rustdocflags`] for more on how Cargo collects them.
+    ///
+    /// [`BuildContext::extra_args_for`]: crate::core::compiler::build_context::BuildContext::extra_args_for
+    /// [`TargetInfo.rustdocflags`]: crate::core::compiler::build_context::TargetInfo::rustdocflags
+    pub rustdocflags: Arc<[String]>,
     // if `true`, the dependency is an artifact dependency, requiring special handling when
     // calculating output directories, linkage and environment variables provided to builds.
     pub artifact: IsArtifact,
@@ -212,6 +223,7 @@ impl UnitInterner {
         mode: CompileMode,
         features: Vec<InternedString>,
         rustflags: Arc<[String]>,
+        rustdocflags: Arc<[String]>,
         is_std: bool,
         dep_hash: u64,
         artifact: IsArtifact,
@@ -246,6 +258,7 @@ impl UnitInterner {
             mode,
             features,
             rustflags,
+            rustdocflags,
             is_std,
             dep_hash,
             artifact,

src/cargo/core/compiler/unit_dependencies.rs

@@ -860,6 +860,7 @@ fn new_unit_dep_with_profile(
         mode,
         features,
         state.target_data.info(kind).rustflags.clone(),
+        state.target_data.info(kind).rustdocflags.clone(),
         state.is_std,
         /*dep_hash*/ 0,
         artifact.map_or(IsArtifact::No, |_| IsArtifact::Yes),

src/cargo/ops/cargo_compile/mod.rs

@@ -697,6 +697,7 @@ fn traverse_and_share(
             unit.mode,
             unit.features.clone(),
             unit.rustflags.clone(),
+            unit.rustdocflags.clone(),
             unit.is_std,
             unit.dep_hash,
             unit.artifact,
@@ -723,6 +724,7 @@ fn traverse_and_share(
         unit.mode,
         unit.features.clone(),
         unit.rustflags.clone(),
+        unit.rustdocflags.clone(),
         unit.is_std,
         new_dep_hash,
         unit.artifact,
@@ -885,6 +887,7 @@ fn override_rustc_crate_types(
             unit.mode,
             unit.features.clone(),
             unit.rustflags.clone(),
+            unit.rustdocflags.clone(),
             unit.is_std,
             unit.dep_hash,
             unit.artifact,

src/cargo/ops/cargo_compile/unit_generator.rs

@@ -172,6 +172,7 @@ impl<'a> UnitGenerator<'a, '_> {
                     target_mode,
                     features.clone(),
                     self.target_data.info(kind).rustflags.clone(),
+                    self.target_data.info(kind).rustdocflags.clone(),
                     /*is_std*/ false,
                     /*dep_hash*/ 0,
                     IsArtifact::No,

tests/testsuite/rustflags.rs

@@ -1632,6 +1632,11 @@ fn target_applies_to_host_rustdocflags_works() {
         .arg("-Ztarget-applies-to-host")
         .env("CARGO_TARGET_APPLIES_TO_HOST", "false")
         .env("RUSTDOCFLAGS", r#"--cfg feature="flag""#)
-        .with_status(0)
+        .with_status(101)
+        .with_stderr_data(
+            "[DOCUMENTING] foo v0.0.1 ([ROOT]/foo)
+[ERROR] flag passed
+...",
+        )
         .run();
 }