Add rustc-link-args to doctest build

Author: chansuke

Diff for: src/cargo/core/compiler/context/mod.rs

@@ -2,15 +2,14 @@ use std::collections::{BTreeSet, HashMap, HashSet};
 use std::path::{Path, PathBuf};
 use std::sync::{Arc, Mutex};
 
-use anyhow::{bail, Context as _};
-use filetime::FileTime;
-use jobserver::Client;
-
 use crate::core::compiler::compilation::{self, UnitOutput};
 use crate::core::compiler::{self, Unit};
 use crate::core::PackageId;
 use crate::util::errors::CargoResult;
 use crate::util::profile;
+use anyhow::{bail, Context as _};
+use filetime::FileTime;
+use jobserver::Client;
 
 use super::build_plan::BuildPlan;
 use super::custom_build::{self, BuildDeps, BuildScriptOutputs, BuildScripts};
@@ -241,6 +240,13 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
                             args.push("--cfg".into());
                             args.push(cfg.into());
                         }
+
+                        for (lt, arg) in &output.linker_args {
+                            if lt.applies_to(&unit.target) {
+                                args.push("-C".into());
+                                args.push(format!("link-arg={}", arg).into());
+                            }
+                        }
                     }
                 }
                 args.extend(self.bcx.rustdocflags_args(unit).iter().map(Into::into));

Diff for: tests/testsuite/build_script_extra_link_arg.rs

@@ -279,3 +279,34 @@ fn link_arg_transitive_not_allowed() {
         .with_stderr_does_not_contain("--bogus")
         .run();
 }
+
+#[cargo_test]
+fn link_arg_with_doctest() {
+    let p = project()
+        .file(
+            "src/lib.rs",
+            r#"
+                //! ```
+                //! let x = 5;
+                //! assert_eq!(x, 5);
+                //! ```
+            "#,
+        )
+        .file(
+            "build.rs",
+            r#"
+                fn main() {
+                    println!("cargo:rustc-link-arg=--this-is-a-bogus-flag");
+                }
+            "#,
+        )
+        .build();
+
+    p.cargo("test --doc -v")
+        .masquerade_as_nightly_cargo()
+        .without_status()
+        .with_stderr_contains(
+            "[RUNNING] `rustdoc [..]--crate-name foo [..]-C link-arg=--this-is-a-bogus-flag[..]",
+        )
+        .run();
+}