path: root/debian/patches/d-bootstrap-cargo-doc-paths.patch

From: Debian Rust Maintainers <pkg-rust-maintainers@alioth-lists.debian.net>
Date: Thu, 14 Jul 2022 13:17:39 +0200
Subject: Fix links to cargo-doc

We package cargo docs in a slightly different location; also tweak linkchecker
to not fail these links.
---
 .../edition-guide/src/editions/advanced-migrations.md  | 14 +++++++-------
 ...ansitioning-an-existing-project-to-a-new-edition.md |  4 ++--
 .../src/rust-2021/default-cargo-resolver.md            | 10 +++++-----
 src/doc/index.md                                       |  2 +-
 src/doc/reference/src/conditional-compilation.md       |  2 +-
 src/doc/reference/src/introduction.md                  |  4 ++--
 src/doc/reference/src/linkage.md                       |  2 +-
 src/doc/reference/src/procedural-macros.md             |  2 +-
 src/doc/rustc/src/tests/index.md                       |  4 ++--
 src/doc/rustc/src/what-is-rustc.md                     |  2 +-
 src/doc/edition-guide/book.toml                        | 18 +++++++++---------
 src/tools/linkchecker/main.rs                          |  6 ++++++
 12 files changed, 38 insertions(+), 32 deletions(-)

diff --git a/src/doc/edition-guide/src/editions/advanced-migrations.md b/src/doc/edition-guide/src/editions/advanced-migrations.md
index b804ae6..b8136d7 100644
--- a/src/doc/edition-guide/src/editions/advanced-migrations.md
+++ b/src/doc/edition-guide/src/editions/advanced-migrations.md
@@ -186,18 +186,18 @@ Afterwards, the line with `extern crate rand;` in `src/lib.rs` will be removed.
 
 We're now more idiomatic, and we didn't have to fix our code manually!
 
-[`cargo check`]: ../../cargo/commands/cargo-check.html
-[`cargo fix`]: ../../cargo/commands/cargo-fix.html
+[`cargo check`]: ../../../cargo-doc/doc/commands/cargo-check.html
+[`cargo fix`]: ../../../cargo-doc/doc/commands/cargo-fix.html
 [`explicit-outlives-requirements`]:  ../../rustc/lints/listing/allowed-by-default.html#explicit-outlives-requirements
 [`keyword-idents`]: ../../rustc/lints/listing/allowed-by-default.html#keyword-idents
 [`rustfix`]: https://github.com/rust-lang/rustfix
 [`unused-extern-crates`]: ../../rustc/lints/listing/allowed-by-default.html#unused-extern-crates
-[Cargo features]: ../../cargo/reference/features.html
-[Cargo package]: ../../cargo/reference/manifest.html#the-package-section
-[Cargo targets]: ../../cargo/reference/cargo-targets.html
-[Cargo workspace]: ../../cargo/reference/workspaces.html
+[Cargo features]: ../../../cargo-doc/doc/reference/features.html
+[Cargo package]: ../../../cargo-doc/doc/reference/manifest.html#the-package-section
+[Cargo targets]: ../../../cargo-doc/doc/reference/cargo-targets.html
+[Cargo workspace]: ../../../cargo-doc/doc/reference/workspaces.html
 [CLI flag]: ../../rustc/lints/levels.html#via-compiler-flag
-[Code generation]: ../../cargo/reference/build-script-examples.html#code-generation
+[Code generation]: ../../../cargo-doc/doc/reference/build-script-examples.html#code-generation
 [conditional compilation]: ../../reference/conditional-compilation.html
 [documentation tests]: ../../rustdoc/documentation-tests.html
 [JSON messages]: ../../rustc/json.html
diff --git a/src/doc/edition-guide/src/editions/transitioning-an-existing-project-to-a-new-edition.md b/src/doc/edition-guide/src/editions/transitioning-an-existing-project-to-a-new-edition.md
index 4343529..7f7f0b6 100644
--- a/src/doc/edition-guide/src/editions/transitioning-an-existing-project-to-a-new-edition.md
+++ b/src/doc/edition-guide/src/editions/transitioning-an-existing-project-to-a-new-edition.md
@@ -83,7 +83,7 @@ If new warnings are issued, you may want to consider running `cargo fix` again (
 
 Congrats! Your code is now valid in both Rust 2015 and Rust 2018!
 
-[`cargo fix`]: ../../cargo/commands/cargo-fix.html
-[`cargo test`]: ../../cargo/commands/cargo-test.html
+[`cargo fix`]: ../../../cargo-doc/doc/commands/cargo-fix.html
+[`cargo test`]: ../../../cargo-doc/doc/commands/cargo-test.html
 [Advanced migration strategies]: advanced-migrations.md
 [nightly channel]: ../../book/appendix-07-nightly-rust.html
diff --git a/src/doc/edition-guide/src/rust-2021/default-cargo-resolver.md b/src/doc/edition-guide/src/rust-2021/default-cargo-resolver.md
index 9abc5a6..dff04a4 100644
--- a/src/doc/edition-guide/src/rust-2021/default-cargo-resolver.md
+++ b/src/doc/edition-guide/src/rust-2021/default-cargo-resolver.md
@@ -21,11 +21,11 @@ The new feature resolver no longer merges all requested features for
 crates that are depended on in multiple ways.
 See [the announcement of Rust 1.51][5] for details.
 
-[4]: ../../cargo/reference/resolver.html#feature-resolver-version-2
+[4]: ../../../cargo-doc/doc/reference/resolver.html#feature-resolver-version-2
 [5]: https://blog.rust-lang.org/2021/03/25/Rust-1.51.0.html#cargos-new-feature-resolver
-[workspace]: ../../cargo/reference/workspaces.html
-[virtual workspace]: ../../cargo/reference/workspaces.html#virtual-manifest
-[`resolver` field]: ../../cargo/reference/resolver.html#resolver-versions
+[workspace]: ../../../cargo-doc/doc/reference/workspaces.html
+[virtual workspace]: ../../../cargo-doc/doc/reference/workspaces.html#virtual-manifest
+[`resolver` field]: ../../../cargo-doc/doc/reference/resolver.html#resolver-versions
 
 ## Migration
 
@@ -176,4 +176,4 @@ This snippet of output shows that the project `foo` depends on `bar` with the "d
 Then, `bar` depends on `bstr` as a build-dependency with the "default" feature.
 We can further see that `bstr`'s  "default" feature enables "unicode" (among other features).
 
-[`cargo tree`]: ../../cargo/commands/cargo-tree.html
+[`cargo tree`]: ../../../cargo-doc/doc/commands/cargo-tree.html
diff --git a/src/doc/index.md b/src/doc/index.md
index 2c92d5e..9be58d5 100644
--- a/src/doc/index.md
+++ b/src/doc/index.md
@@ -87,7 +87,7 @@ accomplishing various tasks.
 
 ## The Cargo Book
 
-[The Cargo Book](cargo/index.html) is a guide to Cargo, Rust's build tool and dependency manager.
+[The Cargo Book](../../cargo-doc/doc/index.html) is a guide to Cargo, Rust's build tool and dependency manager.
 
 ## The Rustdoc Book
 
diff --git a/src/doc/reference/src/conditional-compilation.md b/src/doc/reference/src/conditional-compilation.md
index 6966cec..0ca3589 100644
--- a/src/doc/reference/src/conditional-compilation.md
+++ b/src/doc/reference/src/conditional-compilation.md
@@ -370,6 +370,6 @@
 [`target_feature` attribute]: attributes/codegen.md#the-target_feature-attribute
 [attribute]: attributes.md
 [attributes]: attributes.md
-[cargo-feature]: ../cargo/reference/features.html
+[cargo-feature]: ../../cargo-doc/doc/reference/features.html
 [crate type]: linkage.md
 [static C runtime]: linkage.md#static-and-dynamic-c-runtimes
diff --git a/src/doc/reference/src/introduction.md b/src/doc/reference/src/introduction.md
index 9038efd..dbfbd39 100644
--- a/src/doc/reference/src/introduction.md
+++ b/src/doc/reference/src/introduction.md
@@ -135,8 +135,8 @@ We also want the reference to be as normative as possible, so if you see anythin
 [the Rust Reference repository]: https://github.com/rust-lang/reference/
 [Unstable Book]: https://doc.rust-lang.org/nightly/unstable-book/
 [_Expression_]: expressions.md
-[cargo book]: ../cargo/index.html
-[cargo reference]: ../cargo/reference/index.html
+[cargo book]: ../../cargo-doc/doc/index.html
+[cargo reference]: ../../cargo-doc/doc/reference/index.html
 [expressions chapter]: expressions.html
 [file an issue]: https://github.com/rust-lang/reference/issues
 [lifetime of temporaries]: expressions.html#temporaries
diff --git a/src/doc/reference/src/linkage.md b/src/doc/reference/src/linkage.md
index b152005..14277bf 100644
--- a/src/doc/reference/src/linkage.md
+++ b/src/doc/reference/src/linkage.md
@@ -201,7 +201,7 @@ fn main() {
 }
 ```
 
-[cargo]: ../cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
+[cargo]: ../../cargo-doc/doc/reference/environment-variables.html#environment-variables-cargo-sets-for-build-scripts
 
 To use this feature locally, you typically will use the `RUSTFLAGS` environment
 variable to specify flags to the compiler through Cargo. For example to compile
diff --git a/src/doc/reference/src/procedural-macros.md b/src/doc/reference/src/procedural-macros.md
index d983394..6f363f6 100644
--- a/src/doc/reference/src/procedural-macros.md
+++ b/src/doc/reference/src/procedural-macros.md
@@ -331,7 +331,7 @@ Note that neither declarative nor proced
 their equivalent `#[doc = r"str"]` attributes when passed to macros.
 
 [Attribute macros]: #attribute-macros
-[Cargo's build scripts]: ../cargo/reference/build-scripts.html
+[Cargo's build scripts]: ../../cargo-doc/doc/reference/build-scripts.html
 [Derive macros]: #derive-macros
 [Function-like macros]: #function-like-procedural-macros
 [`Delimiter::None`]: ../proc_macro/enum.Delimiter.html#variant.None
diff --git a/src/doc/rustc/src/tests/index.md b/src/doc/rustc/src/tests/index.md
index 32baed9..53c97f8 100644
--- a/src/doc/rustc/src/tests/index.md
+++ b/src/doc/rustc/src/tests/index.md
@@ -301,7 +301,7 @@ Experimental support for using custom test harnesses is available on the
 [`--test` option]: ../command-line-arguments.md#option-test
 [`-Z panic-abort-tests`]: https://github.com/rust-lang/rust/issues/67650
 [`available_parallelism`]: ../../std/thread/fn.available_parallelism.html
-[`cargo test`]: ../../cargo/commands/cargo-test.html
+[`cargo test`]: ../../../cargo-doc/doc/commands/cargo-test.html
 [`libtest`]: ../../test/index.html
 [`main` function]: ../../reference/crates-and-source-files.html#main-functions
 [`Result`]: ../../std/result/index.html
@@ -311,7 +311,7 @@ Experimental support for using custom test harnesses is available on the
 [attribute-should_panic]: ../../reference/attributes/testing.html#the-should_panic-attribute
 [attribute-test]: ../../reference/attributes/testing.html#the-test-attribute
 [bench-docs]: ../../unstable-book/library-features/test.html
-[Cargo]: ../../cargo/index.html
+[Cargo]: ../../../cargo-doc/doc/index.html
 [crate type]: ../../reference/linkage.html
 [custom_test_frameworks documentation]: ../../unstable-book/language-features/custom-test-frameworks.html
 [nightly channel]: ../../book/appendix-07-nightly-rust.html
diff --git a/src/doc/rustc/src/what-is-rustc.md b/src/doc/rustc/src/what-is-rustc.md
index 39a05cf..d106986 100644
--- a/src/doc/rustc/src/what-is-rustc.md
+++ b/src/doc/rustc/src/what-is-rustc.md
@@ -5,7 +5,7 @@ language, provided by the project itself. Compilers take your source code and
 produce binary code, either as a library or executable.
 
 Most Rust programmers don't invoke `rustc` directly, but instead do it through
-[Cargo](../cargo/index.html). It's all in service of `rustc` though! If you
+[Cargo](../../cargo-doc/doc/index.html). It's all in service of `rustc` though! If you
 want to see how Cargo calls `rustc`, you can
 
 ```bash
diff --git a/src/doc/edition-guide/book.toml b/src/doc/edition-guide/book.toml
index 8d8b263..8d31dfe 100644
--- a/src/doc/edition-guide/book.toml
+++ b/src/doc/edition-guide/book.toml
@@ -53,15 +53,15 @@ git-repository-url = "https://github.com/rust-lang/edition-guide"
 "/rust-2018/the-compiler/incremental-compilation-for-faster-compiles.html" = "https://blog.rust-lang.org/2018/02/15/Rust-1.24.html#incremental-compilation"
 "/rust-2018/the-compiler/an-attribute-for-deprecation.html" = "../../../reference/attributes/diagnostics.html#the-deprecated-attribute"
 "/rust-2018/rustup-for-managing-rust-versions.html" = "https://rust-lang.github.io/rustup/"
-"/rust-2018/cargo-and-crates-io/index.html" = "../../../cargo/index.html"
-"/rust-2018/cargo-and-crates-io/cargo-check-for-faster-checking.html" = "../../../cargo/commands/cargo-check.html"
-"/rust-2018/cargo-and-crates-io/cargo-install-for-easy-installation-of-tools.html" = "../../../cargo/commands/cargo-install.html"
+"/rust-2018/cargo-and-crates-io/index.html" = "../../../../cargo-doc/doc/index.html"
+"/rust-2018/cargo-and-crates-io/cargo-check-for-faster-checking.html" = "../../../../cargo-doc/doc/commands/cargo-check.html"
+"/rust-2018/cargo-and-crates-io/cargo-install-for-easy-installation-of-tools.html" = "../../../../cargo-doc/doc/commands/cargo-install.html"
 "/rust-2018/cargo-and-crates-io/cargo-new-defaults-to-a-binary-project.html" = "https://blog.rust-lang.org/2018/03/29/Rust-1.25.html#cargo-features"
-"/rust-2018/cargo-and-crates-io/cargo-rustc-for-passing-arbitrary-flags-to-rustc.html" = "../../../cargo/commands/cargo-rustc.html"
-"/rust-2018/cargo-and-crates-io/cargo-workspaces-for-multi-package-projects.html" = "../../../cargo/reference/workspaces.html"
-"/rust-2018/cargo-and-crates-io/multi-file-examples.html" = "../../../cargo/guide/project-layout.html"
-"/rust-2018/cargo-and-crates-io/replacing-dependencies-with-patch.html" = "../../../cargo/reference/overriding-dependencies.html#the-patch-section"
-"/rust-2018/cargo-and-crates-io/cargo-can-use-a-local-registry-replacement.html" = "../../../cargo/reference/source-replacement.html"
+"/rust-2018/cargo-and-crates-io/cargo-rustc-for-passing-arbitrary-flags-to-rustc.html" = "../../../../cargo-doc/doc/commands/cargo-rustc.html"
+"/rust-2018/cargo-and-crates-io/cargo-workspaces-for-multi-package-projects.html" = "../../../../cargo-doc/doc/reference/workspaces.html"
+"/rust-2018/cargo-and-crates-io/multi-file-examples.html" = "../../../../cargo-doc/doc/guide/project-layout.html"
+"/rust-2018/cargo-and-crates-io/replacing-dependencies-with-patch.html" = "../../../../cargo-doc/doc/reference/overriding-dependencies.html#the-patch-section"
+"/rust-2018/cargo-and-crates-io/cargo-can-use-a-local-registry-replacement.html" = "../../../../cargo-doc/doc/reference/source-replacement.html"
 "/rust-2018/cargo-and-crates-io/crates-io-disallows-wildcard-dependencies.html" = "https://blog.rust-lang.org/2016/01/21/Rust-1.6.html#cratesio-disallows-wildcards"
 "/rust-2018/documentation/index.html" = "../../../index.html"
 "/rust-2018/documentation/new-editions-of-the-book.html" = "../../../book/index.html"
@@ -93,4 +93,4 @@ git-repository-url = "https://github.com/rust-lang/edition-guide"
 "/rust-next/future.html" = "../../std/future/trait.Future.html"
 "/rust-next/alloc.html" = "https://blog.rust-lang.org/2019/07/04/Rust-1.36.0.html#the-alloc-crate-is-stable"
 "/rust-next/maybe-uninit.html" = "https://blog.rust-lang.org/2019/07/04/Rust-1.36.0.html#maybeuninitt-instead-of-memuninitialized"
-"/rust-next/cargo-vendor.html" = "../../cargo/commands/cargo-vendor.html"
+"/rust-next/cargo-vendor.html" = "../../../cargo-doc/doc/commands/cargo-vendor.html"
diff --git a/src/tools/linkchecker/main.rs b/src/tools/linkchecker/main.rs
index a22dc5f..c8d521a 100644
--- a/src/tools/linkchecker/main.rs
+++ b/src/tools/linkchecker/main.rs
@@ -262,6 +262,12 @@
                             return;
                         }
                     }
+                    if let Some(path_str) = path.to_str() {
+                        if path_str.contains("/cargo-doc/doc/") {
+                            // link to related cargo-doc, ok for our Debian build
+                            return;
+                        }
+                    }
                     if is_exception(file, &target_pretty_path) {
                         report.links_ignored_exception += 1;
                     } else {
Index: rust/compiler/rustc_error_codes/src/error_codes/E0462.md
===================================================================
--- rust.orig/compiler/rustc_error_codes/src/error_codes/E0462.md
+++ rust/compiler/rustc_error_codes/src/error_codes/E0462.md
@@ -26,7 +26,7 @@ prefer `staticlib` for linking with C pr
 `crate_type`s in [this section of the Reference](../reference/linkage.html).
 
 This error can be fixed by:
- * Using [Cargo](../cargo/index.html), the Rust package manager, automatically
+ * Using [Cargo](../../cargo-doc/doc/index.html), the Rust package manager, automatically
    fixing this issue.
  * Recompiling the crate as a `rlib` or `dylib`; formats suitable for Rust
    linking.
Index: rust/compiler/rustc_error_codes/src/error_codes/E0460.md
===================================================================
--- rust.orig/compiler/rustc_error_codes/src/error_codes/E0460.md
+++ rust/compiler/rustc_error_codes/src/error_codes/E0460.md
@@ -68,4 +68,4 @@ This error can be fixed by:
  * Recompiling crate `a` so that both crate `b` and `main` have a uniform
    version to depend on.
 
-[Cargo]: ../cargo/index.html
+[Cargo]: ../../cargo-doc/doc/index.html
Index: rust/compiler/rustc_error_codes/src/error_codes/E0514.md
===================================================================
--- rust.orig/compiler/rustc_error_codes/src/error_codes/E0514.md
+++ rust/compiler/rustc_error_codes/src/error_codes/E0514.md
@@ -27,7 +27,7 @@ the compiler cannot be sure about *how*
 versions, and therefore this error occurs.
 
 This error can be fixed by:
- * Using [Cargo](../cargo/index.html), the Rust package manager and
+ * Using [Cargo](../../cargo-doc/doc/index.html), the Rust package manager and
    [Rustup](https://rust-lang.github.io/rustup/), the Rust toolchain installer,
    automatically fixing this issue.
  * Recompiling the crates with a uniform `rustc` version.
Index: rust/src/doc/unstable-book/src/compiler-flags/branch-protection.md
===================================================================
--- rust.orig/src/doc/unstable-book/src/compiler-flags/branch-protection.md
+++ rust/src/doc/unstable-book/src/compiler-flags/branch-protection.md
@@ -15,4 +15,4 @@ For example, `-Z branch-protection=bti,p
 
 Rust's standard library does not ship with BTI or pointer authentication enabled by default.
 In Cargo projects the standard library can be recompiled with pointer authentication using the nightly
-[build-std](../../cargo/reference/unstable.html#build-std) feature.
+[build-std](../../../cargo-doc/doc/reference/unstable.html#build-std) feature.
Index: rust/src/doc/unstable-book/src/compiler-flags/control-flow-guard.md
===================================================================
--- rust.orig/src/doc/unstable-book/src/compiler-flags/control-flow-guard.md
+++ rust/src/doc/unstable-book/src/compiler-flags/control-flow-guard.md
@@ -39,7 +39,7 @@ It is strongly recommended to also enabl
 
 To enable CFG in the standard library, use the [cargo `-Z build-std` functionality][build-std] to recompile the standard library with the same configuration options as the main program.
 
-[build-std]: ../../cargo/reference/unstable.html#build-std
+[build-std]: ../../../cargo-doc/doc/reference/unstable.html#build-std
 
 For example:
 ```cmd
Index: rust/src/doc/unstable-book/src/compiler-flags/sanitizer.md
===================================================================
--- rust.orig/src/doc/unstable-book/src/compiler-flags/sanitizer.md
+++ rust/src/doc/unstable-book/src/compiler-flags/sanitizer.md
@@ -691,7 +691,7 @@ It is strongly recommended to combine sa
 instrumented standard library, for example using [cargo `-Zbuild-std`
 functionality][build-std].
 
-[build-std]: ../../cargo/reference/unstable.html#build-std
+[build-std]: ../../../cargo-doc/doc/reference/unstable.html#build-std
 
 # Build scripts and procedural macros
 
Index: rust/compiler/rustc_error_codes/src/error_codes/E0461.md
===================================================================
--- rust.orig/compiler/rustc_error_codes/src/error_codes/E0461.md
+++ rust/compiler/rustc_error_codes/src/error_codes/E0461.md
@@ -25,6 +25,6 @@ architectures. This issue also extends t
 `std` is operating-system specific.
 
 This error can be fixed by:
- * Using [Cargo](../cargo/index.html), the Rust package manager, automatically
+ * Using [Cargo](../../cargo-doc/doc/index.html), the Rust package manager, automatically
    fixing this issue.
  * Recompiling either crate so that they target a consistent target triple.
Index: rust/compiler/rustc_error_codes/src/error_codes/E0519.md
===================================================================
--- rust.orig/compiler/rustc_error_codes/src/error_codes/E0519.md
+++ rust/compiler/rustc_error_codes/src/error_codes/E0519.md
@@ -34,7 +34,7 @@ The above example compiles two crates wi
 impossible for the compiler to distinguish between symbols (`pub` item names).
 
 This error can be fixed by:
- * Using [Cargo](../cargo/index.html), the Rust package manager, automatically
+ * Using [Cargo](../../cargo-doc/doc/index.html), the Rust package manager, automatically
    fixing this issue.
  * Recompiling the crate with different metadata (different name/
    `crate_type`).
Index: rust/src/doc/rustc/src/linker-plugin-lto.md
===================================================================
--- rust.orig/src/doc/rustc/src/linker-plugin-lto.md
+++ rust/src/doc/rustc/src/linker-plugin-lto.md
@@ -112,7 +112,7 @@ targeting Windows-like targets
 This is fixed if you explicitly set the target, for example
 `cargo build --target x86_64-pc-windows-msvc`
 Without an explicit --target the flags will be passed to all compiler invocations (including build
-scripts and proc macros), see [cargo docs on rustflags](../cargo/reference/config.html#buildrustflags)
+scripts and proc macros), see [cargo docs on rustflags](../../cargo-doc/doc/reference/config.html#buildrustflags)
 
 If you have dependencies using the `cc` crate, you will need to set these
 environment variables:
Index: rust/src/doc/rustc/src/platform-support/fuchsia.md
===================================================================
--- rust.orig/src/doc/rustc/src/platform-support/fuchsia.md
+++ rust/src/doc/rustc/src/platform-support/fuchsia.md
@@ -870,7 +870,7 @@ ${SDK_PATH}/tools/${ARCH}/ffx debug conn
 [Fuchsia]: https://fuchsia.dev/
 [source tree]: https://fuchsia.dev/fuchsia-src/get-started/learn/build
 [rustup]: https://rustup.rs/
-[cargo]: ../../cargo/index.html
+[cargo]: ../../../cargo-doc/doc/index.html
 [Fuchsia SDK]: https://chrome-infra-packages.appspot.com/p/fuchsia/sdk/core
 [overview of CML]: https://fuchsia.dev/fuchsia-src/concepts/components/v2/component_manifests
 [reference for the file format]: https://fuchsia.dev/reference/cml
Index: rust/src/doc/rustc/src/targets/custom.md
===================================================================
--- rust.orig/src/doc/rustc/src/targets/custom.md
+++ rust/src/doc/rustc/src/targets/custom.md
@@ -14,4 +14,4 @@ To see it for a different target, add th
 rustc +nightly -Z unstable-options --target=wasm32-unknown-unknown --print target-spec-json
 ```
 
-To use a custom target, see the (unstable) [`build-std` feature](../../cargo/reference/unstable.html#build-std) of `cargo`.
+To use a custom target, see the (unstable) [`build-std` feature](../../../cargo-doc/doc/reference/unstable.html#build-std) of `cargo`.