Auto merge of #6892 - Goirad:doctest-xcompile, r=alexcrichton

Added ability to crosscompile doctests

This commit adds the ability to cross-compile and run doctests.
Like before cargo checks if target == host, the difference is that if there is a runtool defined in config.toml, it passes the information forward to rustdoc so that it can run the doctests with that tool. If no tool is defined and the target != host, cargo instead displays a message that doctests will not be compiled because of the missing runtool.

See [here](rust-lang/rust#60387) for the companion PR in the rust project that modifies rustdoc to accept the relevant options as well as allow ignoring doctests on a per target level.
Partially resolves [#6460](#6460)

See [here](#7040) for the tracking issue.

src/cargo/core/compiler/compilation.rs

@@ -163,7 +163,7 @@ impl<'cfg> Compilation<'cfg> {
         self.fill_env(process(cmd), pkg, true)
     }
 
-    fn target_runner(&self) -> &Option<(PathBuf, Vec<String>)> {
+    pub fn target_runner(&self) -> &Option<(PathBuf, Vec<String>)> {
         &self.target_runner
     }
 

src/cargo/core/features.rs

@@ -336,6 +336,7 @@ pub struct CliUnstable {
     pub binary_dep_depinfo: bool,
     pub build_std: Option<Vec<String>>,
     pub timings: Option<Vec<String>>,
+    pub doctest_xcompile: bool,
 }
 
 impl CliUnstable {
@@ -393,6 +394,7 @@ impl CliUnstable {
                 self.build_std = Some(crate::core::compiler::standard_lib::parse_unstable_flag(v))
             }
             "timings" => self.timings = Some(parse_timings(v)),
+            "doctest-xcompile" => self.doctest_xcompile = true,
             _ => failure::bail!("unknown `-Z` flag specified: {}", k),
         }
 

src/cargo/ops/cargo_test.rs

@@ -140,8 +140,14 @@ fn run_doc_tests(
     let mut errors = Vec::new();
     let config = options.compile_opts.config;
 
-    // We don't build/run doc tests if `target` does not equal `host`.
-    if compilation.host != compilation.target {
+    // The unstable doctest-xcompile feature enables both per-target-ignores and
+    // cross-compiling doctests. As a side effect, this feature also gates running
+    // doctests with runtools when target == host.
+    let doctest_xcompile = config.cli_unstable().doctest_xcompile;
+    let mut runtool: &Option<(std::path::PathBuf, Vec<String>)> = &None;
+    if doctest_xcompile {
+        runtool = compilation.target_runner();
+    } else if compilation.host != compilation.target {
         return Ok((Test::Doc, errors));
     }
 
@@ -158,6 +164,19 @@ fn run_doc_tests(
             .arg("--crate-name")
             .arg(&target.crate_name());
 
+        if doctest_xcompile {
+            p.arg("--target").arg(&compilation.target);
+            p.arg("-Zunstable-options");
+            p.arg("--enable-per-target-ignores");
+        }
+
+        runtool.as_ref().map(|(runtool, runtool_args)| {
+            p.arg("--runtool").arg(runtool);
+            for arg in runtool_args {
+                p.arg("--runtool-arg").arg(arg);
+            }
+        });
+
         for &rust_dep in &[&compilation.deps_output] {
             let mut arg = OsString::from("dependency=");
             arg.push(rust_dep);
@@ -194,7 +213,6 @@ fn run_doc_tests(
         if let Some(flags) = compilation.rustdocflags.get(&package.package_id()) {
             p.args(flags);
         }
-
         config
             .shell()
             .verbose(|shell| shell.status("Running", p.to_string()))?;

tests/testsuite/test.rs

@@ -8,6 +8,7 @@ use cargo_test_support::registry::Package;
 use cargo_test_support::{
     basic_bin_manifest, basic_lib_manifest, basic_manifest, cargo_exe, project,
 };
+use cargo_test_support::{cross_compile, is_nightly, paths};
 use cargo_test_support::{rustc_host, sleep_ms};
 
 #[cargo_test]
@@ -3660,3 +3661,232 @@ fn test_dep_with_dev() {
         )
         .run();
 }
+
+#[cargo_test]
+fn cargo_test_doctest_xcompile_ignores() {
+    if !is_nightly() {
+        return;
+    }
+    let p = project()
+        .file("Cargo.toml", &basic_lib_manifest("foo"))
+        .file(
+            "src/lib.rs",
+            r#"
+            ///```ignore-x86_64
+            ///assert!(cfg!(not(target_arch = "x86_64")));
+            ///```
+            pub fn foo() -> u8 {
+                4
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("build").run();
+    #[cfg(not(target_arch = "x86_64"))]
+    p.cargo("test")
+        .with_stdout_contains(
+            "\
+             test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out\
+             ",
+        )
+        .run();
+    #[cfg(target_arch = "x86_64")]
+    p.cargo("test")
+        .with_status(101)
+        .with_stdout_contains(
+            "\
+             test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out\
+             ",
+        )
+        .run();
+
+    #[cfg(not(target_arch = "x86_64"))]
+    p.cargo("test -Zdoctest-xcompile")
+        .masquerade_as_nightly_cargo()
+        .with_stdout_contains(
+            "\
+             test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out\
+             ",
+        )
+        .run();
+
+    #[cfg(target_arch = "x86_64")]
+    p.cargo("test -Zdoctest-xcompile")
+        .masquerade_as_nightly_cargo()
+        .with_stdout_contains(
+            "\
+             test result: ok. 0 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out\
+             ",
+        )
+        .run();
+}
+
+#[cargo_test]
+fn cargo_test_doctest_xcompile() {
+    if !is_nightly() {
+        return;
+    }
+    let p = project()
+        .file("Cargo.toml", &basic_lib_manifest("foo"))
+        .file(
+            "src/lib.rs",
+            r#"
+
+            ///```
+            ///assert!(1 == 1);
+            ///```
+            pub fn foo() -> u8 {
+                4
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("build").run();
+    p.cargo(&format!("test --target {}", cross_compile::alternate()))
+        .with_stdout_contains(
+            "\
+             running 0 tests\
+             ",
+        )
+        .run();
+    p.cargo(&format!(
+        "test --target {} -Zdoctest-xcompile",
+        cross_compile::alternate()
+    ))
+    .masquerade_as_nightly_cargo()
+    .with_stdout_contains(
+        "\
+         test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out\
+         ",
+    )
+    .run();
+}
+
+#[cargo_test]
+fn cargo_test_doctest_xcompile_runner() {
+    use std::fs;
+    if !is_nightly() {
+        return;
+    }
+
+    let runner = project()
+        .file("Cargo.toml", &basic_bin_manifest("runner"))
+        .file(
+            "src/main.rs",
+            r#"
+            pub fn main() {
+                eprintln!("this is a runner");
+                let args: Vec<String> = std::env::args().collect();
+                std::process::Command::new(&args[1]).spawn();
+            }
+            "#,
+        )
+        .build();
+
+    runner.cargo("build").run();
+    assert!(runner.bin("runner").is_file());
+    let runner_path = paths::root().join("runner");
+    fs::copy(&runner.bin("runner"), &runner_path).unwrap();
+
+    let config = paths::root().join(".cargo/config");
+
+    fs::create_dir_all(config.parent().unwrap()).unwrap();
+    File::create(config)
+        .unwrap()
+        .write_all(
+            format!(
+                r#"
+[target.'cfg(target_arch = "x86")']
+runner = "{}"
+"#,
+                runner_path.to_str().unwrap()
+            )
+            .as_bytes(),
+        )
+        .unwrap();
+
+    let p = project()
+        .file("Cargo.toml", &basic_lib_manifest("foo"))
+        .file(
+            "src/lib.rs",
+            r#"
+            ///```
+            ///assert!(cfg!(target_arch = "x86"));
+            ///```
+            pub fn foo() -> u8 {
+                4
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("build").run();
+    p.cargo(&format!("test --target {}", cross_compile::alternate()))
+        .with_stdout_contains(
+            "\
+             running 0 tests\
+             ",
+        )
+        .run();
+    p.cargo(&format!(
+        "test --target {} -Zdoctest-xcompile",
+        cross_compile::alternate()
+    ))
+    .masquerade_as_nightly_cargo()
+    .with_stdout_contains(
+        "\
+         test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out\
+         ",
+    )
+    .with_stderr_contains(
+        "\
+         this is a runner\
+         ",
+    )
+    .run();
+}
+
+#[cargo_test]
+fn cargo_test_doctest_xcompile_no_runner() {
+    if !is_nightly() {
+        return;
+    }
+
+    let p = project()
+        .file("Cargo.toml", &basic_lib_manifest("foo"))
+        .file(
+            "src/lib.rs",
+            r#"
+
+            ///```
+            ///assert!(cfg!(target_arch = "x86"));
+            ///```
+            pub fn foo() -> u8 {
+                4
+            }
+            "#,
+        )
+        .build();
+
+    p.cargo("build").run();
+    p.cargo(&format!("test --target {}", cross_compile::alternate()))
+        .with_stdout_contains(
+            "\
+             running 0 tests\
+             ",
+        )
+        .run();
+    p.cargo(&format!(
+        "test --target {} -Zdoctest-xcompile",
+        cross_compile::alternate()
+    ))
+    .masquerade_as_nightly_cargo()
+    .with_stdout_contains(
+        "\
+         test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out\
+         ",
+    )
+    .run();
+}