Use cargo check -Zbuild-std instead of cargo miri setup

This should be more reliable (not building with `cfg(miri)` and more
accurately knowing whether a target supports std).

Known targets affected by this change:
- cygwin: should now build since it only breaks in `cfg(miri)`
- i686-pc-nto-qnx700: officially doesn't support std

closes #4

migrations/20250705120351_rename-miri-std.sql

@@ -0,0 +1,3 @@
+UPDATE finished_nightly SET mode = 'std' WHERE mode = 'miri-std';
+
+UPDATE build_info SET mode = 'std' WHERE mode = 'miri-std';

src/build.rs

@@ -61,7 +61,11 @@ pub async fn background_builder(db: Db) -> Result<()> {
 
     loop {
         if let Err(err) = background_builder_inner(&db).await {
-            error!("error in background builder: {err}");
+            error!(
+                ?err,
+                "error in background builder, waiting for an hour before retrying: {err}"
+            );
+            tokio::time::sleep(Duration::from_secs(3600)).await;
         }
     }
 }
@@ -145,20 +149,7 @@ async fn install_toolchain(toolchain: &Toolchain, mode: BuildMode) -> Result<()>
     if !result.status.success() {
         bail!("rustup failed: {:?}", String::from_utf8(result.stderr));
     }
-    if mode == BuildMode::MiriStd {
-        let result = Command::new("rustup")
-            .arg("component")
-            .arg("add")
-            .arg("miri")
-            .arg("--toolchain")
-            .arg(&toolchain.0)
-            .output()
-            .await
-            .wrap_err("failed to spawn rustup")?;
-        if !result.status.success() {
-            bail!("rustup failed: {:?}", String::from_utf8(result.stderr));
-        }
-    }
+
     Ok(())
 }
 
@@ -289,23 +280,24 @@ async fn build_target(
 ) -> Result<BuildResult> {
     let mut rustflags = None;
 
-    let output = match mode {
+    let init = Command::new("cargo")
+        .args(["init", "--lib", "--name", "target-test"])
+        .current_dir(tmpdir)
+        .output()
+        .await
+        .wrap_err("spawning cargo init")?;
+    if !init.status.success() {
+        bail!("init failed: {}", String::from_utf8(init.stderr)?);
+    }
+
+    let librs = tmpdir.join("src").join("lib.rs");
+    std::fs::write(&librs, "#![no_std]\n")
+        .wrap_err_with(|| format!("writing to {}", librs.display()))?;
+
+    let mut cmd = Command::new("cargo");
+
+    match mode {
         BuildMode::Core => {
-            let init = Command::new("cargo")
-                .args(["init", "--lib", "--name", "target-test"])
-                .current_dir(tmpdir)
-                .output()
-                .await
-                .wrap_err("spawning cargo init")?;
-            if !init.status.success() {
-                bail!("init failed: {}", String::from_utf8(init.stderr)?);
-            }
-
-            let librs = tmpdir.join("src").join("lib.rs");
-            std::fs::write(&librs, "#![no_std]\n")
-                .wrap_err_with(|| format!("writing to {}", librs.display()))?;
-
-            let mut cmd = Command::new("cargo");
             cmd.arg(format!("+{toolchain}"))
                 .args(["build", "-Zbuild-std=core", "--release"])
                 .args(["--target", target]);
@@ -319,23 +311,20 @@ async fn build_target(
                 cmd.env("RUSTFLAGS", &flags);
                 rustflags = Some(flags);
             }
-
-            cmd.current_dir(tmpdir)
-                .output()
-                .await
-                .wrap_err("spawning cargo build")?
         }
-        BuildMode::MiriStd => Command::new("cargo")
-            .arg(format!("+{toolchain}"))
-            .args(["miri", "setup"])
-            .args(["--target", target])
-            .current_dir(tmpdir)
-            .env("MIRI_SYSROOT", tmpdir)
-            .output()
-            .await
-            .wrap_err("spawning cargo build")?,
+        BuildMode::Std => {
+            cmd.arg(format!("+{toolchain}"))
+                .args(["check", "-Zbuild-std"])
+                .args(["--target", target]);
+        }
     };
 
+    let output = cmd
+        .current_dir(tmpdir)
+        .output()
+        .await
+        .wrap_err("spawning cargo build")?;
+
     let stderr = String::from_utf8(output.stderr).wrap_err("cargo stderr utf8")?;
 
     let status = if output.status.success() {

src/db.rs

@@ -14,26 +14,25 @@ pub struct Db {
 
 pub static MIGRATOR: Migrator = sqlx::migrate!();
 
-#[derive(Debug, Clone, Copy, sqlx::Type, Serialize, Deserialize, PartialEq, Eq, Hash)]
+#[derive(Debug, Clone, Copy, sqlx::Type, Serialize, PartialEq, Eq, Hash)]
 #[sqlx(rename_all = "kebab-case")]
-#[serde(rename_all = "kebab-case")]
 pub enum BuildMode {
-    /// `-Zbuild-std=core`
+    /// `build -Zbuild-std=core`
     Core,
-    /// `cargo miri setup`
-    MiriStd,
+    /// `check -Zbuild-std`
+    Std,
 }
 
 impl Display for BuildMode {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Self::Core => f.write_str("core"),
-            Self::MiriStd => f.write_str("miri-std"),
+            Self::Std => f.write_str("std"),
         }
     }
 }
 
-#[derive(sqlx::FromRow, Serialize, Deserialize, Clone)]
+#[derive(sqlx::FromRow, Serialize, Clone)]
 pub struct BuildInfo {
     pub nightly: String,
     pub target: String,
@@ -41,7 +40,7 @@ pub struct BuildInfo {
     pub mode: BuildMode,
 }
 
-#[derive(Clone, sqlx::FromRow, Serialize, Deserialize)]
+#[derive(Clone, sqlx::FromRow, Serialize)]
 pub struct FullBuildInfo {
     pub nightly: String,
     pub target: String,

src/nightlies.rs

@@ -44,7 +44,7 @@ impl Nightlies {
 
         self.all
             .iter()
-            .flat_map(|nightly| [(nightly, BuildMode::Core), (nightly, BuildMode::MiriStd)])
+            .flat_map(|nightly| [(nightly, BuildMode::Core), (nightly, BuildMode::Std)])
             .find(|(nightly, mode)| {
                 !already_finished.contains(&FinishedNightly {
                     nightly: (*nightly).to_owned(),

src/web.rs

@@ -34,11 +34,33 @@ pub async fn webserver(db: Db) -> Result<()> {
     axum::serve(listener, app).await.wrap_err("failed to serve")
 }
 
+#[derive(Debug, Clone, Copy)]
+pub struct LegacyBuildMode(BuildMode);
+
+impl<'de> serde::Deserialize<'de> for LegacyBuildMode {
+    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        match s.as_str() {
+            "core" => Ok(LegacyBuildMode(BuildMode::Core)),
+            "std" => Ok(LegacyBuildMode(BuildMode::Std)),
+            // This mode used to be called "miri-std" but it has been renamed to "std" using build-std.
+            // Allow the old value to keep links working but map it to std.
+            "miri-std" => Ok(LegacyBuildMode(BuildMode::Std)),
+            _ => Err(serde::de::Error::custom(format!(
+                "invalid build mode, expected 'core', 'std', or 'miri-std'"
+            ))),
+        }
+    }
+}
+
 #[derive(Deserialize)]
 struct BuildQuery {
     nightly: String,
     target: String,
-    mode: Option<BuildMode>,
+    mode: Option<LegacyBuildMode>,
 }
 
 async fn web_build(State(state): State<AppState>, Query(query): Query<BuildQuery>) -> Response {
@@ -63,7 +85,7 @@ async fn web_build(State(state): State<AppState>, Query(query): Query<BuildQuery
         .build_status_full(
             &query.nightly,
             &query.target,
-            query.mode.unwrap_or(BuildMode::Core),
+            query.mode.map(|mode| mode.0).unwrap_or(BuildMode::Core),
         )
         .await
     {
@@ -132,8 +154,8 @@ async fn web_target(State(state): State<AppState>, Query(query): Query<TargetQue
                 .max_by_key(|elem| elem.nightly.clone());
 
             let status = match (latest_core, latest_miri) {
-                (Some(core), Some(miri)) => {
-                    if core.status == Status::Error || miri.status == Status::Error {
+                (Some(core), Some(std)) => {
+                    if core.status == Status::Error || std.status == Status::Error {
                         Status::Error
                     } else {
                         Status::Pass
@@ -150,7 +172,7 @@ async fn web_target(State(state): State<AppState>, Query(query): Query<TargetQue
                 let v = builds_grouped.entry(build.nightly.clone()).or_default();
                 match build.mode {
                     BuildMode::Core => v.0 = Some(build),
-                    BuildMode::MiriStd => v.1 = Some(build),
+                    BuildMode::Std => v.1 = Some(build),
                 }
             }
 
@@ -213,7 +235,7 @@ async fn web_nightly(State(state): State<AppState>, Query(query): Query<NightlyQ
                     let v = builds_grouped.entry(build.target.clone()).or_default();
                     match build.mode {
                         BuildMode::Core => v.0 = Some(build.clone()),
-                        BuildMode::MiriStd => v.1 = Some(build.clone()),
+                        BuildMode::Std => v.1 = Some(build.clone()),
                     }
                 }
 
@@ -223,7 +245,7 @@ async fn web_nightly(State(state): State<AppState>, Query(query): Query<NightlyQ
                     if build.status == Status::Error {
                         match build.mode {
                             BuildMode::Core => core_failures += 1,
-                            BuildMode::MiriStd => std_failures += 1,
+                            BuildMode::Std => std_failures += 1,
                         }
                     }
                 }
@@ -244,7 +266,7 @@ async fn web_nightly(State(state): State<AppState>, Query(query): Query<NightlyQ
                     .and_then(|info| info.broken_error.clone());
                 let std_broken = info
                     .iter()
-                    .find(|info| info.mode == BuildMode::MiriStd && info.is_broken)
+                    .find(|info| info.mode == BuildMode::Std && info.is_broken)
                     .and_then(|info| info.broken_error.clone());
 
                 let page = NightlyPage {

templates/nightly.html

@@ -15,10 +15,12 @@
       codegen/linking of core works, but does not check whether std builds.
     </p>
     <p>
-      std is being built with <code>cargo miri setup</code>. If a target does
-      not support std, the std column represents core/alloc. This checks that
-      std builds (on targets that have it) but does not check whether
+      std is being built with <code>cargo check -Zbuild-std</code>. If a target
+      does not support std, the std column represents core/alloc. This checks
+      that std checks (on targets that have it) but does not check whether
       codegen/linking works.
+
+      For older builds, <code>cargo miri setup</code> was used instead.
     </p>
     {% if let Some(core_broken) = core_broken %}
     <p>

templates/target.html

@@ -23,10 +23,12 @@
       codegen/linking of core works, but does not check whether std builds.
     </p>
     <p>
-      std is being built with <code>cargo miri setup</code>. If a target does
-      not support std, the std column represents core/alloc. This checks that
-      std builds (on targets that have it) but does not check whether
+      std is being built with <code>cargo check -Zbuild-std</code>. If a target
+      does not support std, the std column represents core/alloc. This checks
+      that std checks (on targets that have it) but does not check whether
       codegen/linking works.
+
+      For older builds, <code>cargo miri setup</code> was used instead.
     </p>
     {% if showing_failures %}
     <p>