output configured targets

src/bin/commands/list_targets.rs

@@ -0,0 +1,131 @@
+use std::str::FromStr;
+
+use clap::Args;
+use cross::docker;
+use cross::shell::MessageInfo;
+
+#[derive(Args, Debug)]
+pub struct ListTargets {
+    /// Format version
+    #[clap(long)]
+    format_version: Option<FormatVersion>,
+    /// Coloring: auto, always, never
+    #[clap(long)]
+    pub color: Option<String>,
+}
+
+#[derive(Debug, Clone, Copy, serde::Serialize)]
+pub enum FormatVersion {
+    #[serde(rename = "1")]
+    One,
+}
+
+#[derive(Debug, thiserror::Error)]
+#[error("invalid format version")]
+pub struct FormatVersionError;
+
+impl FromStr for FormatVersion {
+    type Err = FormatVersionError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "1" => Ok(FormatVersion::One),
+            _ => Err(FormatVersionError),
+        }
+    }
+}
+
+#[derive(serde::Serialize)]
+pub struct Output {
+    format_version: FormatVersion,
+    #[serde(flatten)]
+    other: serde_json::Value,
+}
+
+impl ListTargets {
+    pub fn verbose(&self) -> bool {
+        false
+    }
+
+    pub fn quiet(&self) -> bool {
+        false
+    }
+
+    pub fn color(&self) -> Option<&str> {
+        self.color.as_deref()
+    }
+
+    pub fn run(self, msg_info: &mut MessageInfo) -> cross::Result<()> {
+        let toml = if let Some(metadata) = cross::cargo_metadata_with_args(None, None, msg_info)? {
+            cross::toml(&metadata, msg_info)?
+        } else {
+            None
+        };
+
+        let config = cross::config::Config::new(toml);
+        let version = if let Some(version) = self.format_version {
+            version
+        } else {
+            msg_info.warn(
+                "please specify `--format-version` flag explicitly to avoid compatibility problems",
+            )?;
+            FormatVersion::One
+        };
+        let data = match version {
+            FormatVersion::One => self.run_v1(&config, msg_info)?,
+        };
+        println!(
+            "{}",
+            serde_json::to_string_pretty(&Output {
+                format_version: version,
+                other: data,
+            })?
+        );
+        Ok(())
+    }
+
+    pub fn run_v1(
+        self,
+        config: &cross::config::Config,
+        _msg_info: &mut MessageInfo,
+    ) -> cross::Result<serde_json::Value> {
+        #[derive(serde::Serialize)]
+        struct Target {
+            triplet: String,
+            platforms: Vec<String>,
+        }
+        let mut targets: Vec<_> = cross::docker::PROVIDED_IMAGES
+            .iter()
+            .filter_map(|i| {
+                Some(Target {
+                    triplet: Some(i.name).filter(|i| *i != "zig")?.to_owned(),
+                    platforms: i.platforms.iter().map(ToString::to_string).collect(),
+                })
+            })
+            .collect();
+        if let Some(toml_targets) = config.targets() {
+            for (target, config) in toml_targets {
+                if targets.iter().any(|t| t.triplet == target.triple()) {
+                    continue;
+                }
+                targets.push(Target {
+                    triplet: target.triple().to_owned(),
+                    platforms: config
+                        .image
+                        .as_ref()
+                        .map(|i| {
+                            i.toolchain
+                                .iter()
+                                .map(ToString::to_string)
+                                .collect::<Vec<_>>()
+                        })
+                        .filter(|v| !v.is_empty())
+                        .unwrap_or_else(|| vec![docker::ImagePlatform::DEFAULT.to_string()]),
+                })
+            }
+        }
+        Ok(serde_json::json!({
+            "targets": targets,
+        }))
+    }
+}

src/bin/commands/mod.rs

@@ -1,7 +1,9 @@
 mod clean;
 mod containers;
 mod images;
+mod list_targets;
 
 pub use self::clean::*;
 pub use self::containers::*;
 pub use self::images::*;
+pub use self::list_targets::*;

src/bin/cross-util.rs

@@ -39,6 +39,8 @@ enum Commands {
     Containers(commands::Containers),
     /// Clean all cross data in local storage.
     Clean(commands::Clean),
+    /// List all cross targets, including those specialized for the current project (if in one).
+    ListTargets(commands::ListTargets),
 }
 
 fn is_toolchain(toolchain: &str) -> cross::Result<Toolchain> {
@@ -103,6 +105,10 @@ pub fn main() -> cross::Result<()> {
             let engine = get_engine!(args, false, msg_info)?;
             args.run(engine, &mut msg_info)?;
         }
+        Commands::ListTargets(args) => {
+            let mut msg_info = get_msg_info!(args)?;
+            args.run(&mut msg_info)?;
+        }
     }
 
     Ok(())

src/config.rs

@@ -212,6 +212,13 @@ impl Config {
         }
     }
 
+    /// Grabs all defined targets in toml
+    pub fn targets(
+        &self,
+    ) -> Option<impl Iterator<Item = (&Target, &crate::cross_toml::CrossTargetConfig)>> {
+        self.toml.as_ref().map(|toml| toml.targets.iter())
+    }
+
     pub fn confusable_target(&self, target: &Target, msg_info: &mut MessageInfo) -> Result<()> {
         if let Some(keys) = self.toml.as_ref().map(|t| t.targets.keys()) {
             for mentioned_target in keys {

src/cross_toml.rs

@@ -43,7 +43,7 @@ pub struct CrossTargetConfig {
     #[serde(default, deserialize_with = "opt_string_bool_or_struct")]
     zig: Option<CrossZigConfig>,
     #[serde(default, deserialize_with = "opt_string_or_struct")]
-    image: Option<PossibleImage>,
+    pub image: Option<PossibleImage>,
     #[serde(default, deserialize_with = "opt_string_or_struct")]
     dockerfile: Option<CrossTargetDockerfileConfig>,
     #[serde(default, deserialize_with = "opt_string_or_string_vec")]

src/docker/image.rs

@@ -155,6 +155,12 @@ impl Serialize for ImagePlatform {
     }
 }
 
+impl std::fmt::Display for ImagePlatform {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.serialize(f)
+    }
+}
+
 impl std::str::FromStr for ImagePlatform {
     type Err = eyre::Report;
     // [os/arch[/variant]=]toolchain

src/lib.rs

@@ -279,13 +279,13 @@ impl Target {
         triple: TargetTriple::DEFAULT,
     };
 
-    fn new_built_in(triple: &str) -> Self {
+    pub fn new_built_in(triple: &str) -> Self {
         Target::BuiltIn {
             triple: triple.into(),
         }
     }
 
-    fn new_custom(triple: &str) -> Self {
+    pub fn new_custom(triple: &str) -> Self {
         Target::Custom {
             triple: triple.into(),
         }
@@ -861,7 +861,7 @@ macro_rules! commit_info {
 ///
 /// The values from `CROSS_CONFIG` or `Cross.toml` are concatenated with the package
 /// metadata in `Cargo.toml`, with `Cross.toml` having the highest priority.
-fn toml(metadata: &CargoMetadata, msg_info: &mut MessageInfo) -> Result<Option<CrossToml>> {
+pub fn toml(metadata: &CargoMetadata, msg_info: &mut MessageInfo) -> Result<Option<CrossToml>> {
     let root = &metadata.workspace_root;
     let cross_config_path = match env::var("CROSS_CONFIG") {
         Ok(var) => PathBuf::from(var),