Add the ability to determine and track the config version.

cargo-dist/src/config/mod.rs

@@ -18,6 +18,9 @@ use crate::{
     METADATA_DIST,
 };
 
+mod version;
+pub use version::get_version;
+
 pub mod v0;
 pub mod v0_to_v1;
 pub mod v1;

cargo-dist/src/config/v0_to_v1.rs

@@ -354,6 +354,8 @@ impl DistMetadata {
 
         TomlLayer {
             dist_version: cargo_dist_version,
+            // v0_to_v1 means we're using a v0 config, so just set that.
+            config_version: 0,
             dist_url_override: cargo_dist_url_override,
             dist,
             allow_dirty,

cargo-dist/src/config/v1/mod.rs

@@ -250,6 +250,7 @@ impl ApplyLayer for WorkspaceConfigInheritable {
             allow_dirty,
             dist_version,
             dist_url_override,
+            config_version: _,
             // app-scope only
             dist: _,
             targets: _,
@@ -361,6 +362,7 @@ impl ApplyLayer for AppConfigInheritable {
             allow_dirty: _,
             dist_version: _,
             dist_url_override: _,
+            config_version: _,
         }: Self::Layer,
     ) {
         self.artifacts.apply_val_layer(artifacts);
@@ -388,6 +390,10 @@ pub struct TomlLayer {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub dist_version: Option<Version>,
 
+    /// The configuration file version.
+    #[serde(default = "crate::config::version::default")]
+    pub config_version: i64,
+
     /// see [`CargoDistUrlOverride`]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub dist_url_override: Option<CargoDistUrlOverride>,

cargo-dist/src/config/version.rs

@@ -0,0 +1,68 @@
+//! For determining which configuration version we're using.
+
+use axoasset::SourceFile;
+use camino::Utf8PathBuf;
+use serde::Deserialize;
+
+use crate::{DistError, DistResult};
+
+const MAX_VERSION: i64 = 1;
+
+// Extremely minimal struct designed to differentiate between config versions.
+// V0 does not have the `config-version` field, so will fail to parse.
+// V1+ should have it, so will parse, and contain a `config_version` field.
+#[derive(Deserialize)]
+#[serde(rename_all = "kebab-case")]
+struct FauxDistTable {
+    #[allow(dead_code)]
+    config_version: i64,
+}
+
+#[derive(Deserialize)]
+struct FauxConfig {
+    #[allow(dead_code)]
+    dist: FauxDistTable,
+}
+
+/// Return the default versioni.
+pub fn default() -> i64 {
+    1
+}
+
+/// Return the config version used for the root workspace.
+pub fn get_version() -> DistResult<i64> {
+    let workspaces = super::get_project()?;
+    let root_workspace = workspaces.root_workspace();
+
+    get_version_for_manifest(root_workspace.manifest_path.to_owned())
+}
+
+
+/// Given a path to a dist manifest (e.g. `dist-workspace.toml`), returns
+/// the config version being used.
+pub fn get_version_for_manifest(dist_manifest_path: Utf8PathBuf) -> DistResult<i64> {
+    if dist_manifest_path.file_name() != Some("dist-workspace.toml") {
+        // If the manifest is in Cargo.toml or dist.toml, we're
+        // definitely using a v0 config.
+        return Ok(0);
+    }
+
+    let src = SourceFile::load_local(&dist_manifest_path)?;
+
+    let Ok(config) = src.deserialize_toml::<FauxConfig>() else {
+        // If we could load it, but can't parse it, it's likely v0.
+        return Ok(0);
+    };
+
+    let version = config.dist.config_version;
+
+    if version <= MAX_VERSION {
+        Ok(version)
+    } else {
+        Err(DistError::InvalidConfigVersion {
+            manifest_path: dist_manifest_path.into(),
+            config_version: version,
+            max_version: MAX_VERSION,
+        })
+    }
+}

cargo-dist/src/errors.rs

@@ -626,6 +626,18 @@ pub enum DistError {
         /// Version the project uses
         your_version: semver::Version,
     },
+
+    /// Project uses a version that doesn't exist yet.
+    #[error("{{manifest_path}} has dist.config-version set to invalid value: {{config_version}}")]
+    #[diagnostic(help("Valid options are 0 through {{max_version}}"))]
+    InvalidConfigVersion {
+        /// The path to the manifest file.
+        manifest_path: String,
+        /// The version specified in the manifest file.
+        config_version: i64,
+        /// The maximum valid version.
+        max_version: i64,
+    },
 }
 
 impl From<minijinja::Error> for DistError {

cargo-dist/src/init.rs

@@ -4,6 +4,7 @@ use camino::Utf8PathBuf;
 use dist_schema::TripleNameRef;
 use semver::Version;
 use serde::Deserialize;
+use tracing::debug;
 
 use crate::{
     config::{
@@ -203,6 +204,7 @@ fn do_migrate_from_dist_toml() -> DistResult<()> {
 pub fn do_migrate() -> DistResult<()> {
     do_migrate_from_rust_workspace()?;
     do_migrate_from_dist_toml()?;
+    debug!("dist.config-version = {}", config::get_version()?);
     //do_migrate_from_v0()?;
     Ok(())
 }