Better error message when package version not exists (#4429)

crates/typst-cli/src/package.rs

@@ -5,6 +5,7 @@ use std::path::{Path, PathBuf};
 use crate::args::PackageStorageArgs;
 use codespan_reporting::term::{self, termcolor};
 use ecow::eco_format;
+use once_cell::sync::OnceCell;
 use termcolor::WriteColor;
 use typst::diag::{bail, PackageError, PackageResult, StrResult};
 use typst::syntax::package::{
@@ -21,6 +22,7 @@ const DEFAULT_PACKAGES_SUBDIR: &str = "typst/packages";
 pub struct PackageStorage {
     pub package_cache_path: Option<PathBuf>,
     pub package_path: Option<PathBuf>,
+    index: OnceCell<Vec<PackageInfo>>,
 }
 
 impl PackageStorage {
@@ -31,7 +33,11 @@ impl PackageStorage {
         let package_path = args.package_path.clone().or_else(|| {
             dirs::data_dir().map(|data_dir| data_dir.join(DEFAULT_PACKAGES_SUBDIR))
         });
-        Self { package_cache_path, package_path }
+        Self {
+            package_cache_path,
+            package_path,
+            index: OnceCell::new(),
+        }
     }
 
     /// Make a package available in the on-disk cache.
@@ -53,7 +59,7 @@ impl PackageStorage {
 
             // Download from network if it doesn't exist yet.
             if spec.namespace == "preview" {
-                download_package(spec, &dir)?;
+                self.download_package(spec, &dir)?;
                 if dir.exists() {
                     return Ok(dir);
                 }
@@ -71,7 +77,7 @@ impl PackageStorage {
         if spec.namespace == "preview" {
             // For `@preview`, download the package index and find the latest
             // version.
-            download_index()?
+            self.download_index()?
                 .iter()
                 .filter(|package| package.name == spec.name)
                 .map(|package| package.version)
@@ -95,8 +101,13 @@ impl PackageStorage {
     }
 }
 
+impl PackageStorage {
     /// Download a package over the network.
-fn download_package(spec: &PackageSpec, package_dir: &Path) -> PackageResult<()> {
+    fn download_package(
+        &self,
+        spec: &PackageSpec,
+        package_dir: &Path,
+    ) -> PackageResult<()> {
         // The `@preview` namespace is the only namespace that supports on-demand
         // fetching.
         assert_eq!(spec.namespace, "preview");
@@ -108,9 +119,15 @@ fn download_package(spec: &PackageSpec, package_dir: &Path) -> PackageResult<()>
         let data = match download_with_progress(&url) {
             Ok(data) => data,
             Err(ureq::Error::Status(404, _)) => {
-            return Err(PackageError::NotFound(spec.clone()))
+                if let Ok(version) = self.determine_latest_version(&spec.versionless()) {
+                    return Err(PackageError::VersionNotFound(spec.clone(), version));
+                } else {
+                    return Err(PackageError::NotFound(spec.clone()));
+                }
+            }
+            Err(err) => {
+                return Err(PackageError::NetworkFailed(Some(eco_format!("{err}"))))
             }
-        Err(err) => return Err(PackageError::NetworkFailed(Some(eco_format!("{err}")))),
         };
 
         let decompressed = flate2::read::GzDecoder::new(data.as_slice());
@@ -121,7 +138,10 @@ fn download_package(spec: &PackageSpec, package_dir: &Path) -> PackageResult<()>
     }
 
     /// Download the `@preview` package index.
-fn download_index() -> StrResult<Vec<PackageInfo>> {
+    ///
+    /// To avoid downloading the index multiple times, the result is cached.
+    fn download_index(&self) -> StrResult<&Vec<PackageInfo>> {
+        self.index.get_or_try_init(|| {
             let url = format!("{HOST}/preview/index.json");
             match download(&url) {
                 Ok(response) => response
@@ -132,6 +152,8 @@ fn download_index() -> StrResult<Vec<PackageInfo>> {
                 }
                 Err(err) => bail!("failed to fetch package index ({err})"),
             }
+        })
+    }
 }
 
 /// Print that a package downloading is happening.

crates/typst-syntax/src/package.rs

@@ -85,6 +85,15 @@ pub struct PackageSpec {
     pub version: PackageVersion,
 }
 
+impl PackageSpec {
+    pub fn versionless(&self) -> VersionlessPackageSpec {
+        VersionlessPackageSpec {
+            namespace: self.namespace.clone(),
+            name: self.name.clone(),
+        }
+    }
+}
+
 impl FromStr for PackageSpec {
     type Err = EcoString;
 

crates/typst/src/diag.rs

@@ -9,7 +9,7 @@ use std::string::FromUtf8Error;
 use comemo::Tracked;
 use ecow::{eco_vec, EcoVec};
 
-use crate::syntax::package::PackageSpec;
+use crate::syntax::package::{PackageSpec, PackageVersion};
 use crate::syntax::{Span, Spanned, SyntaxError};
 use crate::{World, WorldExt};
 
@@ -503,6 +503,8 @@ pub type PackageResult<T> = Result<T, PackageError>;
 pub enum PackageError {
     /// The specified package does not exist.
     NotFound(PackageSpec),
+    /// The specified package found, but the version does not exist.
+    VersionNotFound(PackageSpec, PackageVersion),
     /// Failed to retrieve the package through the network.
     NetworkFailed(Option<EcoString>),
     /// The package archive was malformed.
@@ -519,6 +521,13 @@ impl Display for PackageError {
             Self::NotFound(spec) => {
                 write!(f, "package not found (searched for {spec})",)
             }
+            Self::VersionNotFound(spec, latest) => {
+                write!(
+                    f,
+                    "package found, but version {} does not exist (latest is {})",
+                    spec.version, latest,
+                )
+            }
             Self::NetworkFailed(Some(err)) => {
                 write!(f, "failed to download package ({err})")
             }