Make the package field optional

in wasmer.toml, the package field will now be optional. This is to add support
for unnamed packages.

Unnamed packages are useful when you don't want to publish and maintain a
package just for an app. In that case, you can simply associate the package with
a webc hash, instead associating it with a package name/version etc.

src/lib.rs

@@ -698,7 +698,7 @@ pub enum ImportsError {
 #[non_exhaustive]
 pub struct Manifest {
     /// Metadata about the package itself.
-    pub package: Package,
+    pub package: Option<Package>,
     /// The package's dependencies.
     #[serde(default, skip_serializing_if = "HashMap::is_empty")]
     #[builder(default)]
@@ -742,12 +742,15 @@ impl Manifest {
             .map_err(|_e| ManifestError::MissingManifest(manifest_path_buf))?;
         let mut manifest: Self = toml::from_str(contents.as_str())?;
 
-        if manifest.package.readme.is_none() {
-            manifest.package.readme = locate_file(path, README_PATHS);
-        }
+        if let Some(mut package) = manifest.package.clone() {
+            if package.readme.is_none() {
+                package.readme = locate_file(path, README_PATHS);
+            }
 
-        if manifest.package.license_file.is_none() {
-            manifest.package.license_file = locate_file(path, LICENSE_PATHS);
+            if package.license_file.is_none() {
+                package.license_file = locate_file(path, LICENSE_PATHS);
+            }
+            manifest.package = Some(package);
         }
         manifest.validate()?;
 
@@ -818,12 +821,14 @@ impl Manifest {
             }
         }
 
-        if let Some(entrypoint) = self.package.entrypoint.as_deref() {
-            if !commands.contains_key(entrypoint) {
-                return Err(ValidationError::InvalidEntrypoint {
-                    entrypoint: entrypoint.to_string(),
-                    available_commands: commands.keys().map(ToString::to_string).collect(),
-                });
+        if let Some(package) = &self.package {
+            if let Some(entrypoint) = package.entrypoint.as_deref() {
+                if !commands.contains_key(entrypoint) {
+                    return Err(ValidationError::InvalidEntrypoint {
+                        entrypoint: entrypoint.to_string(),
+                        available_commands: commands.keys().map(ToString::to_string).collect(),
+                    });
+                }
             }
         }
 
@@ -868,7 +873,7 @@ fn locate_file(path: &Path, candidates: &[&str]) -> Option<PathBuf> {
 impl ManifestBuilder {
     pub fn new(package: Package) -> Self {
         let mut builder = ManifestBuilder::default();
-        builder.package(package);
+        builder.package(Some(package));
         builder
     }
 
@@ -958,7 +963,7 @@ mod tests {
     #[test]
     fn test_to_string() {
         Manifest {
-            package: Package {
+            package: Some(Package {
                 name: "package/name".to_string(),
                 version: Version::parse("1.0.0").unwrap(),
                 description: "test".to_string(),
@@ -972,7 +977,7 @@ mod tests {
                 rename_commands_to_raw_command_name: false,
                 entrypoint: None,
                 private: false,
-            },
+            }),
             dependencies: HashMap::new(),
             modules: vec![Module {
                 name: "test".to_string(),
@@ -1198,7 +1203,21 @@ annotations = { file = "Runefile.yml", kind = "yaml" }
             description = "The best package."
         };
         let manifest: Manifest = wasmer_toml.try_into().unwrap();
-        assert!(!manifest.package.disable_command_rename);
+        if let Some(package) = manifest.package {
+            assert!(!package.disable_command_rename);
+        }
+    }
+
+    #[test]
+    fn parse_manifest_without_package_section() {
+        let wasmer_toml = toml! {
+            [[module]]
+            name = "test-module"
+            source = "data.wasm"
+            abi = "wasi"
+        };
+        let manifest: Manifest = wasmer_toml.try_into().unwrap();
+        assert!(manifest.package.is_none());
     }
 
     #[test]