Autogenerate possible values for enums in reference documentation (#5137)

## Summary

For example:

![Screenshot 2024-07-16 at 7 44
10 PM](https://github.com/user-attachments/assets/73ce16ba-eb0e-43c4-a741-65a54637452f)

Closes https://github.com/astral-sh/uv/issues/5129.

Cargo.lock

@@ -5070,6 +5070,7 @@ dependencies = [
 name = "uv-settings"
 version = "0.0.1"
 dependencies = [
+ "clap",
  "dirs-sys",
  "distribution-types",
  "fs-err",

crates/uv-dev/src/generate_options_reference.rs

@@ -216,7 +216,18 @@ fn emit_field(output: &mut String, name: &str, field: &OptionField, parents: &[S
     output.push_str("\n\n");
     output.push_str(&format!("**Default value**: `{}`\n", field.default));
     output.push('\n');
-    output.push_str(&format!("**Type**: `{}`\n", field.value_type));
+    if let Some(possible_values) = field
+        .possible_values
+        .as_ref()
+        .filter(|values| !values.is_empty())
+    {
+        output.push_str("**Possible values**:\n\n");
+        for value in possible_values {
+            output.push_str(format!("- {value}\n").as_str());
+        }
+    } else {
+        output.push_str(&format!("**Type**: `{}`\n", field.value_type));
+    }
     output.push('\n');
     output.push_str("**Example usage**:\n\n");
     output.push_str(&format_tab(

crates/uv-macros/src/options_metadata.rs

@@ -8,7 +8,7 @@ use syn::meta::ParseNestedMeta;
 use syn::spanned::Spanned;
 use syn::{
     AngleBracketedGenericArguments, Attribute, Data, DataStruct, DeriveInput, ExprLit, Field,
-    Fields, Lit, LitStr, Meta, Path, PathArguments, PathSegment, Type, TypePath,
+    Fields, GenericArgument, Lit, LitStr, Meta, Path, PathArguments, PathSegment, Type, TypePath,
 };
 use textwrap::dedent;
 
@@ -194,6 +194,7 @@ fn handle_option(field: &Field, attr: &Attribute) -> syn::Result<proc_macro2::To
         value_type,
         example,
         scope,
+        possible_values,
     } = parse_field_attributes(attr)?;
     let kebab_name = LitStr::new(&ident.to_string().replace('_', "-"), ident.span());
 
@@ -224,6 +225,25 @@ fn handle_option(field: &Field, attr: &Attribute) -> syn::Result<proc_macro2::To
         quote!(None)
     };
 
+    let possible_values = if possible_values == Some(true) {
+        let inner_type = get_inner_type_if_option(&field.ty).unwrap_or(&field.ty);
+        let inner_type = quote!(#inner_type);
+        quote!(
+            Some(
+                <#inner_type as clap::ValueEnum>::value_variants()
+                    .iter()
+                    .filter_map(clap::ValueEnum::to_possible_value)
+                    .map(|value| uv_options_metadata::PossibleValue {
+                        name: value.get_name().to_string(),
+                        help: value.get_help().map(ToString::to_string),
+                    })
+                    .collect()
+            )
+        )
+    } else {
+        quote!(None)
+    };
+
     Ok(quote_spanned!(
         ident.span() => {
             visit.record_field(#kebab_name, uv_options_metadata::OptionField{
@@ -232,7 +252,8 @@ fn handle_option(field: &Field, attr: &Attribute) -> syn::Result<proc_macro2::To
                 value_type: &#value_type,
                 example: &#example,
                 scope: #scope,
-                deprecated: #deprecated
+                deprecated: #deprecated,
+                possible_values: #possible_values,
             })
         }
     ))
@@ -244,6 +265,7 @@ struct FieldAttributes {
     value_type: String,
     example: String,
     scope: Option<String>,
+    possible_values: Option<bool>,
 }
 
 fn parse_field_attributes(attribute: &Attribute) -> syn::Result<FieldAttributes> {
@@ -251,6 +273,7 @@ fn parse_field_attributes(attribute: &Attribute) -> syn::Result<FieldAttributes>
     let mut value_type = None;
     let mut example = None;
     let mut scope = None;
+    let mut possible_values = None;
 
     attribute.parse_nested_meta(|meta| {
         if meta.path.is_ident("default") {
@@ -262,6 +285,8 @@ fn parse_field_attributes(attribute: &Attribute) -> syn::Result<FieldAttributes>
         } else if meta.path.is_ident("example") {
             let example_text = get_string_literal(&meta, "value_type", "option")?.value();
             example = Some(dedent(&example_text).trim_matches('\n').to_string());
+        } else if meta.path.is_ident("possible_values") {
+            possible_values = get_bool_literal(&meta, "possible_values", "option")?;
         } else {
             return Err(syn::Error::new(
                 meta.path.span(),
@@ -292,6 +317,7 @@ fn parse_field_attributes(attribute: &Attribute) -> syn::Result<FieldAttributes>
         value_type,
         example,
         scope,
+        possible_values,
     })
 }
 
@@ -318,6 +344,23 @@ fn parse_deprecated_attribute(attribute: &Attribute) -> syn::Result<DeprecatedAt
     Ok(deprecated)
 }
 
+fn get_inner_type_if_option(ty: &Type) -> Option<&Type> {
+    if let Type::Path(type_path) = ty {
+        if type_path.path.segments.len() == 1 && type_path.path.segments[0].ident == "Option" {
+            if let PathArguments::AngleBracketed(angle_bracketed_args) =
+                &type_path.path.segments[0].arguments
+            {
+                if angle_bracketed_args.args.len() == 1 {
+                    if let GenericArgument::Type(inner_type) = &angle_bracketed_args.args[0] {
+                        return Some(inner_type);
+                    }
+                }
+            }
+        }
+    }
+    None
+}
+
 fn get_string_literal(
     meta: &ParseNestedMeta,
     meta_name: &str,
@@ -351,6 +394,32 @@ fn get_string_literal(
     }
 }
 
+fn get_bool_literal(
+    meta: &ParseNestedMeta,
+    meta_name: &str,
+    attribute_name: &str,
+) -> syn::Result<Option<bool>> {
+    let expr: syn::Expr = meta.value()?.parse()?;
+
+    let mut value = &expr;
+    while let syn::Expr::Group(e) = value {
+        value = &e.expr;
+    }
+
+    if let syn::Expr::Lit(ExprLit {
+        lit: Lit::Bool(lit),
+        ..
+    }) = value
+    {
+        Ok(Some(lit.value))
+    } else {
+        Err(syn::Error::new(
+            expr.span(),
+            format!("expected {attribute_name} attribute to be a boolean: `{meta_name} = true`"),
+        ))
+    }
+}
+
 #[derive(Default, Debug)]
 struct DeprecatedAttribute {
     since: Option<String>,

crates/uv-options-metadata/src/lib.rs

@@ -119,6 +119,7 @@ impl OptionSet {
     ///             example: "",
     ///             scope: None,
     ///             deprecated: None,
+    ///             possible_values: None
     ///         });
     ///     }
     /// }
@@ -141,7 +142,8 @@ impl OptionSet {
     ///             value_type: "bool",
     ///             example: "",
     ///             scope: None,
-    ///             deprecated: None
+    ///             deprecated: None,
+    ///             possible_values: None
     ///         });
     ///
     ///         visit.record_set("format", Nested::metadata());
@@ -158,7 +160,8 @@ impl OptionSet {
     ///             value_type: "bool",
     ///             example: "",
     ///             scope: None,
-    ///             deprecated: None
+    ///             deprecated: None,
+    ///             possible_values: None
     ///         });
     ///     }
     /// }
@@ -190,7 +193,8 @@ impl OptionSet {
     ///     value_type: "bool",
     ///     example: "",
     ///     scope: None,
-    ///     deprecated: None
+    ///     deprecated: None,
+    ///     possible_values: None
     ///  };
     ///
     /// impl OptionsMetadata for WithOptions {
@@ -213,7 +217,8 @@ impl OptionSet {
     ///     value_type: "bool",
     ///     example: "",
     ///     scope: None,
-    ///     deprecated: None
+    ///     deprecated: None,
+    ///     possible_values: None
     /// };
     ///
     /// struct Root;
@@ -226,7 +231,8 @@ impl OptionSet {
     ///             value_type: "bool",
     ///             example: "",
     ///             scope: None,
-    ///             deprecated: None
+    ///             deprecated: None,
+    ///             possible_values: None
     ///         });
     ///
     ///         visit.record_set("format", Nested::metadata());
@@ -388,6 +394,7 @@ pub struct OptionField {
     pub scope: Option<&'static str>,
     pub example: &'static str,
     pub deprecated: Option<Deprecated>,
+    pub possible_values: Option<Vec<PossibleValue>>,
 }
 
 #[derive(Debug, Clone, Eq, PartialEq, Serialize)]
@@ -400,8 +407,22 @@ impl Display for OptionField {
     fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
         writeln!(f, "{}", self.doc)?;
         writeln!(f)?;
+
         writeln!(f, "Default value: {}", self.default)?;
-        writeln!(f, "Type: {}", self.value_type)?;
+
+        if let Some(possible_values) = self
+            .possible_values
+            .as_ref()
+            .filter(|values| !values.is_empty())
+        {
+            writeln!(f, "Possible values:")?;
+            writeln!(f)?;
+            for value in possible_values {
+                writeln!(f, "- {value}")?;
+            }
+        } else {
+            writeln!(f, "Type: {}", self.value_type)?;
+        }
 
         if let Some(deprecated) = &self.deprecated {
             write!(f, "Deprecated")?;
@@ -420,3 +441,21 @@ impl Display for OptionField {
         writeln!(f, "Example usage:\n```toml\n{}\n```", self.example)
     }
 }
+
+/// A possible value for an enum, similar to Clap's `PossibleValue` type (but without a dependency
+/// on Clap).
+#[derive(Debug, Eq, PartialEq, Clone, Serialize)]
+pub struct PossibleValue {
+    pub name: String,
+    pub help: Option<String>,
+}
+
+impl Display for PossibleValue {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "`\"{}\"`", self.name)?;
+        if let Some(help) = &self.help {
+            write!(f, ": {help}")?;
+        }
+        Ok(())
+    }
+}

crates/uv-settings/Cargo.toml

@@ -14,18 +14,19 @@ workspace = true
 
 [dependencies]
 distribution-types = { workspace = true, features = ["schemars"] }
-install-wheel-rs = { workspace = true, features = ["schemars"] }
+install-wheel-rs = { workspace = true, features = ["schemars", "clap"] }
 pep508_rs = { workspace = true }
 pypi-types = { workspace = true }
-uv-configuration = { workspace = true, features = ["schemars"] }
+uv-configuration = { workspace = true, features = ["schemars", "clap"] }
 uv-fs = { workspace = true }
 uv-macros = { workspace = true }
 uv-normalize = { workspace = true, features = ["schemars"] }
 uv-options-metadata = { workspace = true }
-uv-python = { workspace = true, features = ["schemars"] }
+uv-python = { workspace = true, features = ["schemars", "clap"] }
-uv-resolver = { workspace = true, features = ["schemars"] }
+uv-resolver = { workspace = true, features = ["schemars", "clap"] }
 uv-warnings = { workspace = true }
 
+clap = { workspace = true }
 dirs-sys = { workspace = true }
 fs-err = { workspace = true }
 schemars = { workspace = true, optional = true }
@@ -35,4 +36,4 @@ toml = { workspace = true }
 tracing = { workspace = true }
 
 [package.metadata.cargo-shear]
-ignored = ["uv-options-metadata"]
+ignored = ["uv-options-metadata", "clap"]

crates/uv-settings/src/settings.rs

@@ -120,7 +120,8 @@ pub struct GlobalOptions {
         value_type = "str",
         example = r#"
             python-preference = "managed"
-        "#
+        "#,
+        possible_values = true
     )]
     pub python_preference: Option<PythonPreference>,
     /// Whether to automatically download Python when required.
@@ -129,7 +130,8 @@ pub struct GlobalOptions {
         value_type = "str",
         example = r#"
             python-fetch = \"automatic\"
-        "#
+        "#,
+        possible_values = true
     )]
     pub python_fetch: Option<PythonFetch>,
 }
@@ -255,18 +257,13 @@ pub struct ResolverInstallerOptions {
     /// limit resolutions to those present on that first index (`first-match`). This prevents
     /// "dependency confusion" attacks, whereby an attack can upload a malicious package under the
     /// same name to a secondary.
-    ///
-    /// Possible values:
-    ///
-    /// - `"first-index"`:        Only use results from the first index that returns a match for a given package name.
-    /// - `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next.
-    /// - `"unsafe-best-match"`:  Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index.
     #[option(
         default = "\"first-index\"",
         value_type = "str",
         example = r#"
             index-strategy = "unsafe-best-match"
-        "#
+        "#,
+        possible_values = true
     )]
     pub index_strategy: Option<IndexStrategy>,
     /// Attempt to use `keyring` for authentication for index URLs.
@@ -290,7 +287,8 @@ pub struct ResolverInstallerOptions {
         value_type = "str",
         example = r#"
             resolution = "lowest-direct"
-        "#
+        "#,
+        possible_values = true
     )]
     pub resolution: Option<ResolutionMode>,
     /// The strategy to use when considering pre-release versions.
@@ -303,7 +301,8 @@ pub struct ResolverInstallerOptions {
         value_type = "str",
         example = r#"
             prerelease = "allow"
-        "#
+        "#,
+        possible_values = true
     )]
     pub prerelease: Option<PreReleaseMode>,
     /// Settings to pass to the PEP 517 build backend, specified as `KEY=VALUE` pairs.
@@ -336,7 +335,8 @@ pub struct ResolverInstallerOptions {
         value_type = "str",
         example = r#"
             link-mode = "copy"
-        "#
+        "#,
+        possible_values = true
     )]
     pub link_mode: Option<LinkMode>,
     /// Compile Python files to bytecode after installation.
@@ -590,18 +590,13 @@ pub struct PipOptions {
     /// limit resolutions to those present on that first index (`first-match`). This prevents
     /// "dependency confusion" attacks, whereby an attack can upload a malicious package under the
     /// same name to a secondary.
-    ///
-    /// Possible values:
-    ///
-    /// - `"first-index"`:        Only use results from the first index that returns a match for a given package name.
-    /// - `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next.
-    /// - `"unsafe-best-match"`:  Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index.
     #[option(
         default = "\"first-index\"",
         value_type = "str",
         example = r#"
             index-strategy = "unsafe-best-match"
-        "#
+        "#,
+        possible_values = true
     )]
     pub index_strategy: Option<IndexStrategy>,
     /// Attempt to use `keyring` for authentication for index URLs.
@@ -734,7 +729,8 @@ pub struct PipOptions {
         value_type = "str",
         example = r#"
             resolution = "lowest-direct"
-        "#
+        "#,
+        possible_values = true
     )]
     pub resolution: Option<ResolutionMode>,
     /// The strategy to use when considering pre-release versions.
@@ -747,7 +743,8 @@ pub struct PipOptions {
         value_type = "str",
         example = r#"
             prerelease = "allow"
-        "#
+        "#,
+        possible_values = true
     )]
     pub prerelease: Option<PreReleaseMode>,
     /// Write the requirements generated by `uv pip compile` to the given `requirements.txt` file.
@@ -966,7 +963,8 @@ pub struct PipOptions {
         value_type = "str",
         example = r#"
             annotation-style = "line"
-        "#
+        "#,
+        possible_values = true
     )]
     pub annotation_style: Option<AnnotationStyle>,
     /// The method to use when installing packages from the global cache.
@@ -978,7 +976,8 @@ pub struct PipOptions {
         value_type = "str",
         example = r#"
             link-mode = "copy"
-        "#
+        "#,
+        possible_values = true
     )]
     pub link_mode: Option<LinkMode>,
     /// Compile Python files to bytecode after installation.

docs/settings.md

@@ -189,15 +189,13 @@ limit resolutions to those present on that first index (`first-match`). This pre
 "dependency confusion" attacks, whereby an attack can upload a malicious package under the
 same name to a secondary.
 
-Possible values:
-
-- `"first-index"`:        Only use results from the first index that returns a match for a given package name.
-- `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next.
-- `"unsafe-best-match"`:  Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index.
-
 **Default value**: `"first-index"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"first-index"`: Only use results from the first index that returns a match for a given package name
+- `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next
+- `"unsafe-best-match"`: Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index
 
 **Example usage**:
 
@@ -284,7 +282,11 @@ Windows.
 
 **Default value**: `"clone" (macOS) or "hardlink" (Linux, Windows)`
 
-**Type**: `str`
+**Possible values**:
+
+- `"clone"`: Clone (i.e., copy-on-write) packages from the wheel into the site packages
+- `"copy"`: Copy packages from the wheel into the site packages
+- `"hardlink"`: Hard link packages from the wheel into the site packages
 
 **Example usage**:
 
@@ -556,7 +558,13 @@ declared specifiers (`if-necessary-or-explicit`).
 
 **Default value**: `"if-necessary-or-explicit"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"disallow"`: Disallow all pre-release versions
+- `"allow"`: Allow all pre-release versions
+- `"if-necessary"`: Allow pre-release versions if all versions of a package are pre-release
+- `"explicit"`: Allow pre-release versions for first-party packages with explicit pre-release markers in their version requirements
+- `"if-necessary-or-explicit"`: Allow pre-release versions if all versions of a package are pre-release, or if the package has an explicit pre-release marker in its version requirements
 
 **Example usage**:
 
@@ -606,7 +614,10 @@ Whether to automatically download Python when required.
 
 **Default value**: `"automatic"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"automatic"`: Automatically fetch managed Python installations when needed
+- `"manual"`: Do not automatically fetch managed Python installations; require explicit installation
 
 **Example usage**:
 
@@ -632,7 +643,13 @@ those that are downloaded and installed by uv.
 
 **Default value**: `"installed"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"only-managed"`: Only use managed Python installations; never use system Python installations
+- `"installed"`: Prefer installed Python installations, only download managed Python installations if no system Python installation is found
+- `"managed"`: Prefer managed Python installations over system Python installations, even if fetching is required
+- `"system"`: Prefer system Python installations over managed Python installations
+- `"only-system"`: Only use system Python installations; never use managed Python installations
 
 **Example usage**:
 
@@ -710,7 +727,11 @@ By default, uv will use the latest compatible version of each package (`highest`
 
 **Default value**: `"highest"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"highest"`: Resolve the highest compatible version of each package
+- `"lowest"`: Resolve the lowest compatible version of each package
+- `"lowest-direct"`: Resolve the lowest compatible version of any direct dependencies, and the highest compatible version of any transitive dependencies
 
 **Example usage**:
 
@@ -852,7 +873,10 @@ source of each package.
 
 **Default value**: `"split"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"line"`: Render the annotations on a single, comma-separated line
+- `"split"`: Render each annotation on its own line
 
 **Example usage**:
 
@@ -1372,15 +1396,13 @@ limit resolutions to those present on that first index (`first-match`). This pre
 "dependency confusion" attacks, whereby an attack can upload a malicious package under the
 same name to a secondary.
 
-Possible values:
-
-- `"first-index"`:        Only use results from the first index that returns a match for a given package name.
-- `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next.
-- `"unsafe-best-match"`:  Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index.
-
 **Default value**: `"first-index"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"first-index"`: Only use results from the first index that returns a match for a given package name
+- `"unsafe-first-match"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next
+- `"unsafe-best-match"`: Search for every package name across all indexes, preferring the "best" version found. If a package version is in multiple indexes, only look at the entry for the first index
 
 **Example usage**:
 
@@ -1497,7 +1519,11 @@ Windows.
 
 **Default value**: `"clone" (macOS) or "hardlink" (Linux, Windows)`
 
-**Type**: `str`
+**Possible values**:
+
+- `"clone"`: Clone (i.e., copy-on-write) packages from the wheel into the site packages
+- `"copy"`: Copy packages from the wheel into the site packages
+- `"hardlink"`: Hard link packages from the wheel into the site packages
 
 **Example usage**:
 
@@ -1906,7 +1932,13 @@ declared specifiers (`if-necessary-or-explicit`).
 
 **Default value**: `"if-necessary-or-explicit"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"disallow"`: Disallow all pre-release versions
+- `"allow"`: Allow all pre-release versions
+- `"if-necessary"`: Allow pre-release versions if all versions of a package are pre-release
+- `"explicit"`: Allow pre-release versions for first-party packages with explicit pre-release markers in their version requirements
+- `"if-necessary-or-explicit"`: Allow pre-release versions if all versions of a package are pre-release, or if the package has an explicit pre-release marker in its version requirements
 
 **Example usage**:
 
@@ -2121,7 +2153,11 @@ By default, uv will use the latest compatible version of each package (`highest`
 
 **Default value**: `"highest"`
 
-**Type**: `str`
+**Possible values**:
+
+- `"highest"`: Resolve the highest compatible version of each package
+- `"lowest"`: Resolve the lowest compatible version of each package
+- `"lowest-direct"`: Resolve the lowest compatible version of any direct dependencies, and the highest compatible version of any transitive dependencies
 
 **Example usage**:
 

uv.schema.json

@@ -71,7 +71,7 @@
       }
     },
     "index-strategy": {
-      "description": "The strategy to use when resolving against multiple index URLs.\n\nBy default, uv will stop at the first index on which a given package is available, and limit resolutions to those present on that first index (`first-match`). This prevents \"dependency confusion\" attacks, whereby an attack can upload a malicious package under the same name to a secondary.\n\nPossible values:\n\n- `\"first-index\"`:        Only use results from the first index that returns a match for a given package name. - `\"unsafe-first-match\"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next. - `\"unsafe-best-match\"`:  Search for every package name across all indexes, preferring the \"best\" version found. If a package version is in multiple indexes, only look at the entry for the first index.",
+      "description": "The strategy to use when resolving against multiple index URLs.\n\nBy default, uv will stop at the first index on which a given package is available, and limit resolutions to those present on that first index (`first-match`). This prevents \"dependency confusion\" attacks, whereby an attack can upload a malicious package under the same name to a secondary.",
       "anyOf": [
         {
           "$ref": "#/definitions/IndexStrategy"
@@ -638,7 +638,7 @@
           ]
         },
         "index-strategy": {
-          "description": "The strategy to use when resolving against multiple index URLs.\n\nBy default, uv will stop at the first index on which a given package is available, and limit resolutions to those present on that first index (`first-match`). This prevents \"dependency confusion\" attacks, whereby an attack can upload a malicious package under the same name to a secondary.\n\nPossible values:\n\n- `\"first-index\"`:        Only use results from the first index that returns a match for a given package name. - `\"unsafe-first-match\"`: Search for every package name across all indexes, exhausting the versions from the first index before moving on to the next. - `\"unsafe-best-match\"`:  Search for every package name across all indexes, preferring the \"best\" version found. If a package version is in multiple indexes, only look at the entry for the first index.",
+          "description": "The strategy to use when resolving against multiple index URLs.\n\nBy default, uv will stop at the first index on which a given package is available, and limit resolutions to those present on that first index (`first-match`). This prevents \"dependency confusion\" attacks, whereby an attack can upload a malicious package under the same name to a secondary.",
           "anyOf": [
             {
               "$ref": "#/definitions/IndexStrategy"