breaking: Rework Cargo features. (#131)

CHANGELOG.md

@@ -6,10 +6,15 @@
 
 - Refactored the internals of how validation errors work.
 - Removed `Config::META` and `ConfigError::META`. Use `Schematic::schema_name()` instead.
+- Removed `url` as a default Cargo feature.
+- Renamed `valid_*` Cargo features to `validate_*`.
 - Renamed some error enum variants.
 
 #### 🚀 Updates
 
+- Added a `env` Cargo feature for toggling environment variable functionality. Enabled by default.
+- Added a `extends` Cargo feature for config extending functionality. Enabled by default.
+- Added a `validate` Cargo feature for toggling validation functionality. Enabled by default.
 - Reworked how parser and validator errors are rendered in the terminal.
 
 #### ⚙️ Internal

Cargo.toml

@@ -14,6 +14,6 @@ semver = "1.0.23"
 serde = { version = "1.0.204", features = ["derive"] }
 serde_json = "1.0.120"
 serde_yaml = "0.9.34"
-toml = "0.8.15"
+toml = "0.8.16"
 tracing = "0.1.40"
 url = "2.5.2"

book/src/config/struct/env.md

@@ -1,5 +1,7 @@
 # Environment variables
 
+> Requires the `env` Cargo feature, which is enabled by default.
+
 > Not supported for enums.
 
 Settings can also inherit values from environment variables via the `#[setting(env)]` attribute

book/src/config/struct/extend.md

@@ -1,5 +1,7 @@
 # Extendable sources
 
+> Requires the `extends` Cargo feature, which is enabled by default.
+
 > Not supported for enums.
 
 Configs can extend other configs, generating an accurate layer chain, via the `#[setting(extend)]`

book/src/config/struct/validate.md

@@ -1,5 +1,7 @@
 # Validation rules
 
+> Requires the `validate` Cargo feature, which is enabled by default.
+
 What kind of configuration crate would this be without built-in validation? As such, we support it
 as a first-class feature, with built-in validation rules provided by the
 [garde](https://crates.io/crates/garde) crate.
@@ -120,6 +122,6 @@ fn using_generics<P, C>(value: &str, partial: &P, context: &C, finalize: bool) -
 
 The following Cargo features can be enabled for more functionality:
 
-- `valid_email` - Enables email validation with the `schematic::validate::email` function.
-- `valid_url` - Enables URL validation with the `schematic::validate::url` and `url_secure`
+- `validate_email` - Enables email validation with the `schematic::validate::email` function.
+- `validate_url` - Enables URL validation with the `schematic::validate::url` and `url_secure`
   functions.

crates/macros/Cargo.toml

@@ -23,5 +23,8 @@ syn = { version = "2.0.72", features = ["full"] }
 [features]
 default = []
 config = []
+env = []
+extends = []
 schema = []
 tracing = []
+validate = []

crates/macros/src/common/field.rs

@@ -40,12 +40,16 @@ pub struct FieldArgs {
     // config
     #[darling(with = "preserve_str_literal", map = "Some")]
     pub default: Option<Expr>,
+    #[cfg(feature = "env")]
     pub env: Option<String>,
+    #[cfg(feature = "extends")]
     pub extend: bool,
     pub merge: Option<ExprPath>,
     pub nested: bool,
+    #[cfg(feature = "env")]
     pub parse_env: Option<ExprPath>,
     pub required: bool,
+    #[cfg(feature = "validate")]
     pub validate: Option<Expr>,
 
     // serde
@@ -111,6 +115,7 @@ impl<'l> Field<'l> {
         self.args.exclude
     }
 
+    #[cfg(feature = "extends")]
     pub fn is_extendable(&self) -> bool {
         self.args.extend
     }
@@ -157,14 +162,17 @@ impl<'l> Field<'l> {
 
     pub fn get_env_var(&self) -> Option<String> {
         if self.is_nested() {
-            None
-        } else if let Some(env_name) = &self.args.env {
-            Some(env_name.to_owned())
-        } else {
-            self.env_prefix
-                .as_ref()
-                .map(|env_prefix| format!("{env_prefix}{}", self.get_name(None)).to_uppercase())
+            return None;
         }
+
+        #[cfg(feature = "env")]
+        if let Some(env_name) = &self.args.env {
+            return Some(env_name.to_owned());
+        }
+
+        self.env_prefix
+            .as_ref()
+            .map(|env_prefix| format!("{env_prefix}{}", self.get_name(None)).to_uppercase())
     }
 
     pub fn get_serde_meta(&self) -> Option<TokenStream> {

crates/macros/src/common/macros.rs

@@ -33,6 +33,7 @@ pub struct MacroArgs {
     // config
     pub allow_unknown_fields: bool,
     pub context: Option<ExprPath>,
+    #[cfg(feature = "env")]
     pub env_prefix: Option<String>,
     pub file: Option<String>,
 
@@ -79,6 +80,7 @@ impl<'l> Macro<'l> {
                                 let mut field = Field::from(f);
                                 field.serde_args.inherit_from_container(&serde_args);
                                 field.casing_format.clone_from(&casing_format);
+                                #[cfg(feature = "env")]
                                 field.env_prefix.clone_from(&args.env_prefix);
                                 field
                             })
@@ -100,6 +102,7 @@ impl<'l> Macro<'l> {
                                 field.index = index;
                                 field.serde_args.inherit_from_container(&serde_args);
                                 field.casing_format.clone_from(&casing_format);
+                                #[cfg(feature = "env")]
                                 field.env_prefix.clone_from(&args.env_prefix);
                                 field
                             })

crates/macros/src/common/variant.rs

@@ -3,7 +3,7 @@ use crate::utils::{extract_common_attrs, format_case};
 use darling::FromAttributes;
 use proc_macro2::{Ident, TokenStream};
 use quote::{quote, ToTokens};
-use syn::{Attribute, Expr, ExprPath, Fields, Variant as NativeVariant};
+use syn::{Attribute, ExprPath, Fields, Variant as NativeVariant};
 
 #[derive(Clone)]
 pub enum TaggedFormat {
@@ -27,7 +27,8 @@ pub struct VariantArgs {
     pub merge: Option<ExprPath>,
     pub nested: bool,
     pub required: bool,
-    pub validate: Option<Expr>,
+    #[cfg(feature = "validate")]
+    pub validate: Option<syn::Expr>,
 
     // serde
     pub rename: Option<String>,

crates/macros/src/config/container.rs

@@ -1,6 +1,6 @@
 use crate::common::Container;
 use proc_macro2::{Ident, TokenStream};
-use quote::{quote, ToTokens};
+use quote::quote;
 
 impl<'l> Container<'l> {
     pub fn generate_default_values(&self) -> TokenStream {
@@ -89,10 +89,13 @@ impl<'l> Container<'l> {
     }
 
     pub fn generate_extends_from(&self) -> TokenStream {
+        #[cfg(feature = "extends")]
         match self {
             Self::NamedStruct {
                 fields: settings, ..
             } => {
+                use quote::ToTokens;
+
                 // Validate only 1 setting is using it
                 let mut names = vec![];
 
@@ -159,6 +162,9 @@ impl<'l> Container<'l> {
                 quote! { None }
             }
         }
+
+        #[cfg(not(feature = "extends"))]
+        quote! { None }
     }
 
     pub fn generate_finalize(&self) -> TokenStream {
@@ -174,6 +180,16 @@ impl<'l> Container<'l> {
                     .map(|s| s.generate_finalize_statement())
                     .collect::<Vec<_>>();
 
+                let env_statement = if cfg!(feature = "env") {
+                    quote! {
+                        if let Some(data) = Self::env_values()? {
+                            partial.merge(context, data)?;
+                        }
+                    }
+                } else {
+                    quote! {}
+                };
+
                 quote! {
                     let mut partial = Self::default();
 
@@ -183,9 +199,7 @@ impl<'l> Container<'l> {
 
                     partial.merge(context, self)?;
 
-                    if let Some(data) = Self::env_values()? {
-                        partial.merge(context, data)?;
-                    }
+                    #env_statement
 
                     #(#finalize_stmts)*
 

crates/macros/src/config/field.rs

@@ -1,7 +1,6 @@
 use crate::common::{Field, FieldValue};
 use proc_macro2::{Literal, TokenStream};
 use quote::{quote, ToTokens, TokenStreamExt};
-use syn::Expr;
 
 impl<'l> Field<'l> {
     pub fn generate_default_value(&self) -> TokenStream {
@@ -20,26 +19,35 @@ impl<'l> Field<'l> {
         let env = self.get_env_var();
 
         if env.is_none() {
+            #[cfg(feature = "env")]
             if self.args.parse_env.is_some() {
                 panic!("Cannot use `parse_env` without `env` or a parent `env_prefix`.");
             }
 
             return None;
         };
 
-        let value = if let Some(parse_env) = &self.args.parse_env {
-            quote! {
-                parse_from_env_var(#env, #parse_env)?
-            }
-        } else {
-            quote! {
-                default_from_env_var(#env)?
-            }
-        };
+        #[cfg(feature = "env")]
+        {
+            let value = if let Some(parse_env) = &self.args.parse_env {
+                quote! {
+                    parse_from_env_var(#env, #parse_env)?
+                }
+            } else {
+                quote! {
+                    default_from_env_var(#env)?
+                }
+            };
 
-        let key = self.get_field_key();
+            let key = self.get_field_key();
 
-        Some(quote! { partial.#key = #value; })
+            Some(quote! { partial.#key = #value; })
+        }
+
+        #[cfg(not(feature = "env"))]
+        {
+            None
+        }
     }
 
     pub fn generate_finalize_statement(&self) -> TokenStream {
@@ -62,6 +70,7 @@ impl<'l> Field<'l> {
         #[allow(clippy::collapsible_else_if)]
         if matches!(self.value_type, FieldValue::Value { .. }) {
             // Reset extendable values since we don't have the entire resolved list
+            #[cfg(feature = "extends")]
             if self.args.extend {
                 return quote! { Default::default() };
             }
@@ -119,7 +128,10 @@ impl<'l> Field<'l> {
         let key_quoted = self.get_field_key_string();
         let mut stmts = vec![];
 
+        #[cfg(feature = "validate")]
         if let Some(expr) = self.args.validate.as_ref() {
+            use syn::Expr;
+
             let func = match expr {
                 // func(arg)()
                 Expr::Call(func) => quote! { #func },