Remove a bunch of cfg attributes

src/error.rs

@@ -1,6 +1,5 @@
 use std::fmt;
 
-#[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
 use std::path::PathBuf;
 
 
@@ -10,6 +9,11 @@ pub struct Error {
     pub(crate) inner: Box<ErrorInner>,
 }
 
+// If all these features are disabled, lots of these errors are unused. But
+// instead of repeating this cfg-attribute a lot in the rest of the file, we
+// just live with these unused variants. It's not like we need to optimize the
+// size of `ErrorInner`.
+#[cfg_attr(not(any(feature = "toml", feature = "yaml", feature = "json5")), allow(dead_code))]
 pub(crate) enum ErrorInner {
     /// Returned by `Config::from_partial` when the partial does not contain
     /// values for all required configuration values. The string is a
@@ -17,14 +21,12 @@ pub(crate) enum ErrorInner {
     MissingValue(String),
 
     /// An IO error occured, e.g. when reading a file.
-    #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
     Io {
         path: Option<PathBuf>,
         err: std::io::Error,
     },
 
     /// Returned by `Source::load` implementations when deserialization fails.
-    #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
     Deserialization {
         /// A human readable description for the error message, describing from
         /// what source it was attempted to deserialize. Completes the sentence
@@ -51,20 +53,17 @@ pub(crate) enum ErrorInner {
     /// Returned by the [`Source`] impls for `Path` and `PathBuf` if the file
     /// extension is not supported by confique or if the corresponding Cargo
     /// feature of confique was not enabled.
-    #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
     UnsupportedFileFormat {
         path: PathBuf,
     },
 
     /// Returned by the [`Source`] impls for `Path` and `PathBuf` if the path
     /// does not contain a file extension.
-    #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
     MissingFileExtension {
         path: PathBuf,
     },
 
     /// A file source was marked as required but the file does not exist.
-    #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
     MissingRequiredFile {
         path: PathBuf,
     }
@@ -73,18 +72,13 @@ pub(crate) enum ErrorInner {
 impl std::error::Error for Error {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match &*self.inner {
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Io { err, .. } => Some(err),
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Deserialization { err, .. } => Some(&**err),
             ErrorInner::MissingValue(_) => None,
             ErrorInner::EnvNotUnicode { .. } => None,
             ErrorInner::EnvDeserialization { .. } => None,
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::UnsupportedFileFormat { .. } => None,
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::MissingFileExtension { .. } => None,
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::MissingRequiredFile { .. } => None,
         }
     }
@@ -96,22 +90,18 @@ impl fmt::Display for Error {
             ErrorInner::MissingValue(path) => {
                 std::write!(f, "required configuration value is missing: '{path}'")
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Io { path: Some(path), .. } => {
                 std::write!(f,
                     "IO error occured while reading configuration file '{}'",
                     path.display(),
                 )
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Io { path: None, .. } => {
                 std::write!(f, "IO error occured while loading configuration")
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Deserialization { source: Some(source), .. } => {
                 std::write!(f, "failed to deserialize configuration from {source}")
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::Deserialization { source: None, .. } => {
                 std::write!(f, "failed to deserialize configuration")
             }
@@ -123,21 +113,18 @@ impl fmt::Display for Error {
                 std::write!(f, "failed to deserialize value `{field}` from \
                     environment variable `{key}`: {msg}")
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::UnsupportedFileFormat { path } => {
                 std::write!(f,
                     "unknown configuration file format/extension: '{}'",
                     path.display(),
                 )
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::MissingFileExtension { path } => {
                 std::write!(f,
                     "cannot guess configuration file format due to missing file extension in '{}'",
                     path.display(),
                 )
             }
-            #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
             ErrorInner::MissingRequiredFile { path } => {
                 std::write!(f,
                     "required configuration file does not exist: '{}'",

src/file.rs

@@ -49,14 +49,6 @@ impl File {
 
     /// Attempts to load the file into the partial configuration `P`.
     pub fn load<P: Partial>(&self) -> Result<P, Error> {
-        // Unfortunately, if no file format is enabled, this emits unused variable
-        // warnings. This should not happen as `self`, a type containing an empty
-        // enum, is in scope, meaning that the code cannot be reached.
-        #![cfg_attr(
-            not(any(feature = "toml", feature = "yaml", feature = "json5")),
-            allow(unused_variables),
-        )]
-
         // Load file contents. If the file does not exist and was not marked as
         // required, we just return an empty layer.
         let file_content = match fs::read(&self.path) {

src/lib.rs

@@ -18,7 +18,7 @@
 //!
 //! Small example:
 //!
-//! ```rust
+//! ```
 //! use confique::Config;
 //!
 //! #[derive(Config)]
@@ -43,7 +43,7 @@
 //! are somewhat structured or have sections. You can do that by including
 //! other types that implement `Config` with `#[config(nested)]`.
 //!
-//! ```rust
+//! ```
 //! use std::path::PathBuf;
 //! use confique::Config;
 //!
@@ -84,7 +84,7 @@
 //! provided high-level methods of [`Config`], like [`Config::from_file`] and
 //! [`Config::builder`].
 //!
-//! ```rust
+//! ```
 //! use confique::Config;
 //!
 //! # #[derive(Config)]
@@ -118,11 +118,12 @@
 //! type via [`Config::from_partial`]. And you probably also want to use
 //! [`Partial::default_values`] as the last layer.
 //!
-//! ```rust,no_run
-//! # #[cfg(feature = "toml")]
-//! use confique::{Config, File, FileFormat, Partial};
+//! ```no_run
 //! # #[cfg(not(feature = "toml"))]
-//! # use confique::{Config, Partial};
+//! # fn main() {}
+//! # #[cfg(feature = "toml")]
+//! # fn main() -> Result<(), confique::Error> {
+//! use confique::{Config, File, FileFormat, Partial};
 //!
 //! #[derive(Config)]
 //! struct Conf {
@@ -130,11 +131,9 @@
 //! }
 //!
 //! type PartialConf = <Conf as Config>::Partial;
-//! # #[cfg(feature = "toml")]
 //! let from_file: PartialConf = File::with_format("/etc/foo/config", FileFormat::Toml)
 //!     .required()
 //!     .load()?;
-//! # #[cfg(not(feature = "toml"))]
 //! let from_file: PartialConf = todo!();
 //! let manual = PartialConf {
 //!     // Remember: all fields in the partial types are `Option`s!
@@ -144,7 +143,8 @@
 //!
 //! let merged = from_file.with_fallback(manual).with_fallback(defaults);
 //! let config = Conf::from_partial(merged)?;
-//! # Ok::<_, confique::Error>(())
+//! # Ok(())
+//! # }
 //! ```
 //!
 //! ## Using your configuration
@@ -162,9 +162,6 @@
 //! - `yaml`: enables YAML support and adds the `serde_yaml` dependency.
 //! - `json5`: enables YAML support and adds the `json5` dependency.
 
-#[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
-use std::path::PathBuf;
-
 use serde::Deserialize;
 
 #[doc(hidden)]
@@ -430,7 +427,7 @@ pub trait Config: Sized {
     /// let conf = Conf::from_file("config.toml");
     /// ```
     #[cfg(any(feature = "toml", feature = "yaml", feature = "json5"))]
-    fn from_file(path: impl Into<PathBuf>) -> Result<Self, Error> {
+    fn from_file(path: impl Into<std::path::PathBuf>) -> Result<Self, Error> {
         let default_values = Self::Partial::default_values();
         let mut file = File::new(path)?;
         if !default_values.is_complete() {