Rework feature flags

.github/workflows/ci.yml

@@ -76,12 +76,12 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - uses: dtolnay/rust-toolchain@stable
-    - run: cargo build -p ${{matrix.package}} --no-default-features
-    - run: cargo build -p ${{matrix.package}} --no-default-features --features alloc
-    - run: cargo build -p ${{matrix.package}} --no-default-features --features std
-    - run: cargo build -p ${{matrix.package}} --no-default-features --features simdutf8
+    - run: cargo build -p ${{matrix.package}} --no-default-features -- -D warnings
+    - run: cargo build -p ${{matrix.package}} --no-default-features --features alloc -- -D warnings
+    - run: cargo build -p ${{matrix.package}} --no-default-features --features std -- -D warnings
+    - run: cargo build -p ${{matrix.package}} --no-default-features --features simdutf8 -- -D warnings
       if: matrix.package == 'musli-storage' || matrix.package == 'musli-wire' || matrix.package == 'musli-descriptive' || matrix.package == 'musli-json'
-    - run: cargo build -p ${{matrix.package}} --no-default-features --features parse-full
+    - run: cargo build -p ${{matrix.package}} --no-default-features --features parse-full -- -D warnings
       if: matrix.package == 'musli-json'
 
   clippy:

crates/musli-allocator/Cargo.toml

@@ -15,8 +15,8 @@ keywords = ["no-std::no-alloc", "no_std", "serialization"]
 categories = ["memory-management", "no-std", "rust-patterns"]
 
 [features]
-default = ["std"]
-std = ["alloc", "musli/std"]
+default = ["std", "alloc"]
+std = ["musli/std"]
 alloc = ["musli/alloc"]
 
 [dependencies]

crates/musli-common/Cargo.toml

@@ -16,8 +16,8 @@ keywords = ["no-std::no-alloc", "no_std", "serialization"]
 categories = ["encoding", "no-std"]
 
 [features]
-default = ["std"]
-std = ["alloc", "musli/std", "simdutf8?/std", "musli-allocator/std"]
+default = ["std", "alloc"]
+std = ["musli/std", "simdutf8?/std", "musli-allocator/std"]
 alloc = ["musli-allocator/alloc"]
 
 [dependencies]

crates/musli-common/src/buf/buf_string.rs

@@ -6,8 +6,8 @@ use musli::Buf;
 
 use crate::fixed::CapacityError;
 
-/// A string around a buffer.
-pub(crate) struct BufString<B> {
+/// A string wrapped around a context buffer.
+pub struct BufString<B> {
     buf: B,
 }
 
@@ -16,7 +16,7 @@ where
     B: Buf,
 {
     /// Construct a new fixed string.
-    pub(crate) const fn new(buf: B) -> BufString<B> {
+    pub const fn new(buf: B) -> BufString<B> {
         BufString { buf }
     }
 

crates/musli-common/src/buf/mod.rs

@@ -1,2 +1,4 @@
+//! Utilitioes for working with buffers.
+
 mod buf_string;
-pub(crate) use self::buf_string::BufString;
+pub use self::buf_string::BufString;

crates/musli-common/src/context/error.rs

@@ -7,6 +7,8 @@
 
 use core::fmt;
 
+use musli::context::StdError;
+
 #[cfg(feature = "alloc")]
 use alloc::string::{String, ToString};
 
@@ -15,7 +17,7 @@ pub trait Error: Sized + 'static + Send + Sync + fmt::Display + fmt::Debug {
     /// Construct a custom error.
     fn custom<T>(error: T) -> Self
     where
-        T: 'static + Send + Sync + fmt::Display + fmt::Debug;
+        T: 'static + Send + Sync + StdError;
 
     /// Collect an error from something that can be displayed.
     ///
@@ -26,7 +28,7 @@ pub trait Error: Sized + 'static + Send + Sync + fmt::Display + fmt::Debug {
         T: fmt::Display;
 }
 
-#[cfg(feature = "std")]
+#[cfg(all(feature = "std", feature = "alloc"))]
 impl Error for std::io::Error {
     fn custom<T>(message: T) -> Self
     where

crates/musli-common/src/context/mod.rs

@@ -14,6 +14,7 @@ use core::cell::{Cell, UnsafeCell};
 use core::fmt;
 use core::marker::PhantomData;
 
+use musli::context::StdError;
 use musli::mode::DefaultMode;
 use musli::{Allocator, Context};
 
@@ -84,7 +85,7 @@ where
     #[inline]
     fn custom<T>(&self, message: T) -> Self::Error
     where
-        T: 'static + Send + Sync + fmt::Display + fmt::Debug,
+        T: 'static + Send + Sync + StdError,
     {
         E::custom(message)
     }
@@ -146,7 +147,7 @@ where
     /// Construct an error or panic.
     pub fn unwrap(self) -> E {
         if self.error.get() {
-            return E::custom("error");
+            return E::message("error");
         }
 
         panic!("did not error")
@@ -231,7 +232,7 @@ where
     #[inline]
     fn custom<T>(&self, error: T) -> ErrorMarker
     where
-        T: 'static + Send + Sync + fmt::Display + fmt::Debug,
+        T: 'static + Send + Sync + StdError,
     {
         // SAFETY: We're restricting access to the context, so that this is
         // safe.

crates/musli-common/src/fixed_bytes.rs

@@ -160,7 +160,7 @@ impl<const N: usize> FixedBytes<N> {
         C: ?Sized + Context,
     {
         if !self.extend_from_slice(source) {
-            return Err(cx.custom(FixedBytesOverflow {
+            return Err(cx.message(FixedBytesOverflow {
                 at: self.init,
                 additional: source.len(),
                 capacity: N,

crates/musli-common/src/int/continuation.rs

@@ -54,7 +54,7 @@ where
         shift += 7;
 
         if shift >= T::BITS {
-            return Err(cx.custom("Bits overflow"));
+            return Err(cx.message("Bits overflow"));
         }
 
         b = r.read_byte(cx)?;

crates/musli-common/src/lib.rs

@@ -34,7 +34,7 @@ pub mod fixed_bytes;
 pub mod int;
 #[macro_use]
 pub mod options;
-mod buf;
+pub mod buf;
 pub mod reader;
 pub mod str;
 pub mod wrap;

crates/musli-common/src/reader.rs

@@ -174,7 +174,7 @@ impl<'de> Reader<'de> for &'de [u8] {
         C: ?Sized + Context,
     {
         if self.len() < n {
-            return Err(cx.custom(SliceUnderflow {
+            return Err(cx.message(SliceUnderflow {
                 n,
                 remaining: self.len(),
             }));
@@ -348,7 +348,7 @@ where
     let outcome = range.start.wrapping_add(len);
 
     if outcome > range.end || outcome < range.start {
-        Err(cx.custom(SliceUnderflow {
+        Err(cx.message(SliceUnderflow {
             n: len,
             remaining: (range.end as usize).wrapping_sub(range.start as usize),
         }))
@@ -385,7 +385,7 @@ where
                 self.remaining = remaining;
                 Ok(())
             }
-            None => Err(cx.custom("Reader out of bounds")),
+            None => Err(cx.message("Reader out of bounds")),
         }
     }
 }

crates/musli-common/src/writer.rs

@@ -172,7 +172,7 @@ impl Writer for &mut [u8] {
         C: ?Sized + Context,
     {
         if self.len() < bytes.len() {
-            return Err(cx.custom(SliceOverflow {
+            return Err(cx.message(SliceOverflow {
                 n: bytes.len(),
                 capacity: self.len(),
             }));

crates/musli-descriptive/Cargo.toml

@@ -16,8 +16,8 @@ keywords = ["no-std::no-alloc", "no_std", "serialization"]
 categories = ["encoding", "no-std"]
 
 [features]
-default = ["std", "simdutf8"]
-std = ["alloc", "musli/std", "musli-common/std", "musli-storage/std"]
+default = ["std", "alloc", "simdutf8"]
+std = ["musli/std", "musli-common/std", "musli-storage/std"]
 alloc = ["musli/alloc", "musli-common/alloc", "musli-storage/alloc"]
 test = []
 simdutf8 = ["musli-common/simdutf8"]

crates/musli-descriptive/src/error.rs

@@ -5,6 +5,8 @@ use alloc::boxed::Box;
 #[cfg(feature = "alloc")]
 use alloc::string::ToString;
 
+use musli::context::StdError;
+
 /// Error raised during descriptive encoding.
 #[derive(Debug)]
 pub struct Error {
@@ -22,31 +24,49 @@ impl fmt::Display for Error {
 enum ErrorImpl {
     #[cfg(feature = "alloc")]
     Message(Box<str>),
+    #[cfg(feature = "alloc")]
+    Custom(Box<dyn 'static + Send + Sync + StdError>),
     #[cfg(not(feature = "alloc"))]
-    Message,
+    Empty,
 }
 
 impl fmt::Display for ErrorImpl {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             #[cfg(feature = "alloc")]
             ErrorImpl::Message(message) => message.fmt(f),
+            #[cfg(feature = "alloc")]
+            ErrorImpl::Custom(message) => message.fmt(f),
             #[cfg(not(feature = "alloc"))]
-            ErrorImpl::Message => write!(f, "Message error (see diagnostics)"),
+            ErrorImpl::Empty => write!(f, "Message error (see diagnostics)"),
         }
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for Error {}
+#[cfg(all(feature = "std", feature = "alloc"))]
+impl std::error::Error for Error {
+    #[inline]
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match &self.err {
+            ErrorImpl::Custom(err) => Some(&**err),
+            _ => None,
+        }
+    }
+}
 
 impl musli_common::context::Error for Error {
     #[inline]
+    #[allow(unused_variables)]
     fn custom<T>(error: T) -> Self
     where
-        T: fmt::Display,
+        T: 'static + Send + Sync + StdError,
     {
-        Self::message(error)
+        Self {
+            #[cfg(feature = "alloc")]
+            err: ErrorImpl::Custom(Box::new(error)),
+            #[cfg(not(feature = "alloc"))]
+            err: ErrorImpl::Empty,
+        }
     }
 
     #[inline]
@@ -59,7 +79,7 @@ impl musli_common::context::Error for Error {
             #[cfg(feature = "alloc")]
             err: ErrorImpl::Message(message.to_string().into()),
             #[cfg(not(feature = "alloc"))]
-            err: ErrorImpl::Message,
+            err: ErrorImpl::Empty,
         }
     }
 }

crates/musli-json/Cargo.toml

@@ -16,7 +16,7 @@ keywords = ["no-std::no-alloc", "no_std", "serialization"]
 categories = ["encoding", "no-std"]
 
 [features]
-default = ["std", "simdutf8", "musli-value", "parse-full"]
+default = ["std", "alloc", "simdutf8", "musli-value", "parse-full"]
 std = ["musli/std", "musli-common/std", "musli-value?/std", "alloc", "lexical/std"]
 alloc = ["musli/alloc", "musli-common/alloc", "musli-value?/alloc"]
 test = []

crates/musli-json/src/error.rs

@@ -19,11 +19,11 @@ impl fmt::Display for Error {
 }
 
 #[derive(Debug)]
-pub(crate) enum ErrorImpl {
+enum ErrorImpl {
     #[cfg(feature = "alloc")]
     Message(Box<str>),
     #[cfg(not(feature = "alloc"))]
-    Message,
+    Empty,
 }
 
 impl fmt::Display for ErrorImpl {
@@ -32,7 +32,7 @@ impl fmt::Display for ErrorImpl {
             #[cfg(feature = "alloc")]
             ErrorImpl::Message(message) => message.fmt(f),
             #[cfg(not(feature = "alloc"))]
-            ErrorImpl::Message => write!(f, "Message error (see diagnostics)"),
+            ErrorImpl::Empty => write!(f, "Message error (see diagnostics)"),
         }
     }
 }
@@ -59,7 +59,7 @@ impl musli_common::context::Error for Error {
             #[cfg(feature = "alloc")]
             err: ErrorImpl::Message(message.to_string().into()),
             #[cfg(not(feature = "alloc"))]
-            err: ErrorImpl::Message,
+            err: ErrorImpl::Empty,
         }
     }
 }
@@ -80,6 +80,15 @@ impl fmt::Display for ErrorMessage {
     }
 }
 
+#[cfg(feature = "std")]
+impl std::error::Error for ErrorMessage {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            ErrorMessage::ParseFloat(error) => Some(error),
+        }
+    }
+}
+
 #[derive(Debug)]
 #[non_exhaustive]
 pub(crate) enum IntegerError {