Add no_std support with a "std" feature.

The "std" feature is enabled by default; disabling it enables no_std
mode.

Cargo.toml

@@ -13,7 +13,7 @@ exclude = ["/.github", "ci"]
 keywords = ["linux"]
 
 [dependencies]
-c-gull = { version = "0.15.22", default-features = false, features = ["eyra"] }
+c-gull = { version = "0.15.25", default-features = false, features = ["eyra"] }
 
 [dev-dependencies]
 assert_cmd = "2.0.12"
@@ -35,6 +35,9 @@ core_simd = { git = "https://github.com/rust-lang/portable-simd" }
 [features]
 default = ["be-std", "threadsafe-setenv", "use-compiler-builtins"]
 
+# Enable features that depend on std. Disable this for `no_std`.
+std = ["c-gull/std"]
+
 # This makes `setenv` and friends thread-safe by leaking memory.
 threadsafe-setenv = ["c-gull/threadsafe-setenv"]
 
@@ -45,7 +48,7 @@ log = ["c-gull/log"]
 atomic-dbg-logger = ["c-gull/atomic-dbg-logger"]
 
 # Install the `env_logger` crate as a logger.
-env_logger = ["c-gull/env_logger"]
+env_logger = ["c-gull/env_logger", "std"]
 
 # Disable logging.
 max_level_off = ["c-gull/max_level_off"]
@@ -55,7 +58,7 @@ max_level_off = ["c-gull/max_level_off"]
 experimental-relocate = ["c-gull/experimental-relocate"]
 
 # Have eyra do `use std::*;` so that it can be used as `std`.
-be-std = []
+be-std = ["std"]
 
 # Should c-scape's `memcpy` etc. use compiler-builtins?
 use-compiler-builtins = ["c-gull/use-compiler-builtins"]

example-crates/all-from-source/Cargo.toml

@@ -13,5 +13,5 @@ eyra = { path = "../..", default-features = false, features = ["be-std", "thread
 lto = true
 codegen-units = 1
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/extern-crate-hello-world/Cargo.toml

@@ -7,5 +7,5 @@ publish = false
 [dependencies]
 eyra = { path = "../.." }
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/eyra-panic-example/Cargo.toml

@@ -7,5 +7,5 @@ publish = false
 [dependencies]
 std = { package = "eyra", path = "../.." }
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/hello-world-lto/Cargo.toml

@@ -11,5 +11,5 @@ std = { package = "eyra", path = "../.." }
 [profile.release]
 lto = true
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/hello-world-small/Cargo.toml

@@ -15,5 +15,5 @@ lto = true
 codegen-units = 1
 panic = "abort"
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/hello-world/Cargo.toml

@@ -7,5 +7,5 @@ publish = false
 [dependencies]
 std = { package = "eyra", path = "../.." }
 
-# This is just an example crate, and not part of the c-ward workspace.
+# This is just an example crate, and not part of the eyra workspace.
 [workspace]

example-crates/no-std/.gitignore

@@ -0,0 +1,2 @@
+/target
+Cargo.lock

example-crates/no-std/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "no-std"
+version = "0.0.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+eyra = { path = "../..", default-features = false }
+rustix-dlmalloc = { version = "0.1.0", features = ["global"] }
+
+# This is just an example crate, and not part of the eyra workspace.
+[workspace]

example-crates/no-std/README.md

@@ -0,0 +1,3 @@
+This crate demonstrates the use of Eyra in no-std mode.
+
+This mode supports fewer features, but supports `no_std`.

example-crates/no-std/build.rs

@@ -0,0 +1,4 @@
+fn main() {
+    // Pass -nostartfiles to the linker.
+    println!("cargo:rustc-link-arg=-nostartfiles");
+}

example-crates/no-std/src/main.rs

@@ -0,0 +1,22 @@
+#![no_std]
+#![no_main]
+#![feature(rustc_private)]
+#![feature(lang_items)]
+#![allow(internal_features)]
+
+extern crate libc;
+extern crate eyra;
+
+#[no_mangle]
+pub extern "C" fn main(_argc: i32, _argv: *const *const u8) -> i32 {
+    0
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! { loop {} }
+
+#[global_allocator]
+static GLOBAL_ALLOCATOR: rustix_dlmalloc::GlobalDlmalloc = rustix_dlmalloc::GlobalDlmalloc;
+
+#[lang = "eh_personality"]
+extern "C" fn eh_personality() {}

src/lib.rs

@@ -1,11 +1,9 @@
 #![doc = include_str!("../README.md")]
-#![no_std]
+#![cfg_attr(not(feature = "std"), no_std)]
 
 // If enabled, re-export `std` so that we can be used as `std` to avoid the
 // `extern crate eyra;`.
 #[cfg(feature = "be-std")]
-extern crate std;
-#[cfg(feature = "be-std")]
 #[doc(hidden)]
 pub use std::*;
 

tests/example_crates.rs

@@ -186,3 +186,8 @@ fn example_crate_extern_crate_eyra_optional_example() {
         None,
     );
 }
+
+#[test]
+fn example_crate_no_std() {
+    test_crate("no-std", &[], &[], "", "", None);
+}

tests/fs.rs

@@ -5,6 +5,7 @@
 #![feature(io_error_uncategorized)]
 #![feature(read_buf)]
 #![feature(maybe_uninit_uninit_array)]
+#![feature(core_io_borrowed_buf)]
 
 extern crate eyra;
 

tests/process.rs

@@ -5,6 +5,7 @@
 #![feature(io_error_uncategorized)]
 #![feature(read_buf)]
 #![feature(maybe_uninit_uninit_array)]
+#![feature(core_io_borrowed_buf)]
 
 extern crate eyra;