Revert "Convert strtold to Rust"

This reverts commit 08485648f6.

build.rs

@@ -0,0 +1,36 @@
+extern crate cc;
+
+use std::{env, fs};
+
+fn get_target() -> String {
+    env::var("TARGET").unwrap_or(
+        option_env!("TARGET").map_or("x86_64-unknown-redox".to_string(), |x| x.to_string()),
+    )
+}
+
+fn main() {
+    let _crate_dir = env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR not set");
+    let target = get_target();
+
+    println!("cargo:rerun-if-changed=src/c");
+
+    let mut cc_builder = &mut cc::Build::new();
+
+    cc_builder = cc_builder.flag("-nostdinc").flag("-nostdlib");
+
+    if target.starts_with("aarch64") {
+        cc_builder = cc_builder.flag("-mno-outline-atomics")
+    }
+
+    cc_builder
+        .flag("-fno-stack-protector")
+        .flag("-Wno-expansion-to-defined")
+        .files(
+            fs::read_dir("src/c")
+                .expect("src/c directory missing")
+                .map(|res| res.expect("read_dir error").path()),
+        )
+        .compile("relibc_c");
+
+    println!("cargo:rustc-link-lib=static=relibc_c");
+}

src/c/stdlib.c

@@ -0,0 +1,5 @@
+double strtod(const char *nptr, char **endptr);
+
+long double strtold(const char *nptr, char **endptr) {
+    return (long double)strtod(nptr, endptr);
+}

src/header/stdlib/cbindgen.toml

@@ -5,8 +5,5 @@ style = "Type"
 no_includes = true
 cpp_compat = true
 
-[export.rename]
-"c_longdouble" = "long double"
-
 [enum]
 prefix_with_name = true

src/header/stdlib/mod.rs

@@ -1479,11 +1479,7 @@ pub unsafe extern "C" fn strtol(s: *const c_char, endptr: *mut *mut c_char, base
     )
 }
 
-/// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strtold.html>.
-#[unsafe(no_mangle)]
-pub unsafe extern "C" fn strtold(s: *const c_char, endptr: *mut *mut c_char) -> c_longdouble {
-    strto_float_impl!(c_longdouble, s, endptr)
-}
+// TODO: strtold(), when long double is available
 
 /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/strtol.html>.
 #[unsafe(no_mangle)]

src/lib.rs

@@ -16,7 +16,6 @@
 #![feature(asm_const)]
 #![feature(c_variadic)]
 #![feature(core_intrinsics)]
-#![feature(f128)]
 #![feature(macro_derive)]
 #![feature(maybe_uninit_slice)]
 #![feature(lang_items)]

src/platform/types.rs

@@ -31,7 +31,6 @@ pub type c_int = i32;
 pub type c_uint = u32;
 pub type c_float = f32;
 pub type c_double = f64;
-pub type c_longdouble = f128;
 pub type c_longlong = i64;
 pub type c_ulonglong = u64;
 pub type intmax_t = i64;