Rollup merge of #124050 - saethlin:less-sysroot-libc, r=ChrisDenton

Remove libc from MSVC targets

``@ChrisDenton`` started working on a project to remove libc from Windows MSVC targets. I'm completing that work here.

The primary change is to cfg out the dependency in `library/`. And then there's a lot of test patching. Happy to separate this more if people want.

Author: matthiaskrgr

library/std/Cargo.toml

@@ -33,9 +33,6 @@ addr2line = { version = "0.21.0", optional = true, default-features = false }
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2.153", default-features = false, features = ['rustc-dep-of-std'], public = true }
 
-[target.'cfg(all(windows, target_env = "msvc"))'.dependencies]
-libc = { version = "0.2.153", default-features = false }
-
 [target.'cfg(all(not(target_os = "aix"), not(all(windows, target_env = "msvc", not(target_vendor = "uwp")))))'.dependencies]
 object = { version = "0.32.0", default-features = false, optional = true, features = ['read_core', 'elf', 'macho', 'pe', 'unaligned', 'archive'] }
 

library/std/src/lib.rs

@@ -435,6 +435,7 @@ extern crate alloc as alloc_crate;
 // so include it here even if it's unused.
 #[doc(masked)]
 #[allow(unused_extern_crates)]
+#[cfg(not(all(windows, target_env = "msvc")))]
 extern crate libc;
 
 // We always need an unwinder currently for backtraces

library/std/src/os/raw/tests.rs

@@ -1,3 +1,5 @@
+#![cfg(not(all(windows, target_env = "msvc")))]
+
 use crate::any::TypeId;
 
 macro_rules! ok {

tests/incremental/foreign.rs

@@ -1,38 +1,21 @@
 // Test what happens we save incremental compilation state that makes
 // use of foreign items. This used to ICE (#34991).
-//@ ignore-sgx no libc
-
 //@ revisions: rpass1
 
-#![feature(rustc_private)]
-
-extern crate libc;
-
 use std::ffi::CString;
 
 mod mlibc {
-    use libc::{c_char, c_long, c_longlong};
-
     extern "C" {
-        pub fn atol(x: *const c_char) -> c_long;
-        pub fn atoll(x: *const c_char) -> c_longlong;
+        // strlen is provided either by an external library or compiler-builtins as a fallback
+        pub fn strlen(x: *const std::ffi::c_char) -> usize;
     }
 }
 
-fn atol(s: String) -> isize {
-    let c = CString::new(s).unwrap();
-    unsafe { mlibc::atol(c.as_ptr()) as isize }
-}
-
-fn atoll(s: String) -> i64 {
+fn strlen(s: String) -> usize {
     let c = CString::new(s).unwrap();
-    unsafe { mlibc::atoll(c.as_ptr()) as i64 }
+    unsafe { mlibc::strlen(c.as_ptr()) }
 }
 
 pub fn main() {
-    assert_eq!(atol("1024".to_string()) * 10, atol("10240".to_string()));
-    assert_eq!(
-        (atoll("11111111111111111".to_string()) * 10),
-        atoll("111111111111111110".to_string())
-    );
+    assert_eq!(strlen("1024".to_string()), strlen("2048".to_string()));
 }

tests/run-make/c-link-to-rust-va-list-fn/checkrust.rs

@@ -1,10 +1,7 @@
 #![crate_type = "staticlib"]
 #![feature(c_variadic)]
-#![feature(rustc_private)]
 
-extern crate libc;
-
-use libc::{c_char, c_double, c_int, c_long, c_longlong};
+use std::ffi::{c_char, c_double, c_int, c_long, c_longlong};
 use std::ffi::VaList;
 use std::ffi::{CString, CStr};
 

tests/run-make/link-path-order/main.rs

@@ -1,10 +1,8 @@
-#![feature(rustc_private)]
-
-extern crate libc;
+use std::ffi::c_int;
 
 #[link(name = "foo", kind = "static")]
 extern "C" {
-    fn should_return_one() -> libc::c_int;
+    fn should_return_one() -> c_int;
 }
 
 fn main() {

tests/ui/env-null-vars.rs

@@ -1,21 +1,15 @@
+// Ensure that env::vars() does not panic if environ is null.
+// Regression test for rust-lang/rust#53200
 //@ run-pass
 
-#![allow(unused_imports)]
-
-//@ ignore-windows
-
-// issue-53200
-
 #![feature(rustc_private)]
-extern crate libc;
-
-use std::env;
 
 // FIXME: more platforms?
 #[cfg(target_os = "linux")]
 fn main() {
+    extern crate libc;
     unsafe { libc::clearenv(); }
-    assert_eq!(env::vars().count(), 0);
+    assert_eq!(std::env::vars().count(), 0);
 }
 
 #[cfg(not(target_os = "linux"))]

tests/ui/error-codes/E0259.rs

@@ -1,8 +1,8 @@
-#![feature(rustc_private)]
+#![feature(test)]
 
 extern crate alloc;
 
-extern crate libc as alloc;
+extern crate test as alloc;
 //~^ ERROR E0259
 
 fn main() {}

tests/ui/error-codes/E0259.stderr

@@ -4,13 +4,13 @@ error[E0259]: the name `alloc` is defined multiple times
 LL | extern crate alloc;
    | ------------------- previous import of the extern crate `alloc` here
 LL |
-LL | extern crate libc as alloc;
+LL | extern crate test as alloc;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `alloc` reimported here
    |
    = note: `alloc` must be defined only once in the type namespace of this module
 help: you can use `as` to change the binding name of the import
    |
-LL | extern crate libc as other_alloc;
+LL | extern crate test as other_alloc;
    |
 
 error: aborting due to 1 previous error

tests/ui/feature-gates/rustc-private.rs

@@ -1,5 +1,5 @@
 // gate-test-rustc_private
 
-extern crate libc; //~ ERROR  use of unstable library feature 'rustc_private'
+extern crate cfg_if; //~ ERROR  use of unstable library feature 'rustc_private'
 
 fn main() {}