Auto merge of rust-lang#77386 - joshtriplett:static-glibc, r=petrochenkov

Support static linking with glibc and target-feature=+crt-static

With this change, it's possible to build on a linux-gnu target and pass
RUSTFLAGS='-C target-feature=+crt-static' or the equivalent via a
`.cargo/config.toml` file, and get a statically linked executable.

Update to libc 0.2.78, which adds support for static linking with glibc.

Add `crt_static_respected` to the `linux_base` target spec.

Update `android_base` and `linux_musl_base` accordingly. Avoid enabling
crt_static_respected on Android platforms, since that hasn't been
tested.

Closes rust-lang#65447.

Author: bors

std/Cargo.toml

@@ -16,7 +16,7 @@ cfg-if = { version = "0.1.8", features = ['rustc-dep-of-std'] }
 panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core" }
-libc = { version = "0.2.77", default-features = false, features = ['rustc-dep-of-std'] }
+libc = { version = "0.2.79", default-features = false, features = ['rustc-dep-of-std'] }
 compiler_builtins = { version = "0.1.35" }
 profiler_builtins = { path = "../profiler_builtins", optional = true }
 unwind = { path = "../unwind" }

std/src/sys/unix/process/process_unix.rs

@@ -461,39 +461,19 @@ impl ExitStatus {
     }
 
     fn exited(&self) -> bool {
-        // On Linux-like OSes this function is safe, on others it is not. See
-        // libc issue: https://github.com/rust-lang/libc/issues/1888.
-        #[cfg_attr(
-            any(target_os = "linux", target_os = "android", target_os = "emscripten"),
-            allow(unused_unsafe)
-        )]
-        unsafe {
-            libc::WIFEXITED(self.0)
-        }
+        libc::WIFEXITED(self.0)
     }
 
     pub fn success(&self) -> bool {
         self.code() == Some(0)
     }
 
     pub fn code(&self) -> Option<i32> {
-        // On Linux-like OSes this function is safe, on others it is not. See
-        // libc issue: https://github.com/rust-lang/libc/issues/1888.
-        #[cfg_attr(
-            any(target_os = "linux", target_os = "android", target_os = "emscripten"),
-            allow(unused_unsafe)
-        )]
-        if self.exited() { Some(unsafe { libc::WEXITSTATUS(self.0) }) } else { None }
+        if self.exited() { Some(libc::WEXITSTATUS(self.0)) } else { None }
     }
 
     pub fn signal(&self) -> Option<i32> {
-        // On Linux-like OSes this function is safe, on others it is not. See
-        // libc issue: https://github.com/rust-lang/libc/issues/1888.
-        #[cfg_attr(
-            any(target_os = "linux", target_os = "android", target_os = "emscripten"),
-            allow(unused_unsafe)
-        )]
-        if !self.exited() { Some(unsafe { libc::WTERMSIG(self.0) }) } else { None }
+        if !self.exited() { Some(libc::WTERMSIG(self.0)) } else { None }
     }
 }
 

unwind/Cargo.toml

@@ -14,7 +14,7 @@ doc = false
 
 [dependencies]
 core = { path = "../core" }
-libc = { version = "0.2.51", features = ['rustc-dep-of-std'], default-features = false }
+libc = { version = "0.2.79", features = ['rustc-dep-of-std'], default-features = false }
 compiler_builtins = "0.1.0"
 cfg-if = "0.1.8"
 

unwind/build.rs

@@ -12,11 +12,9 @@ fn main() {
     } else if target.contains("x86_64-fortanix-unknown-sgx") {
         llvm_libunwind::compile();
     } else if target.contains("linux") {
+        // linking for Linux is handled in lib.rs
         if target.contains("musl") {
-            // linking for musl is handled in lib.rs
             llvm_libunwind::compile();
-        } else if !target.contains("android") {
-            println!("cargo:rustc-link-lib=gcc_s");
         }
     } else if target.contains("freebsd") {
         println!("cargo:rustc-link-lib=gcc_s");

unwind/src/lib.rs

@@ -42,6 +42,13 @@ cfg_if::cfg_if! {
 #[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
 extern "C" {}
 
+// When building with crt-static, we get `gcc_eh` from the `libc` crate, since
+// glibc needs it, and needs it listed later on the linker command line. We
+// don't want to duplicate it here.
+#[cfg(all(target_os = "linux", target_env = "gnu", not(feature = "llvm-libunwind")))]
+#[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]
+extern "C" {}
+
 #[cfg(target_os = "redox")]
 #[link(name = "gcc_eh", kind = "static-nobundle", cfg(target_feature = "crt-static"))]
 #[link(name = "gcc_s", cfg(not(target_feature = "crt-static")))]