Small fixes

compiler/rustc_driver/src/lib.rs

@@ -1312,16 +1312,17 @@ pub fn init_env_logger(env: &str) {
     tracing::subscriber::set_global_default(subscriber).unwrap();
 }
 
+#[cfg(unix)]
 extern "C" {
-    // Only available in glibc
     fn backtrace_symbols_fd(buffer: *const *mut libc::c_void, size: libc::c_int, fd: libc::c_int);
 }
 
 #[cfg(unix)]
-fn print_stack_trace(_: libc::c_int) {
+extern "C" fn print_stack_trace(_: libc::c_int) {
+    const MAX_FRAMES: usize = 256;
+    static mut STACK_TRACE: [*mut libc::c_void; MAX_FRAMES] = [std::ptr::null_mut(); MAX_FRAMES];
     unsafe {
-        static mut STACK_TRACE: [*mut libc::c_void; 256] = [std::ptr::null_mut(); 256];
-        let depth = libc::backtrace(STACK_TRACE.as_mut_ptr(), 256);
+        let depth = libc::backtrace(STACK_TRACE.as_mut_ptr(), MAX_FRAMES as i32);
         if depth == 0 {
             return;
         }
@@ -1332,35 +1333,34 @@ fn print_stack_trace(_: libc::c_int) {
 #[cfg(unix)]
 // When an error signal (such as SIGABRT or SIGSEGV) is delivered to the
 // process, print a stack trace and then exit.
-fn print_stack_trace_on_error_signal() {
+fn install_signal_handler() {
     unsafe {
         const ALT_STACK_SIZE: usize = libc::MINSIGSTKSZ + 64 * 1024;
         let mut alt_stack: libc::stack_t = std::mem::zeroed();
         alt_stack.ss_sp =
-            std::alloc::alloc(std::alloc::Layout::from_size_align_unchecked(ALT_STACK_SIZE, 1))
+            std::alloc::alloc(std::alloc::Layout::from_size_align(ALT_STACK_SIZE, 1).unwrap())
                 as *mut libc::c_void;
         alt_stack.ss_size = ALT_STACK_SIZE;
         libc::sigaltstack(&mut alt_stack, std::ptr::null_mut());
 
         let mut sa: libc::sigaction = std::mem::zeroed();
-        sa.sa_sigaction =
-            print_stack_trace as fn(libc::c_int) as *mut libc::c_void as libc::sighandler_t;
+        sa.sa_sigaction = print_stack_trace as libc::sighandler_t;
         sa.sa_flags = libc::SA_NODEFER | libc::SA_RESETHAND | libc::SA_ONSTACK;
         libc::sigemptyset(&mut sa.sa_mask);
         libc::sigaction(libc::SIGSEGV, &sa, std::ptr::null_mut());
     }
 }
 
-#[cfg(windows)]
+#[cfg(not(unix))]
 // When an error signal (such as SIGABRT or SIGSEGV) is delivered to the
 // process, print a stack trace and then exit.
-fn print_stack_trace_on_error_signal() {}
+fn install_signal_handler() {}
 
 pub fn main() -> ! {
     let start_time = Instant::now();
     let start_rss = get_resident_set_size();
     init_rustc_env_logger();
-    print_stack_trace_on_error_signal();
+    install_signal_handler();
     let mut callbacks = TimePassesCallbacks::default();
     install_ice_hook();
     let exit_code = catch_with_exit_code(|| {