Suggest using RUST_MIN_STACK if rustc overflowed

compiler/rustc_driver_impl/src/signal_handler.rs

@@ -1,6 +1,7 @@
 //! Signal handler for rustc
 //! Primarily used to extract a backtrace from stack overflow
 
+use rustc_interface::util::{DEFAULT_STACK_SIZE, STACK_SIZE};
 use std::alloc::{alloc, Layout};
 use std::{fmt, mem, ptr};
 
@@ -100,7 +101,10 @@ extern "C" fn print_stack_trace(_: libc::c_int) {
         written += 1;
     }
     raw_errln!("note: we would appreciate a report at https://github.com/rust-lang/rust");
-    written += 1;
+    // get the current stack size WITHOUT blocking and double it
+    let new_size = STACK_SIZE.get().copied().unwrap_or(DEFAULT_STACK_SIZE) * 2;
+    raw_errln!("help: you can increase rustc's stack size by setting RUST_MIN_STACK={new_size}");
+    written += 2;
     if written > 24 {
         // We probably just scrolled the earlier "we got SIGSEGV" message off the terminal
         raw_errln!("note: backtrace dumped due to SIGSEGV! resuming signal");

compiler/rustc_interface/src/util.rs

@@ -48,8 +48,8 @@ pub fn add_configuration(cfg: &mut Cfg, sess: &mut Session, codegen_backend: &dy
     }
 }
 
-static STACK_SIZE: OnceLock<usize> = OnceLock::new();
-const DEFAULT_STACK_SIZE: usize = 8 * 1024 * 1024;
+pub static STACK_SIZE: OnceLock<usize> = OnceLock::new();
+pub const DEFAULT_STACK_SIZE: usize = 8 * 1024 * 1024;
 
 fn init_stack_size() -> usize {
     // Obey the environment setting or default