Add panic-strategy-std to bootstrap config

config.example.toml

@@ -504,6 +504,10 @@
 # Defaults to rust.overflow-checks value
 #overflow-checks-std = rust.overflow-checks (boolean)
 
+# The panic strategy used for compiling std
+# This is only applied for stage1 onwards
+#panic-strategy-std = "unwind"
+
 # Debuginfo level for most of Rust code, corresponds to the `-C debuginfo=N` option of `rustc`.
 # `0` - no debug info
 # `1` - line tables only - sufficient to generate backtraces that include line

library/alloc/src/alloc.rs

@@ -377,15 +377,14 @@ pub const fn handle_alloc_error(layout: Layout) -> ! {
         panic!("allocation failed");
     }
 
-    #[inline]
-    fn rt_error(layout: Layout) -> ! {
-        unsafe {
-            __rust_alloc_error_handler(layout.size(), layout.align());
-        }
-    }
-
     #[cfg(not(feature = "panic_immediate_abort"))]
     unsafe {
+        #[inline]
+        fn rt_error(layout: Layout) -> ! {
+            unsafe {
+                __rust_alloc_error_handler(layout.size(), layout.align());
+            }
+        }
         core::intrinsics::const_eval_select((layout,), ct_error, rt_error)
     }
 

library/core/src/str/mod.rs

@@ -104,6 +104,7 @@ const fn slice_error_fail_ct(_: &str, _: usize, _: usize) -> ! {
 }
 
 #[track_caller]
+#[cfg(not(feature = "panic_immediate_abort"))]
 fn slice_error_fail_rt(s: &str, begin: usize, end: usize) -> ! {
     const MAX_DISPLAY_LENGTH: usize = 256;
     let trunc_len = s.floor_char_boundary(MAX_DISPLAY_LENGTH);

library/std/src/panicking.rs

@@ -15,7 +15,7 @@ use core::panic::{Location, PanicInfo, PanicPayload};
 use crate::any::Any;
 use crate::fmt;
 use crate::intrinsics;
-use crate::mem::{self, ManuallyDrop};
+use crate::mem;
 use crate::process;
 use crate::sync::atomic::{AtomicBool, Ordering};
 use crate::sync::{PoisonError, RwLock};
@@ -306,7 +306,7 @@ pub mod panic_count {
     }
 
     #[inline]
-    pub fn increase(run_panic_hook: bool) -> Option<MustAbort> {
+    pub fn increase(_run_panic_hook: bool) -> Option<MustAbort> {
         None
     }
 
@@ -470,6 +470,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
 #[cfg(not(feature = "panic_immediate_abort"))]
 pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+    use mem::ManuallyDrop;
     union Data<F, R> {
         f: ManuallyDrop<F>,
         r: ManuallyDrop<R>,
@@ -835,7 +836,5 @@ fn rust_panic(msg: &mut dyn PanicPayload) -> ! {
 #[cfg_attr(not(test), rustc_std_internal_symbol)]
 #[cfg(feature = "panic_immediate_abort")]
 fn rust_panic(_: &mut dyn PanicPayload) -> ! {
-    unsafe {
-        crate::intrinsics::abort();
-    }
+    crate::intrinsics::abort();
 }

src/bootstrap/src/core/build_steps/compile.rs

@@ -427,7 +427,12 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
             .arg("--features")
             .arg(features);
     } else {
-        features += &builder.std_features(target);
+        features += &builder.std_features(target, stage);
+        if stage > 0
+            && matches!(builder.config.rust_panic_strategy_std, crate::PanicStrategy::Abort)
+        {
+            cargo.rustflag("-Cpanic=abort");
+        }
         features.push_str(compiler_builtins_c_feature);
 
         cargo

src/bootstrap/src/core/config/config.rs

@@ -105,6 +105,14 @@ impl Display for DebuginfoLevel {
     }
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum PanicStrategy {
+    #[default]
+    Unwind,
+    Abort,
+}
+
 /// LLD in bootstrap works like this:
 /// - Self-contained lld: use `rust-lld` from the compiler's sysroot
 /// - External: use an external `lld` binary
@@ -272,6 +280,7 @@ pub struct Config {
     pub rust_profile_generate: Option<String>,
     pub rust_lto: RustcLto,
     pub rust_validate_mir_opts: Option<u32>,
+    pub rust_panic_strategy_std: PanicStrategy,
     pub llvm_profile_use: Option<String>,
     pub llvm_profile_generate: bool,
     pub llvm_libunwind_default: Option<LlvmLibunwind>,
@@ -1111,6 +1120,7 @@ define_config! {
         download_rustc: Option<StringOrBool> = "download-rustc",
         lto: Option<String> = "lto",
         validate_mir_opts: Option<u32> = "validate-mir-opts",
+        panic_strategy_std: Option<PanicStrategy> = "panic-strategy-std",
     }
 }
 
@@ -1562,6 +1572,7 @@ impl Config {
                 stack_protector,
                 strip,
                 lld_mode,
+                panic_strategy_std,
             } = rust;
 
             set(&mut config.channel, channel);
@@ -1594,6 +1605,7 @@ impl Config {
             debuginfo_level_std = debuginfo_level_std_toml;
             debuginfo_level_tools = debuginfo_level_tools_toml;
             debuginfo_level_tests = debuginfo_level_tests_toml;
+            set(&mut config.rust_panic_strategy_std, panic_strategy_std);
 
             config.rust_split_debuginfo = split_debuginfo
                 .as_deref()

src/bootstrap/src/lib.rs

@@ -16,6 +16,7 @@
 //! More documentation can be found in each respective module below, and you can
 //! also check out the `src/bootstrap/README.md` file for more information.
 
+use core::config::PanicStrategy;
 use std::cell::{Cell, RefCell};
 use std::collections::{HashMap, HashSet};
 use std::env;
@@ -707,8 +708,12 @@ impl Build {
 
     /// Gets the space-separated set of activated features for the standard
     /// library.
-    fn std_features(&self, target: TargetSelection) -> String {
-        let mut features = " panic-unwind".to_string();
+    fn std_features(&self, target: TargetSelection, stage: u32) -> String {
+        let mut features = match self.config.rust_panic_strategy_std {
+            PanicStrategy::Abort if stage > 0 => " panic_immediate_abort",
+            _ => " panic-unwind",
+        }
+        .to_string();
 
         match self.config.llvm_libunwind(target) {
             LlvmLibunwind::InTree => features.push_str(" llvm-libunwind"),