Add bootstrap.toml option to control debug breaking on ICEs on windows

bootstrap.example.toml

@@ -856,6 +856,9 @@
 # as libstd features, this option can also be used to configure features such as optimize_for_size.
 #rust.std-features = ["panic_unwind"]
 
+# Trigger a `DebugBreak` after an internal compiler error during bootstrap on Windows
+#rust.break-on-ice = true
+
 # =============================================================================
 # Distribution options
 #

src/bootstrap/src/core/builder/cargo.rs

@@ -877,8 +877,11 @@ impl Builder<'_> {
             .env("RUSTC_LIBDIR", libdir)
             .env("RUSTDOC", self.bootstrap_out.join("rustdoc"))
             .env("RUSTDOC_REAL", rustdoc_path)
-            .env("RUSTC_ERROR_METADATA_DST", self.extended_error_dir())
-            .env("RUSTC_BREAK_ON_ICE", "1");
+            .env("RUSTC_ERROR_METADATA_DST", self.extended_error_dir());
+
+        if self.config.rust_break_on_ice {
+            cargo.env("RUSTC_BREAK_ON_ICE", "1");
+        }
 
         // Set RUSTC_WRAPPER to the bootstrap shim, which switches between beta and in-tree
         // sysroot depending on whether we're building build scripts.

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

@@ -221,6 +221,7 @@ pub struct Config {
     pub rust_lto: RustcLto,
     pub rust_validate_mir_opts: Option<u32>,
     pub rust_std_features: BTreeSet<String>,
+    pub rust_break_on_ice: bool,
     pub llvm_profile_use: Option<String>,
     pub llvm_profile_generate: bool,
     pub llvm_libunwind_default: Option<LlvmLibunwind>,
@@ -550,6 +551,7 @@ impl Config {
             strip: rust_strip,
             lld_mode: rust_lld_mode,
             std_features: rust_std_features,
+            break_on_ice: rust_break_on_ice,
         } = toml.rust.unwrap_or_default();
 
         let Llvm {
@@ -1269,6 +1271,7 @@ impl Config {
             reproducible_artifacts: flags_reproducible_artifact,
             reuse: build_reuse.map(PathBuf::from),
             rust_analyzer_info,
+            rust_break_on_ice: rust_break_on_ice.unwrap_or(true),
             rust_codegen_backends: rust_codegen_backends
                 .map(|backends| parse_codegen_backends(backends, "rust"))
                 .unwrap_or(vec![CodegenBackendKind::Llvm]),

src/bootstrap/src/core/config/toml/rust.rs

@@ -65,6 +65,7 @@ define_config! {
         lto: Option<String> = "lto",
         validate_mir_opts: Option<u32> = "validate-mir-opts",
         std_features: Option<BTreeSet<String>> = "std-features",
+        break_on_ice: Option<bool> = "break-on-ice",
     }
 }
 
@@ -355,6 +356,7 @@ pub fn check_incompatible_options_for_ci_rustc(
         download_rustc: _,
         validate_mir_opts: _,
         frame_pointers: _,
+        break_on_ice: _,
     } = ci_rust_config;
 
     // There are two kinds of checks for CI rustc incompatible options:

src/bootstrap/src/utils/change_tracker.rs

@@ -536,4 +536,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "It is no longer possible to `x test` with stage 0, except for running compiletest and opting into `build.compiletest-allow-stage0`.",
     },
+    ChangeInfo {
+        change_id: 145976,
+        severity: ChangeSeverity::Info,
+        summary: "Added a new option `rust.break-on-ice` to control if internal compiler errors cause a debug break on Windows.",
+    },
 ];