Add a way to voluntarily crash on stack overflow in CI

scripts/runner.node.mjs

@@ -1040,6 +1040,7 @@ async function spawnBun(execPath, { args, cwd, timeout, env, stdout, stderr }) {
     SHELL: shellPath,
     FORCE_COLOR: "1",
     BUN_FEATURE_FLAG_INTERNAL_FOR_TESTING: "1",
+    BUN_FEATURE_FLAG_CRASH_ON_STACK_OVERFLOW: "1",
     BUN_DEBUG_QUIET_LOGS: "1",
     BUN_GARBAGE_COLLECTOR_LEVEL: "1",
     BUN_JSC_randomIntegrityAuditRate: "1.0",

src/bun.js/bindings/JSGlobalObject.zig

@@ -4,6 +4,12 @@ pub const JSGlobalObject = opaque {
     }
     extern fn JSGlobalObject__throwStackOverflow(this: *JSGlobalObject) void;
     pub fn throwStackOverflow(this: *JSGlobalObject) void {
+        if (comptime bun.Environment.is_canary) {
+            if (bun.getRuntimeFeatureFlag(.BUN_FEATURE_FLAG_CRASH_ON_STACK_OVERFLOW)) {
+                @panic("Stack overflow");
+            }
+        }
+
         JSGlobalObject__throwStackOverflow(this);
     }
     extern fn JSGlobalObject__throwOutOfMemoryError(this: *JSGlobalObject) void;

src/bun.zig

@@ -3730,6 +3730,12 @@ pub const StackCheck = struct {
 // Workaround for lack of branch hints.
 pub noinline fn throwStackOverflow() StackOverflow!void {
     @branchHint(.cold);
+    if (comptime bun.Environment.is_canary) {
+        if (bun.getRuntimeFeatureFlag(.BUN_FEATURE_FLAG_CRASH_ON_STACK_OVERFLOW)) {
+            @panic("Stack overflow");
+        }
+    }
+
     return error.StackOverflow;
 }
 const StackOverflow = error{StackOverflow};

src/feature_flags.zig

@@ -40,6 +40,8 @@ pub const RuntimeFeatureFlag = enum {
     BUN_NO_CODESIGN_MACHO_BINARY,
     BUN_TRACE,
     NODE_NO_WARNINGS,
+
+    BUN_FEATURE_FLAG_CRASH_ON_STACK_OVERFLOW,
 };
 
 /// Enable breaking changes for the next major release of Bun