From ecac9eb95402d0da5fe7cbf8f639ee95d194dcdf Mon Sep 17 00:00:00 2001
From: Jan de Mooij <jdemooij@mozilla.com>
Date: Fri, 22 Jun 2018 11:15:51 +0200
Subject: [PATCH] Bug 1465693 - Disallow toggling werror in the JS shell when
 there are off-thread jobs. r=jonco

---
 .../tests/basic/werror-off-thread-parsing.js    |  7 +++++++
 js/src/shell/js.cpp                             | 17 ++++++++++++-----
 2 files changed, 19 insertions(+), 5 deletions(-)
 create mode 100644 js/src/jit-test/tests/basic/werror-off-thread-parsing.js

diff --git a/js/src/jit-test/tests/basic/werror-off-thread-parsing.js b/js/src/jit-test/tests/basic/werror-off-thread-parsing.js
new file mode 100644
index 000000000000..9f53ebeab4ef
--- /dev/null
+++ b/js/src/jit-test/tests/basic/werror-off-thread-parsing.js
@@ -0,0 +1,7 @@
+// |jit-test| error:toggle werror
+if (helperThreadCount() === 0)
+    throw "toggle werror";
+options("werror");
+offThreadCompileScript("function f(){return 1;''}");
+options("werror");
+runOffThreadScript();
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 15709b7d0e21..a7145d0f70dd 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -1481,15 +1481,22 @@ Options(JSContext* cx, unsigned argc, Value* vp)
         if (!opt.encodeUtf8(cx, str))
             return false;
 
-        if (strcmp(opt.ptr(), "strict") == 0)
+        if (strcmp(opt.ptr(), "strict") == 0) {
             JS::ContextOptionsRef(cx).toggleExtraWarnings();
-        else if (strcmp(opt.ptr(), "werror") == 0)
+        } else if (strcmp(opt.ptr(), "werror") == 0) {
+            // Disallow toggling werror when there are off-thread jobs, to avoid
+            // confusing CompileError::throwError.
+            ShellContext* sc = GetShellContext(cx);
+            if (!sc->offThreadJobs.empty()) {
+                JS_ReportErrorASCII(cx, "can't toggle werror when there are off-thread jobs");
+                return false;
+            }
             JS::ContextOptionsRef(cx).toggleWerror();
-        else if (strcmp(opt.ptr(), "throw_on_asmjs_validation_failure") == 0)
+        } else if (strcmp(opt.ptr(), "throw_on_asmjs_validation_failure") == 0) {
             JS::ContextOptionsRef(cx).toggleThrowOnAsmJSValidationFailure();
-        else if (strcmp(opt.ptr(), "strict_mode") == 0)
+        } else if (strcmp(opt.ptr(), "strict_mode") == 0) {
             JS::ContextOptionsRef(cx).toggleStrictMode();
-        else {
+        } else {
             JS_ReportErrorUTF8(cx,
                                "unknown option name '%s'."
                                " The valid names are strict,"