Borrow hazard during Response::finish

[jdm]

26:07.08 pid:99319 Full command: /Users/worker/tasks/task_1567196401/repo/target/release/servo --hard-fail -u Servo/wptrunner -Z replace-surrogates -z http://web-platform.test:8000/xhr/overridemimetype-blob.html --user-stylesheet /Users/worker/tasks/task_1567196401/repo/resources/ahem.css --certificate-path /Users/worker/tasks/task_1567196401/repo/tests/wpt/web-platform-tests/tools/certs/cacert.pem --pref=js.mem.gc.zeal.level=2 --pref=js.mem.gc.zeal.frequency=10
pid:99319 
27:15.17 pid:99319 DomRefCell<T> already mutably borrowed: BorrowError (thread ScriptThread PipelineId { namespace_id: PipelineNamespaceId(1), index: PipelineIndex(1) }, at src/libcore/result.rs:1084)
27:15.32 pid:99319 stack backtrace:
27:15.32 pid:99319    0: __ZN9backtrace9backtrace5trace17hc4a0d1f273e07024E (0x10a73123b)
27:15.32 pid:99319    1: __ZN9backtrace7capture9Backtrace3new17h765760e39b281a50E (0x10a730427)
27:15.32 pid:99319    2: __ZN5servo4main28_$u7b$$u7b$closure$u7d$$u7d$17h510947304905906eE (0x106e9393b)
27:15.32 pid:99319    3: __ZN3std9panicking20rust_panic_with_hook17h099fe3773ce1a793E (0x10a8bd301)
27:15.32 pid:99319    4: __ZN3std9panicking18continue_panic_fmt17h8a4b76634870b383E (0x10a8bcd6c)
27:15.32 pid:99319    5: _rust_begin_unwind (0x10a8bcc68)
27:15.32 pid:99319    6: __ZN4core9panicking9panic_fmt17h885799c19d2b8b0cE (0x10a8dd49e)
27:15.32 pid:99319    7: __ZN4core6result13unwrap_failed17h91161a3faccc6622E (0x10a8dd578)
27:15.32 pid:99319    8: __ZN110_$LT$script..dom..bindings..cell..DomRefCell$LT$T$GT$$u20$as$u20$script..dom..bindings..trace..JSTraceable$GT$5trace17h9797e02ad9957a99E (0x1074bc1c4)
27:15.32 pid:99319    9: ___rust_maybe_catch_panic (0x10a8c569e)
27:15.32 pid:99319   10: __ZN6script3dom8bindings7codegen8Bindings15ResponseBinding15ResponseBinding6_trace17h1e307327fc13c2faE (0x107c8b0b7)
27:15.32 pid:99319   11: __ZNK2js5Class7doTraceEP8JSTracerP8JSObject (0x10888c09b)
27:15.32 pid:99319   12: __ZL13CallTraceHookIZN2js8GCMarker19processMarkStackTopERNS0_11SliceBudgetEEUlT_E_EPNS0_12NativeObjectEOS4_P8JSTracerP8JSObject15CheckGeneration (0x108b1ca43)
27:15.33 pid:99319   13: __ZN2js8GCMarker19processMarkStackTopERNS_11SliceBudgetE (0x108ad538f)
27:15.33 pid:99319   14: __ZN2js8GCMarker24markUntilBudgetExhaustedERNS_11SliceBudgetE (0x108ab95f4)
27:15.33 pid:99319   15: __ZN2js2gc9GCRuntime24markUntilBudgetExhaustedERNS_11SliceBudgetENS_7gcstats9PhaseKindE (0x108ab63a5)
27:15.33 pid:99319   16: __ZN2js2gc9GCRuntime16incrementalSliceERNS_11SliceBudgetEN2JS8GCReasonERNS0_13AutoGCSessionE (0x108abe623)
27:15.33 pid:99319   17: __ZN2js2gc9GCRuntime7gcCycleEbNS_11SliceBudgetEN2JS8GCReasonE (0x108ac02f2)
27:15.33 pid:99319   18: __ZN2js2gc9GCRuntime7collectEbNS_11SliceBudgetEN2JS8GCReasonE (0x108ac19a3)
27:15.33 pid:99319   19: __ZN2js2gc9GCRuntime2gcE18JSGCInvocationKindN2JS8GCReasonE (0x108a8b176)
27:15.33 pid:99319   20: __ZN2js2gc9GCRuntime10runDebugGCEv (0x108a8aef4)
27:15.33 pid:99319   21: __ZN2js2gc9GCRuntime22gcIfNeededAtAllocationEP9JSContext (0x108a8a865)
27:15.33 pid:99319   22: __ZN2js2gc9GCRuntime19checkAllocatorStateILNS_7AllowGCE1EEEbP9JSContextNS0_9AllocKindE (0x108a85eb1)
27:15.33 pid:99319   23: __ZN2js18AllocateStringImplI17JSFatInlineStringLNS_7AllowGCE1EEEPT_P9JSContextNS_2gc11InitialHeapE (0x108a86c06)
27:15.33 pid:99319   24: __ZN2js14AllocateStringI17JSFatInlineStringLNS_7AllowGCE1EEEPT_P9JSContextNS_2gc11InitialHeapE (0x1088f9e0e)
27:15.33 pid:99319   25: __ZN17JSFatInlineString4new_ILN2js7AllowGCE1EEEPS_P9JSContext (0x1088f9ce6)
27:15.33 pid:99319   26: __ZN2jsL20AllocateInlineStringILNS_7AllowGCE1EhEEP14JSInlineStringP9JSContextmPPT0_ (0x108684c0f)
27:15.33 pid:99319   27: __ZL23NewInlineStringDeflatedILN2js7AllowGCE1EEP14JSInlineStringP9JSContextN7mozilla5RangeIKDsEE (0x10868b431)
27:15.33 pid:99319   28: __ZL17NewStringDeflatedILN2js7AllowGCE1EEP12JSFlatStringP9JSContextPKDsm (0x108689c3c)
27:15.33 pid:99319   29: __ZN2js14NewStringCopyNILNS_7AllowGCE1EDsEEP12JSFlatStringP9JSContextPKT0_m (0x10868adce)
27:15.33 pid:99319   30: __ZN2js10JSONParserIDsE10readStringILNS_14JSONParserBase10StringTypeE1EEENS3_5TokenEv (0x1084a11b7)
27:15.33 pid:99319   31: __ZN2js10JSONParserIDsE7advanceEv (0x10849f79a)
27:15.33 pid:99319   32: __ZN2js10JSONParserIDsE5parseEN2JS13MutableHandleINS2_5ValueEEE (0x10849e5b2)
27:15.34 pid:99319   33: __ZN2js27MutableWrappedPtrOperationsINS_10JSONParserIDsEEN2JS6RootedIS2_EEE5parseENS3_13MutableHandleINS3_5ValueEEE (0x1082a5cfd)
27:15.34 pid:99319   34: __ZN2js20ParseJSONWithReviverIDsEEbP9JSContextN7mozilla5RangeIKT_EEN2JS6HandleINS8_5ValueEEENS8_13MutableHandleISA_EE (0x1082b8709)
27:15.34 pid:99319   35: __Z12JS_ParseJSONP9JSContextPKDsjN2JS13MutableHandleINS3_5ValueEEE (0x10886e033)
27:15.34 pid:99319   36: __ZN6script4body23run_json_data_algorithm17hf534158dfe76a0bfE (0x107974819)
27:15.34 pid:99319   37: __ZN6script4body25consume_body_with_promise17hb298939f1da61fe9E (0x1079738c8)
27:15.34 pid:99319   38: __ZN6script3dom8response8Response6finish17h8d0100192c012cc3E (0x107d0600a)
27:15.34 pid:99319   39: __ZN81_$LT$script..fetch..FetchContext$u20$as$u20$net_traits..FetchResponseListener$GT$20process_response_eof17h2a62f33273c3c37bE (0x107b74338)
27:15.34 pid:99319   40: __ZN76_$LT$net_traits..FetchResponseMsg$u20$as$u20$net_traits..Action$LT$T$GT$$GT$7process17h5a61201b1a7b0b55E (0x107f85d0b)
27:15.34 pid:99319   41: __ZN101_$LT$script..network_listener..ListenerTask$LT$A$C$Listener$GT$$u20$as$u20$script..task..TaskOnce$GT$8run_once17h85af352354819a3cE (0x107e1943c)
27:15.34 pid:99319   42: __ZN43_$LT$T$u20$as$u20$script..task..TaskBox$GT$7run_box17h1fbddac42b7cdce0E (0x107fa9d1e)
27:15.34 pid:99319   43: __ZN6script13script_thread12ScriptThread22handle_msg_from_script17h9e03eb14b1d6d27aE (0x107b85f27)
27:15.34 pid:99319   44: __ZN6script13script_thread12ScriptThread11handle_msgs17h689a61696977da24E.llvm.1967242945246974025 (0x107b7dd4b)
27:15.34 pid:99319   45: __ZN14profile_traits3mem12ProfilerChan25run_with_memory_reporting17h7b6e9bd38e1ab8feE (0x107cb0ea7)
27:15.34 pid:99319   46: __ZN3std10sys_common9backtrace28__rust_begin_short_backtrace17he46720d101a3e6efE (0x107f5e47b)
27:15.34 pid:99319   47: __ZN3std9panicking3try7do_call17h5f1d988e7dc73db4E.llvm.16932765531113996662 (0x10742b6aa)
27:15.34 pid:99319   48: ___rust_maybe_catch_panic (0x10a8c569e)
27:15.34 pid:99319   49: __ZN4core3ops8function6FnOnce40call_once$u7b$$u7b$vtable.shim$u7d$$u7d$17hc92a2538c3cac723E (0x107667bf5)
27:15.34 pid:99319   50: __ZN83_$LT$alloc..boxed..Box$LT$F$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17hb03304ace7f89c63E (0x10a8aca2d)
27:15.34 pid:99319   51: __ZN3std3sys4unix6thread6Thread3new12thread_start17hd2d570f25bb299f3E (0x10a8c4bcd)
27:15.34 pid:99319   52: __pthread_body (0x7fff63578660)
27:15.34 pid:99319   53: __pthread_start (0x7fff6357850c)

[gterzian]

This can probably be fixed by flattening the below call, so that self.body_promise is not borrowed while running consume_body_with_promise:

servo/components/script/dom/response.rs

Line 418 in 461bce1

if let Some((p, body_type)) = self.body_promise.borrow_mut().take() {

[gterzian]

@jdm Ah you fixed all those already...