Before I start moaning let me state I am very impressed with Dafny.
I have managed to get Dafny-VScode frozen on several occasions and would like to know if there is a better way to "reboot" Dafny with out just shutting down VS code. The example below is a cut down version of what I am working on so it may seem a little pointless:
method sortOfImp(s:seq<int>) returns (r:seq<int>)
{
var i:int:= 1;
r:=[];
if |s|>= 2 {
while (i<|s|)
decreases |s| - i
invariant i<=|s|
// invariant forall j:nat :: 0<j<i ==> ( s[j]<=s[j-1] ==>
// (exists ii:nat :: ii<|r| && r[ii]==s[j]) )
{
if s[|s|-i-1] <= s[|s|-i] { r:= [s[|s|-i]]+r;}
i:=i+1;
}
}
}
loads and behaves nicely. But if you uncomment the two lines an error is reported (no problem there) now restore the comments and the errors do not go away plus other errors are not reported.
The only solution I have found is to quit VS code and when restarted the errors are no longer reported and everything works as you would expect.
The other part of the question is:
what part of the invariant does dafny object?
Related
During testing my iOS app, (it's a workout app), the app crashed (EXC_BREAKPOINT) as it was trying to save the workout data.
The crash was an index out of range issue whereby the array count is 1 lesser than the workout seconds. (I should have started the seconds counter from 1 instead of 0)
for i in 0...seconds {
let data = "\(i),\(dataArray.powerGenY[i-1]),\(dataArray.powerGenYAlt[i-1])\n"
do {
try data.appendToURL(fileURL: fileURL)
}
catch {
print("Could not write data to file")
}
}
anyways, the error dropped me to LLDB. Is there any way I an Use LLDB to bypass this error and continue execution?
Having worked out for a hour, I wasn't prepared to have this crash take my data along with it. Since the crashed dropped me into LLDB, I wanted to see if there's any way to salvage the data by stepping over / bypassing / changing the value of i so that the program execution can continue.
Initially I tried
(lldb) po i = 3327
error: <EXPR>:3:1: error: cannot assign to value: 'i' is immutable
i = 3327
^
but it won't let me change the value (I is immutable)
Then I tried thread jump -l 1 but it spewed some error about not the code execution outside of current function.
(lldb) th j -l 29
error: CSVExport.swift:29 is outside the current function.
Finally, going thru this site https://www.inovex.de/blog/lldb-patch-your-code-with-breakpoints/ and trying a few things. The one that helped was thread jump
thread return
The mentioned disadvantage of thread jump can be avoided by using a
different technique to change control flow behaviour. Instead of
manipulating the affected lines of code directly the idea is to
manipulate other parts of the program which in turn results in the
desired behaviour. For the given example this means changing the
return value of can_pass() from 0 to 1. Which, of course, can be done
through LLDB. The command to use is thread just like before, but this
time with the subcommand return to prematurely return from a stack
frame, thereby short-circuiting its execution.
Executing thread return 1 did the trick. This returned true (1) to the index out of range issue and then continued the execution to the next line of code.
I have tested two cases:
I use STEPCAFControl_Reader then STEPControl_Reader to read my step file but both methods crash when I call STEPCAFControl_Reader::Transfer, repsectively STEPControl_Reader:: TransferRoots.
By using STEPControl_Reader, I displayed a log on my console, then there is a message like this:
1 F:(BOUNDED_SURFACE,B_SPLINE_SURFACE,B_SPLINE_SURFACE_WITH_KNOTS,GEOMETRIC_REPRESENTATION_ITEM,RATIONAL_B_SPLINE_SURFACE,REPRESENTATION_ITEM,SURFACE): Count of Parameters is not 1 for representation_item
EDIT:
There is a null reference inside TransferRoots() method.
const Handle(Transfer_TransientProcess) &proc = thesession->TransferReader()->TransientProcess();
if (proc->GetProgress().IsNull())
{
//This condition does not exist from the source code
std::cout << "GetProgress is null" << std::endl;
return 0;
}
Message_ProgressSentry PS ( proc->GetProgress(), "Root", 0, nb, 1 );
My app and FreeCAD crash but if I use CAD Assitant which OCC official viewer, it loads.
It looks like comments already provide an answer to the question - or more precisely answers:
STEPCAFControl_Reader::ReadFile() returns reading status, which should be checked before calling STEPCAFControl_Reader::Transfer().
Normally, it is a good practice to put OCCT algorithm into try/catch block and check for OCCT exceptions (Standard_Failure).
Add OCC_CATCH_SIGNALS at the beginning of try statements (required only on Linux) and OSD::SetSignal(false) within working thread creation to redirect abnormal cases (access violation, NULL dereference and others) to C++ exceptions (OSD_Signal which is subclass of Standard_Failure). This may conflict other signal handlers in mixed environment - so check also documentation of other frameworks used by application.
If you catch failures like NULL dereference on calling OCCT algorithm with valid arguments - this is a bug in OCCT which is desirable to be fixed in one or another way, even if input STEP file contains syntax/logical errors triggering such kind of issues. Report the issue on OCCT Bugtracker with sufficient information for reproducing bug, including sample files - it is not helpful to developers just saying that OCCT crashes somewhere. Consider also contributing into this open source project by debugging OCCT code and suggesting patches.
Check STEP file reading log for possible errors in the file itself. Consider reporting an issue to system producing a broken file, even if main file content can be loaded by STEP readers.
It is a common practice to use OSD::SetSignal() within OCCT-based applications (like CAD Assistant) to improve their robustness on non-fatal errors in application/OCCT code. It is more user friendly reporting an internal error message instead of silently crashing.
But it should be noted, that OSD::SetSignal() doesn't guarantee application not being crashed nor that application can work properly after catching such failure - due to asynchronous nature of some signals, the memory can be already corrupted at the moment, when C++ exception has been raised leading to all kinds of undesired behavior. For that reason, it is better not ignoring such kind of exceptions, even if it looks like application works fine with them.
OSD::SetSignal(false); // should be called ones at application startup
STEPCAFControl_Reader aReader;
try
{
OCC_CATCH_SIGNALS // necessary for redirecting signals on Linux
if (aReader.ReadFile (theFilePath) != IFSelect_RetDone) { return false; }
if (!aReader.Transfer (myXdeDoc)) { return false; }
}
catch (Standard_Failure const& theFailure)
{
std::cerr << "STEP import failed: " << theFailure.GetMessageString() << "\n";
return false;
}
return true;
I have a pyclips / clips program for which I wrote some unit tests using pytest.
Each test case involes an initial clips.Clear() followed by the execution of real clips COOL code via clips.Load(rule_file.clp). Running each test individually works fine.
Yet, when telling pytest to run all tests, some fail with ClipsError: S03: environment could not be cleared. In fact, it depends on the order of the tests in the .py file. There seem to be test cases, that cause the subsequent test case to throw the exception.
Maybe some clips code is still "in use" so that the clearing fails?
I read here that (clear)
Clears CLIPS. Removes all constructs and all associated data structures (such as facts and instances) from the CLIPS environment. A clear may be performed safely at any time, however, certain constructs will not allow themselves to be deleted while they are in use.
Could this be the case here? What is causing the (clear) command to fail?
EDIT:
I was able to narrow down the problem. It occurs under the following circumstances:
test_case_A comes right before test_case_B.
In test_case_A there is a test such as
(test (eq (type ?f_bio_puts) clips_FUNCTION))
but f_bio_puts has been set to
(slot f_bio_puts (default [nil]))
So testing the type of a slot variable, which has been set to [nil] initially, seems to cause the (clear) command to fail. Any ideas?
EDIT 2
I think I know what is causing the problem. It is the test line. I adapted my code to make it run in the clips Dialog Windows. And I got this error when loading via (batch ...)
[INSFUN2] No such instance nil in function type.
[DRIVE1] This error occurred in the join network
Problem resided in associated join
Of pattern #1 in rule part_1
I guess it is a bug of pyclips that this is masked.
Change the EnvClear function in the CLIPS source code construct.c file adding the following lines of code to reset the error flags:
globle void EnvClear(
void *theEnv)
{
struct callFunctionItem *theFunction;
/*==============================*/
/* Clear error flags if issued */
/* from an embedded controller. */
/*==============================*/
if ((EvaluationData(theEnv)->CurrentEvaluationDepth == 0) &&
(! CommandLineData(theEnv)->EvaluatingTopLevelCommand) &&
(EvaluationData(theEnv)->CurrentExpression == NULL))
{
SetEvaluationError(theEnv,FALSE);
SetHaltExecution(theEnv,FALSE);
}
I have a strange problem with the new Xcode 8 (no beta version) and swift3.
Once every other 3-4 times that I compile my code I get a 'command failed due to signal segmentation fault 11' error. I just need to enter new empty line, or sometimes changing some spaces, or add a comment (everywhere in the code) and the error disappears and I can compile again.
This is really strange because I'm not changing anything in the code! And sometimes I can compile and it works, then I don't change anything, I compile again and I get the error.
This is really annoying!
I have noticed this is happening since I have installed several 'Firebase' pods (Firebase, Firebase/Auth etc...). But I need them.
Anyone has any suggestion?
PS: I have set the Enable Bitcode of my project to No as many solution suggested, but nothing. In the error message it is not indicated any swift page where the error can be, an example is:
While loading members for 'Class_name' at
While deserializing 'func_name' (FuncDecl #42)
'func_name' is this one:
public class func loginUser(fir_user: FIRUser) {
let user = SFUser()
user.email = fir_user.email
user.isLogged = true
try! sfRealm.write() {
sfRealm.add(user, update:true)
}
var userToAdd = [String:AnyObject]()
userToAdd["email"] = fir_user.email! as NSString
let ref=FIRDatabase.database().reference()
let usersRef = ref.child(childName)
usersRef.setValue([key:value])
}
But then, as I said, I can just enter an empty row in another file and it compiles!
Thanks
I have the same issue i just figure out that i was using xcode 8.1 and the project's working copy was in xcode 8.2.1 so i just re install xcode 8.2.1 and problem got solved. Hope other can get the help trough this.
Ok, it seems that I have found the solution: it is a problem with Firebase and cocoapods, so 2 solutions:
Download Firebase and import into your project
I, instead, updated cocoapods to the last version and it worked. Upgraded Firebase - Now Getting Swift Compile Error
In my case there was some type checking issue deep down the compiler so the editor didn't give error in the gutter but on building the project I was getting signal setmentation fault 11 error:
1. While type-checking 'GetStoreAPIRequestModel' at /Users/.../StoreAPIModel.swift:9:1
2. While type-checking expression at [/Users/.../StoreAPIModel.swift:15:18 - line:15:31] RangeText="[Dictionary]()"
3. While resolving type [Dictionary] at [/Users/.../StoreAPIModel.swift:15:18 - line:15:29] RangeText="[Dictionary]"
So I changed my code from:
var stores = [Dictionary]() {
willSet {
allStores.removeAll()
for model in newValue {
allStores.append(StoreAPIModel(dictionary: model as! Dictionary).getModel())
}
}
}
To (more descriptive dictionary):
var stores = [[String : Any]]() {
willSet {
allStores.removeAll()
for model in newValue {
allStores.append(StoreAPIModel(dictionary: model as [String : AnyObject]).getModel())
}
}
}
This is tricky problem. Issue can be with line of code or syntax. I was getting similar error and it was due to incorrect usage of dictionary. I was trying to increment the value of dictionary element.
Solution is to triage the code, detailed error provide which module has issue, so try commenting part of code until you find the line which is causing the issue.
Hi i had the same issue with FireBase , my problem was that i was extending FIRStorageReference and FIRDatabaseReference and some time it compile successfully some time i get
command failed due to signal segmentation fault 11
so i removed that files and implement the method other way , now everything works fine.
Found my problem when this occurred. (No cocoapods.) I thought I had left the program in a working state, but I was wrong. I am writing a straightforward command-line program. What it does is somewhat general, so I defined all the strings that make it specific in let statements at the top of the program so that I could someday use the program in a different context.
Since that was working so well, I thought I'd be clever and do the same with a filter of an array of dictionaries. I turned:
list.filter { $0["SearchStrings"] == nil }
into:
let test = { $0["SearchStrings"] == nil }
// ...
list.filter(test)
meaning to continue working on the let, but I never went back and did that. Building gave me the segmentation fault error. Defining test as a function fixed the problem.
(Incidentally, I understand how to strip a filtering function down to the terse braces notation in the context of the call to Array.filter, and why that works, but I don't understand why I can't assign the brace expression to a constant and use it as such.)
That sinking feeling when you realize you have no idea what's going on...
I've been using this code in my network code for almost two years without problems.
if (!CFReadStreamOpen(myReadStream)) {
CFStreamError myErr = CFReadStreamGetError(myReadStream);
if (myErr.error != 0) {
// An error has occurred.
if (myErr.domain == kCFStreamErrorDomainPOSIX) {
// Interpret myErr.error as a UNIX errno.
strerror(myErr.error);
} else if (myErr.domain == kCFStreamErrorDomainMacOSStatus) {
OSStatus macError = (OSStatus)myErr.error;
}
// Check other domains.
}
}
I believe it was originally based on the code samples given here:
http://developer.apple.com/library/mac/#documentation/Networking/Conceptual/CFNetwork/CFStreamTasks/CFStreamTasks.html
I recently noticed, however, that some connections are failing, because CFReadStreamOpen returns false but the error code is 0. After staring at the above link some more, I noticed the CFRunLoopRun() statement, and added it:
if (!CFReadStreamOpen(myReadStream)) {
CFStreamError myErr = CFReadStreamGetError(myReadStream);
if (myErr.error != 0) {
// An error has occurred.
if (myErr.domain == kCFStreamErrorDomainPOSIX) {
// Interpret myErr.error as a UNIX errno.
strerror(myErr.error);
} else if (myErr.domain == kCFStreamErrorDomainMacOSStatus) {
OSStatus macError = (OSStatus)myErr.error;
}
// Check other domains.
} else
// start the run loop
CFRunLoopRun();
}
This fixed the connection problem. However, my app started showing random problems - interface sometimes not responsive, or not drawing, text fields not editable, that kind of stuff.
I've read up on CFReadStreamOpen and on run loops (specifically, that the main run loop runs by itself and I shouldn't run a run loop unless I'm setting it up myself in a secondary thread - which I'm not, as far as I know). But I'm still confused about what's actually happening above. Specifically:
1) Why does CFReadStreamOpen sometimes return FALSE and error code 0? What does that actually mean?
2) What does the CFRunLoopRun call actually do in the above code? Why does the sample code make that call - if this code is running in the main thread I shouldn't have to run the run loop?
I guess I'll answer my own question, as much as I can.
1) In my code, at least, CFReadStreamOpen always seems to return false. The documentation is a bit confusing, but I read it to mean the stream wasn't opened yet, but will be open later in the run loop.
2) Most of the calls I was making were happening in the main thread, where the run loop was already running, so calling CFRunLoopRun was unnecessary. The call that was giving me problems was happening inside a block, which apparently spawned a new thread. This new thread didn't start a new run loop - so the stream would never open unless I explicitly ran the new thread's run loop.
I'm still not 100% clear on what happens if I call CFRunLoopRun() on a thread with an already running run loop, but it's obviously not good.
I ended up ditching my home-brewed networking code and switching to ASIHTTPRequest, which I was considering to do anyway.