When compiling the following code:
module Interface {
function addSome(n: nat): nat
ensures addSome(n) > n
}
module Mod {
import A : Interface
method m() {
assert 6 <= A.addSome(5);
print "Test\n";
}
}
module Implementation refines Interface {
function addSome(n: nat): nat
ensures addSome(n) == n + 1
{
n + 1
}
}
module Mod2 refines Mod {
import A = Implementation
}
method Main() {
Mod2.m();
}
I get the output
Dafny program verifier finished with 5 verified, 0 errors
Compilation error: Function _0_Interface_Compile._default.addSome has no body
Given that Implementation refines Interface, why does the compiler need Interface.addSome to have a body, particularly when addSome is ghost anyway so shouldn't be involved in compilation?
You need to mark both Interface and Mod as abstract. Among other things, this means they will not be compiled, so you won't get that error.
After those two small changes, the rest of your file compiles correctly.
Related
I have taken this function from another mql4 script. The other script compiles absolutely fine with no error. Strangely, now that I have copied this function into my script I get the error } not all control paths return a value
I understand the concept of return a value but not sure when there is a compile difference between the scripts
int ModifyOrder(int ord_ticket,double op, double price,double tp, color mColor)
{
int CloseCnt, err;
CloseCnt=0;
while (CloseCnt < 3)
{
if (OrderModify(ord_ticket,op,price,tp,0,mColor))
{
CloseCnt = 3;
}
else
{
err=GetLastError();
Print(CloseCnt," Error modifying order : (", err , ") " + ErrorDescription(err));
if (err>0) CloseCnt++;
}
}
}
Most likely the difference is in #property strict. if using strict mode, you have to redeclare local variables, return value from every function (except void, of course) and some other differences.
In your example the function has to be ended with return CloseCnt; or maybe something else.
No way to declare non-strict mode - simply do not declare the strict one.
Once you declared it, it is applied to that file, and included into other files if importing.
I am running a simple code from SimpleStorage example and just added few lines on top of it which I was using for my other contracts. The contract compiles fine from truffle. But on the Cakeshop Integrated IDE it shows compilation error.
pragma solidity ^0.4.24;
pragma experimental ABIEncoderV2;
contract SimpleStorage {
uint public storedData;
event Change(string message, uint newVal);
function SimpleStorage(uint initVal) {
Change("initialized", initVal);
storedData = initVal;
}
function set(uint x) {
Change("set", x);
storedData = x;
}
function get() constant returns (uint retVal) {
return storedData;
}
}
It should compile on the cakeshop web UI as it compiles on local machine
Utilizing Remix, it seems the following could be potential issues with your contract:
You are using the Contract name for the constructor. You should use the constructor keyword instead.
All of your functions are missing visibility modifiers. Consider adding the public modifier to each function including the constructor.
Events should be invoked using the emit keyword. Example: emit Change("set", x);
I have been trying to initialize a parent class using it's creation method.
class A {
public A.creator (int x, int y) {
// do some magic
}
}
class B : A {
public B.creator (int x, int y) {
// I want to do something like
base.creator (x, y);
}
}
I am facing an error while trying to run the above code.
error: chain up to 'A.creator' not supported
What's the correct way to accomplish this in vala?
When I try to compile your code I get:
chain.vala:1.1-1.7: error: Class name `A' is too short
class A {
^^^^^^^
chain.vala:7.1-7.11: error: Class name `B' is too short
class B : A {
^^^^^^^^^^^
Compilation failed: 2 error(s), 0 warning(s)
After renaming A to Aaa and B to Bbb the code compiles just fine with valac 0.36.15.
My first thought was that you might have to derive A from Object, but apparently that is not the case.
I would like to use clang to preprocess objective C files from an iOS app. I looked over the source code and am trying to implement a pre-processor based on the RecursiveASTVisitor class. However, I seem to be running into many issues that I cannot resolve. I developed a preprocessor to add a "Enter" call at the beginning of each method and an "Exit" call at the end. I also added an "Exit" call before each return statement. I am using the following code to do the instrumentation:
class ExampleVisitor : public RecursiveASTVisitor<ExampleVisitor> {
private:
ASTContext *astContext; // used for getting additional AST info
std::string funcName;
public:
explicit ExampleVisitor(CompilerInstance *CI)
: astContext(&(CI->getASTContext())) // initialize private members
{
rewriter.setSourceMgr(astContext->getSourceManager(), astContext->getLangOpts());
}
virtual bool VisitObjCMethodDecl(ObjCMethodDecl *ND) {
funcName = ND->getDeclName().getAsString();
errs() << "Testing function: " << funcName << "\n";
if (ND->hasBody()) {
rewriter.InsertText(ND->getBody()->getSourceRange().getBegin().getLocWithOffset(1), "\nEnter(\""+funcName+"\");\n");
rewriter.InsertText(ND->getBody()->getSourceRange().getEnd(),"Exit(\""+funcName+"\");\n");
}
return true;
}
virtual bool VisitReturnStmt(ReturnStmt *ret) {
rewriter.InsertText(ret->getSourceRange().getBegin(), "\nExit(\""+funcName+"\");\n");
errs() << "** Rewrote ReturnStmt\n";
return true;
}
virtual ~ExampleVisitor() {}
};
class ExampleASTConsumer : public ASTConsumer {
private:
ExampleVisitor *visitor; // doesn't have to be private
public:
// override the constructor in order to pass CI
explicit ExampleASTConsumer(CompilerInstance *CI)
: visitor(new ExampleVisitor(CI)) // initialize the visitor
{ }
// override this to call our ExampleVisitor on the entire source file
virtual void HandleTranslationUnit(ASTContext &Context) {
/* we can use ASTContext to get the TranslationUnitDecl, which is
a single Decl that collectively represents the entire source file */
visitor->TraverseDecl(Context.getTranslationUnitDecl());
}
};
The code compiles. I created a command line executable "instrument". I then used the following command to run this on a simple Objective C program generated by Xcode:
instrument AppDelegate.m --
I run into two problems. First, I get the error: 'UIKit/UIKit.h' file not found. This is one of the includes generated by Xcode. Second, I'm seeing only some of the return statements being processed in the file. Can someone give me some insights into what is happening?
I'm using the 3.7.0 version of llvm.
I have used go/parser to parse a golang file and examine it's AST. I have a specific problem for which I want to use go/parser but I hit a roadblock.
Consider that the following files are present in GOPATH/src
$GOPATH/src/
example.go
example_package/
example_package.go
The following are the contents of the files above
example.go
package main
import (
"example_package"
)
type MyObject struct {
base *example_package.BaseObject
}
func DoMyThing(arg *example_package.FirstArg) {
arg.Write(10)
}
func DoMyAnotherThing() {
}
func main() {
example_package.GetItStarted(&MyObject{})
}
example_package.go
package example_package
func GetItStarted(obj interface{}) {
}
type FirstArg interface {
Read() int
Write(x int)
}
type BaseObject struct {
}
func (p *BaseObject) DoSomething(arg *FirstArg, a int) {
arg.Write(arg.Read() + a)
}
My intention is to write a go program called gen_structure that is used like this
$ gen_structure example.go
The output would be
> MyObject
- DoMyThing(arg)
- base
- DoSomething(arg, a)
What did gen_structure do?
It parses example.go and
Extracts "MyObject" from the line example_package.GetItStarted(&MyObject{}) from inside the main() function.
Looks for methods on MyObject that have atleast one argument with the first one being of type *package_example.FirstArg. It finds DoMyThing (and ignored DoMyAnotherThing).
Identifies the member base and peeks inside (by opening the example_package).
Applies the same process to find methods as above and finds DoSomething
Using the collected information, it prints the required output.
I understand I can parse a single file or a bunch of files in the same directory using the functionality within go/parser. However, I am unable to figure out how to resolve symbols across packages (In this case, example_package).
How do I do this?
Call ast.NewPackage to resolve a package names. You will need to supply an importer that returns an *ast.Object for the given import path. If all you want to do is resolve the name to a path, the importer can simply return an *ast.Object with the Kind set to ast.Pkg and the Name set to name of the package. Most of the heavy lifting in the importer can be done with the go/build package. If want to resolve do the AST for the target package, you will need to parse the package and return the ast.Object for the package. To prevent loading the same package multiple times, use the map argument to the importer as a cache of previously loaded packages.
Here's some untested code for finding the resolved package path from the *ast.SelectorExpr se:
if x, _ := se.X.(*ast.Ident); x != nil {
if obj := x.Obj; obj != nil && obj.Kind == ast.Pkg {
if spec, _ := obj.Decl.(*ast.ImportSpec); spec != nil {
if path, err := strconv.Unquote(spec.Path.Value); err == nil {
// path is resolved path for selector expression se.
}
}
}
}
The go/types package can also be used to get this information and more. I recommend using go/types instead of using go/ast directly.