We are currently using the Microsoft.VisualStudio.TestTools.CppUnitTestFramework which defines test classes with a macro, ex:
TEST_CLASS(Class1)
{
public:
TEST_METHOD(Method1)
{
Logger::WriteMessage("In Method1");
Assert::AreEqual(0, 0);
}
};
I am having a hard time getting clang-format to "understand" that TEST_CLASS is a struct/class definition. After trying a couple of things the current best solution I got is to define two new macros to wrap the class:
#define START_TEST(className) TEST_CLASS(className){
#define END_TEST };
and define them as a block start/end:
MacroBlockBegin: ^START_TEST.*$
MacroBlockEnd: ^END_TEST.*$
I am wondering if there is a better solution that does not involve adding more macros...
Related
I'm new to LLVM and I'm stuck on something that might seem basic.
I'm writing a LLVM pass to apply some transformations to global variables before they are use.
I would like to detect somehow when is the first usage of a global variable to only apply the transformation there, and not in all places where the global variable is used. But it must be the first time it is used otherwise the program crashes.
I have been reading about the AnalysisManager, and I would say that I want something similar to DominatorTree which is used for basic blocks in a function.
So the idea is to get the DominatorTree of a GlobalVariable to get the first time it is used in the code and apply there my transformation.
Given the following example
int MyGlobal = 30;
void foo()
{
printf("%s\n", MyGlobal);
}
int main()
{
printf("%s\n", MyGlobal);
foo();
}
In the example above, I only want to apply the transformation just before the first printf in the main function
Given the following example
int MyGlobal = 30;
void foo()
{
printf("%s\n", MyGlobal);
}
int main()
{
foo();
printf("%s\n", MyGlobal);
}
For the example above I would like to apply the transformation inside the foo function.
I want to avoid to create a stub function at the beginning of the program to process all globals before start running (This is what actually Im doing)
Does LLVM provide something that can help me doing this? or what should be the best approach to implement it?
I'm a bit confused about the implications of the using declaration. The keyword implies that a new type is merely declared. This would allow for incomplete types. However, in some cases it is also a definition, no? Compare the following code:
#include <variant>
#include <iostream>
struct box;
using val = std::variant<std::monostate, box, int, char>;
struct box
{
int a;
long b;
double c;
box(std::initializer_list<val>) {
}
};
int main()
{
std::cout << sizeof(val) << std::endl;
}
In this case I'm defining val to be some instantiation of variant. Is this undefined behaviour? If the using-declaration is in fact a declaration and not a definition, incomplete types such as box would be allowed to instantiate the variant type. However, if it is also a definition, it would be UB no?
For the record, both gcc and clang both create "32" as output.
Since you've not included language-lawyer, I'm attempting a non-lawyer answer.
Why should that be UB?
With a using delcaration, you're just providing a synonym for std::variant<whatever>. That doesn't require an instantiation of the object, nor of the class std::variant, pretty much like a function declaration with a parameter of that class doesn't require it:
void f(val); // just fine
The problem would occur as soon as you give to that function a definition (if val is still incomplete because box is still incomplete):
void f(val) {}
But it's enough just to change val to val& for allowing a definition,
void f(val&) {}
because the compiler doesn't need to know anything else of val than its name.
Furthermore, and here I'm really inventing, "incomplete type" means that some definition is lacking at the point it's needed, so I expect you should discover such an issue at compile/link time, and not by being hit by UB. As in, how can the compiler and linker even finish their job succesfully if a definition to do something wasn't found?
In most cases Im happy by the way SWIG is handling data, however Im facing an issue and cannot find an answer in the documentation.
First of all Im using SWIG with Lua and have the following structures wrapped:
typedef struct
{
%mutable;
float x,y,z;
...
...
} Vector3;
typedef struct
{
...
...
%immutable;
Vector3 gravity;
...
...
%extend
{
void SetGravity(Vector3 gravity)
{
WorldSetGravity($self,gravity);
}
};
} World;
As you can see the gravity XYZ can be affected by calling the SetGravity function, and it work great.
However, in order to be more intuitive and easier to use, I would like to give the opportunity to the user to set component (XY or Z) independently like:
world.gravity.x=-10;
But I need to call in the background SetGravity in order to be able to send the proper value to the physics engine (which is not exposed to Lua).
I would like to know if there’s a way to %extend variables which will allow me to call SetGravity when the world.gravity.xy or z is called?
Or be able to implement my own version of the wrap function for each component like: _wrap_World_gravity_set_x which will allot me to call SetGravity in the background.
Firstly it's worth noting that this problem is harder than simply making a "virtual" member variable using %extend that automatically calls an extra function when someone modifies it. This is because you want the fact that it's a member of another class to alter the behaviour.
I can see several fundamental approaches you could take to get this behaviour:
Inject some extra code in the target scripting language to hook the set
Inject some extra stuff in the SWIG interface to transparently convert the Vector3 inside World to something that still looks and feels the same, but has the behaviour you want under the hood.
Inject some extra code into the memberin typemap for Vector3 that checks the context it's being called from and modifies the behaviour accordingly.
Of these #2 is my preferred solution because #1 is language specific (and I don't know Lua well enough to do it!) and #3 feels dirty from a software engineering perspective.
To implement #2 I did the following:
%module test
%{
#include "test.h"
%}
typedef struct
{
%mutable;
float x,y,z;
} Vector3;
%nodefaultctor Vector3Gravity;
%{
// Inside C this is just a typedef!
typedef Vector3 Vector3Gravity;
// But we have magic for sets/gets now:
#define MEMBER_VAR(ct,vt,rt,n) \
SWIGINTERN void ct##_##n##_set(ct *self, const vt val) { \
self->n = val; \
/* Need to find a way to lookup world here */ \
WorldSetGravity(world, self); \
} \
SWIGINTERN vt ct##_##n##_get(const ct *self) { return self->n; }
MEMBER_VAR(Vector3Gravity, float, Vector3, x)
MEMBER_VAR(Vector3Gravity, float, Vector3, y)
MEMBER_VAR(Vector3Gravity, float, Vector3, z)
%}
// Inside SWIG Vector3Gravity is a distinct type:
typedef struct
{
%mutable;
%extend {
float x,y,z;
}
} Vector3Gravity;
%typemap(memberin,noblock=1) Vector3Gravity gravity %{
$1 = *((const Vector3*)$input);
WorldSetGravity($self, $1); // This gets expanded to automatically make this call
%}
typedef struct
{
// This is a blatant lie!
Vector3Gravity gravity;
} World;
Essentially we're lying and claiming that the gravity member of world is a "special" type, whereas really it's just a Vector3. Our special type has two distinct features. Firstly sets/gets on its members are implemented a C code by us. Secondly when we set this member we automatically make an extra call rather than just pass the values in.
There are two things possibly missing from this example that you might want:
Transparent conversion from Vector3Gravity to Vector3. (As it stands anything other than the set for gravity will refuse to accept Vector3Gravity instances). You can make that transparent by using the overload resolution mechanisms of SWIG/Lua if needed.
Inside the setters for Vector3Gravity we don't know which world this gravity belongs to.
We could solve that in several ways, the simplest being to implicitly set a static pointer every time we create a Vector3Gravity. This would make sense if there only ever is one world.
Another approach would be to use a global map of Vector3Gravity instances to worlds that gets maintained automatically.
Finally, instead of using a typedef for the Vector3Gravity type we could make it a real distinct type, with a compatible layout, but add a pointer to the World it came from. That's more work though.
I am trying to make some reusable blocks for my application.
CommonBlocks.h
void (^testBlock)(int) = ^(int number) {
// do nothing for now;
};
VariousImplementationFile.m
#import "CommonBlocks.h"
(void)setup {
testBlock(5);
}
Unfortunately, when I try to push this code to iOS device I receive error: linker command failed with exit code 1 (use -v to see invocation). It seems that I missing some.
Any advice?
Thanks
You try add static keyword before the declaration:
static void (^testBlock)(int) = ^(int number) {
// do nothing for now;
};
Your code causes error because you have non-static variable testBlock declared in .h header file.
When you call #import "CommonBlocks.h" in VariousImplementationFile.m, testBlock is declared once. Then you import CommonBlocks.h in some where else, testBlock is declared once more, so you'll get symbol duplicate error.
Declare block in CommonBlocks.h this way
typedef void (^RCCompleteBlockWithResult) (BOOL result, NSError *error);
Then you may use in any method for example:
-(void)getConversationFromServer:(NSInteger)placeId completionBlock:(RCCompleteBlockWithResult)completionBlock
This is not specific to blocks. Basically, you want to know how to have a global variable that is accessible from multiple files.
Basically, the issue is that in in C, each "symbol" can only be "defined" once (it can be "declared" multiple times, but just be "defined" once). Thus, you cannot put the "definition" of a symbol in a header file, because it will be included in multiple source files, so effectively, the same symbol will be "defined" multiple times.
For a function, the prototype is declaration, and the implementation with the code is the definition. You cannot implement a function in a header file for this reason. For a regular variable, writing the name and type of the variable is defining it. To only "declare" it, you need to use extern.
It is also worth mentioning static. static makes a variable local to a particular source file. That way, its name won't interfere with variables with the same name elsewhere. You can use this to make global variables that are "private" to a particular file. However, that is not what you are asking for -- you are asking for the exact opposite -- a variable that is "public", i.e. shared among files.
The standard way to do it is this:
CommonBlocks.h
extern void (^testBlock)(int); // any file can include the declaration
CommonBlocks.m
// but it's only defined in one source file
void (^testBlock)(int) = ^(int number) {
// do nothing for now;
};
There are 3 (which I know) ways to suppress the "unused variable" warning. Any particular way is better than other ?
First
- (void)testString:(NSString *)testString
{
(void)testString;
}
Second
- (void)testString:(NSString *)__unused testString
{
}
Third
- (void)testString:(NSString *)testString
{
#pragma unused(testString)
}
This is the approach I use: cross platform macro for silencing unused variables warning
It allows you to use one macro for any platform (although the definitions may differ, depending on the compiler), so it's a very portable approach to express your intention to popular compilers for C based languages. On GCC and Clang, it is equivalent of wrapping your third example (#pragma unused(testString)) into a macro.
Using the example from the linked answer:
- (void)testString:(NSString *)testString
{
MONUnusedParameter(testString);
}
I've found this approach best for portability and clarity, in use with some pretty large C, C++, ObjC, and ObjC++ codebases.
If you are compiling with GCC, you can take advantage of attribute extensions to set the 'unused' attribute. Like this:
int somevar __attribute__((unused));
It also works for unused parameter warnings (-Wunused-parameter)
To make it shorter to write I am using this macro:
#define _U_ __attribute__((unused))
And declare like this:
int somevar _U_ ;
One way to do it is just to assign a variable pointlessly after it is declared For example:
int foo;
foo = 0;
This should suppress the unused variable warning. It is just a pointless assignment.
But otherwise I would agree with ouah, the first method is the most reliable, if you must choose from those three.