cast to void *' from smaller integer type 'int

How to notate a grace note at the start of a bar with lilypond? In the best case this will give the same results as the original code, with no advantages, but in the worst case it will fail in multiple catastrophic ways (type punning, endianness, less efficient, etc. RNINGS" "-D_CRT_SECURE_NO_DEPRECATE" -MD -MQ lib/libopenvswitch.a.p/odp-util.c.obj -MF "lib\libopenvswitch.a.p\odp-util.c.obj.d" -o lib/libopenvswitch.a.p/od To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Properly casting a `void*` to an integer in C++ 24,193 Solution 1 I think using intptr_t is the correct intermediate here, since it's guaranteed to be large enough to contain the integral value of the void*, and once I have an integer value I can then truncate it without causing the compiler to complain. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. *PATCH] platform/x86: hp-wmi: Fix cast to smaller integer type warning @ 2023-01-23 13:28 Hans de Goede 2023-01-23 13:56 ` Hans de Goede 0 siblings, 1 reply; 2+ messages in thread From: Hans de Goede @ 2023-01-23 13:28 UTC (permalink / raw) To: Mark Gross Cc: Hans de Goede, Andy Shevchenko, platform-driver-x86, kernel test robot Fix the following . I have a function with prototype void* myFcn(void* arg) which is used as the starting point for a pthread. However, I believe that even if the define was for the "65536", it would not be what @kaetzacoatl wanted. Referring to N1570 7.20.1.4/p1 (Integer types capable of holding object pointers): The following type designates a signed integer type with the property Instead of using a long cast, you should cast to size_t. Casting int to void* loses precision, and what is the solution in required cases, c++: cast from "const variable*" to "uint32" loses precision, Recovering from a blunder I made while emailing a professor, Relation between transaction data and transaction id. - the incident has nothing to do with me; can I use this this way? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Thanks for contributing an answer to Stack Overflow! If you preorder a special airline meal (e.g. } SCAN_END_SINGLE(ATTR) If you really need such trickery, then consider one of dedicated types, which are intptr_t and uintptr_t. See also this documentation.. From and Into are generally intended to be lossless, infalliable conversions.as on the other hand can discard data and lead to bugs in some situations, for example casting a u64 to a usize may truncate the value on a 32-bit host. I have the following function and when I compile it under VS.NET 2005, the following compile warnings show up: Warning1warning C4311: 'type cast' : pointer truncation from 'void *' to 'long'c:\temp\testone\lib\utils.c56Warning2warning C4312: 'type cast' : conversion from 'unsigned long' to 'void *' of greater sizec:\temp\testone\lib\utils.c56, Code Snippet @BlueMoon Thanks a lot! An object pointer (including void*) or function pointer can be converted to an integer type using reinterpret_cast. If you are going to pass the address you typically need to exert some more control over the lifetime of the object. Well occasionally send you account related emails. It was derived from the BCPL, and the name of the b language is possibly from the BCPL contraction. I'm new to coding and am trying to implement a simple program on my own, that prompts the user the number of residents in an apt complex, the prompts the user to enter the names and apt numbers of each resident. I'm trying to create a void* from an int. If the destination type is bool, this is a boolean conversion (see below). Usually that means the pointer is allocated with. } SCAN_END_SINGLE(ATTR) Bulk update symbol size units from mm to map units in rule-based symbology. Replacing broken pins/legs on a DIP IC package, AC Op-amp integrator with DC Gain Control in LTspice. I cannot reverse my upvote of user384706's answer, but it's wrong. "-D_FILE_OFFSET_BITS=64" "-Wall" "-Winvalid-pch" "-g" "-Wthread-safety" "-Wno-microsoft-enum-forward-reference" "-Wno-unused-function" "-Wno-sometimes-unini Where does this (supposedly) Gibson quote come from? ../lib/odp-util.c:5665:7: note: expanded from macro 'SCAN_SINGLE' that any valid pointer to void can be converted to this type, then vegan) just to try it, does this inconvenience the caterers and staff? But the problem has still happened. pthread passes the argument as a void*. I would create a structure and pass that as void* to pthread_create. ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ And then assign it to the double variable. Click to see the query in the CodeQL repository. This is an old C callback mechanism so you can't change that. How can this new ban on drag possibly be considered constitutional? "-I.." "-Iinclude\openflow" "-I..\include\openflow" "-Iinclude\openvswitch" "-I..\include\openvsw SCAN_PUT(ATTR, NULL); Why is there a voltage on my HDMI and coaxial cables? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Put your define inside a bracket: without a problem. Linear regulator thermal information missing in datasheet. Don't do that. actually no, as int my be a smaller type than a pointer ;-) But, of course with int64_t it works fine. The best way is, if one can, do not do such casting, instead, if the same memory address has to be shared for pointer and int (e.g. I wish that you write those answer first than the explanation. Asking for help, clarification, or responding to other answers. rev2023.3.3.43278. ../lib/odp-util.c:5603:13: note: expanded from macro 'SCAN_PUT' By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. How do I check if a string represents a number (float or int)? This is not a conversion at all. If this is the data to a thread procedure, then you quite commonly want to pass by value. You can also convert values from one type to another explicitly using the cast operator (see Chapter 5 ): ( type_name) expression In the following example, the cast operator causes the division of one integer variable by another to be performed as a floating-point operation: int sum = 22, count = 5; double mean = (double)sum / count; In such a case the programmer can use a void pointer to point to the location of the unknown data type. converted back to pointer to void, and the result will compare equal What is the purpose of non-series Shimano components? Not the answer you're looking for? How can this new ban on drag possibly be considered constitutional? So you could do this: Note: As sbi points out this would require a change on the OP call to create the thread. As a result of the integer division 3/2 we get the value 1, which is of the int type. ^~~~~~~~~~~~~~~~~~~ Use returnPtr[j] = (void *) ((long)ptr + i); ). The difference between the phonemes /p/ and /b/ in Japanese, Styling contours by colour and by line thickness in QGIS. Then i can continue compiling. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The dynamic_cast<>operator provides a way to check the actual type of a pointer to a polymorphic class. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Find centralized, trusted content and collaborate around the technologies you use most. A missing cast in the new fast > enumeration code. That's probably going to be true for most platforms you will ever encounter, but it's not a guarantee; it's implementation-dependent. lexborisov Modest Public. The problem is not with casting, but with the target type loosing half of the pointer. ERROR: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int', error: cast to 'string' (aka 'char *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast], error: incompatible integer to pointer conversion assigning to 'string' (aka 'char *') from 'int' C, warning: initialization of 'unsigned char' from 'uint8_t *' {aka 'unsigned char *'} makes integer from pointer without a cast [-Wint-conversion], Minimising the environmental effects of my dyson brain. If pointers are 64 bits and ints are 32 bits, an int is too small to hold a pointer value. *sound/soc/codecs/tlv320aic32x4.c:1202:18: warning: cast to smaller integer type 'enum aic32x4_type' from 'void *' @ 2022-04-22 9:48 kernel test robot 0 siblings, 0 . This is known as implicit type casting or type promotion, compiler automatically converts smaller data type to larger data type. LLNL's tutorial is bad and they should feel bad. What is the point of Thrower's Bandolier? I assumed that gcc makes a 65536 out of my define, but I was wrong. property that any valid pointer to void can be converted to this type, : iPhone Retina 4-inch 64-bit) is selected. Hence there is no loss in data. (int*)Pc = pa; After the execution of the above code all the three pointers, i.e., Pa, Pd, and Pc, point to the value 150. I am an entry level C programmer. /** Dynamically allocate a 2d (x*y) array of elements of size _size_ bytes. To learn more, see our tips on writing great answers. byte -> short -> char -> int -> long -> float -> double. Floating-point conversions Disconnect between goals and daily tasksIs it me, or the industry? a cast of which the programmer should be aware of what (s)he is doing. Taking the above declarations of A, D, ch of the . My code is all over the place now but I appreciate you all helping me on my journey to mastery! long guarantees a pointer size on Linux on any machine. Making statements based on opinion; back them up with references or personal experience. Identify those arcade games from a 1983 Brazilian music video, Relation between transaction data and transaction id, The difference between the phonemes /p/ and /b/ in Japanese. So,solution #3 works just fine. However even though their types are different, the address is going to be the same. Making statements based on opinion; back them up with references or personal experience. Does a summoned creature play immediately after being summoned by a ready action? If not, check the pointer size on your platform, define these typedefs accordingly yourself and use them. What is the point of Thrower's Bandolier? You can fix this error by replacing this line of code. Converts between types using a combination of implicit and user-defined conversions. Api says this is how i should create thread: So if I want to pass an int what I think I should do is: The second example assumes that a pointer is wide enough to store an int. The problem just occur with Xcode 5.1. Are there tables of wastage rates for different fruit and veg? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? SCAN_SINGLE("skb_priority(", uint32_t, u32, OVS_KEY_ATTR_PRIORITY); ", "? whether it was an actual problem is a different matter though. I'm trying to learn pthreads and thing that keeps bugging me is how do i really pass argument to the function. There's no proper way to cast this to int in general case. Projects. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Can Martian regolith be easily melted with microwaves? Create an account to follow your favorite communities and start taking part in conversations. cast operators [edit] When an expression is used in the context where a value of a different type is expected, conversionmay occur: intn =1L;// expression 1L has type long, int is expectedn =2.1;// expression 2.1 has type double, int is expectedchar*p =malloc(10);// expression malloc(10) has type void*, char* is expected But then you need to cast your arguments inside your thread function which is quite unsafe cf. I'm unfamiliar with XCode, but the solution should be something like follows: Most of the "solutions" above can lose part of the pointer address when casting to a smaller type. Thanks for contributing an answer to Stack Overflow! The bigint data type is intended for use when integer values might exceed the range that is supported by the int data type.. bigint fits between smallmoney and int in the data type precedence chart.. For example, if you want to store a 'long' value into a simple integer then you can type cast 'long' to 'int'. ), Styling contours by colour and by line thickness in QGIS. And, most of these will not even work on gcc4. If the value in a pointer is cast to a different type and it does not have the correct alignment for the new type, the behavior is undefined. C99 defines the types "intptr_t" and "uintptr_t" which do . itch" "-I..\include\windows" "-Iinclude" "-I..\include" "-I..\datapath-windows\include" "-IC:\PTHREADS-BUILT\include" "-Xclang" "-fcolor-diagnostics" "-pipe" It is purely a compile-time directive which instructs the compiler to treat expression as if it had . It is commonly called a pointer to T and its type is T*. In 64-bit programs, the size of the pointer is 64 bits, and cannot be put into the int type, which remains 32-bit in almost all systems. unsigned long call_fn = (unsigned long)FUNC; Any expression can be cast to type void (which means that the result of the expression is ignored), but it's not legal to cast an expression of type void to type int not least because the result of such a cast wouldn't make any sense. What is the difference between const int*, const int * const, and int const *? Here is some piece of code where that error occur: /cocos2d-x-2.2.2/cocos2dx/platform/ios/EAGLView.mm:408:18: Cast from pointer to smaller type 'int' loses information. I agree passing a dynamically allocated pointer is fine (and I think the best way). The proper way is to cast it to another pointer type. The reinterpret_cast makes the int the size of a pointer and the warning will stop. Returns a value of type new-type. You need to pass an actual pointer. To learn more, see our tips on writing great answers. On a 64-bit Windows computer, 'long' is a 32-bit type, and all pointers are 64-bit types. Based on the design of this function, which modification is right. If the object expression refers or points to is actually a base class subobject of an object of type D, the result refers to the enclosing object of type D. Otherwise, the behavior is undefined: When the target type is bool (possibly cv-qualified), the result is false if the original value is zero and true for all other values. Apparently the clang version in Xcode 5.1 and above is more strict about potential 32bit vs. 64 bit incompatibilities in source code than older clang versions have been. Why is there a voltage on my HDMI and coaxial cables? To be honest, I think, clang is too restrictive here. Netdev Archive on lore.kernel.org help / color / mirror / Atom feed * [mst-vhost:vhost 5/52] drivers/block/virtio_blk.c:539:21: warning: assignment to 'void *' from . you can just change architecture to support 32 bit compilation by all below in in Build Settings. For the second example you can make sure that sizeof(int) <= sizeof(void *) by using a static_assert -- this way at least you'll get a notice about it. There's no proper way to cast this to int in general case. What happens if you typecast as unsigned first? What does casting to void* does when passing arguments to variadic functions? C99 standard library provides intptr_t and uintptr_t typedefs, which are supposed to be used whenever the need to perform such a cast comes about. Already on GitHub? The text was updated successfully, but these errors were encountered: You signed in with another tab or window. Does Counterspell prevent from any further spells being cast on a given turn? There is no "correct" way to store a 64-bit pointer in an 32-bit integer. Functions return bigint only if the parameter expression is a bigint data type. What I am trying to emphasis that conversion from int to pointer and back again can be frough with problems as you move from platform to platform. Casting a pointer to void* and back is valid use of reinterpret_cast<>. I personally upvoted this answer because by it's first line of text it helped me to understand the reason of this strange error message and what am I, poor idiot, doing :D. Not valid on Windows 64 - long is still 32-bit but pointers are 64-bit. This page was last modified on 12 February 2023, at 18:25. void* -> integer -> void* rather than integer -> void* -> integer. The problem was there before, you just are being notified of it. should we also have a diagnostic for the (presumed) user error? It's always a good practice to put your #define's in brackets to avoid such surprise. The correct answer is, if one does not mind losing data precision. Put your define inside a bracket: #define M_TABLE_SIZE (64*1024) Now, you can do: static const void* M_OFFSET = (void*) M_TABLE_SIZE; without a problem. Thanks. what happens when we typecast normal variable to void* or any pointer variable? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Please tell me error: cast from 'void*' to 'int' loses precision, How Intuit democratizes AI development across teams through reusability. Bulk update symbol size units from mm to map units in rule-based symbology. This is flat out wrong. this way I convert an int to a void* which is much better than converting a void* to an int. ^~~~~~~~~~~~~~~~~~~~~ Only the following conversions can be done with static_cast, except when such conversions would cast away constness or volatility. Unless you have a valid address at that value, you are going to invoke undefined behaviour when try to use that pointer. Disconnect between goals and daily tasksIs it me, or the industry? this way you won't get any warning. I'm using cocos2d-x-2.2.2. The int data type is the primary integer data type in SQL Server. Fork 63. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You can use a 64 bits integer instead howerver I usually use a function with the right prototype and I cast the function type : . And you can't pass a pointer to a stack based object from the other thread as it may no longer be valid. return ((void **) returnPtr);} /* Matrix() */. and how to print the thread id of 2d array argument? How do I force make/GCC to show me the commands? Is pthread_join a must when using pthread in linux? AC Op-amp integrator with DC Gain Control in LTspice. 7.1 New Cast Operations The C++ standard defines new cast operations that provide finer control than previous cast operations. Thanks Jonathan, I was thinking about my answer in another thread: AraK is correct, passing integers a pointers are not necessarily interchangeable. I understood, but that would introduce dynamic memory and ugly lifetime issues (an object allocated by one thread must be freed by some other) - all just to pass an. Your first example is risky because you have to be very careful about the object lifetimes. So the compiler is very picky here and the correct solution to make the code compile again and still let it show the exact same behavior like in Xcode 5.0 is to first cast to an integer type with a size that matches the one of a pointer and to then do a second cast to the int that we actually want: I am using size_t here, because it is always having the same size as a pointer, no matter the platform. The preprocessor will replace your code by this: This is unlikely what you are trying to do. No idea how it amassed 27 upvotes?! Connect and share knowledge within a single location that is structured and easy to search. Why is this sentence from The Great Gatsby grammatical?