compiler-warnings

Here is the code: #include <stdint.h> unsigned char f(uint32_t RGBA) { return (RGBA>>24) & 0xFF; } When compiled with -Wconversion it causes "warning: conversion to ‘unsigned char’ from ‘uint32_t {aka unsigned int}’ may alter its value [-Wconversion]". If I lower the shift value to 23 or less the warning disappears. I've looked through the C99 standard and I don't understand what happens here. If I remove the & operator then the warning is always emitted and that is probably good, as the result of the expression (after integer promotions) is larger than unsigned char . My only idea is that the

Why can this code run successfully in Code::block. The IDB just reports warning: "reference to local variable ‘tmp’ returned", but ouput the result "hello world" successfully. #include <iostream> #include<string> using namespace std; const string &getString(const string &s) { string tmp = s; return tmp; } int main() { string a; cout<<getString("hello world")<<endl; return 0; } prvit Maybe this link will help you. Upon leaving a function, all local variables are destroyed. By returning a reference to tmp , you are returning a reference to an object that soon ceases to exist (that is,

Consider this example: #include <algorithm> #include <iostream> int main() { std::string str = "abcde4fghijk4l5mnopqrs6t8uvwxyz"; std::string str2; std::remove_copy_if(str.begin(), str.end(), std::back_inserter(str2), [](char& c) { if (std::isdigit(c)) return true; // <----- warning here else return false; } ); std::cout << str2 << '\n'; } With GCC 4.6.1, this compiles fine and prints expected output (the alphabet) but I get a warning saying "lambda return type can only be deduced when the return statement is the only statement in the function body" . Now, I know how to get rid of the warning

When repeatedly building a project, when there are warnings but no errors in a translation unit, the main source file is typically not recompiled. This can make it difficult to work through errors and warnings to attempt to get the project to build with no warnings. Typically one must keep iteratively building until all errors are taken care of, then do a full clean and build to ensure that there are no warnings (as well as to ensure that the previously-completed build wasn't a "fluke" caused by leftover build artifacts). Is there any way with CMake (or some other utility such as a Bash script

I have an error reporting functionality in my little C library I'm writing. I want to provide an errorf function in addition to the plain error function to allow embedding information in error messages easily. /* * Prints a formatted error message. Use it as you would use 'printf'. See the * 'sio_error' function. */ void sio_errorf(const char *format, ...) { // Print the error prefix if (g_input == STDIN) fputs("error: ", stderr); else fprintf(stderr, "%s: ", g_progname); // Pass on the varargs on to 'vfprintf'. va_list arglist; va_start(arglist, format); // This may produce the following

Since the update to Xcode 5.1 I can't archive my project any more. Xcode always says "Multiple methods named "count" found with mismatched result, parameter type or attributes. This problem is new and simulator and running on device works fine. Here is the code: for ( int i = 0; i<[parseJSONArray count];i++){ for (int j = 0; j<[JSON[@"data"][@"menu"][i][@"item"] count];j++){ [pictureURL addObject:JSON[@"data"][@"menu"][i][@"item"][j][@"image"]]; } } Xcode shows the error at this point : [JSON[@"data"][@"menu"][i][@"item"] count] JSON is a NSDictionary . Whats wrong with this? Ask yourself:

I have some code for testing that i added upfront the rest of the code, so the rest would never be reached in the test. Since i have warning level 4 set, this results in an c4702: unreachable-code warning I tried disabling like this: //do something return 0; /*-------------------------------------------------------------------------*/ #pragma warning(disable: 4702) //real code but the compiler still moans. And because i have set to treat every warning as an error, this won't compile... I am using Visual Studio 2012 Premium... Any help would be gladly appreciated. You maybe just need to place

I have added the scalac command line argument -Ywarn-value-discard to my build because this would have caught a subtle bug that I just found in my code. However, I now get some warnings for "discarded non-Unit value" that are about intentional discards, not bugs. How do I suppress those warnings? You suppress these warning by explictly returning unit (that is () ). By example turn this: def method1() = { println("Hello") "Bye" } def method2() { method1() // Returns "Bye", whihc is implicitly discarded } into: def method1() = { println("Hello") "Bye" } def method2() { method1() () // Explicitly