compiler-warnings

问题 I wonder if is there any ways to make OCaml compiler report warnings about unused functions ? I googled but there are not much topics discussed about this feature. In particular, in the following program, there are two functions "foo" and "bar" which are declared but "bar" is not used in the "_" function. So I think that the OCaml compiler should report "bar" as an unused function. let foo x y = x + y let bar x y z = x + y + z (* should be reported unused *) let _ = let x = foo 1 2 in x 回答1:

问题 I did some research to find out why a missing return cannot be an error but is undefined behavior instead. I found this comment in a bug report that uses the following example to illustrate why it cannot be an error: template<typename T> T maybe_call(std::function<T(void)> f) { if (f) return f(); else abort_program(); // Cannot write a return here, because we have no way to create a value of t } Note that this example is completely valid code. It has no return on all branches, but still there

问题 I did some research to find out why a missing return cannot be an error but is undefined behavior instead. I found this comment in a bug report that uses the following example to illustrate why it cannot be an error: template<typename T> T maybe_call(std::function<T(void)> f) { if (f) return f(); else abort_program(); // Cannot write a return here, because we have no way to create a value of t } Note that this example is completely valid code. It has no return on all branches, but still there

问题 I'm using MSVC to compile some C code which uses standard-library functions, such as getenv() , sprintf and others, with /W3 set for warnings. I'm told by MSVC that: 'getenv': This function or variable may be unsafe. Consider using _dupenv_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS Questions: Why would this be unsafe, theoretically - as opposed to its use on other platforms? Is it unsafe on Windows in practice? Assuming I'm not writing security-oriented code - should I

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 I have the following code in C: (void)fscanf(fp, "%*d %*d %d %d %d\n",&z, &e, &a); I cast the call to void as the return value of fscanf is irrelevant for me. But I get the following warning when compiling: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] (void)fscanf(fp, "%*d %*d %d %d %d\n",&z, &e, &a); Shouldn't the '(void)' have taken that warning out? 回答1: That's a nice warning, since ignoring the return value of fscanf() could lead

问题 In line tab[i] = tab[i+1] - tab[i] + (tab[i+1] = tab[i]); I have a warning [Warning] operation on '*(tab + ((sizetype)i + 1u) * 4u)' may be undefined [-Wsequence-point] I want to swap these two integer arrays elements without temporary variable and without violation of ANSI C. Program still works, but is it ok? 回答1: Your code relies on behaviour that is not covered by the standard. So your code may behave differently on different compilers, different versions of the same compiler and even

问题 I am getting the warning: function used but not defined . I have static __inline__ in header file say a.h . The header file is included in a.c . I would like put all those inline function which are in header files into the .c files. Following code gives the idea of my problem. Orginal code: a.h: static __inline__ function1(){ function definition; } I changed: a.h: static function1(); a.c: #include "a.h" static function1(){ function definition; } On doing above I got the warning: warning: