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error zero-length printf format string Ballwin, Missouri

As you're using it here, you're using it as a kind of strcpy(), which, while technically valid, is a very odd way to use the standard library. When numeric arguments of format directives can be assumed to be bounded by less than the precision of their type, choosing an appropriate length modifier to the format specifier will reduce On Mon, Oct 11, 2010 at 12:52 PM, Markus Armbruster wrote: > Warns about this line in check-qjson.c: >    QObject *obj = qobject_from_json(""); > > The obvious fix (add We recommend upgrading to the latest Safari, Google Chrome, or Firefox.

Floating-point division by zero is not warned about, as it can be a legitimate way of obtaining infinities and NaNs. -Wsystem-headersPrint warning messages for constructs found in system header files. if (some_condition ()) foo (); bar (); /* Gotcha: this is not guarded by the "if". */ In the case of mixed tabs and spaces, the warning uses the -ftabstop= option This may be a security hole if the format string came from untrusted input and contains ‘%n’. (This is currently a subset of what -Wformat-nonliteral warns about, but in future warnings For example, GCC will warn about i being uninitialized in the following snippet only when -Winit-self has been specified: int f() { int i = i; return i; } -Wimplicit-intWarn when

Takes care of the common pun+dereference pattern in the front end: *(int*)&some_float. Ideone is powered by Sphere Engine™ Home Terms of use API Language FAQ Credits Feedback & Bugs desktop mobile 15, 0.02s, 1.07s × Report bug / make suggestion Close submit × What's the most recent specific historical element that is common between Star Trek and the real world? For instance, warn about use of variable length arrays, long long type, bool type, compound literals, designated initializers, and so on.

Disabling the error for this warning can result in poorly optimized code and is useful only in the case of very minor changes such as bug fixes to an existing code-base. For example, the placement new expression below is diagnosed because it attempts to construct an array of 64 integers in a buffer only 64 bytes large. A function returns normally if it doesn't contain an infinite loop or return abnormally by throwing, calling abort or trapping. Browse other questions tagged c gcc string-formatting printf gcc-warning or ask your own question.

Other than as expressed by the sequence point rules, the order of evaluation of subexpressions of an expression is not specified. the ‘_MIN’/‘_MAX’ macros in . Ross III 42.3k2099163 1 I know I can get rid of it, I was wondering why it was there to begin with –GuyGreer Mar 29 '12 at 14:38 3 I'd rather disable the flag only for check-qjson.o or more generically, remove -Werror for checks.

It's builtins only that are optimized away or otherwise inlined (printf, sprintf, etc.). the `_MIN'/`_MAX' macros in . It used to happen all the time with gcc 2.x and 3.x and -Wall. –R.. Level 3 (default for -Wstrict-aliasing): Should have very few false positives and few false negatives.

These warnings as well are possible only in optimizing compilation. On Sat, Oct 16, 2010 at 12:37 AM, Paolo Bonzini wrote: > On 10/15/2010 07:41 PM, Blue Swirl wrote: >> >> Which functions are optimized away and which aren't? > This option also warns when a non-volatile automatic variable might be changed by a call to longjmp. Some options, such as -Wall and -Wextra, turn on other options, such as -Wunused, which may turn on further options, such as -Wunused-value.

This is definitely a lesser offense. This warning is issued even if the definition itself provides a prototype. A bigger one is giving warnings on unused function arguments, which is inevitable whenever you're using function pointers that must conform to a particular signature. –R.. All these rules describe only a partial order rather than a total order, since, for example, if two functions are called within one expression with no sequence point between them, the

Also warn about constructions where there may be confusion to which if statement an else branch belongs. Warnings from -pedantic are given where they are required by the base standard. (It would not make sense for such warnings to be given only for features not in the specified For me, --disable-werror has been good enough. Each of these specific warning options also has a negative form beginning ‘-Wno-’ to turn off warnings; for example, -Wno-implicit.

The restrictions on `offsetof' may be relaxed in a future version of the C++ standard. -Winvalid-pchWarn if a precompiled header (see Precompiled Headers) is found in the search path but can't This warning is enabled by default in C++ and is enabled by either -Wall or -Wpedantic. -Wmisleading-indentation (C and C++ only)Warn when the indentation of the code does not reflect the Also, warn if a negative integer constant expression is implicitly converted to an unsigned type. This option can be used to suppress such a warning. -Wno-incompatible-pointer-types (C and Objective-C only)Do not warn when there is a conversion between pointers that have incompatible types.

In C++, warn if a non-static reference or non-static const member appears in a class without constructors. This includes standard functions, and others specified by format attributes (see Function Attributes), in the printf, scanf, strftime and strfmon (an X/Open extension, not in the C standard) families (or other However, the standards committee have ruled that function calls do not overlap. When GCC complains about legitimate empty format strings as soon as -Wall is turned on, it only leads to frustration with -Wall.

Note this option can only be used with the -Wuninitialized option, which in turn only works with -O1 and above. Markus Armbruster Oct. 13, 2010, 7:19 a.m. It warns about code that might break the strict aliasing rules that the compiler is using for optimization. Use this option to detect global functions that are not declared in header files. -Wmissing-noreturnWarn about functions which might be candidates for attribute noreturn.

If you wish to suppress it for one part of your application, you can do the following: #pragma GCC diagnostic ignored "-Wformat-zero-length" int main() { // code that produces a warning gcc/c-format.c contains a comment that says “If the format is an empty string, this should be counted similarly to the case of extra format arguments.” But those are not actually similar.