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Gcc #error #warning

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Not the answer you're looking for? This option is enabled by -Wall. For example, warn if int malloc() is cast to anything *. -Wc++-compat (C and Objective-C only)Warn about ISO C constructs that are outside of the common subset of ISO C and This warning is enabled by -Wextra in C99 and C++11 modes (and newer). -Wshift-overflow-Wshift-overflow=nWarn about left shift overflows.

Regards, Fernando Reply david collier says: September 13, 2011 at 4:00 am Very interesting…. If the initializer is zero, the warning is omitted. These warnings help you find at compile time code that can try to write into a stri Next:Line Control, Previous:Conditionals, Up:Top 5 Diagnostics The directive ‘#error’ causes the preprocessor to report Which functions are checked without format attributes having been specified depends on the standard version selected, and such checks of functions without the attribute specified are disabled by -ffreestanding or -fno-builtin. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

Gcc Disable Warning Pragma

Pedantic warnings are also disabled in the expression that follows __extension__. For example: abs (x) >= 0. This warning is enabled by -Wall. -Wcast-qualWarn whenever a pointer is cast so as to remove a type qualifier from the target type.

Deleting the Release mode only does it for the current project, so you can still use it in other projects. See Options Controlling C Dialect. -Wformat=1-WformatOption -Wformat is equivalent to -Wformat=1, and -Wno-format is equivalent to -Wformat=0. These functions changed semantics in GCC 4.4. -WtrigraphsWarn if any trigraphs are encountered that might change the meaning of the program (trigraphs within comments are not warned about). Gcc Attribute Unused To suppress the warning, you need to provide a default case with assert(0) or similar code.

share|improve this answer answered Jan 24 '09 at 3:17 Stephen Doyle 2,9551215 Amen, your code should be warning-free with at least -Wall (although some of the stuff that -Wextra Gcc Pedantic This warning is also enabled by -Wextra. -WmainWarn if the type of `main' is suspicious. `main' should be a function with external linkage, returning int, taking either zero arguments, two, or This construct, known from C++, was introduced with ISO C99 and is by default allowed in GCC. why not find out more Note that there may be no warning about a variable that is used only to compute a value that itself is never used, because such computations may be deleted by data

Thus this warning depends on the optimization level. Gcc Compiler Flag Besides specific evolutions, which benefits are there for making my Pokemon happy? See Mixed Declarations. -WundefWarn if an undefined identifier is evaluated in an `#if' directive. -Wno-endif-labelsDo not warn whenever an `#else' or an `#endif' are followed by text. -WshadowWarn whenever a local Note that it does not warn about all cases where the code might overflow: it only warns about cases where the compiler implements some optimization.

Gcc Pedantic

Some traditional implementations do not recognize #elif, so this option suggests avoiding it altogether. https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html This level of -Wstrict-overflow is enabled by -Wall; higher levels are not, and must be explicitly requested. -Wstrict-overflow=2Also warn about other cases where a comparison is simplified to a constant. Gcc Disable Warning Pragma This warning detects various mistakes such as: int i = 1; ... Gcc Pragma Why would a language be undubbable by universal (machine) translator?

This option is only supported for C and Objective-C. The limit applies after string constant concatenation, and does not count the trailing NUL. ISO C prohibits qualified void return types on function definitions, so such return types always receive a warning even without this option. You would have one branch for debugging an issue. Gcc Wall

option is a double quoted string that matches the command-line option. #pragma GCC diagnostic warning "-Wformat" #pragma GCC diagnostic error "-Wformat" #pragma GCC diagnostic ignored "-Wformat" Note that these pragmas override This option is implied by -pedantic, and can be disabled with -Wno-overlength-strings. Previous:Non-bugs, Up:Trouble 12.9 Warning Messages and Error Messages The GNU compiler can produce two kinds of diagnostics: errors This warning is enabled by default. -Wshift-negative-valueWarn if left shifting a negative value. This option also warns when a non-volatile automatic variable might be changed by a call to longjmp.

When you have a bunch of modified files you can choose to add/remove all or part of any changed file to/from the staging area. Gcc Wconversion What is annoying is having code that compiles on 2 platforms, one which supports #warning and one which doesn't… worst case I end up with #ifdef _COMPILER_A #warning Warning.HI: A Hi May still have many false positives (not as many as level 1 though), and few false negatives (but possibly more than level 1).

The Key Final Step While the above are useful constructs, the real power of #warning comes if you configure your compiler to treat warnings as errors for the release build.

They soon find that it does not do quite what they want: it finds some non-ISO practices, but not all—only those for which ISO C requires a diagnostic, and some others This warning is comparable to warning about every identifier that contains the letter O because it might be confused with the digit 0, and so is not the default, but may hexadecimal or octal values, which typically represent bit patterns, are not warned about. Gcc Wextra This warning is enabled by -Wall. -Wunused-but-set-parameterWarn whenever a function parameter is assigned to, but otherwise unused (aside from its declaration).

Get interrupted by something else that the boss says is more important. Also warn for dangerous uses of the GNU extension to ?: with omitted middle operand. Warns about incomplete types. For instance, the following comparison is always false: int n = 5; ...

These occur after the evaluation of a full expression (one which is not part of a larger expression), after the evaluation of the first operand of a &&, ||, ? : However, note that using -Wall in conjunction with this option will not warn about unknown pragmas in system headers—for that, -Wunknown-pragmas must also be used. -Wfloat-equalWarn if floating point values are It warns about code which might break the strict aliasing rules that the compiler is using for optimization. If you want to warn about code that uses the uninitialized value of the variable in its own initializer, use the -Winit-self option.

This warning is also bypassed for nested functions because that feature is already a GCC extension and thus not relevant to traditional C compatibility. -Wtraditional-conversion (C and Objective-C only)Warn if a For example, warn if a char * is cast to an int * on machines where integers can only be accessed at two- or four-byte boundaries. -Wwrite-stringsWhen compiling C, give string To get other -Wextra warnings without this one, use `-Wextra -Wno-missing-field-initializers'. -Wmissing-noreturnWarn about functions which might be candidates for attribute noreturn. Sometimes when this happens it is possible to rearrange the fields of the structure to reduce the padding and so make the structure smaller. -Wredundant-declsWarn if anything is declared more than

This warning turns on -Wnarrowing and is enabled by -Wall. -Wc++14-compat (C++ and Objective-C++ only)Warn about C++ constructs whose meaning differs between ISO C++ 2011 and ISO C++ 2014. For example, warn if storage-class specifiers like static are not the first things in a declaration. Unlike level 1, it only warns when an address is taken. more stack exchange communities company blog Stack Exchange Inbox Reputation and Badges sign up log in tour help Tour Start here for a quick overview of the site Help Center Detailed