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Gcc Error Messages

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This warning is enabled by -Wall. -WunusedAll the above -Wunused options combined. Thanks to Dexen. The clang command-line compiler driver uses this information to print "point diagnostics". (IDEs can use the information to display in-line error markup.) This is nice because it makes it very easy 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. check over here

Example: #include int main (void) { if (1) { printf ("Hello World!\n"); return 0; /* no closing brace */ } An additional closing brace is needed in this program to This error will cause you no end of trouble. To suppress this warning use the unused attribute (see Variable Attributes). -Wunused-const-variable-Wunused-const-variable=nWarn whenever a constant static variable is unused aside from its declaration. -Wunused-const-variable=1 is enabled by -Wunused-variable for C, but It is, in my opinion, a clain that is just plain wrong.

Gcc Warnings

Many issues can be solved through a make clean && make or just a touch myproject.pro && make. Also warn if a comparison like x<=y<=z appears; this is equivalent to (x<=y ? 1 : 0) <= z, which is a different interpretation from that of ordinary mathematical notation. However, note that using -Wall in conjunction with this option does not warn about unknown pragmas in system headers—for that, -Wunknown-pragmas must also be used. -Wtautological-compareWarn if a self-comparison always evaluates

There are two pieces of good news though. Subscribed! As far as a command-line compiler goes, this basically boils down to making the diagnostics (error and warning messages) generated by the compiler be as useful as possible. Clang Warnings Note that non-constant initializers are allowed in C++. <<< previous table of contents next >>> Published under the terms of the GNU General Public License Design by

This means that you have not followed the basic rules of C. Gcc Error Message Format A concrete example of this: chatmaster.cpp:220: error: no matching function for call to ‘ChatMaster::connect(const ContactList*&, const char [35], ChatMaster* const, const char [39])’
/usr/lib/qt3/include/qobject.h:116: note: candidates are: static bool QObject::connect(const Here is one example of how this can happen: { int x; switch (y) { case 1: x = 1; break; case 2: x = 4; break; case 3: x = browse this site character constant too long In C and C++ character codes are written using single quotes, e.g. 'a' gives the ASCII code for the letter a (67), and '\n' gives the ASCII

See also -Wvla-larger-than=n. -Warray-bounds-Warray-bounds=nThis option is only active when -ftree-vrp is active (default for -O2 and above). Gcc Options 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. In some cases, however, the C and C++ standards specify that certain extensions are forbidden, and a diagnostic must be issued by a conforming compiler. typedef struct { ... } Foo; void function() { struct Foo foo; … } The solution is trivial - but hard to spot if you don't know what to look for.

Gcc Error Message Format

A feature to report any failure to conform to ISO C might be useful in some instances, but would require considerable additional work and would be quite different from -Wpedantic. http://stackoverflow.com/questions/656420/is-there-any-way-to-get-readable-gcc-error-and-warning-output-at-the-command-lin Qt Peculiarities Sometimes Qt's build system and GCC steps on one anothers toes, resulting in confusion. Gcc Warnings warning: implicit declaration of function `printf' You must have a #include at the top of the file. Gcc Pragma Warning c++ c gcc gcc-warning share|improve this question asked Mar 17 '09 at 23:27 mikeh 1 I just make the window very wide... –i_am_jorf Mar 17 '09 at 23:33

If you have implemented and declared the member foo, you are probably trying to use a method from a forward declared class. check my blog Also, if MY_CC_PREFIX is not defined, you will just use g++ as expected. –Ryan Mar 25 '13 at 18:42 add a comment| up vote 3 down vote check diagcc out, you Because these warnings depend on optimization, the exact variables or elements for which there are warnings depends on the precise optimization options and version of GCC used. Note, however, that in this case it has suppressed the more informative error. Gcc Wall

The maximum length of string arguments can be bounded by specifying the precision in the format directive. There is a way to reach the end of a non-void function without returning something. Example: struct btree * data; int main (void) { data->size = 0; /* incomplete type */ return 0; } This program has a forward declaration of the btree struct data. this content The next lines indicate the errors/warnings that occur in that function and program file.

This is not the case if the warnings are only enabled by the -Wall command-line option. -Wno-pragmasDo not warn about misuses of pragmas, such as incorrect parameters, invalid syntax, or conflicts Gcc #error Turn this array into a matrix How do you indicate that an item is not selectable? warning: control reaches end of non-void function You must have a return statement at the end of main() or any function that returns a value.

This warning is enabled by -Wall. -Wimplicit-fallthrough-Wimplicit-fallthrough is the same as -Wimplicit-fallthrough=3 and -Wno-implicit-fallthrough is the same as -Wimplicit-fallthrough=0. -Wimplicit-fallthrough=nWarn when a switch case falls through.

The warning/error lines following the function/program file identification line is a record of the program file containing the error; the line number in the source file at which the error occurred; Note, that even seemingly correct code involving signed integers could cause a warning: void func (signed int n) { if (n < 500) { p = alloca (n); f (p); } What now? Cflags The C standard specifies that such arguments are ignored.

Yet it's a clear violation of C99's paragraph 7.26.3. std::string foo;
printf( "Foo: %s\n", foo ); The result in run-time can be something like Illegal instruction (core dumped). For instance, warn about use of anonymous structures and unions, _Atomic type qualifier, _Thread_local storage-class specifier, _Alignas specifier, Alignof operator, _Generic keyword, and so on. have a peek at these guys It is not specified when between sequence points modifications to the values of objects take effect.

Other than as expressed by the sequence point rules, the order of evaluation of subexpressions of an expression is not specified. case 5: i = 5; ... } This warning is enabled by default for C and C++ programs. -Wsync-nand (C and C++ only)Warn when __sync_fetch_and_nand and __sync_nand_and_fetch built-in functions are used. Warning: ‘foo’ is used uninitialized in this function Warning message: ‘foo’ is used uninitialized in this function . This warning is also enabled by -Wall. -Wimplicit (C and Objective-C only)Same as -Wimplicit-int and -Wimplicit-function-declaration.

Because their types are incompatible, if a programmer accidentally uses one in place of the other, type checking will catch that and emit an error or warning. There are even special pieces of software called debuggers that have been written to help people hunt for run time errors. By default, this warning is enabled and is treated as an error. -Wno-coverage-mismatch can be used to disable the warning or -Wno-error=coverage-mismatch can be used to disable the error. Moving on with a missing opening parenthesis:
static int foo (int a, int b) { return a + b; }
int bar (int a) { return foo a);

This could surely be remedied by someone with better bash-fu. #!/bin/bash # SUBSTITUTION RULES: # Note: All substitution rules must end in a semi-colon, inside of the closing quote subColonSpace='s/: /:\n Unknown string arguments whose length cannot be assumed to be bounded either by the directive's precision, or by a finite set of string literals they may evaluate to, or the character In C++ the return statement can be omitted from the main function--the return value of the C++ main function defaults to 0 if unspecified. This includes an expression-statement or the left-hand side of a comma expression that contains no side effects.

switch (cond) { case 1: if (i > 3) { bar (5); break; } else if (i < 1) { bar (0); } else return; default: ... } Since there are An optimization that assumes that signed overflow does not occur is perfectly safe if the values of the variables involved are such that overflow never does, in fact, occur. This warning is also enabled by -Wunused together with -Wextra. -Wunused-but-set-variableWarn whenever a local variable is assigned to, but otherwise unused (aside from its declaration). I have seen this twice.

This error message isn't telling you about an error in your code, it's telling you about an internal failure (almost certainly a bug) in the compiler. Warns about incomplete types. Use of these macros in user code might normally lead to spurious warnings, however GCC's integrated preprocessor has enough context to avoid warning in these cases. For example: $ clang -fsyntax-only t.cpp t.cpp:12:7: error: incompatible type assigning 'vector', expected 'std::string' (aka 'class std::basic_string') str = vec; ^ ~~~ Fix-it Hints "Fix-it" hints provide advice for fixing small,

To suppress the warning, you need to provide a default case with assert(0) or similar code.