gcc-warning

With GNU GCC 4.7.0+ I got a few strict aliasing warnings, which I would like to resolve. I have a payload (from hardware): unsigned char payload[davidlt::PAYLOAD_SIZE]; I had this line: *(uint32_t*)(payload + davidlt::DATA_OFFSET) = (pid & davidlt::PID_MASK) << davidlt::PID_SHIFT; This creates a pointer to a specific location in payload and 4 bytes are interpreted as uint32_t . A new value uint32_t type is calculated and replaced in the payload. I get: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing] I was hoping to solve it by using reinterpret

I have the following code: struct A { short b; }; struct B { double a; }; void foo (struct B* src) { struct B* b = src; struct A* a = (struct A*)src; b->a = sin(rand()); if(a->b == rand()) { printf("Where are you strict aliasing warnings?\n"); } } I'm compiling the code with the following command line: gcc -c -std=c99 -Wstrict-aliasing=2 -Wall -fstrict-aliasing -O3 foo.c I'm using GCC 4.5.0. I expected the compiler to print out the warning: warning: dereferencing type-punned pointer will break strict-aliasing rules But it never is. I can get the warning to be printed out for other cases, but I

Consider this situation: uint64_t add(uint32_t a, uint32_t b) { return a + b; // programmer neglected (uint64_t) a + b. } How do we get the C or C++ front-end of GCC (or of any other compiler) to warn about this situation: that an operation is being done in a narrow type that is immediately widened? I've read through the current GCC documentation, and tried various warnings like -Wconversion , but nothing. I am not aware of a flag to GCC that will cause a warning. The Coverity static analyzer will issue an OVERFLOW_BEFORE_WIDEN warning as this is flagged in the CERT standards. Disclaimer: I

Im trying to remove the first char of the string and keep the remainder, my current code doesnt compile and im confused on how to fix it. My code: char * newStr (char * charBuffer) { int len = strlen(charBuffer); int i = 1; char v; if(charBuffer[0] == 'A' || charBuffer[0] == 'Q'){ for(i=1;i<len;i++) v = v + charBuffer[i]; } v = v + '\0'; return v; } Gcc: "Warning: return makes pointer from integer without a cast" Also: "char * newStr (char * charBuffer)" needs to remain the same. Strings don't work like this in C. You're summing up all of the characters in the buffer into the v variable. You

I'm curious if there is an option to disable gcc warnings about a parameter not being valid for the language being compiled. Ex: cc1: warning: command line option "-Wno-deprecated" is valid for C++/Java/ObjC++ but not for C Our build system passes the warnings we have decided on globally across a build. We have both C/C++ code and the warnings get real annoying when trying to find actual warnings. Any suggestions? It seems to me that if there were such an option, there would have to be a further option to turn off warnings about that option, and so on infinitely. So I suspect there isn't.

int i = 3.1 / 2 does not cause any warnings,even with -Wall option.Sometimes,I would like to know where precision lose.Why gcc does not support this warning,while msvc support this one? thanks. EDIT: my gcc -v shows Configured with: ../../gcc-4.4.1/configure --prefix=/mingw --build=mingw32 --enable-languages=c,ada,c++,fortran,objc,obj-c++ --disable-nls --disable-win32-registry --enable-libgomp --enable-cxx-flags='-fno-function-sections -fno-data-sections' --disable-werror --enable-threads --disable-symvers --enable-version-specific-runtime-libs --enable-fully-dynamic-string --with-pkgversion=