How to use C++ 20 in g++
C++20 features are available since GCC 8. To enable C++20 support, add the command-line parameter -std=c++20 For G++ 9 and earlier use -std=c++2a Or, to enable GNU extensions in addition to C++20 features, add -std=gnu++20
g++
“not declared in this scope” error with templates and inheritance [duplicate]
myOption is not a dependent name, i.e. it doesn’t depend on the template arguments explicitly so the compiler tries to look it up early. You must make it a dependent name: template <typename InterfaceType> void ChildClass<InterfaceType>::set() { this->myOption = 10; } Now it depends on the type of this and thus on the template arguments. … Read more
g++ linking order dependency when linking c code to c++ code
The order you specify object files and libraries is VERY important in GCC – if you haven’t been bitten by this before you have lead a charmed life. The linker searches symbols in the order that they appear, so if you have a source file that contains a call to a library function, you need … Read more
What does the >?= operator mean?
It’s a GCC extension that was removed in GCC version 4.2 and later. The equivalent of a >?= b is a = max(a,b); There is also a very similar operator a <?= b which means the same as a = min(a, b);.
What’s the best g++ optimization level when building a debug target?
GCC 4.8 introduces a new optimization level: -Og for the best of both worlds. -Og Optimize debugging experience. -Og enables optimizations that do not interfere with debugging. It should be the optimization level of choice for the standard edit-compile-debug cycle, offering a reasonable level of optimization while maintaining fast compilation and a good debugging experience. … Read more
Why does alias template give a conflicting declaration?
The problem relies on SFINAE. If you rewrite your member function to be value_t<S<T>>, like the outside declaration, then GCC will happily compile it: template<class T> struct S { using value_type = int; static const value_t<S<T>> C = 0; }; template<class T> const value_t<S<T>> S<T>::C; Because the expression is now functionally equivalent. Things like substitution … Read more
How to use multiple versions of GCC
Refer “How to install multiple versions of GCC” here in the GNU GCC FAQ. There’s also a white paper here.
std::this_thread::sleep_for() and GCC
Confirmed that it doesn’t work here as well. (Recent GCC 4.6 snapshot). You could do the obvious and simply define it before you include any std:: headers. A bit dirty but will work until GCC fixes it (unless this is intended behavior). The #define shouldn’t break anything anyways. Either in source or -D_GLIBCXX_USE_NANOSLEEP flag to … Read more
C to C++ table inline definition
You can mix C and C++ code easily. You should keep the C code to be compiled with C compiler (gcc), rest of the code can be C++ and be compiled with C++ compiler (g++). then link all object (.o) files together. like this: file name: a.c const char* aTable[12] = { [4]=”seems”, [6]=” it … Read more
Is there an easy way to COLOR-CODE the compiler outputs?
Gcc 4.9 seems to have added this feature via the -fdiagnostics-color flag: