ICC 2017 Preprocessor bug with tokens concatenation

[Andrei_P_1]

Hello. I'm found a bug with tokens concatenation. Simple example to reproduce:

#define test(x, y) sizeof(x##y)
#define test2(x, y) sizeof(##x##y)
int main()
{
	int a = test(in, t); // works fine
	int b = test2(in, t); // error
}

Compilation on windows (msvc integration):

1>  main.cpp
1>..\main.cpp(6): error : identifier "in" is undefined
1>    	int b = test2(in, t); // error
1>    	        ^
1>  
1>..\main.cpp(6): error : expected a ")"
1>    	int b = test2(in, t); // error

Preprocessor output to file:

#line 1 "..\\main.cpp"

int main()
{
	int a = sizeof(int); 
	int b = sizeof(int); 
}

[Judith_W_Intel]

You are correct that we should try to emulate what Microsoft is doing, but your code is definitely incorrect according to the standard.

The GNU compiler gives this error:

sptxl15-134> g++ -c main.cpp
main.cpp:9:1: error: pasting "(" and "in" does not give a valid preprocessing token
sptxl15-135>

The token paste operator must result in a valid token and the second expansion does not have one.

https://gcc.gnu.org/onlinedocs/cpp/Concatenation.html

[Andrei_P_1]

Thanks for the answer. I am found it by accident, when a working project didn't builded after replacing MSVC to ICC 17. The similar code also worked with ICC for linux. So, I was thinked that it's a bug. But in fact, the work of this code is not necessary, this situation was caused by a typo when copypasting. It will be enough to display a correct error message like it does GCC.