Support __LINE__ macro for the caller of a macro

[swoods-nv]

[Posted on behalf of a user without GH account]

We are using the __LINE__ macro in combination with GPU printing to implement an assert in shader code. The assert roughly looks like this:

#define STR2(X) # X
#define STR(X) STR2(X)
#define CARB_ASSERT(X) \                     //<-- let's say this is line 100 in our file
if (!(X)) { \
        println_assert("Assertion triggered in " __FILE__ ":" STR(__LINE__) ", expression : " #X); \
}

this assert is used just as expected

void main(dispatchIdx...)
{
    float3 radiance = compute();
    CARB_ASSERT(!isNanOrInf(radiance)); ///< will show line 100 from different file, not this line
}

I browsed tests\preprocessor\special-macro-complex.slang but didn't find a matching test for it. I did find this comment which shows the usage of LINE in a macro but probably expects a different result:

// LINE number will be for the macro invocation, not the expansion

[csyonghe]

This is duplicate with #2134

[swoods-nv]

Should we raise the priority / pull it in to Q2, in that case? It affects a current client, but they have a workaround.

[csyonghe]

Yes, we can try to fix this in Q2.