I have a macro that passes the line number and file name to an error handler:
#define SYSTEM_FAILURE (error_code, comment) \
System_Failure((error_code), (comment), __LINE__, __FILE__);
How will the __LINE__ be resolved when used inside an inlined function?
file.h:
inline int divide(int x, int y)
{
if (y == 0)
{
SYSTEM_FAILURE(ENUM_DIVIDE_BY_ZERO, "divide by zero error");
}
return x/y;
}
Will __LINE__ contain the line number within the header file, or the line number of the source file where the inline function is called (assuming compiler does a "paste" in the source code)?
In C and C++, macros aren't (for the most part) evaluated with any knowledge of the actual code and are processed before the code (hence the name "preprocessor"). Therefore, __FILE__ would evaluate to "file.h", and __LINE__ would evaluate to the line number corresponding to the line on which SYSTEM_FAILURE appears in file.h.
Since macros are replaced by their definitions before compilation, the __LINE__ will contain the actual line of the file in which you used the macro. Inlining will not affect this behaviour at all.
__LINE__ will be the line of the header file since the preprocessor will evaluate it before the compiler will ever see it.
来源：https://stackoverflow.com/questions/11214260/behavior-of-line-in-inline-functions