Line numbers (as returned by the predefined name
__LINE__ ) may be set by the directive #line whose syntax is described below.
#line constant "filename"
- The constant is a decimal integer. The number of the line that follows is considered
to be the value of the constant.
- The optional filename sets the name of file currently being preprocessed.
The predefined name __FILE__ subsequently returns
the specified value.
- If no filename is specified then the current file name is left unchanged.
- Macros occurring in a #line directive are expanded
prior to further processing of the directive.
- All subsequent messages emitted by the compiler make use of the specified line
number and file name.