All the stacktrace_entry query functions treat
errors other than memory allocation errors
as βno information availableβ and do not throw in that case.
Returns: The presumed or actual name of the source file ([cpp.predefined])
that lexically contains the expression or statement
whose evaluation is represented by *this, or an empty string.
Returns: 0, or a 1-based line number that lexically relates to the evaluation
represented by *this.
If source_file returns the presumed name of the source file,
returns the presumed line number;
if source_file returns the actual name of the source file,
returns the actual line number.