if fr.Func != nil {
			// Use function-relative line numbering.
			// f:+2 means two lines into function f.
			// f:-1 should never happen, but be conservative.
			_, entryLine := fr.Func.FileLine(fr.Entry)
			loc = fmt.Sprintf("%s.%s:%+d", path, fname, fr.Line-entryLine)
		} else {
			// The function is non-Go code or is fully inlined:
			// use absolute line number within enclosing file.
			loc = fmt.Sprintf("%s.%s:=%d", path, fname, fr.Line)