The line number specifies the name involved. In the example, 1 is foo.

Next, cgo must learn the details of each type, variable, function, or
constant. It can do this by reading object files. If cgo has decided
that t1 is a type, v2 and v3 are variables or functions, and i4, i5
are integer constants, u6 is an unsigned integer constant, and f7 and f8