I just saw this on the Go language site from http://golang.org/cmd/gc/
gives the overall design of the tool chain. Aside from a few adapted pieces, such as the optimizer, the Go compilers are wholly new programs.
The compiler reads in a set of Go files, typically suffixed ".go". They must all be part of one package. The output is a single intermediate file representing the "binary assembly" of the compiled package, ready as input for the linker (6l, etc.).
The generated files contain type information about the symbols exported by the package and about types used by symbols imported by the package from other packages. It is therefore not necessary when compiling client C of package P to read the files of P's dependencies, only the compiled output of P.
/quote notice that they removed the need for header files.
