Moves the Protobuf & gRPC dependencies to a separate file which uses
buildGo.external to build the dependencies.
The versions are pinned at master of 2019-11-26.
Adds two new parameters to buildGo.external:
* `srcOnly` toggles whether the created derivation should contain only
the source code, or the built package.
This is useful in situations where some sub-packages of a larger
package are needed and the build should be deferred to the package
depending on them.
It defaults to false, meaning that external packages are built by
default.
* `targets` controls which "sub-packages" of the target package are
built. It defaults to building all sub-packages.
Adds a buildGo.external function that can build packages following the
default go-tool package layout. Dependencies work the same way as they
do for other buildGo-packages, but instead of being passed straight to
the compiler a fake GOPATH is assembled using a symlink forest.
External currently supports very few direct configuration options and
was primarily created to build the protobuf packages, but it is also
useful for including external dependencies in buildGo-native projects.
The previous complex build logic for the protobuf package has been
replaced with a call to `external`.
Adds a 'buildGo.proto' function which takes a single .proto file as
its source and generates a corresponding Go library which can then be
imported.
'proto' takes these arguments (Yants-style type definition):
struct "protoArgs" {
# required:
name = string;
proto = path;
# optional:
extraDeps = list goLib; # defaults to [ ]
protocFlags = option string;
}
Note that proto libraries will automatically have dependencies for the
required protobuf Go libraries added to them.
gRPC is not (yet) supported.
