When setProvider() is called, hash the provider and store the hash in
the module. Then after the build is done, hash all the providers again
and compare the hashes. It's an error if they don't match.
Also add a flag to control it in case this check gets slow as we convert
more things to providers. However right now it's fast (unnoticable
in terms of whole seconds) so just have the flag always enabled.
Bug: 322069292
Test: m nothing
Change-Id: Ie4e806a6a9f20542ffcc7439eef376d3fb6a98ca
Now that nothing calls *Context.*Provider directly, make the blueprint
methods return a nil any interface instead of the zero value that was
constructed via reflection. The type-safe wrappers will return a
zero value that can be constructed without any reflection or copying.
Bug: 316410648
Test: provider_test.go
Change-Id: I0abde5bacab9964a83f03c1644b51295a6c34d0b
Using generics for the providers API allows a type to be associated
with a ProviderKey, resulting in a type-safe API without that doesn't
require runtime type assertions by every caller.
Unfortunately, Go does not allow generic types in methods, only in
functions [1]. This prevents a type-safe API on ModuleContext, and
requires moving the API to be functions that take a ModuleContext as
a parameter.
[1] https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md#no-parameterized-methods)
Bug: 316410648
Test: provider_test.go
Change-Id: Ide91de9f2a2a7d075b05e287c7cc86b395db0edb
Providers are a new concept for Blueprint, based on providers in Bazel:
https://docs.bazel.build/versions/master/skylark/rules.html#providers
Providers aim to simplify the interaction between modules by replacing
type asserting to arbitrary interfaces with requesting optional data
objects from modules. This will also move Blueprint closer to supporting
incremental analysis by serializing the providers and only rerunning
the analysis phase on modules whose inputs have changed.
Change-Id: I39f5f78b372412a7dbf151ceccb3f917f6c874bf
