Use generics for providers API

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.

This CL creates the new API, but doesn't convert all of the callers.

[1] https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md#no-parameterized-methods)

Bug: 316410648
Test: builds
Change-Id: I3e30d68b966b730efd968166a38a25cc144bd6de

1 files changed, 25 insertions, 2 deletions

diff --git a/android/singleton.go b/android/singleton.go
index 7c6cf4fd6..8936cac65 100644
--- a/android/singleton.go
+++ b/android/singleton.go
@@ -20,6 +20,8 @@ import (
 
 // SingletonContext
 type SingletonContext interface {
+	blueprintSingletonContext() blueprint.SingletonContext
+
 	Config() Config
 	DeviceConfig() DeviceConfig
 
@@ -38,10 +40,12 @@ type SingletonContext interface {
 	// return value can always be type-asserted to the type of the provider.  The return value should
 	// always be considered read-only.  It panics if called before the appropriate mutator or
 	// GenerateBuildActions pass for the provider on the module.
-	ModuleProvider(module blueprint.Module, provider blueprint.ProviderKey) interface{}
+	ModuleProvider(module blueprint.Module, provider blueprint.AnyProviderKey) any
 
 	// ModuleHasProvider returns true if the provider for the given module has been set.
-	ModuleHasProvider(module blueprint.Module, provider blueprint.ProviderKey) bool
+	ModuleHasProvider(module blueprint.Module, provider blueprint.AnyProviderKey) bool
+
+	moduleProvider(module blueprint.Module, provider blueprint.AnyProviderKey) (any, bool)
 
 	ModuleErrorf(module blueprint.Module, format string, args ...interface{})
 	Errorf(format string, args ...interface{})
@@ -135,6 +139,10 @@ type singletonContextAdaptor struct {
 	ruleParams  map[blueprint.Rule]blueprint.RuleParams
 }
 
+func (s *singletonContextAdaptor) blueprintSingletonContext() blueprint.SingletonContext {
+	return s.SingletonContext
+}
+
 func (s *singletonContextAdaptor) Config() Config {
 	return s.SingletonContext.Config().(Config)
 }
@@ -282,3 +290,18 @@ func (s *singletonContextAdaptor) ModuleVariantsFromName(referer Module, name st
 	}
 	return result
 }
+
+func (s *singletonContextAdaptor) ModuleProvider(module blueprint.Module, provider blueprint.AnyProviderKey) any {
+	value, _ := s.SingletonContext.ModuleProvider(module, provider)
+	return value
+}
+
+// ModuleHasProvider returns true if the provider for the given module has been set.
+func (s *singletonContextAdaptor) ModuleHasProvider(module blueprint.Module, provider blueprint.AnyProviderKey) bool {
+	_, ok := s.SingletonContext.ModuleProvider(module, provider)
+	return ok
+}
+
+func (s *singletonContextAdaptor) moduleProvider(module blueprint.Module, provider blueprint.AnyProviderKey) (any, bool) {
+	return s.SingletonContext.ModuleProvider(module, provider)
+}