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

android/provider.go

@@ -0,0 +1,120 @@
+package android
+
+import (
+	"github.com/google/blueprint"
+)
+
+// OtherModuleProviderContext is a helper interface that is a subset of ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext for use in OtherModuleProvider.
+type OtherModuleProviderContext interface {
+	otherModuleProvider(m blueprint.Module, provider blueprint.AnyProviderKey) (any, bool)
+}
+
+var _ OtherModuleProviderContext = BaseModuleContext(nil)
+var _ OtherModuleProviderContext = ModuleContext(nil)
+var _ OtherModuleProviderContext = BottomUpMutatorContext(nil)
+var _ OtherModuleProviderContext = TopDownMutatorContext(nil)
+
+// OtherModuleProvider reads the provider for the given module.  If the provider has been set the value is
+// returned and the boolean is true.  If it has not been set the zero value of the provider's type  is returned
+// and the boolean is false.  The value returned may be a deep copy of the value originally passed to SetProvider.
+//
+// OtherModuleProviderContext is a helper interface that accepts ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext.
+func OtherModuleProvider[K any](ctx OtherModuleProviderContext, module blueprint.Module, provider blueprint.ProviderKey[K]) (K, bool) {
+	value, ok := ctx.otherModuleProvider(module, provider)
+	if !ok {
+		var k K
+		return k, false
+	}
+	return value.(K), ok
+}
+
+// ModuleProviderContext is a helper interface that is a subset of ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext for use in ModuleProvider.
+type ModuleProviderContext interface {
+	provider(provider blueprint.AnyProviderKey) (any, bool)
+}
+
+var _ ModuleProviderContext = BaseModuleContext(nil)
+var _ ModuleProviderContext = ModuleContext(nil)
+var _ ModuleProviderContext = BottomUpMutatorContext(nil)
+var _ ModuleProviderContext = TopDownMutatorContext(nil)
+
+// ModuleProvider reads the provider for the current module.  If the provider has been set the value is
+// returned and the boolean is true.  If it has not been set the zero value of the provider's type  is returned
+// and the boolean is false.  The value returned may be a deep copy of the value originally passed to SetProvider.
+//
+// ModuleProviderContext is a helper interface that accepts ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext.
+func ModuleProvider[K any](ctx ModuleProviderContext, provider blueprint.ProviderKey[K]) (K, bool) {
+	value, ok := ctx.provider(provider)
+	if !ok {
+		var k K
+		return k, false
+	}
+	return value.(K), ok
+}
+
+type SingletonModuleProviderContext interface {
+	moduleProvider(blueprint.Module, blueprint.AnyProviderKey) (any, bool)
+}
+
+var _ SingletonModuleProviderContext = SingletonContext(nil)
+var _ SingletonModuleProviderContext = (*TestContext)(nil)
+
+// SingletonModuleProvider wraps blueprint.SingletonModuleProvider to provide a type-safe method to retrieve the value
+// of the given provider from a module using a SingletonContext.  If the provider has not been set the first return
+// value will be the zero value of the provider's type, and the second return value will be false.  If the provider has
+// been set the second return value will be true.
+func SingletonModuleProvider[K any](ctx SingletonModuleProviderContext, module blueprint.Module, provider blueprint.ProviderKey[K]) (K, bool) {
+	value, ok := ctx.moduleProvider(module, provider)
+	if !ok {
+		var k K
+		return k, false
+	}
+	return value.(K), ok
+}
+
+// SetProviderContext is a helper interface that is a subset of ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext for use in SetProvider.
+type SetProviderContext interface {
+	SetProvider(provider blueprint.AnyProviderKey, value any)
+}
+
+var _ SetProviderContext = BaseModuleContext(nil)
+var _ SetProviderContext = ModuleContext(nil)
+var _ SetProviderContext = BottomUpMutatorContext(nil)
+var _ SetProviderContext = TopDownMutatorContext(nil)
+
+// SetProvider sets the value for a provider for the current module.  It panics if not called
+// during the appropriate mutator or GenerateBuildActions pass for the provider, if the value
+// is not of the appropriate type, or if the value has already been set.  The value should not
+// be modified after being passed to SetProvider.
+//
+// SetProviderContext is a helper interface that accepts ModuleContext, BottomUpMutatorContext, or
+// TopDownMutatorContext.
+func SetProvider[K any](ctx SetProviderContext, provider blueprint.ProviderKey[K], value K) {
+	ctx.SetProvider(provider, value)
+}
+
+var _ OtherModuleProviderContext = (*otherModuleProviderAdaptor)(nil)
+
+// An OtherModuleProviderFunc can be passed to NewOtherModuleProviderAdaptor to create an OtherModuleProviderContext
+// for use in tests.
+type OtherModuleProviderFunc func(module blueprint.Module, provider blueprint.AnyProviderKey) (any, bool)
+
+type otherModuleProviderAdaptor struct {
+	otherModuleProviderFunc OtherModuleProviderFunc
+}
+
+func (p *otherModuleProviderAdaptor) otherModuleProvider(module blueprint.Module, provider blueprint.AnyProviderKey) (any, bool) {
+	return p.otherModuleProviderFunc(module, provider)
+}
+
+// NewOtherModuleProviderAdaptor returns an OtherModuleProviderContext that proxies calls to otherModuleProvider to
+// the provided OtherModuleProviderFunc.  It can be used in tests to unit test methods that need to call
+// android.OtherModuleProvider.
+func NewOtherModuleProviderAdaptor(otherModuleProviderFunc OtherModuleProviderFunc) OtherModuleProviderContext {
+	return &otherModuleProviderAdaptor{otherModuleProviderFunc}
+}