Merge of cross-cutting work for new provider naming

This merge introduces various work across the whole codebase to prepare
codepaths to deal with the new decentralized provider naming scheme and
to use the new provider installation codepaths that are aware of the
new scheme.

The incoming branch of commits here (the second commit in the merge)
contains a period where the tests were not passing as a tradeoff to keep
the individual changes separated while accepting that that makes that
part of the history unsuitable for "git bisect" usage. If you are using
git bisect on this portion of the history, exclude the commits from
the incoming branch.

Author: apparentlymart

addrs/provider.go

@@ -23,21 +23,48 @@ type Provider struct {
 // not have an explicit hostname.
 const DefaultRegistryHost = svchost.Hostname("registry.terraform.io")
 
+// BuiltInProviderHost is the pseudo-hostname used for the "built-in" provider
+// namespace. Built-in provider addresses must also have their namespace set
+// to BuiltInProviderNamespace in order to be considered as built-in.
+const BuiltInProviderHost = svchost.Hostname("terraform.io")
+
+// BuiltInProviderNamespace is the provider namespace used for "built-in"
+// providers. Built-in provider addresses must also have their hostname
+// set to BuiltInProviderHost in order to be considered as built-in.
+//
+// The this namespace is literally named "builtin", in the hope that users
+// who see FQNs containing this will be able to infer the way in which they are
+// special, even if they haven't encountered the concept formally yet.
+const BuiltInProviderNamespace = "builtin"
+
 // LegacyProviderNamespace is the special string used in the Namespace field
 // of type Provider to mark a legacy provider address. This special namespace
 // value would normally be invalid, and can be used only when the hostname is
 // DefaultRegistryHost because that host owns the mapping from legacy name to
 // FQN.
 const LegacyProviderNamespace = "-"
 
-// String returns an FQN string, indended for use in output.
+// String returns an FQN string, indended for use in machine-readable output.
 func (pt Provider) String() string {
 	if pt.IsZero() {
 		panic("called String on zero-value addrs.Provider")
 	}
 	return pt.Hostname.ForDisplay() + "/" + pt.Namespace + "/" + pt.Type
 }
 
+// ForDisplay returns a user-friendly FQN string, simplified for readability. If
+// the provider is using the default hostname, the hostname is omitted.
+func (pt Provider) ForDisplay() string {
+	if pt.IsZero() {
+		panic("called ForDisplay on zero-value addrs.Provider")
+	}
+
+	if pt.Hostname == DefaultRegistryHost {
+		return pt.Namespace + "/" + pt.Type
+	}
+	return pt.Hostname.ForDisplay() + "/" + pt.Namespace + "/" + pt.Type
+}
+
 // NewProvider constructs a provider address from its parts, and normalizes
 // the namespace and type parts to lowercase using unicode case folding rules
 // so that resulting addrs.Provider values can be compared using standard
@@ -64,6 +91,30 @@ func NewProvider(hostname svchost.Hostname, namespace, typeName string) Provider
 	}
 }
 
+// ImpliedProviderForUnqualifiedType represents the rules for inferring what
+// provider FQN a user intended when only a naked type name is available.
+//
+// For all except the type name "terraform" this returns a so-called "default"
+// provider, which is under the registry.terraform.io/hashicorp/ namespace.
+//
+// As a special case, the string "terraform" maps to
+// "terraform.io/builtin/terraform" because that is the more likely user
+// intent than the now-unmaintained "registry.terraform.io/hashicorp/terraform"
+// which remains only for compatibility with older Terraform versions.
+func ImpliedProviderForUnqualifiedType(typeName string) Provider {
+	switch typeName {
+	case "terraform":
+		// Note for future maintainers: any additional strings we add here
+		// as implied to be builtin must never also be use as provider names
+		// in the registry.terraform.io/hashicorp/... namespace, because
+		// otherwise older versions of Terraform could implicitly select
+		// the registry name instead of the internal one.
+		return NewBuiltInProvider(typeName)
+	default:
+		return NewDefaultProvider(typeName)
+	}
+}
+
 // NewDefaultProvider returns the default address of a HashiCorp-maintained,
 // Registry-hosted provider.
 func NewDefaultProvider(name string) Provider {
@@ -74,6 +125,16 @@ func NewDefaultProvider(name string) Provider {
 	}
 }
 
+// NewBuiltInProvider returns the address of a "built-in" provider. See
+// the docs for Provider.IsBuiltIn for more information.
+func NewBuiltInProvider(name string) Provider {
+	return Provider{
+		Type:      MustParseProviderPart(name),
+		Namespace: BuiltInProviderNamespace,
+		Hostname:  BuiltInProviderHost,
+	}
+}
+
 // NewLegacyProvider returns a mock address for a provider.
 // This will be removed when ProviderType is fully integrated.
 func NewLegacyProvider(name string) Provider {
@@ -109,6 +170,17 @@ func (pt Provider) IsZero() bool {
 	return pt == Provider{}
 }
 
+// IsBuiltIn returns true if the receiver is the address of a "built-in"
+// provider. That is, a provider under terraform.io/builtin/ which is
+// included as part of the Terraform binary itself rather than one to be
+// installed from elsewhere.
+//
+// These are ignored by the provider installer because they are assumed to
+// already be available without any further installation.
+func (pt Provider) IsBuiltIn() bool {
+	return pt.Hostname == BuiltInProviderHost && pt.Namespace == BuiltInProviderNamespace
+}
+
 // LessThan returns true if the receiver should sort before the other given
 // address in an ordered list of provider addresses.
 //

addrs/provider_test.go

@@ -7,6 +7,84 @@ import (
 	svchost "github.com/hashicorp/terraform-svchost"
 )
 
+func TestProviderString(t *testing.T) {
+	tests := []struct {
+		Input Provider
+		Want  string
+	}{
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "hashicorp",
+			},
+			DefaultRegistryHost.ForDisplay() + "/hashicorp/test",
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  "registry.terraform.com",
+				Namespace: "hashicorp",
+			},
+			"registry.terraform.com/hashicorp/test",
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "othercorp",
+			},
+			DefaultRegistryHost.ForDisplay() + "/othercorp/test",
+		},
+	}
+
+	for _, test := range tests {
+		got := test.Input.String()
+		if got != test.Want {
+			t.Errorf("wrong result for %s\n", test.Input.String())
+		}
+	}
+}
+
+func TestProviderDisplay(t *testing.T) {
+	tests := []struct {
+		Input Provider
+		Want  string
+	}{
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "hashicorp",
+			},
+			"hashicorp/test",
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  "registry.terraform.com",
+				Namespace: "hashicorp",
+			},
+			"registry.terraform.com/hashicorp/test",
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "othercorp",
+			},
+			"othercorp/test",
+		},
+	}
+
+	for _, test := range tests {
+		got := test.Input.ForDisplay()
+		if got != test.Want {
+			t.Errorf("wrong result for %s\n", test.Input.String())
+		}
+	}
+}
+
 func TestProviderIsDefault(t *testing.T) {
 	tests := []struct {
 		Input Provider
@@ -46,6 +124,77 @@ func TestProviderIsDefault(t *testing.T) {
 	}
 }
 
+func TestProviderIsBuiltIn(t *testing.T) {
+	tests := []struct {
+		Input Provider
+		Want  bool
+	}{
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  BuiltInProviderHost,
+				Namespace: BuiltInProviderNamespace,
+			},
+			true,
+		},
+		{
+			Provider{
+				Type:      "terraform",
+				Hostname:  BuiltInProviderHost,
+				Namespace: BuiltInProviderNamespace,
+			},
+			true,
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  BuiltInProviderHost,
+				Namespace: "boop",
+			},
+			false,
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: BuiltInProviderNamespace,
+			},
+			false,
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "hashicorp",
+			},
+			false,
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  "registry.terraform.com",
+				Namespace: "hashicorp",
+			},
+			false,
+		},
+		{
+			Provider{
+				Type:      "test",
+				Hostname:  DefaultRegistryHost,
+				Namespace: "othercorp",
+			},
+			false,
+		},
+	}
+
+	for _, test := range tests {
+		got := test.Input.IsBuiltIn()
+		if got != test.Want {
+			t.Errorf("wrong result for %s\ngot:  %#v\nwant: %#v", test.Input.String(), got, test.Want)
+		}
+	}
+}
+
 func TestProviderIsLegacy(t *testing.T) {
 	tests := []struct {
 		Input Provider

backend/local/backend_apply_test.go

@@ -59,7 +59,7 @@ func TestLocal_applyBasic(t *testing.T) {
 	checkState(t, b.StateOutPath, `
 test_instance.foo:
   ID = yes
-  provider = provider["registry.terraform.io/-/test"]
+  provider = provider["registry.terraform.io/hashicorp/test"]
   ami = bar
 `)
 }
@@ -176,7 +176,7 @@ func TestLocal_applyError(t *testing.T) {
 	checkState(t, b.StateOutPath, `
 test_instance.foo:
   ID = foo
-  provider = provider["registry.terraform.io/-/test"]
+  provider = provider["registry.terraform.io/hashicorp/test"]
   ami = bar
 	`)
 }
@@ -226,7 +226,7 @@ func TestLocal_applyBackendFail(t *testing.T) {
 	checkState(t, "errored.tfstate", `
 test_instance.foo:
   ID = yes
-  provider = provider["registry.terraform.io/-/test"]
+  provider = provider["registry.terraform.io/hashicorp/test"]
   ami = bar
 	`)
 }

backend/local/backend_plan_test.go

@@ -216,7 +216,7 @@ func TestLocal_planDeposedOnly(t *testing.T) {
 			}`),
 			},
 			addrs.AbsProviderConfig{
-				Provider: addrs.NewLegacyProvider("test"),
+				Provider: addrs.NewDefaultProvider("test"),
 				Module:   addrs.RootModule,
 			},
 		)
@@ -660,7 +660,7 @@ func testPlanState() *states.State {
 			}`),
 		},
 		addrs.AbsProviderConfig{
-			Provider: addrs.NewLegacyProvider("test"),
+			Provider: addrs.NewDefaultProvider("test"),
 			Module:   addrs.RootModule,
 		},
 	)
@@ -687,7 +687,7 @@ func testPlanState_withDataSource() *states.State {
 			}`),
 		},
 		addrs.AbsProviderConfig{
-			Provider: addrs.NewLegacyProvider("test"),
+			Provider: addrs.NewDefaultProvider("test"),
 			Module:   addrs.RootModule,
 		},
 	)
@@ -704,7 +704,7 @@ func testPlanState_withDataSource() *states.State {
 			}`),
 		},
 		addrs.AbsProviderConfig{
-			Provider: addrs.NewLegacyProvider("test"),
+			Provider: addrs.NewDefaultProvider("test"),
 			Module:   addrs.RootModule,
 		},
 	)
@@ -731,7 +731,7 @@ func testPlanState_tainted() *states.State {
 			}`),
 		},
 		addrs.AbsProviderConfig{
-			Provider: addrs.NewLegacyProvider("test"),
+			Provider: addrs.NewDefaultProvider("test"),
 			Module:   addrs.RootModule,
 		},
 	)