command: Providers schema shows required_providers

The providers schema command is using the Config.ProviderTypes method,
which had not been kept up to date with the changes to provider
requirements detection made in Config.ProviderRequirements. This
resulted in any currently-unused providers being omitted from the
output.

This commit changes the ProviderTypes method to use the same underlying
logic as ProviderRequirements, which ensures that `required_providers`
blocks are taken into account.

Includes an integration test case to verify that this fixes the provider
schemas command bug.

command/testdata/providers-schema/required/output.json

@@ -0,0 +1,41 @@
+{
+    "format_version": "0.1",
+    "provider_schemas": {
+        "registry.terraform.io/hashicorp/test": {
+            "provider": {
+                "version": 0,
+                "block": {
+                    "attributes": {
+                        "region": {
+                            "description_kind": "plain",
+                            "optional": true,
+                            "type": "string"
+                        }
+                    },
+                    "description_kind": "plain"
+                }
+            },
+            "resource_schemas": {
+                "test_instance": {
+                    "version": 0,
+                    "block": {
+                        "attributes": {
+                            "ami": {
+                                "type": "string",
+                                "optional": true,
+                                "description_kind": "plain"
+                            },
+                            "id": {
+                                "type": "string",
+                                "optional": true,
+                                "computed": true,
+                                "description_kind": "plain"
+                            }
+                        },
+                        "description_kind": "plain"
+                    }
+                }
+            }
+        }
+    }
+}

command/testdata/providers-schema/required/provider.tf

@@ -0,0 +1,7 @@
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+    }
+  }
+}

configs/config.go

@@ -226,6 +226,7 @@ func (c *Config) addProviderRequirements(reqs getproviders.Requirements, recurse
 	var diags hcl.Diagnostics
 
 	// First we'll deal with the requirements directly in _our_ module...
+	if c.Module.ProviderRequirements != nil {
 		for _, providerReqs := range c.Module.ProviderRequirements.RequiredProviders {
 			fqn := providerReqs.Type
 			if _, ok := reqs[fqn]; !ok {
@@ -253,6 +254,8 @@ func (c *Config) addProviderRequirements(reqs getproviders.Requirements, recurse
 			}
 			reqs[fqn] = append(reqs[fqn], constraints...)
 		}
+	}
+
 	// Each resource in the configuration creates an *implicit* provider
 	// dependency, though we'll only record it if there isn't already
 	// an explicit dependency on the same provider.
@@ -323,11 +326,11 @@ func (c *Config) addProviderRequirements(reqs getproviders.Requirements, recurse
 // provider version selection in an earlier step and have identified suitable
 // versions for each provider.
 func (c *Config) ProviderTypes() []addrs.Provider {
-	m := make(map[addrs.Provider]struct{})
-	c.gatherProviderTypes(m)
+	// Ignore diagnostics here because they relate to version constraints
+	reqs, _ := c.ProviderRequirements()
 
-	ret := make([]addrs.Provider, 0, len(m))
-	for k := range m {
+	ret := make([]addrs.Provider, 0, len(reqs))
+	for k := range reqs {
 		ret = append(ret, k)
 	}
 	sort.Slice(ret, func(i, j int) bool {
@@ -336,32 +339,6 @@ func (c *Config) ProviderTypes() []addrs.Provider {
 	return ret
 }
 
-func (c *Config) gatherProviderTypes(m map[addrs.Provider]struct{}) {
-	if c == nil {
-		return
-	}
-
-	for _, pc := range c.Module.ProviderConfigs {
-		fqn := c.Module.ProviderForLocalConfig(addrs.LocalProviderConfig{LocalName: pc.Name})
-		m[fqn] = struct{}{}
-	}
-	for _, rc := range c.Module.ManagedResources {
-		providerAddr := rc.ProviderConfigAddr()
-		fqn := c.Module.ProviderForLocalConfig(providerAddr)
-		m[fqn] = struct{}{}
-	}
-	for _, rc := range c.Module.DataResources {
-		providerAddr := rc.ProviderConfigAddr()
-		fqn := c.Module.ProviderForLocalConfig(providerAddr)
-		m[fqn] = struct{}{}
-	}
-
-	// Must also visit our child modules, recursively.
-	for _, cc := range c.Children {
-		cc.gatherProviderTypes(m)
-	}
-}
-
 // ResolveAbsProviderAddr returns the AbsProviderConfig represented by the given
 // ProviderConfig address, which must not be nil or this method will panic.
 //

configs/config_test.go

@@ -32,6 +32,7 @@ func TestConfigProviderTypes(t *testing.T) {
 		addrs.NewDefaultProvider("aws"),
 		addrs.NewDefaultProvider("null"),
 		addrs.NewDefaultProvider("template"),
+		addrs.NewDefaultProvider("test"),
 	}
 	for _, problem := range deep.Equal(got, want) {
 		t.Error(problem)

configs/testdata/valid-files/providers-explicit-implied.tf

@@ -13,3 +13,11 @@ resource "aws_instance" "foo" {
 resource "null_resource" "foo" {
 
 }
+
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+    }
+  }
+}