jsonconfig: fix keys for default providers

internal/command/jsonconfig/config.go

@@ -231,9 +231,37 @@ func marshalProviderConfigs(
 			p.VersionConstraint = getproviders.VersionConstraintsString(vc)
 		}
 
+		if c.Parent != nil {
+			parentKey := opaqueProviderKey(pr.Name, c.Parent.Path.String())
+			p.parentKey = findSourceProviderKey(parentKey, m)
+		}
+
 		m[key] = p
 	}
 
+	// In child modules, providers defined in the parent module can be implicitly used.
+	// Such providers could have no requirements and configuration blocks defined.
+	if c.Parent != nil {
+		for req := range reqs {
+			// Implicit inheritance only applies to the default provider,
+			// so the provider name must be same as the provider type.
+			key := opaqueProviderKey(req.Type, c.Path.String())
+			if _, exists := m[key]; exists {
+				continue
+			}
+
+			parentKey := opaqueProviderKey(req.Type, c.Parent.Path.String())
+			p := providerConfig{
+				Name:          req.Type,
+				FullName:      req.String(),
+				ModuleAddress: c.Path.String(),
+				parentKey:     findSourceProviderKey(parentKey, m),
+			}
+
+			m[key] = p
+		}
+	}
+
 	// Must also visit our child modules, recursively.
 	for name, mc := range c.Module.ModuleCalls {
 		// Keys in c.Children are guaranteed to match those in c.Module.ModuleCalls
@@ -259,22 +287,7 @@ func marshalProviderConfigs(
 
 			key := opaqueProviderKey(moduleProviderName, cc.Path.String())
 			parentKey := opaqueProviderKey(parentProviderName, cc.Parent.Path.String())
-
-			// Traverse up the module call tree until we find the provider
-			// configuration which has no linked parent config. This is then
-			// the source of the configuration used in this module call, so
-			// we link to it directly
-			for {
-				parent, exists := m[parentKey]
-				if !exists {
-					break
-				}
-				p.parentKey = parentKey
-				parentKey = parent.parentKey
-				if parentKey == "" {
-					break
-				}
-			}
+			p.parentKey = findSourceProviderKey(parentKey, m)
 
 			m[key] = p
 		}
@@ -527,3 +540,20 @@ func opaqueProviderKey(provider string, addr string) (key string) {
 	}
 	return key
 }
+
+// Traverse up the module call tree until we find the provider
+// configuration which has no linked parent config. This is then
+// the source of the configuration used in this module call, so
+// we link to it directly
+func findSourceProviderKey(startKey string, m map[string]providerConfig) string {
+	parentKey := startKey
+	for {
+		parent, exists := m[parentKey]
+		if !exists || parent.parentKey == "" {
+			break
+		}
+		parentKey = parent.parentKey
+	}
+
+	return parentKey
+}

internal/command/testdata/show-json/provider-aliasing-default/child/main.tf

@@ -0,0 +1,19 @@
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+    }
+  }
+}
+
+resource "test_instance" "test" {
+  ami = "bar"
+}
+
+module "with_requirement" {
+  source = "./nested"
+}
+
+module "no_requirements" {
+  source = "./nested-no-requirements"
+}

internal/command/testdata/show-json/provider-aliasing-default/child/nested-no-requirements/main.tf

@@ -0,0 +1,3 @@
+resource "test_instance" "test" {
+  ami = "qux"
+}

internal/command/testdata/show-json/provider-aliasing-default/child/nested/main.tf

@@ -0,0 +1,11 @@
+terraform {
+  required_providers {
+    test = {
+      source = "hashicorp/test"
+    }
+  }
+}
+
+resource "test_instance" "test" {
+  ami = "baz"
+}

internal/command/testdata/show-json/provider-aliasing-default/main.tf

@@ -0,0 +1,19 @@
+provider "test" {
+  region = "somewhere"
+}
+
+provider "test" {
+  alias  = "backup"
+  region = "elsewhere"
+}
+
+resource "test_instance" "test" {
+  ami = "foo"
+}
+
+module "child" {
+  source = "./child"
+  providers = {
+    test = test.backup
+  }
+}