allow parsing of required_providers containing ref

The syntax for configuration_aliases contains bare references to match
their use in other parts of the configuration. These however cannot be
decoded directly without an EvalContext, as they represent variables.

Refactor decodeRequiredProvidersBlock to use the lower level ExprMap
function.

tfconfig/provider_ref.go

@@ -1,9 +1,11 @@
 package tfconfig
 
 import (
+	"fmt"
+
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/hcl/v2/gohcl"
-	"github.com/zclconf/go-cty/cty/gocty"
+	"github.com/zclconf/go-cty/cty"
 )
 
 // ProviderRef is a reference to a provider configuration within a module.
@@ -23,13 +25,8 @@ func decodeRequiredProvidersBlock(block *hcl.Block) (map[string]*ProviderRequire
 	attrs, diags := block.Body.JustAttributes()
 	reqs := make(map[string]*ProviderRequirement)
 	for name, attr := range attrs {
-		expr, err := attr.Expr.Value(nil)
-		if err != nil {
-			diags = append(diags, err...)
-		}
-
-		switch {
-		case expr.Type().IsPrimitiveType():
+		// Look for a legacy version in the attribute first
+		if expr, err := attr.Expr.Value(nil); err == nil && expr.Type().IsPrimitiveType() {
 			var version string
 			valDiags := gohcl.DecodeExpression(attr.Expr, nil, &version)
 			diags = append(diags, valDiags...)
@@ -38,46 +35,73 @@ func decodeRequiredProvidersBlock(block *hcl.Block) (map[string]*ProviderRequire
 					VersionConstraints: []string{version},
 				}
 			}
+			continue
+		}
+
+		kvs, mapDiags := hcl.ExprMap(attr.Expr)
+		if mapDiags.HasErrors() {
+			diags = append(diags, &hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  "Invalid required_providers object",
+				Detail:   "Required providers entries must be strings or objects.",
+				Subject:  attr.Expr.Range().Ptr(),
+			})
+			continue
+		}
+
+		var pr ProviderRequirement
+
+		for _, kv := range kvs {
+			key, keyDiags := kv.Key.Value(nil)
+			if keyDiags.HasErrors() {
+				diags = append(diags, keyDiags...)
+				continue
+			}
 
-		case expr.Type().IsObjectType():
-			var pr ProviderRequirement
-			if expr.Type().HasAttribute("version") {
-				var version string
-				err := gocty.FromCtyValue(expr.GetAttr("version"), &version)
-				if err == nil {
-					pr.VersionConstraints = append(pr.VersionConstraints, version)
-				} else {
+			if key.Type() != cty.String {
+				diags = append(diags, &hcl.Diagnostic{
+					Severity: hcl.DiagError,
+					Summary:  "Invalid Attribute",
+					Detail:   fmt.Sprintf("Invalid attribute value for provider requirement: %#v", key),
+					Subject:  kv.Key.Range().Ptr(),
+				})
+				continue
+			}
+
+			switch key.AsString() {
+			case "version":
+				version, valDiags := kv.Value.Value(nil)
+				if valDiags.HasErrors() || !version.Type().Equals(cty.String) {
 					diags = append(diags, &hcl.Diagnostic{
 						Severity: hcl.DiagError,
 						Summary:  "Unsuitable value type",
 						Detail:   "Unsuitable value: string required",
 						Subject:  attr.Expr.Range().Ptr(),
 					})
+					continue
 				}
-			}
-			if expr.Type().HasAttribute("source") {
-				var source string
-				err := gocty.FromCtyValue(expr.GetAttr("source"), &source)
-				if err == nil {
-					pr.Source = source
-				} else {
+				if !version.IsNull() {
+					pr.VersionConstraints = append(pr.VersionConstraints, version.AsString())
+				}
+
+			case "source":
+				source, err := kv.Value.Value(nil)
+				if err != nil || !source.Type().Equals(cty.String) {
 					diags = append(diags, &hcl.Diagnostic{
 						Severity: hcl.DiagError,
 						Summary:  "Unsuitable value type",
 						Detail:   "Unsuitable value: string required",
 						Subject:  attr.Expr.Range().Ptr(),
 					})
+					continue
+				}
+
+				if !source.IsNull() {
+					pr.Source = source.AsString()
 				}
 			}
-			reqs[name] = &pr
 
-		default:
-			diags = append(diags, &hcl.Diagnostic{
-				Severity: hcl.DiagError,
-				Summary:  "Unsuitable value type",
-				Detail:   "Unsuitable value: string required",
-				Subject:  attr.Expr.Range().Ptr(),
-			})
+			reqs[name] = &pr
 		}
 	}
 

tfconfig/testdata/provider-aliases/provider-aliases.out.json

@@ -5,6 +5,7 @@
   "required_providers": {
     "bar": {},
     "baz": {},
+    "bleep": {},
     "empty": {},
     "foo": {}
   },

tfconfig/testdata/provider-aliases/provider-aliases.out.md

@@ -4,6 +4,7 @@
 Provider Requirements:
 * **bar:** (any version)
 * **baz:** (any version)
+* **bleep:** (any version)
 * **empty:** (any version)
 * **foo:** (any version)
 

tfconfig/testdata/provider-aliases/provider-aliases.tf

@@ -1,3 +1,11 @@
+terraform {
+  required_providers {
+    bleep = {
+      configuration_aliases = [ bleep.bloop ]
+    }
+  }
+}
+
 provider "foo" {
   alias = "blue"
 }

tfconfig/testdata/type-errors/type-errors.out.json

@@ -75,8 +75,8 @@
         },
         {
             "severity": "error",
-            "summary": "Unsuitable value type",
-            "detail": "Unsuitable value: string required",
+            "summary": "Invalid required_providers object",
+            "detail": "Required providers entries must be strings or objects.",
             "pos": {
                 "filename": "testdata/type-errors/type-errors.tf",
                 "line": 27

tfconfig/testdata/type-errors/type-errors.out.md

@@ -67,9 +67,9 @@ Provider argument requires a provider name followed by an optional alias, like "
 
 Unsuitable value: string required
 
-## Error: Unsuitable value type
+## Error: Invalid required_providers object
 
 (at `testdata/type-errors/type-errors.tf` line 27)
 
-Unsuitable value: string required
+Required providers entries must be strings or objects.