unused_required_providers: provider functions (#214)

Author: bgpat

rules/terraform_required_providers_test.go

@@ -546,6 +546,30 @@ resource "google_compute_instance" "foo" {
 				},
 			},
 		},
+		{
+			Name: "provider-defined function",
+			Content: `
+output "foo" {
+	value = provider::time::rfc3339_parse("2023-07-25T23:43:16Z")
+}`,
+			Expected: helper.Issues{
+				{
+					Rule:    NewTerraformRequiredProvidersRule(),
+					Message: "Missing version constraint for provider \"time\" in `required_providers`",
+					Range: hcl.Range{
+						Filename: "module.tf",
+						Start: hcl.Pos{
+							Line:   3,
+							Column: 10,
+						},
+						End: hcl.Pos{
+							Line:   3,
+							Column: 63,
+						},
+					},
+				},
+			},
+		},
 	}
 
 	rule := NewTerraformRequiredProvidersRule()

rules/terraform_unused_required_providers_test.go

@@ -244,6 +244,22 @@ func Test_TerraformUnusedRequiredProvidersRule(t *testing.T) {
 			`,
 			Expected: helper.Issues{},
 		},
+		{
+			Name: "used - provider-defined function",
+			Content: `
+				terraform {
+					required_providers {
+						time = {
+							source = "hashicorp/time"
+						}
+					}
+				}
+				output "foo" {
+					value = provider::time::rfc3339_parse("2023-07-25T23:43:16Z")
+				}
+			`,
+			Expected: helper.Issues{},
+		},
 	}
 
 	rule := NewTerraformUnusedRequiredProvidersRule()

terraform/runner.go

@@ -4,6 +4,7 @@ import (
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
+	"github.com/hashicorp/hcl/v2/hclsyntax"
 	"github.com/terraform-linters/tflint-plugin-sdk/hclext"
 	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
 )
@@ -104,7 +105,7 @@ func (r *Runner) GetLocals() (map[string]*Local, hcl.Diagnostics) {
 	return locals, diags
 }
 
-// GetProviderRefs returns all references to providers in resources, data, provider declarations, and module calls.
+// GetProviderRefs returns all references to providers in resources, data, provider declarations, module calls, and provider-defined functinos.
 func (r *Runner) GetProviderRefs() (map[string]*ProviderRef, hcl.Diagnostics) {
 	providerRefs := map[string]*ProviderRef{}
 
@@ -241,5 +242,23 @@ func (r *Runner) GetProviderRefs() (map[string]*ProviderRef, hcl.Diagnostics) {
 		}
 	}
 
-	return providerRefs, nil
+	walkDiags := r.WalkExpressions(tflint.ExprWalkFunc(func(expr hcl.Expression) hcl.Diagnostics {
+		if fce, ok := expr.(*hclsyntax.FunctionCallExpr); ok {
+			parts := strings.Split(fce.Name, "::")
+			if len(parts) < 2 || parts[0] != "provider" || parts[1] == "" {
+				return nil
+			}
+			providerRefs[parts[1]] = &ProviderRef{
+				Name:     parts[1],
+				DefRange: expr.Range(),
+			}
+		}
+		return nil
+	}))
+	diags = diags.Extend(walkDiags)
+	if walkDiags.HasErrors() {
+		return providerRefs, diags
+	}
+
+	return providerRefs, diags
 }

terraform/runner_test.go

@@ -260,6 +260,16 @@ check "my_check" {
 				"aws": {Name: "aws", DefRange: hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 3, Column: 3}, End: hcl.Pos{Line: 3, Column: 24}}},
 			},
 		},
+		{
+			name: "provider-defined function",
+			content: `
+output "foo" {
+  value = provider::time::rfc3339_parse("2023-07-25T23:43:16Z")
+}`,
+			want: map[string]*ProviderRef{
+				"time": {Name: "time", DefRange: hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 3, Column: 11}, End: hcl.Pos{Line: 3, Column: 64}}},
+			},
+		},
 	}
 
 	for _, test := range tests {