wrong operation during destroy plan walk

The destroy plan walk was identifying itself as a normal plan, and
causing providers to be configured when they were not needed. Since the
provider configuration may not be complete during the minimal destroy
plan walk, validation or configuration may fail.

terraform/context.go

@@ -633,7 +633,7 @@ func (c *Context) destroyPlan() (*plans.Plan, tfdiags.Diagnostics) {
 	}
 
 	// Do the walk
-	walker, walkDiags := c.walk(graph, walkPlan)
+	walker, walkDiags := c.walk(graph, walkPlanDestroy)
 	diags = diags.Append(walker.NonFatalDiagnostics)
 	diags = diags.Append(walkDiags)
 	if walkDiags.HasErrors() {

terraform/context_plan2_test.go

@@ -439,3 +439,49 @@ output "result" {
 		}
 	}
 }
+
+func TestContext2Plan_destroyNoProviderConfig(t *testing.T) {
+	// providers do not need to be configured during a destroy plan
+	p := simpleMockProvider()
+	p.ValidateProviderConfigFn = func(req providers.ValidateProviderConfigRequest) (resp providers.ValidateProviderConfigResponse) {
+		v := req.Config.GetAttr("test_string")
+		if v.IsNull() || !v.IsKnown() || v.AsString() != "ok" {
+			resp.Diagnostics = resp.Diagnostics.Append(errors.New("invalid provider configuration"))
+		}
+		return resp
+	}
+
+	m := testModuleInline(t, map[string]string{
+		"main.tf": `
+locals {
+  value = "ok"
+}
+
+provider "test" {
+  test_string = local.value
+}
+`,
+	})
+
+	addr := mustResourceInstanceAddr("test_object.a")
+	state := states.BuildState(func(s *states.SyncState) {
+		s.SetResourceInstanceCurrent(addr, &states.ResourceInstanceObjectSrc{
+			AttrsJSON: []byte(`{"test_string":"foo"}`),
+			Status:    states.ObjectReady,
+		}, mustProviderConfig(`provider["registry.terraform.io/hashicorp/test"]`))
+	})
+
+	ctx := testContext2(t, &ContextOpts{
+		Config: m,
+		State:  state,
+		Providers: map[addrs.Provider]providers.Factory{
+			addrs.NewDefaultProvider("test"): testProviderFuncFixed(p),
+		},
+		Destroy: true,
+	})
+
+	_, diags := ctx.Plan()
+	if diags.HasErrors() {
+		t.Fatal(diags.Err())
+	}
+}