trace: add more logging around variable validations (#35535)

internal/checks/state_report.go

@@ -5,6 +5,7 @@ package checks
 
 import (
 	"fmt"
+	"log"
 
 	"github.com/hashicorp/terraform/internal/addrs"
 )
@@ -50,6 +51,7 @@ func (c *State) ReportCheckableObjects(configAddr addrs.ConfigCheckable, objectA
 			checks[checkType] = make([]Status, count)
 		}
 
+		log.Printf("[TRACE] ReportCheckableObjects: %s -> %s", configAddr, objectAddr)
 		st.objects.Put(objectAddr, checks)
 	}
 }

internal/terraform/graph.go

@@ -51,6 +51,14 @@ func (g *Graph) walk(walker GraphWalker) tfdiags.Diagnostics {
 		log.Printf("[TRACE] vertex %q: starting visit (%T)", dag.VertexName(v), v)
 
 		defer func() {
+			if r := recover(); r != nil {
+				// If the walkFn panics, we get confusing logs about how the
+				// visit was complete. To stop this, we'll catch the panic log
+				// that the vertex panicked without finishing and re-panic.
+				log.Printf("[ERROR] vertex %q panicked", dag.VertexName(v))
+				panic(r) // re-panic
+			}
+
 			if diags.HasErrors() {
 				for _, diag := range diags {
 					if diag.Severity() == tfdiags.Error {

internal/terraform/node_module_variable.go

@@ -68,6 +68,7 @@ func (n *nodeExpandModuleVariable) DynamicExpand(ctx EvalContext) (*Graph, tfdia
 	forEachModuleInstance(expander, n.Module, false, func(module addrs.ModuleInstance) {
 		addr := n.Addr.Absolute(module)
 		if checkableAddrs != nil {
+			log.Printf("[TRACE] nodeExpandModuleVariable: found checkable object %s", addr)
 			checkableAddrs.Add(addr)
 		}