fix: nested maps not rendered if no value attribute is present. (#1957)

## What this PR does / why we need it:

The nested `map` blocks are not rendered if the `value` block do not
contain attributes.

## Which issue(s) this PR fixes:
none

## Special notes for your reviewer:

## Does this PR introduce a user-facing change?
```
yes, fixes a bug.
```

Author: i4ki

CHANGELOG.md

@@ -26,6 +26,10 @@ Given a version number `MAJOR.MINOR.PATCH`, we increment the:
 
 - Add `terramate.stack.parent.id` metadata to stacks that are part of a parent-child hierarchy.
 
+### Fixed
+
+- Nested `map` blocks not rendered if the `value` block contain no attributes.
+
 ## v0.11.1
 
 ### Added

globals/globals_map_test.go

@@ -736,6 +736,109 @@ func TestGlobalsMap(t *testing.T) {
 				),
 			},
 		},
+		{
+			name:   "regression test: nested map not rendered with no flat attribute",
+			layout: []string{"s:stack"},
+			configs: []hclconfig{
+				{
+					path: "/",
+					add: Globals(
+						Expr("lst", `[
+							{
+								val: "a", 
+								lst: [1, 2, 3]
+							},
+							{
+								val: "b",
+								lst: [4, 5, 6]
+							},
+							{
+								val: "c",
+								lst: [7, 8, 9]
+							}
+						]`),
+						Map(
+							Labels("var"),
+							Expr("for_each", `global.lst`),
+							Expr("key", "element.new.val"),
+
+							Value(
+								Map(
+									Labels("var"),
+									Expr("for_each", "element.new.lst"),
+									Expr("key", "tm_tostring(el.new)"),
+									Expr("value", "el.new"),
+									Expr("iterator", "el"),
+								),
+								Map(
+									Labels("var2"),
+									Expr("for_each", "element.new.lst"),
+									Expr("key", "tm_tostring(el2.new)"),
+									Expr("value", "el2.new"),
+									Expr("iterator", "el2"),
+								),
+							),
+						),
+					),
+				},
+			},
+			want: map[string]*hclwrite.Block{
+				"/stack": Globals(
+					EvalExpr(t, "lst", `[
+						{
+							val: "a", 
+							lst: [1, 2, 3]
+						},
+						{
+							val: "b",
+							lst: [4, 5, 6]
+						},
+						{
+							val: "c",
+							lst: [7, 8, 9]
+						}
+					]`),
+					EvalExpr(t, "var", `{
+						a = {
+							var = {
+								"1" = 1
+								"2" = 2
+								"3" = 3
+							}
+							var2 = {
+								"1" = 1
+								"2" = 2
+								"3" = 3
+							}
+						}
+						b = {
+							var = {
+								"4" = 4
+								"5" = 5
+								"6" = 6
+							}
+							var2 = {
+								"4" = 4
+								"5" = 5
+								"6" = 6
+							}
+						}
+						c = {
+							var = {
+								"7" = 7
+								"8" = 8
+								"9" = 9
+							}
+							var2 = {
+								"7" = 7
+								"8" = 8
+								"9" = 9
+							}
+						}
+					}`),
+				),
+			},
+		},
 	} {
 		testGlobals(t, tc)
 	}

mapexpr/map.go

@@ -19,7 +19,7 @@ import (
 type MapExpr struct {
 	Origin   info.Range
 	Attrs    Attributes
-	Children []*MapExpr
+	Children []varMap
 }
 
 // Attributes of the MapExpr block.
@@ -31,9 +31,14 @@ type Attributes struct {
 	ValueBlock *ast.MergedBlock
 }
 
+type varMap struct {
+	Name string
+	Map  *MapExpr
+}
+
 // NewMapExpr creates a new MapExpr instance.
 func NewMapExpr(block *ast.MergedBlock) (*MapExpr, error) {
-	children := []*MapExpr{}
+	children := []varMap{}
 	var valueBlock *ast.MergedBlock
 	for _, subBlock := range block.Blocks {
 		if valueBlock != nil {
@@ -49,7 +54,10 @@ func NewMapExpr(block *ast.MergedBlock) (*MapExpr, error) {
 			if err != nil {
 				return nil, errors.E(err, "creating nested `map` expression")
 			}
-			children = append(children, m)
+			children = append(children, varMap{
+				Name: childBlock.Labels[0],
+				Map:  m,
+			})
 		}
 	}
 
@@ -167,23 +175,18 @@ func (m *MapExpr) Value(ctx *hhcl.EvalContext) (cty.Value, hhcl.Diagnostics) {
 				}
 
 				valueMap[attr.Name] = attrVal
+			}
 
-				for _, subBlock := range m.Attrs.ValueBlock.Blocks {
-					childEvaluator := evaluator.Copy()
-					// only `map` block allowed inside `value` block.
-					subMap, err := NewMapExpr(subBlock)
-					if err != nil {
-						mapErr = errors.E(err, "evaluating nested %q map block", subBlock.Labels[0])
-						return true
-					}
-					val, diags := subMap.Value(childEvaluator.Unwrap())
-					if diags.HasErrors() {
-						mapErr = errors.E(diags, "evaluating nested %q map block", subBlock.Labels[0])
-						return true
-					}
-
-					valueMap[subBlock.Labels[0]] = val
+			for _, subMap := range m.Children {
+				childEvaluator := evaluator.Copy()
+
+				val, diags := subMap.Map.Value(childEvaluator.Unwrap())
+				if diags.HasErrors() {
+					mapErr = errors.E(diags, "evaluating nested %q map block", subMap.Name)
+					return true
 				}
+
+				valueMap[subMap.Name] = val
 			}
 
 			valVal = cty.ObjectVal(valueMap)
@@ -238,7 +241,7 @@ func (m *MapExpr) Variables() []hhcl.Traversal {
 		}
 
 		for _, childMap := range m.Children {
-			appendVars(childMap.Variables())
+			appendVars(childMap.Map.Variables())
 		}
 	}
 	return allvars