configs/configupgrade: Upgrade the resource "lifecycle" nested block

The main tricky thing here is ignore_changes, which contains strings that
are better given as naked traversals in 0.12. We also handle here mapping
the old special case ["*"] value to the new "all" keyword.

configs/configupgrade/test-fixtures/valid/lifecycle/input/lifecycle.tf

@@ -0,0 +1,29 @@
+resource "test_instance" "foo" {
+  lifecycle {
+    create_before_destroy = true
+    prevent_destroy       = true
+  }
+}
+
+resource "test_instance" "bar" {
+  lifecycle {
+    ignore_changes = ["*"]
+  }
+}
+
+resource "test_instance" "baz" {
+  lifecycle {
+    ignore_changes = [
+      "image",
+      "tags.name",
+    ]
+  }
+}
+
+resource "test_instance" "boop" {
+  lifecycle {
+    ignore_changes = [
+      "image",
+    ]
+  }
+}

configs/configupgrade/test-fixtures/valid/lifecycle/want/lifecycle.tf

@@ -0,0 +1,27 @@
+resource "test_instance" "foo" {
+  lifecycle {
+    create_before_destroy = true
+    prevent_destroy       = true
+  }
+}
+
+resource "test_instance" "bar" {
+  lifecycle {
+    ignore_changes = all
+  }
+}
+
+resource "test_instance" "baz" {
+  lifecycle {
+    ignore_changes = [
+      image,
+      tags.name,
+    ]
+  }
+}
+
+resource "test_instance" "boop" {
+  lifecycle {
+    ignore_changes = [image]
+  }
+}

configs/configupgrade/test-fixtures/valid/lifecycle/want/versions.tf

@@ -0,0 +1,3 @@
+terraform {
+  required_version = ">= 0.12"
+}

configs/configupgrade/upgrade_body.go

@@ -65,20 +65,7 @@ func maybeBareKeywordAttributeRule(filename string, an *analysis, specials map[s
 
 func maybeBareTraversalAttributeRule(filename string, an *analysis) bodyItemRule {
 	exprRule := func(val interface{}) ([]byte, tfdiags.Diagnostics) {
-		// If the expression is a literal that would be valid as a naked
-		// absolute traversal then we'll turn it into one.
-		if lit, isLit := val.(*hcl1ast.LiteralType); isLit {
-			if lit.Token.Type == hcl1token.STRING {
-				trStr := lit.Token.Value().(string)
-				trSrc := []byte(trStr)
-				_, trDiags := hcl2syntax.ParseTraversalAbs(trSrc, "", hcl2.Pos{})
-				if !trDiags.HasErrors() {
-					return trSrc, nil
-				}
-			}
-		}
-
-		return upgradeExpr(val, filename, false, an)
+		return upgradeTraversalExpr(val, filename, an)
 	}
 	return attributeRule(filename, cty.String, an, exprRule)
 }
@@ -373,3 +360,54 @@ func justAttributesBodyRules(filename string, body *hcl1ast.ObjectType, an *anal
 	}
 	return rules
 }
+
+func lifecycleBlockBodyRules(filename string, an *analysis) bodyContentRules {
+	return bodyContentRules{
+		"create_before_destroy": noInterpAttributeRule(filename, cty.Bool, an),
+		"prevent_destroy":       noInterpAttributeRule(filename, cty.Bool, an),
+		"ignore_changes": func(buf *bytes.Buffer, blockAddr string, item *hcl1ast.ObjectItem) tfdiags.Diagnostics {
+			var diags tfdiags.Diagnostics
+			val, ok := item.Val.(*hcl1ast.ListType)
+			if !ok {
+				diags = diags.Append(&hcl2.Diagnostic{
+					Severity: hcl2.DiagError,
+					Summary:  "Invalid providers argument",
+					Detail:   `The "providers" argument must be a map from provider addresses in the child module to corresponding provider addresses in this module.`,
+					Subject:  hcl1PosRange(filename, item.Keys[0].Pos()).Ptr(),
+				})
+				return diags
+			}
+
+			// As a special case, we'll map the single-element list ["*"] to
+			// the new keyword "all".
+			if len(val.List) == 1 {
+				if lit, ok := val.List[0].(*hcl1ast.LiteralType); ok {
+					if lit.Token.Value() == "*" {
+						printAttribute(buf, item.Keys[0].Token.Value().(string), []byte("all"), item.LineComment)
+						return diags
+					}
+				}
+			}
+
+			var exprBuf bytes.Buffer
+			multiline := len(val.List) > 1
+			exprBuf.WriteByte('[')
+			if multiline {
+				exprBuf.WriteByte('\n')
+			}
+			for _, node := range val.List {
+				itemSrc, moreDiags := upgradeTraversalExpr(node, filename, an)
+				diags = diags.Append(moreDiags)
+				exprBuf.Write(itemSrc)
+				if multiline {
+					exprBuf.WriteString(",\n")
+				}
+			}
+			exprBuf.WriteByte(']')
+
+			printAttribute(buf, item.Keys[0].Token.Value().(string), exprBuf.Bytes(), item.LineComment)
+
+			return diags
+		},
+	}
+}

configs/configupgrade/upgrade_expr.go

@@ -392,6 +392,18 @@ Value:
 	return buf.Bytes(), diags
 }
 
+func upgradeTraversalExpr(val interface{}, filename string, an *analysis) ([]byte, tfdiags.Diagnostics) {
+	if lit, ok := val.(*hcl1ast.LiteralType); ok && lit.Token.Type == hcl1token.STRING {
+		trStr := lit.Token.Value().(string)
+		trSrc := []byte(trStr)
+		_, trDiags := hcl2syntax.ParseTraversalAbs(trSrc, "", hcl2.Pos{})
+		if !trDiags.HasErrors() {
+			return trSrc, nil
+		}
+	}
+	return upgradeExpr(val, filename, false, an)
+}
+
 var hilArithmeticOpSyms = map[hilast.ArithmeticOp]string{
 	hilast.ArithmeticOpAdd: " + ",
 	hilast.ArithmeticOpSub: " - ",

configs/configupgrade/upgrade_native.go

@@ -327,6 +327,7 @@ func (u *Upgrader) upgradeNativeSyntaxResource(filename string, buf *bytes.Buffe
 	rules := schemaDefaultBodyRules(filename, schema, an, adhocComments)
 	rules["count"] = normalAttributeRule(filename, cty.Number, an)
 	rules["provider"] = maybeBareTraversalAttributeRule(filename, an)
+	rules["lifecycle"] = nestedBlockRule(filename, lifecycleBlockBodyRules(filename, an), an, adhocComments)
 
 	printComments(buf, item.LeadComment)
 	printBlockOpen(buf, blockType, labels, item.LineComment)