Add support for Terraform v1.11 (#2258)

* Avoid crash due to map with `null` values

Follow up of hashicorp/terraform#36611

* Update Terraform compatibility guide

* Return error when the template's single interpolation results in null value

Follow up of hashicorp/terraform#36658

* Bump patch version

Author: wata727

docs/user-guide/compatibility.md

@@ -4,7 +4,7 @@ TFLint interprets the [Terraform language](https://developer.hashicorp.com/terra
 
 The parser supports Terraform v1.x syntax and semantics. The language compatibility on Terraform v1.x is defined by [Compatibility Promises](https://developer.hashicorp.com/terraform/language/v1-compatibility-promises). TFLint follows this promise. New features are only supported in newer TFLint versions, and bug and experimental features compatibility are not guaranteed.
 
-The latest supported version is Terraform v1.10.
+The latest supported version is Terraform v1.11.
 
 ## Input Variables
 

terraform/lang/funcs/collection.go

@@ -582,8 +582,14 @@ var TransposeFunc = function.New(&function.Spec{
 
 		for it := inputMap.ElementIterator(); it.Next(); {
 			inKey, inVal := it.Element()
+			if inVal.IsNull() {
+				return cty.MapValEmpty(cty.List(cty.String)), errors.New("input must not contain null list")
+			}
 			for iter := inVal.ElementIterator(); iter.Next(); {
 				_, val := iter.Element()
+				if val.IsNull() {
+					return cty.MapValEmpty(cty.List(cty.String)), errors.New("input list must not contain null string")
+				}
 				if !val.Type().Equals(cty.String) {
 					return cty.MapValEmpty(cty.List(cty.String)), errors.New("input must be a map of lists of strings")
 				}

terraform/lang/funcs/collection_test.go

@@ -1833,6 +1833,37 @@ func TestTranspose(t *testing.T) {
 			}).WithMarks(cty.NewValueMarks("beep", "boop", "bloop")),
 			false,
 		},
+		{
+			cty.NullVal(cty.Map(cty.List(cty.String))),
+			cty.NilVal,
+			true,
+		},
+		{
+			cty.MapVal(map[string]cty.Value{
+				"test": cty.NullVal(cty.List(cty.String)),
+			}),
+			cty.NilVal,
+			true,
+		},
+		{
+			cty.MapVal(map[string]cty.Value{
+				"test": cty.ListVal([]cty.Value{cty.NullVal(cty.String)}),
+			}),
+			cty.NilVal,
+			true,
+		},
+		{
+			cty.UnknownVal(cty.Map(cty.List(cty.String))),
+			cty.UnknownVal(cty.Map(cty.List(cty.String))).RefineNotNull(),
+			false,
+		},
+		{
+			cty.MapVal(map[string]cty.Value{
+				"test": cty.ListVal([]cty.Value{cty.UnknownVal(cty.String)}),
+			}),
+			cty.UnknownVal(cty.Map(cty.List(cty.String))).RefineNotNull(),
+			false,
+		},
 	}
 
 	for _, test := range tests {

terraform/lang/funcs/string.go

@@ -380,6 +380,14 @@ func makeRenderTemplateFunc(funcsCb func() (funcs map[string]function.Function,
 		if diags.HasErrors() {
 			return cty.DynamicVal, diags
 		}
+		if val.IsNull() {
+			return cty.DynamicVal, &hcl.Diagnostic{
+				Severity: hcl.DiagError,
+				Summary:  "Template result is null",
+				Detail:   "The result of the template is null, which is not a valid result for a templatestring call.",
+				Subject:  expr.Range().Ptr(),
+			}
+		}
 		return val, nil
 	}
 }

terraform/lang/funcs/string_test.go

@@ -273,6 +273,28 @@ func TestTemplateString(t *testing.T) {
 		want         cty.Value
 		wantErr      string
 	}{
+		{ // a single string interpolation that evaluates to null should fail
+			`template`,
+			map[string]cty.Value{
+				"template": cty.StringVal(`${test}`),
+			},
+			cty.ObjectVal(map[string]cty.Value{
+				"test": cty.NullVal(cty.String),
+			}),
+			cty.NilVal,
+			`<templatestring argument>:1,1-8: Template result is null; The result of the template is null, which is not a valid result for a templatestring call.`,
+		},
+		{ // a single string interpolation that evaluates to unknown should not fail
+			`template`,
+			map[string]cty.Value{
+				"template": cty.StringVal(`${test}`),
+			},
+			cty.ObjectVal(map[string]cty.Value{
+				"test": cty.UnknownVal(cty.String),
+			}),
+			cty.UnknownVal(cty.String).RefineNotNull(),
+			``,
+		},
 		{
 			`template`,
 			map[string]cty.Value{