Add a VariableSourceType for names .tfvars files

This new source type should be used for variables loaded from .tfvars files that were explicitly passed as command line arguments (e.g. -var-file=foo.tfvars)

backend/unparsed_value.go

@@ -45,7 +45,7 @@ func ParseVariableValues(vv map[string]UnparsedVariableValue, decls map[string]*
 
 		if !declared {
 			switch val.SourceType {
-			case terraform.ValueFromConfig, terraform.ValueFromFile:
+			case terraform.ValueFromConfig, terraform.ValueFromAutoFile, terraform.ValueFromNamedFile:
 				// These source types have source ranges, so we can produce
 				// a nice error message with good context.
 				diags = diags.Append(&hcl.Diagnostic{

command/meta_vars.go

@@ -9,7 +9,6 @@ import (
 	"github.com/hashicorp/hcl2/hcl"
 	"github.com/hashicorp/hcl2/hcl/hclsyntax"
 	hcljson "github.com/hashicorp/hcl2/hcl/json"
-
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/configs"
 	"github.com/hashicorp/terraform/terraform"
@@ -59,12 +58,12 @@ func (m *Meta) collectVariableValues() (map[string]backend.UnparsedVariableValue
 	// (DefaultVarsFilename) along with the later-added search for all files
 	// ending in .auto.tfvars.
 	if _, err := os.Stat(DefaultVarsFilename); err == nil {
-		moreDiags := m.addVarsFromFile(DefaultVarsFilename, terraform.ValueFromFile, ret)
+		moreDiags := m.addVarsFromFile(DefaultVarsFilename, terraform.ValueFromAutoFile, ret)
 		diags = diags.Append(moreDiags)
 	}
 	const defaultVarsFilenameJSON = DefaultVarsFilename + ".json"
 	if _, err := os.Stat(defaultVarsFilenameJSON); err == nil {
-		moreDiags := m.addVarsFromFile(defaultVarsFilenameJSON, terraform.ValueFromFile, ret)
+		moreDiags := m.addVarsFromFile(defaultVarsFilenameJSON, terraform.ValueFromAutoFile, ret)
 		diags = diags.Append(moreDiags)
 	}
 	if infos, err := ioutil.ReadDir("."); err == nil {
@@ -74,7 +73,7 @@ func (m *Meta) collectVariableValues() (map[string]backend.UnparsedVariableValue
 			if !isAutoVarFile(name) {
 				continue
 			}
-			moreDiags := m.addVarsFromFile(name, terraform.ValueFromFile, ret)
+			moreDiags := m.addVarsFromFile(name, terraform.ValueFromAutoFile, ret)
 			diags = diags.Append(moreDiags)
 		}
 	}
@@ -106,7 +105,7 @@ func (m *Meta) collectVariableValues() (map[string]backend.UnparsedVariableValue
 			}
 
 		case "-var-file":
-			moreDiags := m.addVarsFromFile(rawFlag.Value, terraform.ValueFromFile, ret)
+			moreDiags := m.addVarsFromFile(rawFlag.Value, terraform.ValueFromNamedFile, ret)
 			diags = diags.Append(moreDiags)
 
 		default:

terraform/semantics.go

@@ -79,7 +79,7 @@ func checkInputVariables(vcs map[string]*configs.Variable, vs InputValues) tfdia
 		_, err := convert.Convert(val.Value, wantType)
 		if err != nil {
 			switch val.SourceType {
-			case ValueFromConfig, ValueFromFile:
+			case ValueFromConfig, ValueFromAutoFile, ValueFromNamedFile:
 				// We have source location information for these.
 				diags = diags.Append(&hcl.Diagnostic{
 					Severity: hcl.DiagError,

terraform/variables.go

@@ -32,10 +32,14 @@ const (
 	// e.g. the default value defined for a variable.
 	ValueFromConfig ValueSourceType = 'C'
 
-	// ValueFromFile indicates that a value came from a "values file", like
-	// a .tfvars file, either passed explicitly on the command line or
-	// implicitly loaded by naming convention.
-	ValueFromFile ValueSourceType = 'F'
+	// ValueFromAutoFile indicates that a value came from a "values file", like
+	// a .tfvars file, that was implicitly loaded by naming convention.
+	ValueFromAutoFile ValueSourceType = 'F'
+
+	// ValueFromNamedFile indicates that a value came from a named "values file",
+	// like a .tfvars file, that was passed explicitly on the command line (e.g.
+	// -var-file=foo.tfvars).
+	ValueFromNamedFile ValueSourceType = 'N'
 
 	// ValueFromCLIArg indicates that the value was provided directly in
 	// a CLI argument. The name of this argument is not recorded and so it must