accept dashes in variable names

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

dotenv/fixtures/special.env

@@ -0,0 +1,3 @@
+VAR.WITH.DOTS=dots
+VAR_WITH_UNDERSCORES=underscores
+VAR-WITH-DASHES=dashes

dotenv/godotenv_test.go

@@ -718,3 +718,11 @@ func TestUTF8BOM(t *testing.T) {
 
 	loadEnvAndCompareValues(t, Load, envFileName, expectedValues, noopPresets)
 }
+
+func TestDash(t *testing.T) {
+	loadEnvAndCompareValues(t, Load, "fixtures/special.env", map[string]string{
+		"VAR-WITH-DASHES":      "dashes",
+		"VAR.WITH.DOTS":        "dots",
+		"VAR_WITH_UNDERSCORES": "underscores",
+	}, noopPresets)
+}

dotenv/parser.go

@@ -108,9 +108,9 @@ loop:
 			offset = i + 1
 			inherited = char == '\n'
 			break loop
-		case '_', '.':
+		case '_', '.', '-':
 		default:
-			// variable name should match [A-Za-z0-9_.]
+			// variable name should match [A-Za-z0-9_.-]
 			if unicode.IsLetter(rchar) || unicode.IsNumber(rchar) {
 				continue
 			}