Disable parsing scientific/complex number notation in template type (#43170)

homeassistant/helpers/template.py

@@ -49,6 +49,8 @@ _RENDER_INFO = "template.render_info"
 _ENVIRONMENT = "template.environment"
 
 _RE_JINJA_DELIMITERS = re.compile(r"\{%|\{\{|\{#")
+# Match "simple" ints and floats. -1.0, 1, +5, 5.0
+_IS_NUMERIC = re.compile(r"^[+-]?\d*(?:\.\d*)?$")
 
 _RESERVED_NAMES = {"contextfunction", "evalcontextfunction", "environmentfunction"}
 
@@ -373,7 +375,19 @@ class Template:
             # render, by not returning right here. The evaluation of strings
             # resulting in strings impacts quotes, to avoid unexpected
             # output; use the original render instead of the evaluated one.
-            if not isinstance(result, str):
+            # Complex and scientific values are also unexpected. Filter them out.
+            if (
+                # Filter out string and complex numbers
+                not isinstance(result, (str, complex))
+                and (
+                    # Pass if not numeric and not a boolean
+                    not isinstance(result, (int, float))
+                    # Or it's a boolean (inherit from int)
+                    or isinstance(result, bool)
+                    # Or if it's a digit
+                    or _IS_NUMERIC.match(render_result) is not None
+                )
+            ):
                 return result
         except (ValueError, TypeError, SyntaxError, MemoryError):
             pass

tests/helpers/test_template.py

@@ -346,7 +346,7 @@ def test_tan(hass):
         (0, 0.0),
         (math.pi, -0.0),
         (math.pi / 180 * 45, 1.0),
-        (math.pi / 180 * 90, 1.633123935319537e16),
+        (math.pi / 180 * 90, "1.633123935319537e+16"),
         (math.pi / 180 * 135, -1.0),
         ("'error'", "error"),
     ]
@@ -2416,5 +2416,16 @@ async def test_parse_result(hass):
         ('{{ "{{}}" }}', "{{}}"),
         ("not-something", "not-something"),
         ("2a", "2a"),
+        ("123E5", "123E5"),
+        ("1j", "1j"),
+        ("1e+100", "1e+100"),
+        ("0xface", "0xface"),
+        ("123", 123),
+        ("123.0", 123.0),
+        (".5", 0.5),
+        ("-1", -1),
+        ("-1.0", -1.0),
+        ("+1", 1),
+        ("5.", 5.0),
     ):
         assert template.Template(tpl, hass).async_render() == result