fix: parenthesize a unary base in the compiled ** expression

[darshjoshi]

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Type of change

• Bug fix (non-breaking change which fixes an issue)

Changes To Core Features:

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Description

number_exponent_operation renders ({lhs} ** {rhs}) as is. JavaScript doesn't allow a unary expression as the base of ** (-2 ** 2 is a SyntaxError, unlike Python where it means -(2 ** 2)), so when the base is a negative literal or a negated var the compiled page doesn't build. For example (-State.velocity) ** 2 renders as (-(…velocity…) ** 2) and rx.Var.create(-2) ** State.n as (-2 ** …n…).

The base is now parenthesized when it starts with a unary operator, so those become ((-(…velocity…)) ** 2) and ((-2) ** …n…). Everything else renders exactly as before ((1 ** 2), (x ** -1), and -(x ** 2) from -x ** 2), so no existing snapshot changes.

Before / After with a one-page app, rx.text("squared: ", (-State.velocity) ** 2), running reflex export --frontend-only:

# before (main)
error: Build failed with 1 error:
[builtin:vite-transform] A unary expression with the '-' operator cannot
be used as the left operand of an exponentiation expression
    ╭─[ app_components/powapp/powapp.jsx:21:10 ]
 21 │ (-(reflex___state____state__powapp___powapp____state.velocity_rx_state_) ** 2)
    │ Help: Wrap the unary expression in parentheses to make the precedence explicit
exit=1

# after
Creating Production Build:  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 4/4
exit=0

I also ran the rendered expressions through Node and they match Python: ((-(x)) ** 2) is 9, ((-2) ** x) is -8, ((-2.5) ** 2) is 6.25 for x = 3.

test_exponent_parenthesizes_a_unary_base covers the negative-literal and negated-var bases and the cases that must stay unwrapped, and fails on main with '(-2 ** 3)' == '((-2) ** 3)'. tests/units passes (11965 passed), along with ruff and pyright on the changed files.

[cubic-dev-ai]

No issues found across 2 files

_{View guided diff | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no outstanding findings remain.

Summary

Fixes JavaScript builds for powers with negative or negated bases.

• Powers with negative bases now compile as JavaScript.

_{Reviews (4) · Last reviewed commit: "Keep test_var.py as it is on the base br..." · Reviewed by Greptile}

[codspeed]

Merging this PR will not alter performance

⚠️ 15 benchmarks spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

• test_cli_startup[run_help]
• test_cli_startup[cloud_help]
• test_import_cli
• test_state_manager_memory_warm_get
• test_set_state[disk]
• test_event_queue_dispatch
• test_state_manager_memory_read_only_modify
• test_get_state[memory]
• test_emit_update
• test_get_state[disk]
• …and 5 more

✅ 148 untouched benchmarks

---

_{Comparing darshjoshi:fix-negative-exponent-base (2150318) with main (5ae5dcd)}

[cubic-dev-ai]

1 issue found across 2 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="tests/units/test_var.py">

<violation number="1" location="tests/units/test_var.py:1593">
P2: This test expects `code_uses_state_contexts` to recognize `useStateContext`, but the helper only recognizes `useContext(StateContexts...)`; the unit suite will fail. Use a representative `useContext(StateContexts.state)` snippet instead.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

View guided diff | Re-trigger cubic</sub>

[cubic-dev-ai]

P2: This test expects code_uses_state_contexts to recognize useStateContext, but the helper only recognizes useContext(StateContexts...); the unit suite will fail. Use a representative useContext(StateContexts.state) snippet instead.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At tests/units/test_var.py, line 1593:

<comment>This test expects `code_uses_state_contexts` to recognize `useStateContext`, but the helper only recognizes `useContext(StateContexts...)`; the unit suite will fail. Use a representative `useContext(StateContexts.state)` snippet instead.</comment>

<file context>
@@ -1598,6 +1587,17 @@ def test_retrieval():
+@pytest.mark.parametrize(
+    ("javascript_code", "expected"),
+    [
+        ("const state = useStateContext('state')", True),
+        ("const state = useContext(ThemeContext)", False),
+    ],
</file context>

Suggested change

	("const state = useStateContext('state')", True),
	("const state = useContext(StateContexts.state)", True),