jax-ml/jax · error · ValueError

Constraint parsing error: must contain one of '==' or '>=' o

Error message

Constraint parsing error: must contain one of '==' or '>=' or '<='

What it means

A constraint string must contain exactly one of the comparison tokens '==', '>=' or '<='. If none of these substrings is found, the parser cannot split it into two sides and raises ValueError.

Source

Thrown at jax/_src/export/shape_poly.py:1054

    if self._explicit_constraints:
      extras.append(" with constraints:")
      for constr in self._explicit_constraints:
        extras.append(f"  {constr.debug_str}")
    loc = source_info_util._summarize_frame(self._location_frame) if self._location_frame else "unknown"
    return f"{id(self)} created at {loc}" + "\n".join(extras)
  __repr__ = __str__

  def _parse_and_process_explicit_constraint(self, c_str: str):
    if not isinstance(c_str, str):
      raise ValueError(
          f"SymbolicScope constraint must be a string: got {repr(c_str)}")
    cmp_pos, cmp, is_geq = c_str.find("=="), Comparator.EQ, True
    if cmp_pos < 0:
      cmp_pos, cmp, is_geq = c_str.find(">="), Comparator.GEQ, True
      if cmp_pos < 0:
        cmp_pos, cmp, is_geq = c_str.find("<="), Comparator.GEQ, False
      if cmp_pos < 0:
        raise ValueError("Constraint parsing error: must contain one of '==' or '>=' or '<='")
    e1_str = c_str[:cmp_pos]
    e1, = _Parser(e1_str, None, repr(e1_str), self).parse()
    e2_str = c_str[cmp_pos + 2:]
    e2, = _Parser(e2_str, None, repr(e2_str), self).parse()
    if cmp == Comparator.GEQ and not is_geq:
      e1, e2 = e2, e1

    # Compute e1 - e2 before we add to normalization rules
    constr = _SymbolicConstraint(debug_str=c_str, cmp=cmp, e1=e1, e2=e2,
                                 diff=e1 - e2)
    self._process_explicit_constraint(constr)

  def _process_explicit_constraint(self, constr: _SymbolicConstraint):
    if (diff_const := _DimExpr._to_constant(constr.diff)) is not None:
      if ((constr.cmp == Comparator.EQ and diff_const != 0) or
          (constr.cmp == Comparator.GEQ and diff_const < 0)):
        raise ValueError(f"Unsatisfiable explicit constraint: {constr.debug_str}")
      return

View on GitHub (pinned to 1e1c6a8fc0)

Solutions

1. Use only '==', '>=', '<=' in constraint strings; rewrite 'n > 4' as 'n >= 5' for integers
2. Fix typos ('=>' -> '>=', '=' -> '==')
3. Validate each constraint contains a supported token before constructing the scope

Example fix

# before
constraints = ('n > 4',)
# after
constraints = ('n >= 5',)  # strict inequalities not supported

import re
assert all(re.search(r'(==|>=|<=)', c) for c in constraints), 'need ==, >=, or <='

def well_formed_constraint(c: str) -> bool:
    return isinstance(c, str) and any(t in c for t in ('==','>=','<='))

When it happens

Trigger: Constraints like 'n > 4' (strict inequality, unsupported), 'n = 4', 'n 4', or 'max(n, 4)' with no comparator.

Common situations: Typos in constraint strings; assuming strict > or < is supported (only >=/<=/== are); copying Python syntax like 'n != 4'.

Related errors

• The symbolic constraints should be a sequence of strings. Go
• SymbolicScope constraint must be a string: got {repr(c_str)}
• Unsatisfiable explicit constraint: {constr.debug_str}
• Invalid equality constraint: {e1} == {e2}. The left-hand-sid
• Found multiple equality constraints with the same left-hand-

AI-assisted analysis of jax-ml/jax@1e1c6a8fc0 (2026-08-27). Data as JSON: /api/errors/e7dd1d7def552f78. Report an issue: GitHub.