test_nested_try.py: nested try/except generates duplicate "try_end"
block labels, which Core rejects as shadowing.

test_try_scope.py: variables declared inside try body are scoped to
the block, but Python expects them visible after the try/except.

Both are marked as expected failures with their current error messages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

These tests now pass after #572 merged, which fixed nested try/except
labels and variable scoping.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add 8 expected-failure tests covering remaining translation and type
checking gaps:
- Slice expressions, ternary (IfExp), tuple for-loop targets
- Augmented assignment (+=), power operator (**)
- F-strings starting with variable interpolation (FormattedValue)
- Undeclared variables from unmodeled imports (e.g. sys.argv)
- Exception handler variable typed as Composite where Any expected

Also add failPrefix matching to Expected so translation errors can
match on the error type without being fragile to AST byte offsets.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- AugAssign: desugar `x += y` to `x = x + y` for arithmetic operators
- Pow: add `**` operator to binary op translation table
- FormattedValue: handle f-string interpolation by translating inner expr
- IfExp/Slice: translate ternary and slice expressions to Hole
- Tuple for-target: destructure `for k, v in ...` into individual vars
- PythonError: type exception variables as Any instead of Composite
- While hoisting: hoist variable declarations from while body to outer scope

Flips 8 regression tests from expected failure to success. Import handling
(test_import_usage) remains as expected failure — needs design work to
distinguish dispatch imports from external module imports.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add moduleAliases field to TranslationContext mapping Python identifiers
  to module names, supporting import aliasing (e.g. `import X as Y`)
- Register imports early in pythonToLaurel' so aliases flow to functions
- Module attribute access on unmodeled modules produces Hole gracefully
- Fix isPackage to recognize module aliases as package references
- Initialize hoisted while-loop variables with AnyNone instead of Hole
  to avoid heap parameterization inferring Composite types
- Mark test_while_var_scope as expected failure (root cause: InstanceCall
  emitting Hole needs proper implementation per pyspec_methods.md plan)
- Flip test_import_usage to success

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Implement InstanceCall in LaurelToCoreTranslator at all 5 positions
  (expression, initializer, assignment, parallel assignment, statement)
  as generic Core call statements with no language-specific logic
- Change PySpec procedures to use Any-typed parameters and return values,
  with type constraints expressed as preconditions (e.g. isfrom_string)
- Emit InstanceCall from PythonToLaurel instead of Hole for instance
  method calls on typed variables
- Fix while loop variable hoisting: emit hoisted declarations as separate
  statements in parent scope instead of wrapping in a Block, preventing
  variables from going out of scope before return
- Handle InstanceCall in computeExprType (LaurelTypes) and isFunction
  (Resolution) to support instance procedure nodes
- Add test_instance_call_result.py; flip test_while_var_scope to success
- Mark test_slice, test_tuple_for, test_augassign as expected failures
  (void list_items return assigned to variable causes arity mismatch)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Handle void procedures (0 outputs) in Core translator: emit call
  without assignment target when assigning result of a void procedure
- Fix HighType.Top → HighType.Unknown for InstanceCall fallback
- Fix translateCombinedLaurel API usage (returns tuple, not Except)
- Reorganize test expectations: all 26 tests now pass with no
  expected failures

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…atures

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Replace custom fmtHighType/fmtParam with Laurel.formatParameter and
Laurel.formatStmtExprVal from LaurelFormat.lean. Update guard_msgs
expectations to validate preconditions (e.g. requires Any..isfrom_string(x))
so the type-to-precondition mapping is tested end-to-end.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Replace anyTesterForType (string list) with anyPreconditionForParam
(monadic, returns StmtExpr). Optional types now generate disjunctions:
  requires Any..isfrom_none(x) | Any..isfrom_string(x)
Add coverage for TReal (isfrom_float), UserDefined (isfrom_ClassInstance),
ListStr/ListAny. Unrecognized types report a warning via reportError
instead of being silently discarded.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Process each arg in one for-loop: build Any-typed input and precondition
together using Array.push (O(n)) instead of intermediate lists with
filterMap and append (O(n²)). Remove unused argToParameter.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>