Z3 incorrectly returns SAT for formulas like `store(store(const(x), i0,
e0), i1, e1) = store(store(const(y), i0, e0), i1, e1) ∧ x ≠ y` when the
index sort has a small finite domain (e.g. `(_ BitVec 2)` = 4 elements).
The quantifier-based encoding of the same constraint correctly returns
UNSAT.
## Changes
### `src/sat/smt/array_solver.cpp` — `add_parent_lambda()`
When a store is added to an array's `m_parent_lambdas` after that array
already has `m_has_default = true` (i.e., a `default(array)` term
already exists in the e-graph), the default axiom for the new store was
silently dropped. This breaks the propagation chain:
```
default(const(x)) = x
↓ [via store default axiom]
default(store(const(x), i, v)) = x
↓ [via store default axiom]
default(store(store(const(x), ...), ...)) = x
↓ [EUF congruence from store equality]
x = y → contradiction
```
Fix: push `default_axiom(lambda)` in `add_parent_lambda` when
`m_has_default` is already set, so late-arriving stores still get their
default axioms instantiated.
```cpp
void solver::add_parent_lambda(theory_var v_child, euf::enode* lambda) {
auto& d = get_var_data(find(v_child));
ctx.push_vec(d.m_parent_lambdas, lambda);
if (should_prop_upward(d))
propagate_select_axioms(d, lambda);
if (d.m_has_default) // new: fire default axiom retroactively
push_axiom(default_axiom(lambda));
}
```
### Known remaining gap
`mk_eq_core` in `array_rewriter.cpp` also has a related issue: the
unconditional store-chain expansion fires only when `domain_size >
num_lhs + num_rhs` (line 893), but the correct threshold is `domain_size
> max(num_lhs, num_rhs)`. With 4-element domain and 2 stores per side,
`2+2 = 4` equals the domain size so the expansion is skipped. The
variant gated by `m_expand_store_eq` already uses `max()` correctly
(line 911); the unconditional path needs the same fix.
---------
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Nikolaj Bjorner <nbjorner@microsoft.com>
* Introduce X-macro-based trace tag definition
- Created trace_tags.def to centralize TRACE tag definitions
- Each tag includes a symbolic name and description
- Set up enum class TraceTag for type-safe usage in TRACE macros
* Add script to generate Markdown documentation from trace_tags.def
- Python script parses trace_tags.def and outputs trace_tags.md
* Refactor TRACE_NEW to prepend TraceTag and pass enum to is_trace_enabled
* trace: improve trace tag handling system with hierarchical tagging
- Introduce hierarchical tag-class structure: enabling a tag class activates all child tags
- Unify TRACE, STRACE, SCTRACE, and CTRACE under enum TraceTag
- Implement initial version of trace_tag.def using X(tag, tag_class, description)
(class names and descriptions to be refined in a future update)
* trace: replace all string-based TRACE tags with enum TraceTag
- Migrated all TRACE, STRACE, SCTRACE, and CTRACE macros to use enum TraceTag values instead of raw string literals
* trace : add cstring header
* trace : Add Markdown documentation generation from trace_tags.def via mk_api_doc.py
* trace : rename macro parameter 'class' to 'tag_class' and remove Unicode comment in trace_tags.h.
* trace : Add TODO comment for future implementation of tag_class activation
* trace : Disable code related to tag_class until implementation is ready (#7663).
#6319 - fix incompleteness in propagation of default to all array terms in the equivalence class.
Fix bug with q_mbi where domain restrictions are not using values because the current model does not evaluate certain bound variables to values. Set model completion when adding these bound variables to the model to ensure their values are not missed.
Add better propagation of diagnostics when tactics and the new solver return unknown. The reason for unknown can now be traced to what theory was culprit (currently no additional information)
