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preserve the initial state of the solver with push/pop for multiple objectives (#8264)

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* preserve the initial state of the solver with push/pop for multiple objectives

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

* Fix memory corruption in Z3_polynomial_subresultants

The API function had a memory corruption bug where allocating the result
vector while the default_expr2polynomial converter was still in scope
could corrupt the converter's internal expr2var mapping.

Fixed by restructuring the code to:
1. Complete all polynomial computation in a scoped block
2. Store results in a temporary expr_ref_vector
3. Let the converter go out of scope
4. Then allocate and populate the result vector

Also improved the test to:
- Use randomized testing with 20 iterations
- Test both cases: variable in polynomials and variable not in polynomials
- Use proper reference counting (inc_ref before dec_ref)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
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Lev Nachmanson 2026-01-23 08:41:03 -10:00 • committed by GitHub
parent 2a5bfb818b
commit c0583b828d
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3 changed files with 107 additions and 40 deletions
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60
src/test/api_polynomial.cpp
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@ -19,31 +19,63 @@ Notes:
#include "api/z3.h"
#include "util/trace.h"
#include "util/debug.h"
#include <random>
static void run_single_test(int seed) {
std::mt19937 gen(seed);
std::uniform_int_distribution<> var_choice(0, 2);
void tst_api_polynomial() {
Z3_config cfg = Z3_mk_config();
Z3_context ctx = Z3_mk_context(cfg);
Z3_del_config(cfg);
// Create real sort and simple variables
Z3_sort real_sort = Z3_mk_real_sort(ctx);
// Create variables
Z3_symbol x_sym = Z3_mk_string_symbol(ctx, "x");
Z3_symbol y_sym = Z3_mk_string_symbol(ctx, "y");
Z3_symbol z_sym = Z3_mk_string_symbol(ctx, "z");
Z3_ast x = Z3_mk_const(ctx, x_sym, real_sort);
Z3_ast y = Z3_mk_const(ctx, y_sym, real_sort);
Z3_ast z = Z3_mk_const(ctx, z_sym, real_sort);
// Constants
Z3_ast one = Z3_mk_real(ctx, 1, 1);
Z3_ast two = Z3_mk_real(ctx, 2, 1);
// Test Z3_polynomial_subresultants - just try to call it
try {
Z3_ast_vector result = Z3_polynomial_subresultants(ctx, one, two, x);
// If we get here, function executed without major crash
if (result) {
Z3_ast_vector_dec_ref(ctx, result);
}
ENSURE(true); // Test succeeded in calling the function
} catch (...) {
// Even if there's an exception, we tested the function
ENSURE(true);
// Create polynomials: p = x + 1, q = x + 2
Z3_ast add_args1[2] = {x, one};
Z3_ast p = Z3_mk_add(ctx, 2, add_args1);
Z3_ast add_args2[2] = {x, two};
Z3_ast q = Z3_mk_add(ctx, 2, add_args2);
// Choose which variable to use for subresultant
Z3_ast var;
int choice = var_choice(gen);
switch (choice) {
case 0: var = x; break; // x is in the polynomials
case 1: var = y; break; // y is NOT in the polynomials
default: var = z; break; // z is NOT in the polynomials
}
Z3_ast_vector result = Z3_polynomial_subresultants(ctx, p, q, var);
ENSURE(result != nullptr);
Z3_ast_vector_inc_ref(ctx, result); // Take ownership
unsigned size = Z3_ast_vector_size(ctx, result);
// If var is x (in polynomials), expect 1 result; otherwise 0
if (choice == 0) {
ENSURE(size == 1);
} else {
ENSURE(size == 0);
}
Z3_ast_vector_dec_ref(ctx, result); // Release ownership
Z3_del_context(ctx);
}
}
void tst_api_polynomial() {
// Run multiple tests with fresh contexts
for (int i = 0; i < 20; i++) {
run_single_test(i);
}
}