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Replace quantifiers with array extensionality for map bijection in verifier #1132

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Merged
copybara-service merged 1 commit into from
Jul 22, 2026
+12 −31
Merged

Replace quantifiers with array extensionality for map bijection in verifier #1132

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38 changes: 9 additions & 29 deletions verifier/src/main/java/dev/cel/verifier/CelAstToZ3Translator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@
import com.microsoft.z3.Expr;
import com.microsoft.z3.FuncDecl;
import com.microsoft.z3.IntExpr;
import com.microsoft.z3.Pattern;
import com.microsoft.z3.Quantifier;
import com.microsoft.z3.SeqExpr;
import com.microsoft.z3.Sort;
Expand Down Expand Up @@ -79,7 +78,6 @@ final class CelAstToZ3Translator {
private static final String EMPTY_MSG_REF_PREFIX = "!empty_msg_ref_";
private static final String EMPTY_LIST_PREFIX = "!empty_list";
private static final String EMPTY_MAP_PREFIX = "!empty_map";
private static final String MAP_BIJECTION_PREFIX = "k_map_bijection";
private final Context ctx;
private final CelZ3TypeSystem typeSystem;
private final CelZ3OperatorTranslator operatorTranslator;
Expand Down Expand Up @@ -819,36 +817,18 @@ private void applyBoundedMapBijection(
}
}

Expr<?> kVar = ctx.mkFreshConst(MAP_BIJECTION_PREFIX, typeSystem.celValueSort());
BoolExpr isValidKey =
ctx.mkOr(
typeSystem.isInt(kVar), typeSystem.isUint(kVar),
typeSystem.isBool(kVar), typeSystem.isString(kVar));
BoolExpr inMap = (BoolExpr) ctx.mkSelect(mapPresence, kVar);
BoolExpr isNotTruncated = ctx.mkLe(lengthExpr, ctx.mkInt(comprehensionUnrollLimit));

List<BoolExpr> inSeqMatches = new ArrayList<>();
ArrayExpr seqMap = ctx.mkConstArray(typeSystem.celValueSort(), ctx.mkFalse());
for (int i = 0; i < comprehensionUnrollLimit; i++) {
BoolExpr match =
ctx.mkAnd(
ctx.mkLt(ctx.mkInt(i), lengthExpr), ctx.mkEq(kVar, ctx.mkNth(seq, ctx.mkInt(i))));
inSeqMatches.add(match);
seqMap =
(ArrayExpr)
ctx.mkITE(
ctx.mkLt(ctx.mkInt(i), lengthExpr),
ctx.mkStore(seqMap, ctx.mkNth(seq, ctx.mkInt(i)), ctx.mkTrue()),
seqMap);
}
BoolExpr inSeq = CelZ3TypeSystem.mkOrFlattened(ctx, inSeqMatches);

BoolExpr isNotTruncated = ctx.mkLe(lengthExpr, ctx.mkInt(comprehensionUnrollLimit));

Pattern inMapPattern = ctx.mkPattern(inMap);

BoolExpr completeness =
ctx.mkForall(
new Expr<?>[] {kVar},
ctx.mkImplies(ctx.mkAnd(isNotTruncated, isValidKey, inMap), inSeq),
1,
new Pattern[] {inMapPattern},
null,
null,
null);
typeConstraints.add(completeness);
typeConstraints.add(ctx.mkImplies(isNotTruncated, ctx.mkEq(mapPresence, seqMap)));
}

private TranslatedValue[] evaluateLoopCondAndStep(
Expand Down
5 changes: 3 additions & 2 deletions verifier/src/test/java/dev/cel/verifier/CelVerifierZ3ImplTest.java
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Expand Up @@ -1430,8 +1430,9 @@ private enum EquivalenceTestCase {
"TestAllTypes{?repeated_int32: optional.of([1, 2])}",
"cel.expr.conformance.proto3.TestAllTypes{repeated_int32: [1, 2]}"),
OPTIONAL_PRUNE_LIST_EQUALITY("[?optional.none(), 1] == [1]", "true"),
OPTIONAL_PRUNE_LIST_COMPREHENSION("[1, ?optional.none()].all(x, x > 0)", "true");

OPTIONAL_PRUNE_LIST_COMPREHENSION("[1, ?optional.none()].all(x, x > 0)", "true"),
MAP_COMPREHENSION(
"{'a': 1, 'b': 2}.exists(k, k == 'a')", "{'a': 1, 'b': 2}.exists(k, k == 'a')");
private final String exprA;
private final String exprB;

Expand Down
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