feat(solver+lattice): Implement IntervalLattice and widening worklist…

… solver

src/detectors/builtin/exitCodeUsage.ts

@@ -0,0 +1,66 @@
+import { CFG, CompilationUnit } from "../../internals/ir";
+import { MistiTactWarning, Severity } from "../../internals/warnings";
+import { DataflowDetector } from "../detector";
+
+/**
+ * A detector that identifies improper use of exit codes outside the developer-allowed range.
+ *
+ * ## Why is it bad?
+ * In the TON blockchain, exit codes are divided into specific ranges: 0 to 127
+ * are reserved for the TVM or FunC, and 128 to 255 are reserved for Tact. This
+ * structure leaves the range from 256 to 65535 for developers to define custom
+ * exit codes.
+ *
+ * When exit codes are defined outside this allowed range, it may lead to
+ * conflicts with existing reserved codes, causing unintended behavior or
+ * errors in the contract.
+ *
+ * ## Example
+ * ```tact
+ * contract Foo {
+ *     const NotOwnerExitCode: Int = 128; // Bad: exit code defined in the reserved range for Tact
+ *     receive("foobar") {
+ *         nativeThrowUnless(self.NotOwnerExitCode, sender() == self.owner);
+ *     }
+ * }
+ * ```
+ *
+ * Use instead:
+ * ```tact
+ * contract Foo {
+ *     const NotOwnerExitCode: Int = 256; // OK: using exit code from the allowed range
+ *     receive("foobar") {
+ *         nativeThrowUnless(self.NotOwnerExitCode, sender() == self.owner);
+ *     }
+ * }
+ * ```
+ *
+ * ## Resources
+ * 1. [Exit Codes | Tact Docs](https://docs.tact-lang.org/book/exit-codes)
+ */
+export class ExitCodeUsage extends DataflowDetector {
+  severity = Severity.CRITICAL;
+
+  async check(cu: CompilationUnit): Promise<MistiTactWarning[]> {
+    const warnings: MistiTactWarning[] = [];
+    cu.forEachCFG(
+      (cfg: CFG) => {
+        const node = cu.ast.getFunction(cfg.id);
+        if (node === undefined) {
+          return;
+        }
+        // const lattice = new CellOverflowLattice();
+        // const transfer = new CellOverflowTransfer();
+        // const solver = new WorklistSolver(
+        //   cu,
+        //   cfg,
+        //   transfer,
+        //   lattice,
+        //   "forward",
+        // );
+      },
+      { includeStdlib: false },
+    );
+    return warnings;
+  }
+}

src/detectors/detector.ts

@@ -385,6 +385,13 @@ export const BuiltInDetectors: Record<string, DetectorEntry> = {
       ),
     enabledByDefault: true,
   },
+  ExitCodeUsage: {
+    loader: (ctx: MistiContext) =>
+      import("./builtin/exitCodeUsage").then(
+        (module) => new module.ExitCodeUsage(ctx),
+      ),
+    enabledByDefault: true,
+  },
 };
 
 /**

src/internals/lattice/index.ts

@@ -0,0 +1,3 @@
+export * from "./generic";
+export * from "./interval";
+export * from "./num";