fix(neverAccessedVariables): False positive on unused fields

src/detectors/builtin/neverAccessedVariables.ts

@@ -154,7 +154,7 @@ export class NeverAccessedVariables extends Detector {
     return Array.from(cu.ast.getFunctions()).reduce((acc, fun) => {
       forEachExpression(fun, (expr) => {
         if (expr.kind === "op_field" && expr.src.kind === "id") {
-          acc.add(expr.src.value);
+          acc.add(expr.name);
         }
       });
       return acc;
@@ -179,7 +179,7 @@ export class NeverAccessedVariables extends Detector {
   }
 
   collectDefinedConstants(cu: CompilationUnit): Set<[ConstantName, ASTRef]> {
-    return Array.from(cu.ast.getConstants(false)).reduce((acc, constant) => {
+    return Array.from(cu.ast.getConstants()).reduce((acc, constant) => {
       acc.add([constant.name, constant.ref]);
       return acc;
     }, new Set<[ConstantName, ASTRef]>());

src/detectors/builtin/unboundLoops.ts

@@ -175,7 +175,7 @@ export class UnboundLoops extends Detector {
     cu: CompilationUnit,
     ctx: Context<ASTRef>,
   ): void {
-    for (const c of cu.ast.getConstants(/* allowStdlib = */ true)) {
+    for (const c of cu.ast.getConstants({ includeStdlib: true })) {
       ctx.addFact("constDef", Fact.from([c.name], c.ref));
     }
   }

src/internals/ir.ts

@@ -24,7 +24,7 @@ export type EntryOrigin = "user" | "stdlib";
 export class TactASTStore {
   /**
    * Constructs a TactASTStore with mappings to all major AST components.
-   * @param stdlibConstants Identifiers of constants defined in stdlib.
+   * @param stdlibIds Identifiers of AST elements defined in stdlib.
    * @param programEntries Identifiers of AST elements defined on the top-level.
    * @param functions Functions and methods including user-defined and special methods.
    * @param constants Constants defined across the compilation unit.
@@ -36,7 +36,7 @@ export class TactASTStore {
    * @param statements All executable statements within all functions of the project.
    */
   constructor(
-    private stdlibConstants = new Set<number>(),
+    private stdlibIds = new Set<number>(),
     private programEntries: Set<number>,
     private functions: Map<number, ASTFunction | ASTReceive | ASTInitFunction>,
     private constants: Map<number, ASTConstant>,
@@ -73,27 +73,48 @@ export class TactASTStore {
       return acc;
     }, [] as ASTNode[]);
   }
+  /**
+   * Returns all the items defined within the program.
+   * @param items The collection of items (functions or constants).
+   * @param params Additional parameters:
+   * - includeStdlib: If true, includes items defined in stdlib.
+   * @returns An iterator for the items.
+   */
+  private getItems<T extends { id: number }>(
+    items: Map<number, T>,
+    params: Partial<{ includeStdlib: boolean }> = {},
+  ): IterableIterator<T> {
+    const { includeStdlib = false } = params;
+    if (includeStdlib) {
+      return items.values();
+    }
+    const userItems = Array.from(items.values()).filter(
+      (c) => !this.stdlibIds.has(c.id),
+    );
+    return userItems.values();
+  }
 
   /**
    * Returns all the functions and methods defined within the program.
+   * @param params Additional parameters:
+   * - includeStdlib: If true, includes functions defined in stdlib.
    */
-  getFunctions(): IterableIterator<ASTFunction | ASTReceive | ASTInitFunction> {
-    return this.functions.values();
+  getFunctions(
+    params: Partial<{ includeStdlib: boolean }> = {},
+  ): IterableIterator<ASTFunction | ASTReceive | ASTInitFunction> {
+    return this.getItems(this.functions, params);
   }
 
   /**
    * Returns all the constants defined within the program, including top-level constants
    * and contract constants.
-   * @param allowStdlib If true, includes constants defined in stdlib.
+   * @param params Additional parameters:
+   * - includeStdlib: If true, includes constants defined in stdlib.
    */
-  getConstants(allowStdlib: boolean = true): IterableIterator<ASTConstant> {
-    if (allowStdlib) {
-      return this.constants.values();
-    }
-    const userConstants = Array.from(this.constants.values()).filter(
-      (c) => !this.stdlibConstants.has(c.id),
-    );
-    return userConstants.values();
+  getConstants(
+    params: Partial<{ includeStdlib: boolean }> = {},
+  ): IterableIterator<ASTConstant> {
+    return this.getItems(this.constants, params);
   }
 
   getContracts(): IterableIterator<ASTContract> {

src/internals/tactIRBuilder.ts

@@ -102,7 +102,7 @@ function hasSubdirs(filePath: string, subdirs: string[]): boolean {
  */
 export class ASTMapper {
   private programEntries = new Set<number>();
-  private stdlibConstants = new Set<number>();
+  private stdlibIds = new Set<number>();
   private functions = new Map<
     number,
     ASTFunction | ASTReceive | ASTInitFunction
@@ -118,6 +118,12 @@ export class ASTMapper {
   constructor(private ast: TactAST) {
     this.ast.functions.forEach((func) => {
       this.programEntries.add(func.id);
+      if (
+        func.ref.file !== null &&
+        hasSubdirs(func.ref.file, STDLIB_PATH_ELEMENTS)
+      ) {
+        this.stdlibIds.add(func.id);
+      }
       if (func.kind == "def_function") {
         this.processFunction(func);
       } else {
@@ -129,7 +135,7 @@ export class ASTMapper {
         constant.ref.file !== null &&
         hasSubdirs(constant.ref.file, STDLIB_PATH_ELEMENTS)
       ) {
-        this.stdlibConstants.add(constant.id);
+        this.stdlibIds.add(constant.id);
       }
       this.programEntries.add(constant.id);
       this.constants.set(constant.id, constant);
@@ -142,7 +148,7 @@ export class ASTMapper {
 
   public getASTStore(): TactASTStore {
     return new TactASTStore(
-      this.stdlibConstants,
+      this.stdlibIds,
       this.programEntries,
       this.functions,
       this.constants,

test/contracts/never-accessed-2.cfg.json

@@ -0,0 +1,39 @@
+{
+  "projectName": "never-accessed-2",
+  "functions": [],
+  "contracts": [
+    {
+      "name": "FieldTest",
+      "methods": [
+        {
+          "name": "FieldTest.init",
+          "cfg": {
+            "nodes": [
+              {
+                "id": 1263,
+                "stmtID": 16730,
+                "srcEdges": [],
+                "dstEdges": []
+              }
+            ],
+            "edges": []
+          }
+        },
+        {
+          "name": "FieldTest.use_f1",
+          "cfg": {
+            "nodes": [
+              {
+                "id": 1264,
+                "stmtID": 16735,
+                "srcEdges": [],
+                "dstEdges": []
+              }
+            ],
+            "edges": []
+          }
+        }
+      ]
+    }
+  ]
+}

test/contracts/never-accessed-2.expected.out

@@ -0,0 +1,8 @@
+test/contracts/never-accessed-2.tact:3:5:
+  2 |     f1: Address;
+> 3 |     f2: Int as uint256 = 0;
+          ^
+  4 | 
+Field is never used
+Help: Consider removing the field
+See: https://nowarp.github.io/docs/misti/docs/detectors/NeverAccessedVariables

test/contracts/never-accessed-2.tact

@@ -0,0 +1,12 @@
+contract FieldTest {
+    f1: Address;
+    f2: Int as uint256 = 0;
+
+    init() {
+        self.f1 = sender();
+    }
+
+    get fun use_f1(): Address {
+        return self.f1;
+    }
+}

test/contracts/readonly-1.cfg.json

@@ -6,101 +6,101 @@
       "cfg": {
         "nodes": [
           {
-            "id": 1262,
-            "stmtID": 16729,
+            "id": 1415,
+            "stmtID": 18935,
             "srcEdges": [],
             "dstEdges": [
-              1264
+              1417
             ]
           },
           {
-            "id": 1263,
-            "stmtID": 16732,
+            "id": 1416,
+            "stmtID": 18938,
             "srcEdges": [
-              1264
+              1417
             ],
             "dstEdges": [
-              1266
+              1419
             ]
           },
           {
-            "id": 1265,
-            "stmtID": 16735,
+            "id": 1418,
+            "stmtID": 18941,
             "srcEdges": [
-              1266
+              1419
             ],
             "dstEdges": [
-              1268
+              1421
             ]
           },
           {
-            "id": 1267,
-            "stmtID": 16742,
+            "id": 1420,
+            "stmtID": 18948,
             "srcEdges": [
-              1268
+              1421
             ],
             "dstEdges": [
-              1270,
-              1274
+              1423,
+              1427
             ]
           },
           {
-            "id": 1269,
-            "stmtID": 16741,
+            "id": 1422,
+            "stmtID": 18947,
             "srcEdges": [
-              1270
+              1423
             ],
             "dstEdges": [
-              1272
+              1425
             ]
           },
           {
-            "id": 1271,
-            "stmtID": 16744,
+            "id": 1424,
+            "stmtID": 18950,
             "srcEdges": [
-              1272
+              1425
             ],
             "dstEdges": []
           },
           {
-            "id": 1273,
-            "stmtID": 16744,
+            "id": 1426,
+            "stmtID": 18950,
             "srcEdges": [
-              1274
+              1427
             ],
             "dstEdges": []
           }
         ],
         "edges": [
           {
-            "id": 1264,
-            "src": 1262,
-            "dst": 1263
+            "id": 1417,
+            "src": 1415,
+            "dst": 1416
           },
           {
-            "id": 1266,
-            "src": 1263,
-            "dst": 1265
+            "id": 1419,
+            "src": 1416,
+            "dst": 1418
           },
           {
-            "id": 1268,
-            "src": 1265,
-            "dst": 1267
+            "id": 1421,
+            "src": 1418,
+            "dst": 1420
           },
           {
-            "id": 1270,
-            "src": 1267,
-            "dst": 1269
+            "id": 1423,
+            "src": 1420,
+            "dst": 1422
           },
           {
-            "id": 1272,
-            "src": 1269,
-            "dst": 1271
+            "id": 1425,
+            "src": 1422,
+            "dst": 1424
           },
           {
-            "id": 1274,
-            "src": 1267,
-            "dst": 1273
+            "id": 1427,
+            "src": 1420,
+            "dst": 1426
           }
         ]
       }