Rust: Exclude results inside macro expansions from unused entity queries

rust/ql/lib/codeql/rust/elements/internal/AstNodeImpl.qll

@@ -26,21 +26,29 @@ module Impl {
     result = getImmediateParent(e)
   }
 
-  /** Gets the nearest enclosing parent of `ast` that is an `AstNode`. */
-  private AstNode getParentOfAst(AstNode ast) {
-    result = getParentOfAstStep*(getImmediateParent(ast))
-  }
-
   class AstNode extends Generated::AstNode {
+    /**
+     * Gets the nearest enclosing parent of this node, which is also an `AstNode`,
+     * if any.
+     */
+    AstNode getParentNode() { result = getParentOfAstStep*(getImmediateParent(this)) }
+
     /** Gets the immediately enclosing callable of this node, if any. */
     cached
     Callable getEnclosingCallable() {
-      exists(AstNode p | p = getParentOfAst(this) |
+      exists(AstNode p | p = this.getParentNode() |
         result = p
         or
         not p instanceof Callable and
         result = p.getEnclosingCallable()
       )
     }
+
+    /** Holds if this node is inside a macro expansion. */
+    predicate isInMacroExpansion() {
+      this = any(MacroCall mc).getExpanded()
+      or
+      this.getParentNode().isInMacroExpansion()
+    }
   }
 }

rust/ql/src/queries/unusedentities/UnreachableCode.ql

@@ -29,7 +29,10 @@ predicate hiddenNode(AstNode n) {
   not succ(n, _) and
   not succ(_, n)
   or
-  n instanceof ControlFlowGraphImpl::PostOrderTree // location is counter-intuitive
+  n instanceof ControlFlowGraphImpl::PostOrderTree and // location is counter-intuitive
+  not n instanceof MacroExpr
+  or
+  n.isInMacroExpansion()
 }
 
 /**

rust/ql/src/queries/unusedentities/UnusedValue.ql

@@ -20,5 +20,6 @@ where
   not write = any(Ssa::WriteDefinition def).getWriteAccess().getAstNode() and
   // avoid overlap with the unused variable query
   not isUnused(v) and
-  not v instanceof DiscardVariable
-select write, "Variable is assigned a value that is never used."
+  not v instanceof DiscardVariable and
+  not write.isInMacroExpansion()
+select write, "Variable $@ is assigned a value that is never used.", v, v.getName()

rust/ql/src/queries/unusedentities/UnusedVariable.ql

@@ -13,4 +13,4 @@ import UnusedVariable
 
 from Variable v
 where isUnused(v)
-select v, "Variable is not used."
+select v, "Variable '" + v + "' is not used."

rust/ql/src/queries/unusedentities/UnusedVariable.qll

@@ -10,5 +10,6 @@ predicate isUnused(Variable v) {
   not exists(v.getAnAccess()) and
   not exists(v.getInitializer()) and
   not v instanceof DiscardVariable and
+  not v.getPat().isInMacroExpansion() and
   exists(File f | f.getBaseName() = "main.rs" | v.getLocation().getFile() = f) // temporarily severely limit results
 }

rust/ql/test/query-tests/unusedentities/UnreachableCode.expected

@@ -1,16 +1,16 @@
-| unreachable.rs:11:9:11:23 | ExprStmt | This code is never reached. |
 | unreachable.rs:19:9:19:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:31:9:31:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:38:9:38:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:59:5:59:19 | ExprStmt | This code is never reached. |
-| unreachable.rs:106:13:106:20 | ExprStmt | This code is never reached. |
-| unreachable.rs:115:13:115:20 | ExprStmt | This code is never reached. |
-| unreachable.rs:141:5:141:19 | ExprStmt | This code is never reached. |
-| unreachable.rs:148:9:148:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:157:13:157:27 | ExprStmt | This code is never reached. |
-| unreachable.rs:163:9:163:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:169:13:169:27 | ExprStmt | This code is never reached. |
+| unreachable.rs:27:9:27:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:39:9:39:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:46:9:46:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:67:5:67:19 | ExprStmt | This code is never reached. |
+| unreachable.rs:114:13:114:20 | MacroExpr | This code is never reached. |
+| unreachable.rs:123:13:123:20 | MacroExpr | This code is never reached. |
+| unreachable.rs:149:5:149:19 | ExprStmt | This code is never reached. |
+| unreachable.rs:156:9:156:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:165:13:165:27 | ExprStmt | This code is never reached. |
+| unreachable.rs:171:9:171:23 | ExprStmt | This code is never reached. |
 | unreachable.rs:177:13:177:27 | ExprStmt | This code is never reached. |
-| unreachable.rs:180:5:180:19 | ExprStmt | This code is never reached. |
-| unreachable.rs:204:9:204:23 | ExprStmt | This code is never reached. |
-| unreachable.rs:220:9:220:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:185:13:185:27 | ExprStmt | This code is never reached. |
+| unreachable.rs:188:5:188:19 | ExprStmt | This code is never reached. |
+| unreachable.rs:212:9:212:23 | ExprStmt | This code is never reached. |
+| unreachable.rs:228:9:228:23 | ExprStmt | This code is never reached. |

rust/ql/test/query-tests/unusedentities/UnusedValue.expected

@@ -1,24 +1,20 @@
-| main.rs:6:9:6:9 | a | Variable is assigned a value that is never used. |
-| main.rs:9:9:9:9 | d | Variable is assigned a value that is never used. |
-| main.rs:35:5:35:5 | b | Variable is assigned a value that is never used. |
-| main.rs:37:5:37:5 | c | Variable is assigned a value that is never used. |
-| main.rs:40:5:40:5 | c | Variable is assigned a value that is never used. |
-| main.rs:44:9:44:9 | d | Variable is assigned a value that is never used. |
-| main.rs:50:5:50:5 | e | Variable is assigned a value that is never used. |
-| main.rs:61:5:61:5 | f | Variable is assigned a value that is never used. |
-| main.rs:63:5:63:5 | f | Variable is assigned a value that is never used. |
-| main.rs:65:5:65:5 | g | Variable is assigned a value that is never used. |
-| main.rs:87:9:87:9 | a | Variable is assigned a value that is never used. |
-| main.rs:108:9:108:10 | is | Variable is assigned a value that is never used. |
-| main.rs:131:13:131:17 | total | Variable is assigned a value that is never used. |
-| main.rs:194:13:194:31 | res | Variable is assigned a value that is never used. |
-| main.rs:206:9:206:24 | kind | Variable is assigned a value that is never used. |
-| main.rs:210:9:210:32 | kind | Variable is assigned a value that is never used. |
-| main.rs:266:13:266:17 | total | Variable is assigned a value that is never used. |
-| main.rs:334:5:334:39 | kind | Variable is assigned a value that is never used. |
-| main.rs:359:9:359:9 | x | Variable is assigned a value that is never used. |
-| main.rs:367:17:367:17 | x | Variable is assigned a value that is never used. |
-| more.rs:24:9:24:11 | val | Variable is assigned a value that is never used. |
-| more.rs:44:9:44:14 | a_ptr4 | Variable is assigned a value that is never used. |
-| more.rs:59:9:59:13 | d_ptr | Variable is assigned a value that is never used. |
-| more.rs:65:9:65:17 | f_ptr | Variable is assigned a value that is never used. |
+| main.rs:8:9:8:9 | a | Variable $@ is assigned a value that is never used. | main.rs:8:9:8:9 | a | a |
+| main.rs:11:9:11:9 | d | Variable $@ is assigned a value that is never used. | main.rs:11:9:11:9 | d | d |
+| main.rs:37:5:37:5 | b | Variable $@ is assigned a value that is never used. | main.rs:28:9:28:9 | b | b |
+| main.rs:39:5:39:5 | c | Variable $@ is assigned a value that is never used. | main.rs:29:13:29:13 | c | c |
+| main.rs:42:5:42:5 | c | Variable $@ is assigned a value that is never used. | main.rs:29:13:29:13 | c | c |
+| main.rs:46:9:46:9 | d | Variable $@ is assigned a value that is never used. | main.rs:30:13:30:13 | d | d |
+| main.rs:52:5:52:5 | e | Variable $@ is assigned a value that is never used. | main.rs:31:13:31:13 | e | e |
+| main.rs:63:5:63:5 | f | Variable $@ is assigned a value that is never used. | main.rs:32:13:32:13 | f | f |
+| main.rs:65:5:65:5 | f | Variable $@ is assigned a value that is never used. | main.rs:32:13:32:13 | f | f |
+| main.rs:67:5:67:5 | g | Variable $@ is assigned a value that is never used. | main.rs:33:9:33:9 | g | g |
+| main.rs:89:9:89:9 | a | Variable $@ is assigned a value that is never used. | main.rs:89:9:89:9 | a | a |
+| main.rs:110:9:110:10 | is | Variable $@ is assigned a value that is never used. | main.rs:110:9:110:10 | is | is |
+| main.rs:133:13:133:17 | total | Variable $@ is assigned a value that is never used. | main.rs:133:13:133:17 | total | total |
+| main.rs:270:13:270:17 | total | Variable $@ is assigned a value that is never used. | main.rs:238:13:238:17 | total | total |
+| main.rs:363:9:363:9 | x | Variable $@ is assigned a value that is never used. | main.rs:363:9:363:9 | x | x |
+| main.rs:371:17:371:17 | x | Variable $@ is assigned a value that is never used. | main.rs:371:17:371:17 | x | x |
+| more.rs:24:9:24:11 | val | Variable $@ is assigned a value that is never used. | more.rs:24:9:24:11 | val | val |
+| more.rs:44:9:44:14 | a_ptr4 | Variable $@ is assigned a value that is never used. | more.rs:44:9:44:14 | a_ptr4 | a_ptr4 |
+| more.rs:59:9:59:13 | d_ptr | Variable $@ is assigned a value that is never used. | more.rs:59:9:59:13 | d_ptr | d_ptr |
+| more.rs:65:9:65:17 | f_ptr | Variable $@ is assigned a value that is never used. | more.rs:65:13:65:17 | f_ptr | f_ptr |

rust/ql/test/query-tests/unusedentities/UnusedVariable.expected

@@ -1,21 +1,21 @@
-| main.rs:25:9:25:9 | a | Variable is not used. |
-| main.rs:90:13:90:13 | d | Variable is not used. |
-| main.rs:139:5:139:5 | y | Variable is not used. |
-| main.rs:166:9:166:9 | x | Variable is not used. |
-| main.rs:236:17:236:17 | a | Variable is not used. |
-| main.rs:244:20:244:22 | val | Variable is not used. |
-| main.rs:258:14:258:16 | val | Variable is not used. |
-| main.rs:273:22:273:24 | val | Variable is not used. |
-| main.rs:280:24:280:26 | val | Variable is not used. |
-| main.rs:288:13:288:15 | num | Variable is not used. |
-| main.rs:303:12:303:12 | j | Variable is not used. |
-| main.rs:323:25:323:25 | y | Variable is not used. |
-| main.rs:326:28:326:28 | a | Variable is not used. |
-| main.rs:329:9:329:9 | p | Variable is not used. |
-| main.rs:347:9:347:13 | right | Variable is not used. |
-| main.rs:353:9:353:14 | right2 | Variable is not used. |
-| main.rs:360:13:360:13 | y | Variable is not used. |
-| main.rs:368:21:368:21 | y | Variable is not used. |
-| main.rs:413:26:413:28 | val | Variable is not used. |
-| main.rs:416:21:416:23 | acc | Variable is not used. |
-| main.rs:437:9:437:14 | unused | Variable is not used. |
+| main.rs:27:9:27:9 | a | Variable 'a' is not used. |
+| main.rs:92:13:92:13 | d | Variable 'd' is not used. |
+| main.rs:141:5:141:5 | y | Variable 'y' is not used. |
+| main.rs:168:9:168:9 | x | Variable 'x' is not used. |
+| main.rs:240:17:240:17 | a | Variable 'a' is not used. |
+| main.rs:248:20:248:22 | val | Variable 'val' is not used. |
+| main.rs:262:14:262:16 | val | Variable 'val' is not used. |
+| main.rs:277:22:277:24 | val | Variable 'val' is not used. |
+| main.rs:284:24:284:26 | val | Variable 'val' is not used. |
+| main.rs:292:13:292:15 | num | Variable 'num' is not used. |
+| main.rs:307:12:307:12 | j | Variable 'j' is not used. |
+| main.rs:327:25:327:25 | y | Variable 'y' is not used. |
+| main.rs:330:28:330:28 | a | Variable 'a' is not used. |
+| main.rs:333:9:333:9 | p | Variable 'p' is not used. |
+| main.rs:351:9:351:13 | right | Variable 'right' is not used. |
+| main.rs:357:9:357:14 | right2 | Variable 'right2' is not used. |
+| main.rs:364:13:364:13 | y | Variable 'y' is not used. |
+| main.rs:372:21:372:21 | y | Variable 'y' is not used. |
+| main.rs:417:26:417:28 | val | Variable 'val' is not used. |
+| main.rs:420:21:420:23 | acc | Variable 'acc' is not used. |
+| main.rs:441:9:441:14 | unused | Variable 'unused' is not used. |

rust/ql/test/query-tests/unusedentities/main.rs

@@ -1,4 +1,6 @@
-//fn cond() -> bool;
+mod unreachable;
+
+use unreachable::*;
 
 // --- locals ---
 
@@ -191,7 +193,7 @@
     }
 
     for x in 1..10 {
-        _ = format!("x is {x}"); // $ SPURIOUS: Alert[rust/unused-value]
+        _ = format!("x is {x}");
     }
 
     for x in 1..10 {
@@ -203,11 +205,13 @@
     }
 
     for x in 1..10 {
-        assert_eq!(x, 1); // $ SPURIOUS: Alert[rust/unused-value]
+        assert_eq!(x, 1);
+        break;
     }
 
     for x in 1..10 {
-        assert_eq!(id(x), id(1)); // $ SPURIOUS: Alert[rust/unused-value]
+        assert_eq!(id(x), id(1));
+        break;
     }
 }
 
@@ -331,7 +335,7 @@
     }
 
     let duration1 = std::time::Duration::new(10, 0); // ten seconds
-    assert_eq!(duration1.as_secs(), 10); // $ SPURIOUS: Alert[rust/unused-value]
+    assert_eq!(duration1.as_secs(), 10);
 
     let duration2: Result<std::time::Duration, String> = Ok(std::time::Duration::new(10, 0));
     match duration2 {
@@ -434,7 +438,7 @@
     fn increment(
         &mut self,
         times: i32,
-        unused: i32, // $ Alert[rust/unused-variable]
+        unused: &mut i32, // $ Alert[rust/unused-variable]
     ) {
         self.value += times;
     }
@@ -443,9 +447,22 @@
 fn traits() {
     let mut i = MyValue { value: 0 };
     let a = 1;
-    let b = 2;
+    let mut b = 2;
+
+    i.increment(a, &mut b);
+}
 
-    i.increment(a, b);
+// --- macros ---
+
+fn macros() {
+    let x;
+    println!(
+        "The value of x is {}",
+        ({
+            x = 10; // $ MISSING: Alert[rust/unused-value]
+            10
+        })
+    )
 }
 
 // --- main ---
@@ -464,12 +481,14 @@
     folds_and_closures();
 
     unreachable_if_1();
-    unreachable_panic();
+    // unreachable_panic();
     unreachable_match();
-    unreachable_loop();
+    // unreachable_loop();
     unreachable_paren();
     unreachable_let_1();
     unreachable_let_2();
     unreachable_if_2();
     unreachable_if_3();
+
+    macros();
 }

rust/ql/test/query-tests/unusedentities/unreachable.rs

@@ -1,12 +1,20 @@
-//fn cond() -> bool;
-//fn get_a_number() -> i32;
-//fn maybe_get_a_number() -> Option<i32>;
+pub fn cond() -> bool {
+    true
+}
+
+fn get_a_number() -> i32 {
+    42
+}
+
+fn maybe_get_a_number() -> Option<i32> {
+    None
+}
 
 // --- unreachable code --
 
 fn do_something() {}
 
-fn unreachable_if_1() {
+pub fn unreachable_if_1() {
     if false {
         do_something(); // $ Alert[rust/dead-code]
     } else {
@@ -59,7 +67,7 @@ fn unreachable_if_1() {
     do_something(); // $ Alert[rust/dead-code]
 }
 
-fn unreachable_panic() {
+pub fn unreachable_panic() {
     if cond() {
         do_something();
         panic!("Oh no!!!");
@@ -119,7 +127,7 @@ fn unreachable_panic() {
     }
 }
 
-fn unreachable_match() {
+pub fn unreachable_match() {
     match get_a_number() {
         1 => {
             return;
@@ -141,7 +149,7 @@ fn unreachable_match() {
     do_something(); // $ Alert[rust/dead-code]
 }
 
-fn unreachable_loop() {
+pub fn unreachable_loop() {
     loop {
         do_something();
         break;
@@ -182,11 +190,11 @@ fn unreachable_loop() {
     do_something();
 }
 
-fn unreachable_paren() {
+pub fn unreachable_paren() {
     let _ = (((1)));
 }
 
-fn unreachable_let_1() {
+pub fn unreachable_let_1() {
     if let Some(_) = maybe_get_a_number() {
         do_something();
         return;
@@ -207,7 +215,7 @@ fn unreachable_let_1() {
     do_something();
 }
 
-fn unreachable_let_2() {
+pub fn unreachable_let_2() {
     let Some(_) = maybe_get_a_number() else {
         do_something();
         return;
@@ -224,7 +232,7 @@ fn unreachable_let_2() {
     do_something();
 }
 
-fn unreachable_if_2() {
+pub fn unreachable_if_2() {
     if cond() {
         do_something();
         return;
@@ -235,7 +243,7 @@ fn unreachable_if_2() {
     do_something();
 }
 
-fn unreachable_if_3() {
+pub fn unreachable_if_3() {
     if !cond() {
         do_something();
         return;