Rust: Implement CFG for ForExprs

Author: hvitved

rust/ql/lib/codeql/rust/controlflow/internal/ControlFlowGraphImpl.qll

@@ -284,7 +284,9 @@ abstract class LoopingExprTree extends PostOrderTree {
 
   abstract Label getLabel();
 
-  /** Whether this loop captures the `c` completion. */
+  abstract predicate entry(AstNode node);
+
+  /** Holds if this loop captures the `c` completion. */
   predicate capturesLoopJumpCompletion(LoopJumpCompletion c) {
     not c.hasLabel()
     or
@@ -305,7 +307,7 @@ abstract class LoopingExprTree extends PostOrderTree {
       or
       c.(LoopJumpCompletion).isContinue() and this.capturesLoopJumpCompletion(c)
     ) and
-    this.first(succ)
+    this.entry(succ)
   }
 
   override predicate last(AstNode last, Completion c) {
@@ -323,6 +325,8 @@ class LoopExprTree extends LoopingExprTree instanceof LoopExpr {
 
   override Label getLabel() { result = LoopExpr.super.getLabel() }
 
+  override predicate entry(AstNode node) { this.first(node) }
+
   override predicate first(AstNode node) { first(this.getLoopBody(), node) }
 }
 
@@ -331,6 +335,8 @@ class WhileExprTree extends LoopingExprTree instanceof WhileExpr {
 
   override Label getLabel() { result = WhileExpr.super.getLabel() }
 
+  override predicate entry(AstNode node) { this.first(node) }
+
   override predicate first(AstNode node) { first(super.getCondition(), node) }
 
   override predicate succ(AstNode pred, AstNode succ, Completion c) {
@@ -353,6 +359,39 @@ class WhileExprTree extends LoopingExprTree instanceof WhileExpr {
   }
 }
 
+class ForExprTree extends LoopingExprTree instanceof ForExpr {
+  override BlockExpr getLoopBody() { result = ForExpr.super.getLoopBody() }
+
+  override Label getLabel() { result = ForExpr.super.getLabel() }
+
+  override predicate entry(AstNode n) { first(super.getPat(), n) }
+
+  override predicate first(AstNode node) { first(super.getIterable(), node) }
+
+  override predicate succ(AstNode pred, AstNode succ, Completion c) {
+    super.succ(pred, succ, c)
+    or
+    last(super.getIterable(), pred, c) and
+    first(super.getPat(), succ) and
+    completionIsNormal(c)
+    or
+    last(super.getPat(), pred, c) and
+    c.(MatchCompletion).succeeded() and
+    first(this.getLoopBody(), succ)
+    or
+    last(super.getPat(), pred, c) and
+    c.(MatchCompletion).failed() and
+    succ = this
+  }
+
+  override predicate last(AstNode last, Completion c) {
+    super.last(last, c)
+    or
+    last(super.getIterable(), last, c) and
+    not completionIsNormal(c)
+  }
+}
+
 class MatchArmTree extends ControlFlowTree instanceof MatchArm {
   override predicate propagatesAbnormal(AstNode child) { child = super.getExpr() }
 

rust/ql/test/library-tests/controlflow/CONSISTENCY/CfgConsistency.expected

@@ -1,5 +1,3 @@
 deadEnd
 | test.rs:230:28:230:33 | ... < ... |
 | test.rs:245:30:245:48 | BlockExpr |
-scopeNoFirst
-| test.rs:65:5:72:5 | test_for |

rust/ql/test/library-tests/controlflow/Cfg.expected

@@ -122,6 +122,27 @@
 | test.rs:61:13:61:21 | ... = ... | test.rs:56:17:62:9 | BlockExpr |  |
 | test.rs:61:13:61:22 | ExprStmt | test.rs:61:13:61:13 | PathExpr |  |
 | test.rs:61:17:61:21 | false | test.rs:61:13:61:21 | ... = ... |  |
+| test.rs:65:5:72:5 | enter test_for | test.rs:66:18:66:18 | 0 |  |
+| test.rs:65:5:72:5 | exit test_for (normal) | test.rs:65:5:72:5 | exit test_for |  |
+| test.rs:65:25:72:5 | BlockExpr | test.rs:65:5:72:5 | exit test_for (normal) |  |
+| test.rs:66:9:71:9 | ForExpr | test.rs:65:25:72:5 | BlockExpr |  |
+| test.rs:66:13:66:13 | i | test.rs:66:9:71:9 | ForExpr | no-match |
+| test.rs:66:13:66:13 | i | test.rs:67:13:69:13 | ExprStmt | match |
+| test.rs:66:18:66:18 | 0 | test.rs:66:21:66:22 | 10 |  |
+| test.rs:66:18:66:22 | RangeExpr | test.rs:66:13:66:13 | i |  |
+| test.rs:66:21:66:22 | 10 | test.rs:66:18:66:22 | RangeExpr |  |
+| test.rs:66:24:71:9 | BlockExpr | test.rs:66:13:66:13 | i |  |
+| test.rs:67:13:69:13 | ExprStmt | test.rs:67:17:67:17 | i |  |
+| test.rs:67:13:69:13 | IfExpr | test.rs:70:13:70:14 | ExprStmt |  |
+| test.rs:67:16:67:23 | ParenExpr | test.rs:67:13:69:13 | IfExpr | false |
+| test.rs:67:16:67:23 | ParenExpr | test.rs:68:17:68:22 | ExprStmt | true |
+| test.rs:67:17:67:17 | i | test.rs:67:22:67:22 | j |  |
+| test.rs:67:17:67:22 | ... == ... | test.rs:67:16:67:23 | ParenExpr |  |
+| test.rs:67:22:67:22 | j | test.rs:67:17:67:22 | ... == ... |  |
+| test.rs:68:17:68:21 | BreakExpr | test.rs:66:9:71:9 | ForExpr | break |
+| test.rs:68:17:68:22 | ExprStmt | test.rs:68:17:68:21 | BreakExpr |  |
+| test.rs:70:13:70:13 | 1 | test.rs:66:24:71:9 | BlockExpr |  |
+| test.rs:70:13:70:14 | ExprStmt | test.rs:70:13:70:13 | 1 |  |
 | test.rs:75:1:78:1 | enter test_nested_function | test.rs:76:5:76:28 | LetStmt |  |
 | test.rs:75:1:78:1 | exit test_nested_function (normal) | test.rs:75:1:78:1 | exit test_nested_function |  |
 | test.rs:75:40:78:1 | BlockExpr | test.rs:75:1:78:1 | exit test_nested_function (normal) |  |