AST: rescue clauses

ql/src/codeql_ruby/ast/Expr.qll

@@ -131,10 +131,16 @@ class StmtSequence extends Expr {
 class BodyStatement extends StmtSequence {
   override BodyStatement::Range range;
 
-  /** Gets the `else` block in this block, if any. */
+  /** Gets the `n`th rescue clause in this block. */
+  final Rescue getRescue(int n) { result = range.getRescue(n) }
+
+  /** Gets a rescue clause in this block. */
+  final Rescue getARescue() { result = this.getRescue(_) }
+
+  /** Gets the `else` clause in this block, if any. */
   final StmtSequence getElse() { result = range.getElse() }
 
-  /** Gets the `ensure` block in this block, if any. */
+  /** Gets the `ensure` clause in this block, if any. */
   final StmtSequence getEnsure() { result = range.getEnsure() }
 
   final predicate hasEnsure() { exists(this.getEnsure()) }
@@ -198,3 +204,58 @@ class Pair extends Expr, @pair {
    */
   final Expr getValue() { result = range.getValue() }
 }
+
+/**
+ * A rescue clause. For example:
+ * ```rb
+ * begin
+ *   write_file
+ * rescue StandardError => msg
+ *   puts msg
+ * end
+ */
+class Rescue extends Expr, @rescue {
+  final override Rescue::Range range;
+
+  /**
+   * Gets the `n`th exception to match, if any. For example `FirstError` or `SecondError` in:
+   * ```rb
+   * begin
+   *  do_something
+   * rescue FirstError, SecondError => e
+   *   handle_error(e)
+   * end
+   * ```
+   */
+  final Expr getException(int n) { result = range.getException(n) }
+
+  /**
+   * Gets an exception to match, if any. For example `FirstError` or `SecondError` in:
+   * ```rb
+   * begin
+   *  do_something
+   * rescue FirstError, SecondError => e
+   *   handle_error(e)
+   * end
+   * ```
+   */
+  final Expr getAnException() { result = getException(_) }
+
+  /**
+   * Gets the variable to which to assign the matched exception, if any.
+   * For example `err` in:
+   * ```rb
+   * begin
+   *  do_something
+   * rescue StandardError => err
+   *   handle_error(err)
+   * end
+   * ```
+   */
+  final Expr getVariable() { result = range.getVariable() }
+
+  /**
+   * Gets the exception handler body.
+   */
+  final StmtSequence getBody() { result = range.getBody() }
+}

ql/src/codeql_ruby/ast/internal/AST.qll

@@ -33,8 +33,6 @@ module AstNode {
       this = any(Generated::Call c).getMethod() and
       not this instanceof Generated::ScopeResolution
       or
-      this instanceof Generated::Rescue
-      or
       this instanceof Generated::RestAssignment
       or
       this = any(Generated::RestAssignment ra).getChild()

ql/src/codeql_ruby/ast/internal/Expr.qll

@@ -196,6 +196,10 @@ module BodyStatement {
         )
     }
 
+    final Rescue getRescue(int n) {
+      result = rank[n + 1](Generated::Rescue node, int i | node = getChild(i) | node order by i)
+    }
+
     final StmtSequence getElse() { result = unique(Generated::Else s | s = getChild(_)) }
 
     final StmtSequence getEnsure() { result = unique(Generated::Ensure s | s = getChild(_)) }
@@ -250,7 +254,21 @@ module Ensure {
 
     final override Stmt getStmt(int n) { result = generated.getChild(n) }
 
-    final override string toString() { result = "ensure ... end" }
+    final override string toString() { result = "ensure ..." }
+  }
+}
+
+module Rescue {
+  class Range extends Expr::Range, @rescue {
+    final override Generated::Rescue generated;
+
+    final Expr getException(int n) { result = generated.getExceptions().getChild(n) }
+
+    final Expr getVariable() { result = generated.getVariable() }
+
+    final StmtSequence getBody() { result = generated.getBody() }
+
+    final override string toString() { result = "rescue ..." }
   }
 }