AST: add ElementReference

ql/src/codeql_ruby/ast/Call.qll

@@ -83,6 +83,18 @@ class Call extends Expr {
   final Block getBlock() { result = range.getBlock() }
 }
 
+/**
+ * An element reference; a call to the `[]` method.
+ * ```rb
+ * a[0]
+ * ```
+ */
+class ElementReference extends Call, @element_reference {
+  final override ElementReference::Range range;
+
+  final override string getAPrimaryQlClass() { result = "ElementReference" }
+}
+
 /**
  * A call to `yield`.
  * ```rb

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

@@ -49,8 +49,6 @@ module AstNode {
       or
       this instanceof Generated::Array
       or
-      this instanceof Generated::ElementReference
-      or
       this instanceof Generated::Complex
       or
       this instanceof Generated::Character

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

@@ -13,7 +13,7 @@ module Call {
 
     abstract Block getBlock();
 
-    final override string toString() { result = "call to " + this.getMethodName() }
+    override string toString() { result = "call to " + this.getMethodName() }
   }
 
   private class IdentifierCallRange extends Call::Range, @token_identifier {
@@ -71,6 +71,22 @@ module Call {
   }
 }
 
+module ElementReference {
+  class Range extends Call::Range, @element_reference {
+    final override Generated::ElementReference generated;
+
+    final override Expr getReceiver() { result = generated.getObject() }
+
+    final override string getMethodName() { result = "[]" }
+
+    final override string toString() { result = "...[...]" }
+
+    final override Expr getArgument(int n) { result = generated.getChild(n) }
+
+    final override Block getBlock() { none() }
+  }
+}
+
 module YieldCall {
   class Range extends Call::Range, @yield {
     final override Generated::Yield generated;

ql/test/library-tests/ast/calls/calls.expected

@@ -84,6 +84,8 @@ callsWithArguments
 | calls.rb:36:3:36:16 | call to yield | yield | 1 | calls.rb:36:14:36:16 | 200 |
 | calls.rb:54:1:54:14 | call to some_func | some_func | 0 | calls.rb:54:11:54:13 | call to foo |
 | calls.rb:55:1:55:17 | call to some_func | some_func | 0 | calls.rb:55:11:55:16 | call to foo |
+| calls.rb:234:1:234:8 | ...[...] | [] | 0 | calls.rb:234:5:234:7 | call to bar |
+| calls.rb:235:1:235:14 | ...[...] | [] | 0 | calls.rb:235:8:235:13 | call to bar |
 | calls.rb:266:1:266:9 | call to foo | foo | 0 | calls.rb:266:5:266:8 | &... |
 | calls.rb:267:1:267:12 | call to foo | foo | 0 | calls.rb:267:5:267:11 | &... |
 | calls.rb:270:1:270:9 | call to foo | foo | 0 | calls.rb:270:5:270:8 | *... |
@@ -156,7 +158,9 @@ callsWithReceiver
 | calls.rb:223:14:223:19 | call to foo | calls.rb:223:14:223:14 | X |
 | calls.rb:229:10:229:15 | call to bar | calls.rb:229:10:229:10 | X |
 | calls.rb:230:3:230:8 | call to baz | calls.rb:230:3:230:3 | X |
+| calls.rb:234:1:234:8 | ...[...] | calls.rb:234:1:234:3 | call to foo |
 | calls.rb:235:1:235:6 | call to foo | calls.rb:235:1:235:1 | X |
+| calls.rb:235:1:235:14 | ...[...] | calls.rb:235:1:235:6 | call to foo |
 | calls.rb:235:8:235:13 | call to bar | calls.rb:235:8:235:8 | X |
 | calls.rb:238:15:238:20 | call to baz | calls.rb:238:15:238:15 | X |
 | calls.rb:242:1:242:6 | call to foo | calls.rb:242:1:242:1 | X |

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

@@ -1038,14 +1038,14 @@ cfg.rb:
 #   68| puts
 #-----|  -> items
 
-#   68| ElementReference
+#   68| ...[...]
 #-----|  -> call to puts
 
 #   68| items
 #-----|  -> 2
 
 #   68| 2
-#-----|  -> ElementReference
+#-----|  -> ...[...]
 
 #   69| print
 #-----|  -> 42
@@ -1298,14 +1298,14 @@ cfg.rb:
 #  103| return
 #-----| return -> exit parameters (normal)
 
-#  103| ElementReference
+#  103| ...[...]
 #-----|  -> return
 
 #  103| kwargs
 #-----|  -> key
 
 #  103| key
-#-----|  -> ElementReference
+#-----|  -> ...[...]
 
 #  106| ... = ...
 #-----|  -> food