Ruby: support anonymous (hash)splat parameters/arguments

Author: aibaars

ruby/ql/lib/codeql/ruby/ast/Parameter.qll

@@ -181,7 +181,10 @@ class HashSplatParameter extends NamedParameter, THashSplatParameter {
 
   final override string getAPrimaryQlClass() { result = "HashSplatParameter" }
 
-  final override LocalVariable getVariable() { result = TLocalVariableReal(_, _, g.getName()) }
+  final override LocalVariable getVariable() {
+    result = TLocalVariableReal(_, _, g.getName()) or
+    result = TLocalVariableSynth(this, 0)
+  }
 
   final override string toString() {
     result = "**" + this.getName()
@@ -307,7 +310,10 @@ class SplatParameter extends NamedParameter, TSplatParameter {
 
   final override string getAPrimaryQlClass() { result = "SplatParameter" }
 
-  final override LocalVariable getVariable() { result = TLocalVariableReal(_, _, g.getName()) }
+  final override LocalVariable getVariable() {
+    result = TLocalVariableReal(_, _, g.getName()) or
+    result = TLocalVariableSynth(this, 0)
+  }
 
   final override string toString() {
     result = "*" + this.getName()

ruby/ql/lib/codeql/ruby/ast/Variable.qll

@@ -36,7 +36,7 @@ class LocalVariable extends Variable, TLocalVariable {
   /** Gets the access where this local variable is first introduced. */
   VariableAccess getDefiningAccess() {
     result = this.(LocalVariableReal).getDefiningAccessImpl() or
-    synthChild(any(BlockParameter p | this = p.getVariable()), 0, result)
+    synthChild(any(NamedParameter p | this = p.getVariable()), 0, result)
   }
 
   /**
@@ -120,7 +120,7 @@ class VariableAccess extends Expr instanceof VariableAccessImpl {
     or
     this = any(HashPattern p).getValue(_)
     or
-    synthChild(any(BlockParameter p), 0, this)
+    synthChild(any(NamedParameter p), 0, this)
   }
 }
 

ruby/ql/lib/codeql/ruby/ast/internal/Operation.qll

@@ -42,7 +42,10 @@ class SplatExprReal extends UnaryOperationImpl, TSplatExprReal {
 
   final override string getOperatorImpl() { result = "*" }
 
-  final override Expr getOperandImpl() { toGenerated(result) = g.getChild() }
+  final override Expr getOperandImpl() {
+    toGenerated(result) = g.getChild() or
+    synthChild(this, 0, result)
+  }
 }
 
 class SplatExprSynth extends UnaryOperationImpl, TSplatExprSynth {
@@ -56,7 +59,10 @@ class HashSplatExprImpl extends UnaryOperationImpl, THashSplatExpr {
 
   HashSplatExprImpl() { this = THashSplatExpr(g) }
 
-  final override Expr getOperandImpl() { toGenerated(result) = g.getChild() }
+  final override Expr getOperandImpl() {
+    toGenerated(result) = g.getChild() or
+    synthChild(this, 0, result)
+  }
 
   final override string getOperatorImpl() { result = "**" }
 }

ruby/ql/lib/codeql/ruby/ast/internal/Synthesis.qll

@@ -1317,46 +1317,62 @@ private module ImplicitHashValueSynthesis {
 
 /**
  * ```rb
- * def foo(&)
- *   bar(&)
+ * def foo(*, **, &)
+ *   bar(*, **, &)
  * end
  * ```
  * desugars to,
  * ```rb
- * def foo(&__synth_0)
- *   bar(&__synth_0)
+ * def foo(*__synth_0, **__synth_1, &__synth_2)
+ *   bar(*__synth_0, **__synth_1, &__synth_2)
  * end
  * ```
  */
-private module AnonymousBlockParameterSynth {
-  private BlockParameter anonymousBlockParameter() {
+private module AnonymousParameterSynth {
+  private class AnonymousParameter = TBlockParameter or THashSplatParameter or TSplatParameter;
+
+  private class AnonymousArgument = TBlockArgument or THashSplatExpr or TSplatExpr;
+
+  private AnonymousParameter anonymousParameter() {
     exists(Ruby::BlockParameter p | not exists(p.getName()) and toGenerated(result) = p)
+    or
+    exists(Ruby::SplatParameter p | not exists(p.getName()) and toGenerated(result) = p)
+    or
+    exists(Ruby::HashSplatParameter p | not exists(p.getName()) and toGenerated(result) = p)
   }
 
-  private BlockArgument anonymousBlockArgument() {
+  private AnonymousArgument anonymousArgument() {
     exists(Ruby::BlockArgument p | not exists(p.getChild()) and toGenerated(result) = p)
+    or
+    exists(Ruby::SplatArgument p | not exists(p.getChild()) and toGenerated(result) = p)
+    or
+    exists(Ruby::HashSplatArgument p | not exists(p.getChild()) and toGenerated(result) = p)
   }
 
-  private class AnonymousBlockParameterSynthesis extends Synthesis {
+  private class AnonymousParameterSynthesis extends Synthesis {
     final override predicate child(AstNode parent, int i, Child child) {
       i = 0 and
-      parent = anonymousBlockParameter() and
+      parent = anonymousParameter() and
       child = SynthChild(LocalVariableAccessSynthKind(TLocalVariableSynth(parent, 0)))
     }
 
-    final override predicate localVariable(AstNode n, int i) {
-      n = anonymousBlockParameter() and i = 0
-    }
+    final override predicate localVariable(AstNode n, int i) { n = anonymousParameter() and i = 0 }
   }
 
-  private class AnonymousBlockArgumentSynthesis extends Synthesis {
+  private class AnonymousArgumentSynthesis extends Synthesis {
     final override predicate child(AstNode parent, int i, Child child) {
       i = 0 and
-      parent = anonymousBlockArgument() and
-      exists(BlockParameter param |
-        param = anonymousBlockParameter() and
+      parent = anonymousArgument() and
+      exists(AnonymousParameter param |
+        param = anonymousParameter() and
         scopeOf(toGenerated(parent)).getEnclosingMethod() = scopeOf(toGenerated(param)) and
         child = SynthChild(LocalVariableAccessSynthKind(TLocalVariableSynth(param, 0)))
+      |
+        param instanceof TBlockParameter and parent instanceof TBlockArgument
+        or
+        param instanceof TSplatParameter and parent instanceof TSplatExpr
+        or
+        param instanceof THashSplatParameter and parent instanceof THashSplatExpr
       )
     }
   }

ruby/ql/test/library-tests/ast/calls/calls.rb

@@ -269,10 +269,12 @@ module SomeModule
 # splat argument
 foo(*bar)
 foo(*X::bar)
+foo(*)
 
 # hash-splat argument
 foo(**bar)
 foo(**X::bar)
+foo(**)
 
 # the value in a keyword argument
 foo(blah: bar)

ruby/ql/test/library-tests/ast/params/params.rb

@@ -84,3 +84,13 @@ def anonymous_block_parameter(array, &)
 end
 
 run_block { |x; y, z | puts x }
+
+# Anonymous splat parameter
+def anonymous_splat_parameter(array, *)
+  array.concat(*)
+end
+
+# Anonymous hash splat parameter
+def anonymous_hash_splat_parameter(hash, **)
+  hash.merge(**)
+end