CFG: Separate scope for method blocks

ql/src/codeql_ruby/controlflow/ControlFlowGraph.qll

@@ -8,7 +8,18 @@ private import internal.Splitting
 private import internal.Completion
 
 /** An AST node with an associated control-flow graph. */
-class CfgScope = Method; // TODO: add more cases (e.g. bodies of lambdas/do blocks)
+class CfgScope extends AstNode {
+  private string name;
+
+  CfgScope() {
+    name = this.(Method).getName().toString()
+    or
+    this = any(MethodCall mc | name = "block for " + mc.getMethod()).getBlock()
+  }
+
+  /** Gets the name of this scope. */
+  string getName() { result = name }
+}
 
 /**
  * A control flow node.

ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll

@@ -256,11 +256,7 @@ private module Trees {
     }
   }
 
-  private class BlockParameterTree extends LeafTree, BlockParameter { }
-
-  private class BlockParametersTree extends StandardPostOrderTree, BlockParameters {
-    final override AstNode getChildNode(int i) { result = this.getChild(i) }
-
+  private class BlockParametersTree extends LeafTree, BlockParameters {
     override predicate isHidden() { any() }
   }
 
@@ -282,6 +278,12 @@ private module Trees {
     override predicate isHidden() { any() }
   }
 
+  private class DoBlockTree extends StandardPreOrderTree, DoBlock {
+    final override AstNode getChildNode(int i) { result = this.getChild(i) }
+
+    override predicate isHidden() { any() }
+  }
+
   private class ElseTree extends StandardPreOrderTree, Else {
     final override AstNode getChildNode(int i) { result = this.getChild(i) }
 
@@ -382,12 +384,11 @@ private module Trees {
   }
 
   private class MethodCallTree extends StandardPostOrderTree, MethodCall {
+    // this.getBlock() is not included as it uses a different scope
     final override AstNode getChildNode(int i) {
       result = this.getArguments() and i = 0
       or
       result = this.getMethod() and i = 1
-      or
-      result = this.getBlock() and i = 2
     }
   }
 

ql/src/codeql_ruby/controlflow/internal/Splitting.qll

@@ -60,7 +60,12 @@ class Split extends TSplit {
   string toString() { none() }
 }
 
-private CfgScope getScope(AstNode n) { result.getAFieldOrChild*() = n }
+private AstNode parent(AstNode n) {
+  result.getAFieldOrChild() = n and
+  not n instanceof CfgScope
+}
+
+private CfgScope getScope(AstNode n) { result = parent+(n) }
 
 /**
  * Holds if split kinds `sk1` and `sk2` may overlap. That is, they may apply