Ruby: Fix captured reads in lambdas

These were previously identified as method calls. The fix is to
recognise lambdas as a scope which can inherit variables from its
parent.

Author: hmac

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

@@ -406,7 +406,11 @@ import Cached
 
 /** Holds if this scope inherits `name` from an outer scope `outer`. */
 private predicate inherits(Scope::Range scope, string name, Scope::Range outer) {
-  (scope instanceof Ruby::Block or scope instanceof Ruby::DoBlock) and
+  (
+    scope instanceof Ruby::Block or
+    scope instanceof Ruby::DoBlock or
+    scope instanceof Ruby::Lambda
+  ) and
   not scopeDefinesParameterVariable(scope, name, _) and
   (
     outer = scope.getOuterScope() and

ruby/ql/test/library-tests/ast/Ast.expected

@@ -714,8 +714,7 @@ calls/calls.rb:
 #  351|     getAnOperand/getRightOperand: [Lambda] -> { ... }
 #  351|       getParameter: [SimpleParameter] x
 #  351|         getDefiningAccess: [LocalVariableAccess] x
-#  351|       getStmt: [MethodCall] call to y
-#  351|         getReceiver: [SelfVariableAccess] self
+#  351|       getStmt: [LocalVariableAccess] y
 #  352|   getStmt: [AssignExpr] ... = ...
 #  352|     getAnOperand/getLeftOperand: [LocalVariableAccess] f
 #  352|     getAnOperand/getRightOperand: [Lambda] -> { ... }
@@ -737,8 +736,7 @@ calls/calls.rb:
 #  354|       getParameter: [SimpleParameter] x
 #  354|         getDefiningAccess: [LocalVariableAccess] x
 #  355|       getStmt: [LocalVariableAccess] x
-#  356|       getStmt: [MethodCall] call to y
-#  356|         getReceiver: [SelfVariableAccess] self
+#  356|       getStmt: [LocalVariableAccess] y
 #  357|       getStmt: [MethodCall] call to unknown_call
 #  357|         getReceiver: [SelfVariableAccess] self
 control/cases.rb:

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

@@ -369,10 +369,8 @@ callsWithReceiver
 | calls.rb:345:1:345:15 | call to foo | calls.rb:345:1:345:15 | self |
 | calls.rb:346:1:346:10 | call to foo | calls.rb:346:1:346:10 | self |
 | calls.rb:347:1:347:7 | call to foo | calls.rb:347:1:347:7 | self |
-| calls.rb:351:14:351:14 | call to y | calls.rb:351:14:351:14 | self |
 | calls.rb:352:13:352:17 | call to foo | calls.rb:352:13:352:17 | self |
 | calls.rb:353:13:353:24 | call to unknown_call | calls.rb:353:13:353:24 | self |
-| calls.rb:356:3:356:3 | call to y | calls.rb:356:3:356:3 | self |
 | calls.rb:357:3:357:14 | call to unknown_call | calls.rb:357:3:357:14 | self |
 callsWithBlock
 | calls.rb:17:1:17:17 | call to foo | calls.rb:17:5:17:17 | { ... } |