Merge pull request github#10741 from hvitved/ruby/no-full-fast-tc

Ruby: Avoid computing full `fastTC` for `AstNode::getParent`

Author: hvitved

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

@@ -486,12 +486,15 @@ private import ResolveImpl
  * methods evaluate the block in the context of some other module/class instead of
  * the enclosing one.
  */
-private ModuleBase enclosingModule(AstNode node) { result = parent*(node).getParent() }
-
-private AstNode parent(AstNode n) {
-  result = n.getParent() and
-  not result instanceof ModuleBase and
-  not result instanceof Block
+private ModuleBase enclosingModule(AstNode node) {
+  result = node.getParent()
+  or
+  exists(AstNode mid |
+    result = enclosingModule(mid) and
+    mid = node.getParent() and
+    not mid instanceof ModuleBase and
+    not mid instanceof Block
+  )
 }
 
 private Module getAncestors(Module m) {

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

@@ -118,7 +118,11 @@ class Synthesis extends TSynthesis {
 private class Desugared extends AstNode {
   Desugared() { this = any(AstNode sugar).getDesugared() }
 
-  AstNode getADescendant() { result = this.getAChild*() }
+  AstNode getADescendant() {
+    result = this
+    or
+    result = this.getADescendant().getAChild()
+  }
 }
 
 /**
@@ -132,7 +136,10 @@ int desugarLevel(AstNode n) { result = count(Desugared desugared | n = desugared
  * Holds if `n` appears in a context that is desugared. That is, a
  * transitive, reflexive parent of `n` is a desugared node.
  */
-predicate isInDesugaredContext(AstNode n) { n = any(AstNode sugar).getDesugared().getAChild*() }
+predicate isInDesugaredContext(AstNode n) {
+  n = any(AstNode sugar).getDesugared() or
+  n = any(AstNode mid | isInDesugaredContext(mid)).getAChild()
+}
 
 /**
  * Holds if `n` is a node that only exists as a result of desugaring some

ruby/ql/lib/codeql/ruby/controlflow/internal/Completion.qll

@@ -71,19 +71,23 @@ private predicate completionIsValidForStmt(AstNode n, Completion c) {
   c = TReturnCompletion()
 }
 
-/**
- * Holds if `c` happens in an exception-aware context, that is, it may be
- * `rescue`d or `ensure`d. In such cases, we assume that the target of `c`
- * may raise an exception (in addition to evaluating normally).
- */
-private predicate mayRaise(Call c) {
-  exists(Trees::BodyStmtTree bst | c = bst.getBodyChild(_, true).getAChild*() |
+private AstNode getARescuableBodyChild() {
+  exists(Trees::BodyStmtTree bst | result = bst.getBodyChild(_, true) |
     exists(bst.getARescue())
     or
     exists(bst.getEnsure())
   )
+  or
+  result = getARescuableBodyChild().getAChild()
 }
 
+/**
+ * Holds if `c` happens in an exception-aware context, that is, it may be
+ * `rescue`d or `ensure`d. In such cases, we assume that the target of `c`
+ * may raise an exception (in addition to evaluating normally).
+ */
+private predicate mayRaise(Call c) { c = getARescuableBodyChild() }
+
 /** A completion of a statement or an expression. */
 abstract class Completion extends TCompletion {
   private predicate isValidForSpecific(AstNode n) {