Ruby: Fix CFG for nodes that may raise

Author: hvitved

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

@@ -90,9 +90,7 @@ 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) {
-    exists(AstNode other | n = other.getDesugared() and this.isValidForSpecific(other))
-    or
+  private predicate isValidForSpecific0(AstNode n) {
     this = n.(NonReturningCall).getACompletion()
     or
     completionIsValidForStmt(n, this)
@@ -110,12 +108,19 @@ abstract class Completion extends TCompletion {
     or
     n = any(RescueModifierExpr parent).getBody() and
     this = [TSimpleCompletion().(TCompletion), TRaiseCompletion()]
+  }
+
+  private predicate isValidForSpecific(AstNode n) {
+    this.isValidForSpecific0(n)
+    or
+    exists(AstNode other | n = other.getDesugared() and this.isValidForSpecific(other))
     or
     mayRaise(n) and
     (
       this = TRaiseCompletion()
       or
-      this = TSimpleCompletion() and not n instanceof NonReturningCall
+      not any(Completion c).isValidForSpecific0(n) and
+      this = TSimpleCompletion()
     )
   }
 

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

@@ -6953,11 +6953,6 @@ raise.rb:
 #-----| true -> [true] ... || ...
 #-----| false -> b2
 
-#  174| ... || ...
-#-----| true -> 1
-#-----| false -> 2
-#-----| raise -> ExceptionA
-
 #  174| [false] ... || ...
 #-----| false -> 2
 #-----| raise -> ExceptionA
@@ -6971,7 +6966,6 @@ raise.rb:
 
 #  174| ... == ...
 #-----| false -> [false] ... || ...
-#-----|  -> ... || ...
 #-----| true -> [true] ... || ...
 #-----| raise -> ExceptionA
 

ruby/ql/test/library-tests/controlflow/graph/Nodes.expected

@@ -367,7 +367,6 @@ positionalArguments
 | raise.rb:160:5:162:7 | call to bar | raise.rb:160:9:162:7 | -> { ... } |
 | raise.rb:161:7:161:14 | call to raise | raise.rb:161:13:161:14 | "" |
 | raise.rb:168:5:168:12 | call to raise | raise.rb:168:11:168:12 | "" |
-| raise.rb:174:8:174:23 | ... \|\| ... | raise.rb:174:14:174:23 | ... == ... |
 | raise.rb:174:8:174:23 | [false] ... \|\| ... | raise.rb:174:14:174:23 | ... == ... |
 | raise.rb:174:8:174:23 | [true] ... \|\| ... | raise.rb:174:14:174:23 | ... == ... |
 | raise.rb:174:14:174:23 | ... == ... | raise.rb:174:20:174:23 | true |