Shared: Remove omittable exists variables

Author: atorralba

shared/regex/codeql/regex/nfa/RegexpMatching.qll

@@ -115,7 +115,7 @@ module Make<RegexTreeViewSig TreeImpl> {
     // The `getAnInputSymbolMatching` relation specialized to the chars that exists in strings tested by a `MatchedRegExp`.
     pragma[noinline]
     private InputSymbol specializedGetAnInputSymbolMatching(string char) {
-      exists(string s, RootTerm r | isCandidate(r, s, _, _) | char = s.charAt(_)) and
+      exists(string s | isCandidate(_, s, _, _) | char = s.charAt(_)) and
       result = getAnInputSymbolMatching(char)
     }
 

shared/regex/codeql/regex/nfa/SuperlinearBackTracking.qll

@@ -288,13 +288,11 @@ module Make<RegexTreeViewSig TreeImpl> {
     StateTuple tuple, int dist
   ) {
     // base case.
-    exists(State q1, State q2, State q3 |
-      isStartLoops(pivot, succ) and
-      step(MkStateTuple(pivot, pivot, succ), s1, s2, s3, tuple) and
-      tuple = MkStateTuple(q1, q2, q3) and
-      trace = Nil() and
-      dist = distBackFromEnd(tuple, MkStateTuple(pivot, succ, succ))
-    )
+    isStartLoops(pivot, succ) and
+    step(MkStateTuple(pivot, pivot, succ), s1, s2, s3, tuple) and
+    tuple = MkStateTuple(_, _, _) and
+    trace = Nil() and
+    dist = distBackFromEnd(tuple, MkStateTuple(pivot, succ, succ))
     or
     // recursive case
     exists(StateTuple p |

shared/ssa/codeql/ssa/Ssa.qll

@@ -870,7 +870,8 @@ module Make<InputSig Input> {
     // Can reach another definition
     lastRefRedefExt(def, _, bb, i, _)
     or
-    exists(SourceVariable v | lastSsaRefExt(def, v, bb, i) |
+    lastSsaRefExt(def, _, bb, i) and
+    (
       // Can reach exit directly
       bb instanceof ExitBasicBlock
       or
@@ -889,7 +890,8 @@ module Make<InputSig Input> {
     // Can reach another definition
     lastRefRedef(def, bb, i, _)
     or
-    exists(SourceVariable v | lastSsaRef(def, v, bb, i) |
+    lastSsaRef(def, _, bb, i) and
+    (
       // Can reach exit directly
       bb instanceof ExitBasicBlock
       or