Use shared getASuccessor and getAPredecessor

Author: owen-mc

go/ql/lib/semmle/go/controlflow/BasicBlocks.qll

@@ -43,12 +43,6 @@ private module Input implements BB::InputSig<Location> {
 private module BbImpl = BB::Make<Location, Input>;
 
 class BasicBlock extends BbImpl::BasicBlock {
-  /** Gets a basic block succeeding this one. */
-  BasicBlock getASuccessor() { result = this.getASuccessor(_) }
-
-  /** Gets a basic block preceding this one. */
-  BasicBlock getAPredecessor() { result.getASuccessor() = this }
-
   /** Gets the innermost function or file to which this basic block belongs. */
   ControlFlow::Root getRoot() { result = this.getScope() }
 }
@@ -59,7 +53,7 @@ cached
 private predicate reachableBB(BasicBlock bb) {
   bb instanceof EntryBasicBlock
   or
-  exists(BasicBlock predBB | predBB.getASuccessor() = bb | reachableBB(predBB))
+  exists(BasicBlock predBB | predBB.getASuccessor(_) = bb | reachableBB(predBB))
 }
 
 /**

go/ql/lib/semmle/go/dataflow/SSA.qll

@@ -285,7 +285,7 @@ abstract class SsaPseudoDefinition extends SsaImplicitDefinition {
  */
 class SsaPhiNode extends SsaPseudoDefinition, TPhi {
   override SsaVariable getAnInput() {
-    result = getDefReachingEndOf(this.getBasicBlock().getAPredecessor(), this.getSourceVariable())
+    result = getDefReachingEndOf(this.getBasicBlock().getAPredecessor(_), this.getSourceVariable())
   }
 
   override predicate definesAt(ReachableBasicBlock bb, int i, SsaSourceVariable v) {

go/ql/lib/semmle/go/dataflow/SsaImpl.qll

@@ -186,7 +186,7 @@ private module Internal {
    * Holds if `v` is live at the beginning of any successor of basic block `bb`.
    */
   private predicate liveAtSuccEntry(ReachableBasicBlock bb, SsaSourceVariable v) {
-    liveAtEntry(bb.getASuccessor(), v)
+    liveAtEntry(bb.getASuccessor(_), v)
   }
 
   /**
@@ -317,7 +317,7 @@ private module Internal {
       SsaSourceVariable v, ReachableBasicBlock b1, ReachableBasicBlock b2
     ) {
       varOccursInBlock(v, b1) and
-      b2 = b1.getASuccessor()
+      b2 = b1.getASuccessor(_)
     }
 
     /**
@@ -335,7 +335,7 @@ private module Internal {
     ) {
       varBlockReaches(v, b1, mid) and
       not varOccursInBlock(v, mid) and
-      b2 = mid.getASuccessor()
+      b2 = mid.getASuccessor(_)
     }
 
     /**

go/ql/src/Security/CWE-020/IncompleteHostnameRegexp.ql

@@ -45,7 +45,7 @@ predicate writesHttpError(ReachableBasicBlock b) {
 predicate onlyErrors(BasicBlock block) {
   writesHttpError(block)
   or
-  forex(ReachableBasicBlock pred | pred = block.getAPredecessor() | onlyErrors(pred))
+  forex(ReachableBasicBlock pred | pred = block.getAPredecessor(_) | onlyErrors(pred))
 }
 
 /** Gets a node that refers to a handler that is considered to return an HTTP error. */