C++: Restore and deprecate getPosInBasicBlock

This predicte was still used in a test, so it might be used in external
code too.

Author: jbj

cpp/ql/src/semmle/code/cpp/controlflow/SubBasicBlocks.qll

@@ -71,7 +71,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
   }
 
   /**
-   * Gets the rank of this `SubBasicBlock` among the other `SubBasicBlock`s in
+   * Gets the (1-based) rank of this `SubBasicBlock` among the other `SubBasicBlock`s in
    * its containing basic block `bb`, where `bb` is equal to `getBasicBlock()`.
    */
   int getRankInBasicBlock(BasicBlock bb) {
@@ -81,6 +81,15 @@ class SubBasicBlock extends ControlFlowNodeBase {
     )
   }
 
+  /**
+   * DEPRECATED: use `getRankInBasicBlock` instead. Note that this predicate
+   * returns a 0-based position, while `getRankInBasicBlock` returns a 1-based
+   * position.
+   */
+  deprecated int getPosInBasicBlock(BasicBlock bb) {
+    result = getRankInBasicBlock(bb) - 1
+  }
+
   pragma[noinline]
   private int getIndexInBasicBlock(BasicBlock bb) {
     this = bb.getNode(result)

cpp/ql/src/semmle/code/cpp/dataflow/internal/SubBasicBlocks.qll

@@ -71,7 +71,7 @@ class SubBasicBlock extends ControlFlowNodeBase {
   }
 
   /**
-   * Gets the rank of this `SubBasicBlock` among the other `SubBasicBlock`s in
+   * Gets the (1-based) rank of this `SubBasicBlock` among the other `SubBasicBlock`s in
    * its containing basic block `bb`, where `bb` is equal to `getBasicBlock()`.
    */
   int getRankInBasicBlock(BasicBlock bb) {
@@ -81,6 +81,15 @@ class SubBasicBlock extends ControlFlowNodeBase {
     )
   }
 
+  /**
+   * DEPRECATED: use `getRankInBasicBlock` instead. Note that this predicate
+   * returns a 0-based position, while `getRankInBasicBlock` returns a 1-based
+   * position.
+   */
+  deprecated int getPosInBasicBlock(BasicBlock bb) {
+    result = getRankInBasicBlock(bb) - 1
+  }
+
   pragma[noinline]
   private int getIndexInBasicBlock(BasicBlock bb) {
     this = bb.getNode(result)