IndexMapBiDi: Define virtual destructor in .cpp file

This fixes compiler warnings from clang:

src/ccutil/indexmapbidi.h:102:7: warning:
 'IndexMapBiDi' has no out-of-line virtual method definitions;
 its vtable will be emitted in every translation unit [-Wweak-vtables]

Signed-off-by: Stefan Weil <[email protected]>

Author: stweil

src/ccutil/indexmapbidi.cpp

@@ -62,6 +62,10 @@ bool IndexMap::DeSerialize(bool swap, FILE* fp) {
   return compact_map_.DeSerialize(swap, fp);
 }
 
+// Destructor.
+// It is defined here, so the compiler can create a single vtable
+// instead of weak vtables in every compilation unit.
+IndexMapBiDi::~IndexMapBiDi() = default;
 
 // Top-level init function in a single call to initialize a map to select
 // a single contiguous subrange [start, end) of the sparse space to be mapped

src/ccutil/indexmapbidi.h

@@ -101,7 +101,7 @@ class IndexMap {
 //    Allows a many-to-one mapping by merging compact space indices.
 class IndexMapBiDi : public IndexMap {
  public:
-  virtual ~IndexMapBiDi() {}
+  virtual ~IndexMapBiDi();
 
   // Top-level init function in a single call to initialize a map to select
   // a single contiguous subrange [start, end) of the sparse space to be mapped