Optimizing search, buggy BlockArena on emscripten, cleanup MergeSort, address sanitizer, compile web on linux

src/basic/basic_alloc.h

@@ -51,7 +51,6 @@ struct BlockArena {
     U8 *end;
     BlockArenaNode *blocks;
     Allocator allocator;
-    bool when_unwinding_make_sure_to_keep_last_block_alive;
 
     operator Allocator() { return {BlockArenaAllocatorProc, this}; }
 };
@@ -96,9 +95,24 @@ API void          Release(VirtualArena *arena);
 
 ///////////////////////////////
 // Scratch
+#if OS_WASM
+struct Scratch {
+    BlockArena arena = {};
+    Scratch() {}
+    Scratch(BlockArena *conflict) {}
+    Scratch(BlockArena *c1, BlockArena *c2) {}
+    Scratch(Allocator conflict) {}
+    Scratch(Allocator c1, Allocator c2) {}
+    ~Scratch() { Release(&arena); }
+    operator BlockArena *() { return &arena; }
+    operator Allocator() { return arena; }
+  private: // @Note: Disable copy constructors, cause its error prone
+    Scratch(Scratch &arena);
+    Scratch(Scratch &arena, Scratch &a2);
+};
+#else
 extern thread_local VirtualArena ScratchArenas[4];
 API VirtualArena *GetScratchEx(VirtualArena **conflicts, int conflict_count);
-
 struct Scratch {
     VirtualArena *arena;
     U64 p;
@@ -131,6 +145,7 @@ struct Scratch {
     Scratch(Scratch &arena);
     Scratch(Scratch &arena, Scratch &a2);
 };
+#endif
 
 const int PAGE_SIZE         = 4096;
 const int DEFAULT_ALIGNMENT = sizeof(void *);