chore: import upstream snapshot with attribution

thirdparty/sparsehash/CMakeLists.txt

@@ -0,0 +1,16 @@
+set(SPARSE_SRC "${CMAKE_CURRENT_SOURCE_DIR}/sparseconfig.h")
+set(SPARSE_DST "${CMAKE_CURRENT_SOURCE_DIR}/sparsehash-2.0.4/src/sparsehash/internal/sparseconfig.h")
+get_filename_component(DESTINATION_DIR "${SPARSE_DST}" DIRECTORY)
+if(NOT EXISTS "${SPARSE_DST}")
+    file(COPY "${SPARSE_SRC}" DESTINATION "${DESTINATION_DIR}")
+endif()
+
+if(MSVC)
+    set(SPARSEHASH_WINDOWS_PATCH ${CMAKE_CURRENT_SOURCE_DIR}/sparsehash.windows.patch)
+    apply_patch_once("sparsehash.windows.patch" "${DESTINATION_DIR}" "${SPARSEHASH_WINDOWS_PATCH}")
+endif()
+
+add_library(sparsehash INTERFACE)
+target_include_directories(
+    sparsehash SYSTEM INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}/sparsehash-2.0.4/src/"
+  )

thirdparty/sparsehash/sparseconfig.h

@@ -0,0 +1,46 @@
+/*
+ * NOTE: This file is for internal use only.
+ *       Do not use these #defines in your own program!
+ */
+
+/* Namespace for Google classes */
+#define GOOGLE_NAMESPACE ::google
+
+/* the location of the header defining hash functions */
+#define HASH_FUN_H <functional>
+
+/* the namespace of the hash<> function */
+#define HASH_NAMESPACE std
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if the system has the type `long long'. */
+#define HAVE_LONG_LONG 1
+
+/* Define to 1 if you have the `memcpy' function. */
+#define HAVE_MEMCPY 1
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if the system has the type `uint16_t'. */
+#define HAVE_UINT16_T 1
+
+/* Define to 1 if the system has the type `u_int16_t'. */
+#define HAVE_U_INT16_T 1
+
+/* Define to 1 if the system has the type `__uint16'. */
+/* #undef HAVE___UINT16 */
+
+/* The system-provided hash function including the namespace. */
+#define SPARSEHASH_HASH HASH_NAMESPACE::hash
+
+/* Stops putting the code inside the Google namespace */
+#define _END_GOOGLE_NAMESPACE_ }
+
+/* Puts following code inside the Google namespace */
+#define _START_GOOGLE_NAMESPACE_ namespace google {

thirdparty/sparsehash/sparsehash.windows.patch

@@ -0,0 +1,13 @@
+diff --git a/src/sparsehash/internal/hashtable-common.h b/src/sparsehash/internal/hashtable-common.h
+index bac2b88..59c752c 100644
+--- a/src/sparsehash/internal/hashtable-common.h
++++ b/src/sparsehash/internal/hashtable-common.h
+@@ -51,7 +51,7 @@ _START_GOOGLE_NAMESPACE_
+ 
+ template <bool> struct SparsehashCompileAssert { };
+ #define SPARSEHASH_COMPILE_ASSERT(expr, msg) \
+-  __attribute__((unused)) typedef SparsehashCompileAssert<(bool(expr))> msg[bool(expr) ? 1 : -1]
++  static_assert(bool(expr), #msg)
+ 
+ namespace sparsehash_internal {
+