sparseconfig.h should not vary based on C++11 capability #145
Description
In sparsehash 2.0.3, the installed sparseconfig.h varies based on whether or not the compiler used to compile sparsehash had full C++11 capabilities. Specifically, here is the difference in that header between a machine running OS X 10.8 (a.k.a. Darwin 12), which uses libstdc++ by default which doesn't have a full C++11 implementation and uses tr1, and one running OS X 10.9 (a.k.a. Darwin 13), which uses libc++ by default which does have a full C++11 implementation and doesn't use tr1:
--- sparsehash-2.0.3_0.darwin_12.x86_64/opt/local/include/sparsehash/internal/sparseconfig.h 2015-10-17 10:41:02.000000000 -0500
+++ sparsehash-2.0.3_0.darwin_13.x86_64/opt/local/include/sparsehash/internal/sparseconfig.h 2015-10-17 10:40:37.000000000 -0500
@@ -7,10 +7,10 @@
#define GOOGLE_NAMESPACE ::google
/* the location of the header defining hash functions */
-#define HASH_FUN_H <tr1/functional>
+#define HASH_FUN_H <functional>
/* the namespace of the hash<> function */
-#define HASH_NAMESPACE std::tr1
+#define HASH_NAMESPACE std
/* Define to 1 if you have the <inttypes.h> header file. */
#define HAVE_INTTYPES_H 1
This causes problems. Although OS X 10.8 defaults to libstdc++, it has libc++ available. Imagine I want to compile a program (textmate 2.0-rc.4) that requires sparsehash and it requires libc++, so it uses -stdlib=libc++. It fails to build with:
In file included from Shared/PCH/prelude.cc:26:
/opt/local/include/sparsehash/dense_hash_map:106:10: fatal error: 'tr1/functional' file not found
#include HASH_FUN_H // for hash<>
^
/opt/local/include/sparsehash/internal/sparseconfig.h:10:20: note: expanded from macro 'HASH_FUN_H'
#define HASH_FUN_H <tr1/functional>
^~~~~~~~~~~~~~~~
1 error generated.
Please install a sparseconfig.h that can be used without modification with both C++11 and pre-C++11 toolchains, since some systems have and need to be able to use both. Use preprocessor directives to pick the right HASH_FUN_H and HASH_NAMESPACE at build time when sparseconfig.h is used, not when it is installed.