[Rcpp-devel] Patch for using Rcpp with Clang + libc++ AND Intel icpc C++11

[Yan Zhou]

Dear Dirk,

Sorry, in may last email I attached an incorrect diff file. Here is the corrected one.

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Best,

Yan Zhou

On Dec 1, 2012, at 12:44 PM, Yan Zhou <zhouyan at me.com> wrote:

> Dear Dirk,
> 
> In addition to my last email which provides a path for clang++ with libc++, I updated the patch to also fix problems with intel icpc in C++11 mode.
> 
> In the RcppCommon.h, there is comments says that Intel ICPC does not support C++11 or TR1. That is not entirely true. Intel compiler does not come with its own standard library. On Linux and Mac OS X it use the libstdc++ come with the system. On Windows it may use others.  The current test has a problem when an Intel C++ compiler is used in C++11 mode. In that case, headers like sugar/sets.h test the C++11 macro and conclude it shall define SET to std::unordered_set. However, C++11 <unordered_set> is not included. So a compiler error happens.
> 
> In general, I found Rcpp does not work with compilers in C++11 mode. The new path, in addition to the own test Clang with libc++, also test the followings,
> 1. If Intel compiler is used, test is it is used with libstdc++. If it is not, then we undef HAS_TR1_... etc. To test if libstdc++ is used, we need to at least include one standard library header before the testing, so I included <cmath>, which shall be harmless
> 2. After trying to include <tr1/unodered_map> etc, we also test if we are using C++11. If it is, then test if we are using libstdc++ (either gcc, clang, intel etc). If it is case, and the libstdc++ is recent enough, we include <unordered_map> and <unordered_set>. Otherwise, if we are using C++11 in Clang with libc++, we also included <unodered_map> etc.
> 
> After this patch, Rcpp shall work seamlessly with GCC, Intel and Clang, in both C++98 and C++11 modes.
> <RcppCommon.h.diff>
> 
> Best,
> 
> Yan Zhou
> 
> 
> 
> On Dec 1, 2012, at 12:12 PM, Yan Zhou <zhouyan at me.com> wrote:
> 
>> Hi Dirk,
>> 
>> Rcpp cannot be compiled with clang++ with libc++, even clang++  provides very good standard conforming in both C++98 and C++11 mode, and libc++ provides 100% C++98/11 features. The problems is Rcpp's use of TR1 instead of C++11, and does not perform some compiler checks properly. I made a small patch to the include/RcppCommon.h header, which makes Rcpp works with Clang++ and libc++ in C++11 mode.
>> 
>> To summary the change, when macro __clang__ is defined, the header use clang's __has_include to check if <tr1/unordered_map> and <tr1/unordered_set> is present, if not, it undef HAS_TR1_UNORDERED_MAP etc. In addition, if __has_include<unordered_map> is tested to be true while HAS_TR1_... etc are not true, the C++11 header is included. So  headers like sugar/sets.h can use C++11 header instead of TR1, since they already test __cplusplus >= 201103L.
>> 
>> With this patch, nothing already works will be broken. This patch only affects clang++ with libc++ situation. Using clang++ with libstdc++ the situation will be exactly the same as before.
>> 
>> At the end of the email is the path, it is also attached as a diff file
>> 
>> Best,
>> 
>> Yan Zhou
>> <RcppCommon.h.diff>
>> 
>> --- Rcpp/inst/include/RcppCommon.h	2012-11-23 01:07:34.000000000 +0000
>> +++ ../Downloads/Rcpp/inst/include/RcppCommon.h	2012-12-01 11:46:48.000000000 +0000
>> @@ -107,6 +107,20 @@
>> //     #endif
>> // #endif
>> 
>> +#ifdef __clang__
>> +    #if !__has_include(<tr1/unordered_map>)
>> +        #undef HAS_TR1
>> +        #undef HAS_TR1_UNORDERED_MAP
>> +    #endif
>> +    #if !__has_include(<tr1/unordered_set>)
>> +        #undef HAS_TR1
>> +        #undef HAS_TR1_UNORDERED_SET
>> +    #endif
>> +    #if !__has_feature(cxx_variadic_templates)
>> +        #undef HAS_VARIADIC_TEMPLATES
>> +    #endif
>> +#endif
>> +
>> #ifdef __INTEL_COMPILER
>>    // This is based on an email by Alexey Stukalov who tested 
>>    // Intel Compiler 12.0 and states that is does support Cxx0x 
>> @@ -149,6 +163,15 @@
>> #include <tr1/unordered_set>
>> #endif
>> 
>> +#ifdef __clang__
>> +    #if !defined(HAS_TR1_UNORDERED_MAP) && __has_include(<unordered_map>)
>> +    #include <unordered_map>
>> +    #endif
>> +    #if !defined(HAS_TR1_UNORDERED_SET) && __has_include(<unordered_set>)
>> +    #include <unordered_set>
>> +    #endif
>> +#endif
>> +
>> std::string demangle( const std::string& name) ;
>> #define DEMANGLE(__TYPE__) demangle( typeid(__TYPE__).name() ).c_str() 
>> 
>> 
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