Clang vs GCC for my Linux Development project

Question

I m in college  and for a project we re using C  We ve explored GCC and Clang  and Clang appears to be much more user friendly than GCC   As a result  I m wondering what the advantages or disadvantages are to using clang  as opposed to GCC  for developing in C and C   on Linux    In my case this would be used for student level programs  not production    If I use Clang  should I debug with GDB and use GNU Make  or use another debugger and make utility

User · Answer

I think clang could be an alternative   GCC and clang have some differences on expressions like a     a  and I ve got many different answers with my peer who use clang on Mac while I use gcc   GCC has become the standard  and clang could be an alternative  Because GCC is very stable and clang is still under developing

User · Answer

I use both because sometimes they give different  useful error messages   The Python project was able to find and fix a number of small buglets when one of the core developers first tried compiling with clang

User · Answer

For student level programs  Clang has the benefit that it is  by default  stricter wrt  the C standard  For example  the following K amp R version of Hello World is accepted without warning by GCC  but rejected by Clang with some pretty descriptive error messages   main         puts  Hello  world         With GCC  you have to give it -Werror to get it to really make a point about this not being a valid C89 program  Also  you still need to use c99 or gcc -std c99 to get the C99 language

User · Answer

As of right now  GCC has much better and more complete support for C  11 features than Clang  Also  the code generator for GCC performs better optimisation than the one in Clang  in my experience  I have not seen any exhaustive tests    On the other hand  Clang often compiles code more quickly than GCC  and produces better error messages when there is something wrong with your code   The choice of which one to use really depends on what things are important to you  I value C  11 support and code generation quality more than I value convenience of compilation  Because of this  I use GCC  For you  the trade-offs could be different

User · Answer

EDIT   The gcc guys really improved the diagnosis experience in gcc  ah competition   They created a wiki page to showcase it here  gcc 4 8 now has quite good diagnostics as well  gcc 4 9x added color support   Clang is still in the lead  but the gap is closing     Original   For students  I would unconditionally recommend Clang   The performance in terms of generated code between gcc and Clang is now unclear  though I think that gcc 4 7 still has the lead  I haven t seen conclusive benchmarks yet   but for students to learn it does not really matter anyway   On the other hand  Clang s extremely clear diagnostics are definitely easier for beginners to interpret   Consider this simple snippet    include  lt string gt   include  lt iostream gt   struct Student   std  string surname  std  string givenname     std  ostream amp  operator lt  lt  std  ostream amp  out  Student const amp  s      return out  lt  lt       lt  lt  s surname  lt  lt        lt  lt  s givenname  lt  lt          int main       Student me      Doe    John       std  cout  lt  lt  me  lt  lt    n       You ll notice right away that the semi-colon is missing after the definition of the Student class  right       Well  gcc notices it too  after a fashion   prog cpp 9  error  expected initializer before     amp     token prog cpp  In function    int main       prog cpp 15  error  no match for    operator lt  lt     in    std  cout  lt  lt  me     usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 112  note  candidates are  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  std  basic ostream lt  CharT   Traits gt  amp      std  basic ostream lt  CharT   Traits gt  amp     with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 121  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  std  basic ios lt  CharT   Traits gt  amp      std  basic ios lt  CharT   Traits gt  amp     with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 131  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  std  ios base amp      std  ios base amp     with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 169  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  long int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 173  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  long unsigned int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 177  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  bool   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 bits ostream tcc 97  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  short int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 184  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  short unsigned int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 bits ostream tcc 111  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 195  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  unsigned int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 204  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  long long int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 208  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  long long unsigned int   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 213  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  double   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 217  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  float   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 225  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  long double   with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 ostream 229  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  const void    with  CharT   char   Traits   std  char traits lt char gt    usr lib gcc i686-pc-linux-gnu 4 3 4 include g  -v4 bits ostream tcc 125  note                  std  basic ostream lt  CharT   Traits gt  amp  std  basic ostream lt  CharT   Traits gt   operator lt  lt  std  basic streambuf lt  CharT   Traits gt     with  CharT   char   Traits   std  char traits lt char gt     And Clang is not exactly starring here either  but still    tmp webcompile  25327 1 cc 9 6  error  redefinition of  ostream  as different kind of symbol std  ostream amp  operator lt  lt  std  ostream amp  out  Student const amp  s           In file included from  tmp webcompile  25327 1 cc 1  In file included from  usr include c   4 3 string 49  In file included from  usr include c   4 3 bits localefwd h 47   usr include c   4 3 iosfwd 134 33  note  previous definition is here   typedef basic ostream lt char gt            ostream             lt   isiosfwd                                            tmp webcompile  25327 1 cc 9 13  error  expected     after top level declarator std  ostream amp  operator lt  lt  std  ostream amp  out  Student const amp  s                                2 errors generated    I purposefully choose an example which triggers an unclear error message  coming from an ambiguity in the grammar  rather than the typical  Oh my god Clang read my mind  examples  Still  we notice that Clang avoids the flood of errors  No need to scare students away

User · Answer

I use both Clang and GCC  I find Clang has some useful warnings  but for my own ray-tracing benchmarks - its consistently 5-15  slower then GCC  take that with grain of salt of course  but attempted to use similar optimization flags for both    So for now I use Clang static analysis and its warnings with complex macros   though now GCC s warnings are pretty much as good - gcc4 8 - 4 9    Some considerations    Clang has no OpenMP support  only matters if you take advantage of that but since I do  its a limitation for me          Cross compilation may not be as well supported  FreeBSD 10 for example still use GCC4 x for ARM   gcc-mingw for example is available on Linux     YMMV   Some IDE s don t yet support parsing Clangs output  QtCreator for example         EDIT  QtCreator now supports Clang s output Some aspects of GCC are better documented and since GCC has been around for longer and is widely used  you might find it easier to get help with warnings   error messages          - these areas are in active development and may soon be supported

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