在mac os x中的make过程中错误未知类型名称'constexpr‘

Question

当我在使用scon做一些程序时，会出现错误，

错误:未知类型名称“constexpr” 错误:预期不合格-id

我已经安装了xcode和x石英最新版本。这是我的mac clang版本

Apple版本8.1.0 (clang-802.0.42)目标: x86_64-apple-darwin16.6.0线程模型: posix InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

我附上了我的全部错误日志以防万一。

/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:54:10: error: unknown type name 'constexpr'
static constexpr double     pi  = 3.1415;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:54:20: error: expected unqualified-id
static constexpr double     pi  = 3.1415;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:55:10: error: unknown type name 'constexpr'
static constexpr double  twopi  = 2*pi;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:55:20: error: expected unqualified-id
static constexpr double  twopi  = 2*pi;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:56:10: error: unknown type name 'constexpr'
static constexpr double halfpi  = pi/2;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:56:20: error: expected unqualified-id
static constexpr double halfpi  = pi/2;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:57:10: error: unknown type name 'constexpr'
static constexpr double     pi2 = pi*pi;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:57:20: error: expected unqualified-id
static constexpr double     pi2 = pi*pi;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:62:10: error: unknown type name 'constexpr'
static constexpr double millimeter  = 1.;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:62:20: error: expected unqualified-id
static constexpr double millimeter  = 1.;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:63:10: error: unknown type name 'constexpr'
static constexpr double millimeter2 = millimeter*millimeter;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:63:20: error: expected unqualified-id
static constexpr double millimeter2 = millimeter*millimeter;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:64:10: error: unknown type name 'constexpr'
static constexpr double millimeter3 = millimeter*millimeter*millimeter;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:64:20: error: expected unqualified-id
static constexpr double millimeter3 = millimeter*millimeter*millimeter;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:66:10: error: unknown type name 'constexpr'
static constexpr double centimeter  = 10.*millimeter;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:66:20: error: expected unqualified-id
static constexpr double centimeter  = 10.*millimeter;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:67:10: error: unknown type name 'constexpr'
static constexpr double centimeter2 = centimeter*centimeter;
       ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:67:20: error: expected unqualified-id
static constexpr double centimeter2 = centimeter*centimeter;
                 ^
/Users/jeon.hk/Documents/geant4/geant4.10.3-install/bin/../include/Geant4/CLHEP/Units/SystemOfUnits.h:68:10: error: unknown type name 'constexpr'
static constexpr double centimeter3 = centimeter*centimeter*centimeter;
       ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
scons: *** [build/macosx64/rat.o] Error 1 
scons: building terminated because of errors.

我真的很感谢你的评论。

Answer 1

正确的答案是在启用c++11支持(对于clang -std=c++11 )的情况下进行编译，以便识别-std=c++11关键字。