[Insight-developers] compilation error when compiled with gnu++0x flag

Wed May 9 11:33:19 EDT 2012

This is a problem with VNL, and I don't know if they've fixed it, or when
ITK will upgrade.

The problem is this, and affects CLang as well: According to the C++
standard, you can only initialize integral types as static data members of
a class.  GCC supports that as an extension, unless you tell it to
actually enforce the standard, which is what you're asking it to do with
-std=gnu++0x.

In VNL, if CMake detects GCC as a compiler, it goes ahead and defines the
static float members in line in the class. Otherwise it declares them
separately in a C++ file.

What I wish is that they'd define these constants separately always.

I can't imagine what they think is gained by having them in-line, unless
it makes the compiler load a constant directly into a register instead of
from memory.  That would be a performance win, I guess, if you write code
that references these constants a lot in inner loop.

What's really maddening with Clang is that it claims to be GCC with
respect to preprocessor symbols. This means when you build ITK, you get a
couple of megabytes of warnings about vnl_math.h.

--
Kent Williams norman-k-williams at uiowa.edu

On 5/9/12 7:00 AM, "Arnaud Gelas" <arnaudgelas at gmail.com> wrote:

>Hi all,
>
>When doing cmake -DCMAKE_CXX_FLAGS=-std=gnu++0x /path/to/ITK && make
>-j8, I get compilation errors in vnl_math (see below).
>
>gcc version: 4.6.3
>cmake version: 2.8.7
>
>What would be the best way to fix these errors?
>
>Thanks,
>Arnaud
>
>---
>
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:87:27:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œe¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:88:31:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œlog2e¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:89:32:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œlog10e¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:90:29:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œln2¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:91:30:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œln10¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:92:28:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œpi¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:93:35:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œpi_over_2¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:94:35:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œpi_over_4¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:95:37:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œone_over_pi¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:96:37:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œtwo_over_pi¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:97:41:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œtwo_over_sqrtpi¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:98:42:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œone_over_sqrt2pi¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:99:31:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œsqrt2¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:100:33:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œsqrt1_2¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:101:31:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œeuler¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:104:29:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œeps¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:105:33:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œsqrteps¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:107:34:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œfloat_eps¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.h:108:38:
>error: Œconstexpr¹ needed for in-class initialization of static data
>member Œfloat_sqrteps¹ of non-integral type
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:84:24:
>error: Œconst double vnl_math::e¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:84:14:
>error: uninitialized const Œvnl_math::e¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:85:24:
>error: Œconst double vnl_math::log2e¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:85:14:
>error: uninitialized const Œvnl_math::log2e¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:86:24:
>error: Œconst double vnl_math::log10e¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:86:14:
>error: uninitialized const Œvnl_math::log10e¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:87:24:
>error: Œconst double vnl_math::ln2¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:87:14:
>error: uninitialized const Œvnl_math::ln2¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:88:24:
>error: Œconst double vnl_math::ln10¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:88:14:
>error: uninitialized const Œvnl_math::ln10¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:89:24:
>error: Œconst double vnl_math::pi¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:89:14:
>error: uninitialized const Œvnl_math::pi¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:90:24:
>error: Œconst double vnl_math::pi_over_2¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:90:14:
>error: uninitialized const Œvnl_math::pi_over_2¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:91:24:
>error: Œconst double vnl_math::pi_over_4¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:91:14:
>error: uninitialized const Œvnl_math::pi_over_4¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:92:24:
>error: Œconst double vnl_math::one_over_pi¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:92:14:
>error: uninitialized const Œvnl_math::one_over_pi¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:93:24:
>error: Œconst double vnl_math::two_over_pi¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:93:14:
>error: uninitialized const Œvnl_math::two_over_pi¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:94:24:
>error: Œconst double vnl_math::two_over_sqrtpi¹ is not a static member
>of Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:94:14:
>error: uninitialized const Œvnl_math::two_over_sqrtpi¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:95:24:
>error: Œconst double vnl_math::one_over_sqrt2pi¹ is not a static member
>of Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:95:14:
>error: uninitialized const Œvnl_math::one_over_sqrt2pi¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:96:24:
>error: Œconst double vnl_math::sqrt2¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:96:14:
>error: uninitialized const Œvnl_math::sqrt2¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:97:24:
>error: Œconst double vnl_math::sqrt1_2¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:97:14:
>error: uninitialized const Œvnl_math::sqrt1_2¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:98:24:
>error: Œconst double vnl_math::euler¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:98:14:
>error: uninitialized const Œvnl_math::euler¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:101:24:
>error: Œconst double vnl_math::eps¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:101:14:
>error: uninitialized const Œvnl_math::eps¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:102:24:
>error: Œconst double vnl_math::sqrteps¹ is not a static member of Œclass
>vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:102:14:
>error: uninitialized const Œvnl_math::sqrteps¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:105:23:
>error: Œconst float vnl_math::float_eps¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:105:13:
>error: uninitialized const Œvnl_math::float_eps¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:106:23:
>error: Œconst float vnl_math::float_sqrteps¹ is not a static member of
>Œclass vnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:106:13:
>error: uninitialized const Œvnl_math::float_sqrteps¹ [-fpermissive]
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:
>In static member function Œstatic double
>vnl_math::angle_0_to_2pi(double)¹:
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:291:16:
>error: Œpi¹ is not a member of Œvnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:292:28:
>error: Œpi¹ is not a member of Œvnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:294:12:
>error: Œpi¹ is not a member of Œvnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:294:47:
>error: Œpi¹ is not a member of Œvnl_math¹
>/home/ajg23/DEVEL/src/ITK/Modules/ThirdParty/VNL/src/vxl/core/vnl/vnl_math
>.cxx:304:21:
>error: Œpi¹ is not a member of Œvnl_math¹
>make[2]: ***
>[Modules/ThirdParty/VNL/src/vxl/core/vnl/CMakeFiles/itkvnl.dir/vnl_math.cx
>x.o]
>Error 1
>make[2]: *** Waiting for unfinished jobs....
>
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