Hi all,

MSVC 10 SP1 gives me a compile error in MatrixBase.h in line 253 when I try to compile the PCL (PointCloudLibrary).

error C2082: redefinition of formal parameter 'n' in
\eigen\src\Core\MatrixBase.h

The comment line above the offending line also says "huuuge hack"... perhaps it is related

Cheers
vernal

Hi,

does MSVC gives you more information as I don't understand this error.

I can tell you that the error goes away by simply renaming that variable n. (Although I don't know if I break something with it as I don't know much about templates).

The error is described in a bit more detail here:
http://msdn.microsoft.com/en-us/library/k4h61sx8(v=VS.90).aspx

(sorry for the delay)

ok, the problem is that here n is a template variable and it is not redefined anywhere. Actually it is even not used. So you say that for instance rewriting the line 253 as:

template<template<typename T, int N> class U>

with a upper case N, fixes your issue? That just does not make sense to me. Bit if that's all you need I'm ok to commit such a change.

Isn't there a typename or type or class missing after that template definition?

For information, I've just had this exact problem and resolved it in exactly the same way. I am compiling Eigen 3.1.1 into my own code and am using the linearRegression class template. I have therefore defined EIGEN2_SUPPORT as a preprocessor definition.

OK, still very strange, anyway:

https://bitbucket.org/eigen/eigen/chang ... 483956b8d/
changeset: 753483956b8d
user: ggael
date: 2012-09-14 09:54:56
summary: workaround weird compilation error with MSVC

https://bitbucket.org/eigen/eigen/chang ... c6bfc83dc/
changeset: 2d7c6bfc83dc
branch: 3.1
user: ggael
date: 2012-09-14 09:54:56
summary: workaround weird compilation error with MSVC
(transplanted from 753483956b8d587f9d2181b0cb7331d034762ea5)