Building a project under Windows including Rcpp and RInside - r

Question

Here's a compilation problem.
The project works on Linux and OS X and must be ported to Windows. It uses RInside and Rcpp librairies.
To do so, I installed R, Cygwin and RTools and compiled the R librairies. It worked fine.
Now the problem:
The QMake step happens with no error, but the building exits with an error. I get this :
error: [1]: No such file or directory
error: Rcpp:::CxxFlags(): Invalid argument
error: [1]: No such file or directory
error: RInside:::CxxFlags(): Invalid argument
Long version:
17:18:36: Débute : "C:\Qt\Qt5.7.0\Tools\mingw530_32\bin\mingw32-make.exe"
C:/Qt/Qt5.7.0/5.7/mingw53_32/bin/qmake.exe -spec win32-g++ CONFIG+=debug CONFIG+=qml_debug -o Makefile ../IHM/Rpp-IHM.pro
C:/Qt/Qt5.7.0/Tools/mingw530_32/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'C:/Users/Henri/Desktop/rpp/src/build-Rpp-IHM-Desktop_Qt_5_7_0_MinGW_32bit-Debug'
g++ -c -pipe -fno-keep-inline-dllexport -Wno-unused-parameter -IC:/Progz/R-3.3.2/include -IC:/Progz/R-3.3.2/include/x64 [1] "Rcpp:::CxxFlags()" [1] "RInside:::CxxFlags()" -g -std=gnu++11 -frtti -Wall -Wextra -fexceptions -mthreads -DUNICODE -DQT_QML_DEBUG -DQT_SVG_LIB -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_NEEDS_QMAIN -I../IHM -I. -I../computer/RppUtils -I../computer/RppEngine -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include/QtSvg -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include/QtWidgets -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include/QtGui -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include/QtANGLE -IC:/Qt/Qt5.7.0/5.7/mingw53_32/include/QtCore -Idebug -IC:/Qt/Qt5.7.0/5.7/mingw53_32/mkspecs/win32-g++ -o debug/WrapperRppR.o ../IHM/WrapperRppR.cpp
g++.exe: error: [1]: No such file or directory
g++.exe: error: Rcpp:::CxxFlags(): Invalid argument
g++.exe: error: [1]: No such file or directory
g++.exe: error: RInside:::CxxFlags(): Invalid argument
Makefile.Debug:2914: recipe for target 'debug/WrapperRppR.o' failed
mingw32-make[1]: *** [debug/WrapperRppR.o] Error 1
mingw32-make[1]: Leaving directory 'C:/Users/Henri/Desktop/rpp/src/build-Rpp-IHM-Desktop_Qt_5_7_0_MinGW_32bit-Debug'
Makefile:34: recipe for target 'debug' failed
mingw32-make: *** [debug] Error 2
17:18:40: Le processus "C:\Qt\Qt5.7.0\Tools\mingw530_32\bin\mingw32-make.exe" s'est terminé avec le code 2.
Erreur lors de la compilation/déploiement du projet Rpp-IHM (kit : Desktop Qt 5.7.0 MinGW 32bit)
When executing step "Make"
In fact, it seems that it doesn't find RInside.h, in spite of the fact that the R_HOM variable is set to the directory of R (here : C:/Progz/R-3.3.2/).
Here's a part of the .pro file:
QT += core gui svg
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = Rpp-IHM
TEMPLATE = app
CONFIG += c++11
CONFIG += -v
## comment this out if you need a different version of R,
## and set set R_HOME accordingly as an environment variable
## R_HOM = $$system($$R_HOME)
win32 {
#A specifier
R_HOM = "C:/Progz/R-3.3.2/"
}
unix:!macx {
# WORKING
R_HOM = "/usr/lib/R/"
}
macx {
# WORKING
R_HOM = "/Library/Frameworks/R.framework/Resources/"
}
## include headers and libraries for R
RCPPFLAGS = $$system($$R_HOM/bin/R CMD config --cppflags)
RLDFLAGS = $$system($$R_HOM/bin/R CMD config --ldflags)
RBLAS = $$system($$R_HOM/bin/R CMD config BLAS_LIBS)
RLAPACK = $$system($$R_HOM/bin/R CMD config LAPACK_LIBS)
## if you need to set an rpath to R itself, also uncomment
RRPATH = -Wl,-rpath,R_HOME/lib
## include headers and libraries for Rcpp interface classes
RCPPINCL = $$system($$R_HOM/bin/Rscript -e \'Rcpp:::CxxFlags\(\)\')
RCPPLIBS = $$system($$R_HOM/bin/Rscript -e \'Rcpp:::LdFlags\(\)\')
## for some reason when building with Qt we get this each time
## so we turn unused parameter warnings off
RCPPWARNING = -Wno-unused-parameter
## include headers and libraries for RInside embedding classes
RINSIDEINCL = $$system($$R_HOM/bin/Rscript -e \'RInside:::CxxFlags\(\)\')
RINSIDELIBS = $$system($$R_HOM/bin/Rscript -e \'RInside:::LdFlags\(\)\')
INCLUDEPATH = ../computer/RppUtils
INCLUDEPATH += ../computer/RppEngine
## compiler etc settings used in default make rules
QMAKE_CXXFLAGS += $$RCPPWARNING $$RCPPFLAGS $$RCPPINCL $$RINSIDEINCL
QMAKE_LFLAGS += $$RLDFLAGS $$RBLAS $$RLAPACK $$RCPPLIBS $$RINSIDELIBS
QMAKE_CXXFLAGS_WARN_OFF += -Wunused-parameter
What did I miss?