Sorry I hadn't be clear in my post. I reformulate it.
This is very simple I cannot compile a simple Qt project the one with the mainwindow. I did via command shell and via QtCreator. first qmake should create makefile with the command rule uic to translate as simple as it should be my ui to a .h.

Here my .pro
__________________________________________________ ________________
#-------------------------------------------------
#
# Project created by QtCreator 2016-06-29T14:49:38
#
#-------------------------------------------------

QT += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled
TEMPLATE = app


SOURCES += main.cpp\
mainwindow.cpp

HEADERS += mainwindow.h

FORMS += mainwindow.ui
__________________________________________________ __
Here my command line in script shell windows
_______________________________________________
C:\workspace_llb_27-05-2016\untitled>qmake.exe untitled.pro -r -spec win32-g++

C:\workspace_llb_27-05-2016\untitled>mingw32-make
mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'C:/workspace_llb_27-05-2016/untitled'
/C/workspace_llb_27-05-2016/untitled/uic_wrapper.sh mainwindow.ui -o ui_mainwindow.h
process_begin: CreateProcess(NULL, /C/workspace_llb_27-05-2016/untitled/uic_wrapper.sh mainwindow.ui -o ui_mainwi
ndow.h, ...) failed.
make (e=2): Le fichier spÚcifiÚ est introuvable.
Makefile.Debug:318: recipe for target 'ui_mainwindow.h' failed
mingw32-make[1]: *** [ui_mainwindow.h] Error 2
mingw32-make[1]: Leaving directory 'C:/workspace_llb_27-05-2016/untitled'
Makefile:34: recipe for target 'debug' failed
mingw32-make: *** [debug] Error 2
__________________________________________________ _________________________

sorry some part are in French. After using many project working I couldn't know what happen. Sometime I use the shadow build It could be that couldn't it ?
Thx