First, open the makefile file to see if the value of the incpath variable contains the header file path involved in the program

MAKEFILE      = Makefile

####### Compiler, tools and options

CC            = /work/tools/usr/local/arm/4.3.2/bin/arm-linux-gcc -lts -ldl
CXX           = /work/tools/usr/local/arm/4.3.2/bin/arm-linux-g++ -lts -ldl
DEFINES       = -DQT_NO_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB
CFLAGS        = -msoft-float -D__GCC_FLOAT_NOT_NEEDED -march=armv7-a -mtune=cortex-a8 -pipe -O2 -Wall -W -D_REENTRANT -fPIC $(DEFINES)
CXXFLAGS      = -msoft-float -D__GCC_FLOAT_NOT_NEEDED -march=armv7-a -mtune=cortex-a8 -msoft-float -D__GCC_FLOAT_NOT_NEEDED -march=armv7-a -mtune=cortex-a8 -pipe -O2 -Wall -W -D_REENTRANT -fPIC $(DEFINES)
INCPATH       = -I. -I. -I/Qt5/include -I/Qt5/include/QtWidgets -I/Qt5/include/QtGui -I/Qt5/include/QtCore -I. -I/Qt5/mkspecs/linux-arm-gnueabi-g++
QMAKE         = /Qt5/bin/qmake
DEL_FILE      = rm -f
CHK_DIR_EXISTS= test -d
MKDIR         = mkdir -p
COPY          = cp -f
COPY_FILE     = cp -f
COPY_DIR      = cp -f -R
INSTALL_FILE  = install -m 644 -p
INSTALL_PROGRAM = install -m 755 -p
INSTALL_DIR   = cp -f -R
DEL_FILE      = rm -f
SYMLINK       = ln -f -s
DEL_DIR       = rmdir

If it does not exist, check whether the file is imported into the. Pro file. You can add it in the form of QT + = XXX, for example:

Prompt “no QApplication…”, then add QT + = widgets, re qmake and then make