使用并行构建时 PRE_TARGETDEPS 失败

我正在使用自定义资源管理（代替 qrc），并尝试将其集成到 Qt Creator 中。

我有一个 Python 脚本，可以生成要编译的源文件。我用QMAKE_EXTRA_TARGETS/PRE_TARGETDEPS告诉QMake该脚本必须在文件编译之前执行。所以我在我的专业文件中这样做：

CONFIG += ordered

generated_file.target   = my_custom_target
generated_file.commands = echo "Generating..." && d:/dev/vobs_ext_2015/tools_ext/python/Python34_light/python.exe $$PWD/pyc_res_generator.py -o $$PWD/generated/generated.cpp && echo "Generated!"
generated_file.depends  = FORCE

QMAKE_EXTRA_TARGETS            += generated_file

PRE_TARGETDEPS                 += my_custom_target

SOURCES                        += generated/generated.cpp

#DEPENDPATH = ./generated

With pyc_res_generator.py只是：

#! /usr/bin/env python
# -*- coding: utf8 *-*

import argparse

parser = argparse.ArgumentParser(description="", formatter_class=argparse.RawTextHelpFormatter)
parser.add_argument("-o", type=str, help="Output file name")

args = parser.parse_args()

with open(args.o, 'w') as output_file:
    output_file.write( "// This is valid C++!" )

为了测试这一点，我在 generated.cpp 中编写了一些无效的 C++（例如fjkfkfk）。当我编译时（目标是Android），我在日志中看到：

echo Generating... && python.exe pyc_res_generator.py -o generated/generated.cpp && echo Generated!
Generating... 
B:\Android\android-ndk-r11b/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++ -c -Wno-psabi -march=armv7-a -mfloat-abi=softfp -mfpu=vfp -ffunction-sections -funwind-tables -fstack-protector -fno-short-enums -DANDROID -Wa,--noexecstack -fno-builtin-memmove -std=c++11 -g -g -marm -O0 -fno-omit-frame-pointer -Wall -Wno-psabi -W -D_REENTRANT -fPIC -DQT_QML_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I..\TestQt -I. -IB:\QtCreator5_6_1\5.6\android_armv7\include -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtWidgets -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtGui -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtCore -I. -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\include -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\libs\armeabi-v7a\include -isystem B:\Android\android-ndk-r11b\platforms\android-9\arch-arm\usr\include -IB:\QtCreator5_6_1\5.6\android_armv7\mkspecs\android-g++ -o main.obj ..\TestQt\main.cpp
B:\Android\android-ndk-r11b/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++ -c -Wno-psabi -march=armv7-a -mfloat-abi=softfp -mfpu=vfp -ffunction-sections -funwind-tables -fstack-protector -fno-short-enums -DANDROID -Wa,--noexecstack -fno-builtin-memmove -std=c++11 -g -g -marm -O0 -fno-omit-frame-pointer -Wall -Wno-psabi -W -D_REENTRANT -fPIC -DQT_QML_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I..\TestQt -I. -IB:\QtCreator5_6_1\5.6\android_armv7\include -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtWidgets -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtGui -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtCore -I. -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\include -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\libs\armeabi-v7a\include -isystem B:\Android\android-ndk-r11b\platforms\android-9\arch-arm\usr\include -IB:\QtCreator5_6_1\5.6\android_armv7\mkspecs\android-g++ -o dialog.obj ..\TestQt\dialog.cpp
B:\Android\android-ndk-r11b/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++ -c -Wno-psabi -march=armv7-a -mfloat-abi=softfp -mfpu=vfp -ffunction-sections -funwind-tables -fstack-protector -fno-short-enums -DANDROID -Wa,--noexecstack -fno-builtin-memmove -std=c++11 -g -g -marm -O0 -fno-omit-frame-pointer -Wall -Wno-psabi -W -D_REENTRANT -fPIC -DQT_QML_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I..\TestQt -I. -IB:\QtCreator5_6_1\5.6\android_armv7\include -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtWidgets -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtGui -IB:\QtCreator5_6_1\5.6\android_armv7\include\QtCore -I. -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\include -isystem B:\Android\android-ndk-r11b\sources\cxx-stl\gnu-libstdc++\4.9\libs\armeabi-v7a\include -isystem B:\Android\android-ndk-r11b\platforms\android-9\arch-arm\usr\include -IB:\QtCreator5_6_1\5.6\android_armv7\mkspecs\android-g++ -o generated.obj ..\TestQt\generated\generated.cpp
B:\QtCreator5_6_1\5.6\android_armv7\bin\moc.exe -DQT_QML_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -IB:/QtCreator5_6_1/5.6/android_armv7/mkspecs/android-g++ -IC:/Users/jp225611/Documents/TestQt -IB:/QtCreator5_6_1/5.6/android_armv7/include -IB:/QtCreator5_6_1/5.6/android_armv7/include/QtWidgets -IB:/QtCreator5_6_1/5.6/android_armv7/include/QtGui -IB:/QtCreator5_6_1/5.6/android_armv7/include/QtCore -I. -IB:\Android\android-ndk-r11b/sources/cxx-stl/gnu-libstdc++/4.9/include -IB:\Android\android-ndk-r11b/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a/include -IB:\Android\android-ndk-r11b/platforms/android-9/arch-arm//usr/include ..\TestQt\dialog.h -o moc_dialog.cpp
..\TestQt\generated\generated.cpp:1:1: error: 'fjkfkfk' does not name a type
   // This is valid C++!
   ^
makefile:670: recipe for target 'generated.obj' failed
mingw32-make: *** [generated.obj] Error 1
mingw32-make: *** Waiting for unfinished jobs....
Generated!
13:59:08: Le processus "B:\QtCreator5_6_1\Tools\mingw492_32\bin\mingw32-make.exe" s'est terminé avec le code 2.
Erreur lors de la compilation/déploiement du projet TestQt (kit : android_armeabi-v7a)
When executing step "Make"
13:59:08: Temps écoulé : 00:03.

我看到了generated\generated.cpp是由正确生成的pyc_res_generator.py（它现在包含// This is valid C++!）...但编译器看到显然为时已晚fjkfkfk... 如您所见，输出报告：

Generating...
B:\Android\android-ndk-r11b/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++ .... ..\TestQt\generated\generated.cpp
Generated...

虽然人们会期望：

Generating...
Generated...
B:\Android\android-ndk-r11b/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++ .... ..\TestQt\generated\generated.cpp

仅当启用并行构建时才会发生这种情况（我设置MAKEFLAGS环境变量为“-j8”）

看起来像我的自定义命令generated_file之前开始generated\generated.cpp已经编译了，但是系统并没有等到它结束才真正编译generated\generated.cpp.

难道我做错了什么？

PRE_TARGETDEPS（自定义目标）在这里不是一个好方法，因为generated_file.target必须与 Makefile 目标名称完全匹配，该名称可能因不同选项而异：

• 是否启用影子构建
• 主机平台（使用斜杠或反斜杠作为文件夹分隔符）
• 可能是目标编译器/平台

然而，自定义编译器显然工作得更好。这就是 moccing 文件的完成方式。自定义编译器可以生成要编译的新文件（然后系统在编译之前等待文件生成，即使在执行并行构建时也是如此）。

# Set fuiles to be generated in a variable
TO_GENERATE = $$PWD/generated/generated.cpp

# Specify custom command output file:
custom_generator.output  = $$PWD/generated/generated.cpp
# Specify custom command:
custom_generator.commands = 'echo "Generating..." && python $$PWD/pyc_res_generator.py -o $$PWD/generated/generated.cpp && echo "Generated..."'
# dependency:
custom_generator.depends = FORCE
# link to input file variable
custom_generator.input = TO_GENERATE
# link to variable to store generated file to
custom_generator.variable_out = SOURCES
# add to qmake:
QMAKE_EXTRA_COMPILERS += custom_generator

然后，您甚至不需要指定SOURCES += $$PWD/generated/generated.cpp。并且，$$PWD/generated/generated.cpp清理后被删除！

这完全符合预期！