Attempting to deal with QTBUG-41361

[RobM]

Here is a link to the bug I believe I am dealing with:

I believe this because during the installation of qt-everywhere-opensource-src-4.8.6 I received a few errors during the make process. Specifically, near the end:

In file included from ../3rdparty/javascriptcore/JavaScriptCore/wtf/FastAllocBase.h:84,
                 from ../3rdparty/javascriptcore/JavaScriptCore/wtf/Vector.h:24,
                 from ../3rdparty/javascriptcore/JavaScriptCore/pcre/pcre_exec.cpp:50:
../3rdparty/javascriptcore/JavaScriptCore/wtf/TypeTraits.h:173:69: error: ‘std::tr1’ has not been declared
     template<typename T> struct HasTrivialConstructor : public std::tr1::has_trivial_constructor<T> { };
                                                                     ^~~
../3rdparty/javascriptcore/JavaScriptCore/wtf/TypeTraits.h:173:74: error: expected ‘{’ before ‘has_trivial_constructor’
     template<typename T> struct HasTrivialConstructor : public std::tr1::has_trivial_constructor<T> { };
                                                                          ^~~~~~~~~~~~~~~~~~~~~~~
../3rdparty/javascriptcore/JavaScriptCore/wtf/TypeTraits.h:174:68: error: ‘std::tr1’ has not been declared
     template<typename T> struct HasTrivialDestructor : public std::tr1::has_trivial_destructor<T> { };
                                                                    ^~~
../3rdparty/javascriptcore/JavaScriptCore/wtf/TypeTraits.h:174:73: error: expected ‘{’ before ‘has_trivial_destructor’
     template<typename T> struct HasTrivialDestructor : public std::tr1::has_trivial_destructor<T> { };
                                                                         ^~~~~~~~~~~~~~~~~~~~~~

Then at the very end of the make process I received:

Makefile:1624: recipe for target 'obj/release/pcre_exec.o' failed
make[1]: *** [obj/release/pcre_exec.o] Error 1
make[1]: Leaving directory '/tmp/qt-everywhere-opensource-src-4.8.6/src/script'
Makefile:525: recipe for target 'sub-script-make_default-ordered' failed
make: *** [sub-script-make_default-ordered] Error 2

I believe the reported bug was for DOS but I am working with Ubuntu 16.04 so I changed: mkspecs\win32-g++\qmake.conf too mkspecs\linux-g++-64\qmake.conf and implemented the proposed solution adding ```
QMAKE_CXXFLAGS = $$QMAKE_CFLAGS -std=gnu++98

So I am wondering if my best bet is to downgrade from gcc 8.x to 4.7 or is there a different way of going about getting around these errors?

[JKSH]

Hi @RobM, std::tr1 is the "preview version" of C++11. After C++11 was released in 2011, compilers stopped supporting std::tr1 by default.

Anyway, since you are building Qt yourself on a modern system with GCC 8, may I ask why you want to install Qt 4.8.6? Qt 4 reached end-of-life in December 2015, and is strongly discouraged for new projects. We are currently at Qt 5.11.1: https://www.qt.io/download

[RobM]

@JKSH Yes, I am working with one of our legacy builds. There are some open PR's that I would like to address. However, I have been running into complications with the build process. I do not believe that the GUI would work without considerable alteration to the code with the newest version of Qt. I was hoping to find a way to get everything working without having to temporarily downgrade my version of gcc to 4.7. At this point it seems that downgrading might be my only option.

Should I attempt to run gcc4.7 side by side with 8.1? I am not sure if downgrading gcc is really an option. Online you find mixed reviews. Some people saying its a terrible idea others saying its a snap.

[RobM]

This post is deleted!

[SGaist]

What distribution are you running ?

AFAIK, most of them still ships Qt 4 and likely Qt 4.8.7 which is the latest version available for the Qt 4 series.

[JKSH]

@RobM said in Attempting to deal with QTBUG-41361:

Should I attempt to run gcc4.7 side by side with 8.1?

I haven't tried this before so I can't say, sorry.

@SGaist said in Attempting to deal with QTBUG-41361:

AFAIK, most of them still ships Qt 4 and likely Qt 4.8.7 which is the latest version available for the Qt 4 series.

+1 this would be best, if available.

Otherwise, how did you go with -std=gnu++98? If it works, you can use it.