cgo fixes via @amlwwalker via @SjB #186

jackman0 · 2018-03-29T02:05:26Z

I did a diff between the @niemeyer code and the @amlwwalker code. This branch should only contain the changes required to get QML to work without using GODEBUG=cgocheck=0. I'm not an expert in cgo or QML, but I know that this branch works for me.

His comments in issue #179:

Hi All,

I ran into this error a while back. I can briefly explain what is going on here. go-qml passes (or receives, I can't remember) a pointer to a pointer to C code within the qml libraries. Doing so means that the Go garbarge collector cannot see whether the pointer has been released by the C code. This can lead to memory leaks so in go1.6 this was made a forbidden thing to do (and is only detected at runtime). So hence the error: cgo argument has Go pointer to Go pointer.

github.com/SjB/qml solves this in its latest branch, however SjB doesn't seem to be monitoring the repo, so I have forked it and although my knowledge of the low level api to the qml libraries is unknown to me, I am managing the code to make the examples work and plan to make small changes to make it convenient to use going forward. You can find it at https://github.com/amlwwalker/qml

I'm using it now actively, so I can help people get set up if they are struggling with post 1.6 qml and Go.

A

Tests can use SetupTesting instead of Run.

GoImageProvider had a memory leak where it got a pointer to a QImage, and never freed it. Qt already has a refcounting system in place so every QImage is actually a pointer to pixel data, but it relies on the destructor for every QImage instance to be called.

Fix ImageProvider data leak in C++ logic. Fix by Carlos Castillo.

Update requirements for OS X.

Update README for v1 branch.

Changed examples URL to match current branch.

http://golang.org/issue/8588

Thanks to David Crawshaw for the suggestion.

qml.v0 seems to be deprecated and doesn't work with the latest Go 1.3.1. Updating the README to reflect this.

Thanks to Ignazio Di Napoli for reporting the issue.

Before 5.3 logic goes mainstream it cannot rely on qt to resolve the missing symbols.

apt-get install ubuntu-app-launch;"upstart-app-launch" >> "ubuntu-app-launch"

Documentation updates.

change "upstart-app-launch" to "ubuntu-app-launch"

apt-get install ubuntu-app-launch;"upstart-app-launch" >> "ubuntu-app-launch"

Documentation updates.

Fixes #107.

Ported some of the qtquickcontrols examples.

Fixes crash in ciborium

Make sure context.file is not null before calling strlen.

Go 1.6 cannot have Go pointer stored into the cgo space. So instead we need to store all Go values in a map and pass a key to the cgo space. When needed the key can be used to retrieve the go value from the map.

Using the C.GoRef datatype instead of uintptr in the go code make it more clear what the variable contains.

added methods to the type so that we can get the GoRef and register the fold in the lookup table, then a function to destroy the reference when we are done with the valueFold.

When unpacking a DataValue of a DTGoAddr type, we forgot to dereference the datap pointer that contained the GoRef. Thanks to immesys on github, for pointing out the bug.

@neclepsio

@neclepsio on github.com found that when connecting a callback function on a MouseArea event the application would panic. This was cause by the extra derefrence on the interface of the function.

jackman0 · 2018-03-29T02:07:56Z

Apparently, this was already done.

jackman0 · 2018-03-29T02:12:02Z

Nevermind. It appears that none of the other pull requests went through. What is keeping this from hitting master or v1 branches?

amlwwalker · 2018-05-17T14:43:20Z

@jackmanlabs
I recommend using therecipe/qt for go and qt/qml for now on. I have had a lot more luck with that project than this one. I have written up my own findings and project to get you started here. Pretty fast to get up and running https://github.com/amlwwalker/got-qt

niemeyer and others added 30 commits May 1, 2014 18:10

New API with Run on main thread.

85e55c7

Tests can use SetupTesting instead of Run.

s/qml.v0/qml.v1/

a664ad4

Move the gl package under work-in-progress.

74294f0

Update all examples with new API.

1b0d88b

update README for v1 branch

534150a

cdata: use g->m

dbdeaea

Changed examples url to match current branch

f020d78

update requirements for OS X

f84f9ae

Merge pull request #88 from cookieo9/memfix

7b344dd

Fix ImageProvider data leak in C++ logic. Fix by Carlos Castillo.

Merge pull request #87 from nf/v1

fcf0740

Update requirements for OS X.

Merge pull request #81 from jhawk28/patch-1

6e78849

Update README for v1 branch.

Merge pull request #82 from perrito666/v1

5f7fdd0

Changed examples URL to match current branch.

Handle Paint panics to workaround Go issue #8588.

4f4a7f5

http://golang.org/issue/8588

New GL API.

97c4e8c

Port GL examples to new API.

8e569b4

Use native Go types for meaningless GL types.

539bf5a

Move common GL types to glbase.

43aa533

Start introducing types for well known objects.

c74beaa

Thanks to David Crawshaw for the suggestion.

Drop types from consecutive params when possible.

b8b5c15

Split func tweaking logic and start doc importing.

8c84461

Commit current gl packages for publishing.

8e7aff4

Port examples to latest API tweak.

a598350

Drop explicit linking with GL libraries.

9031cc6

Update README to use qml.v1

4432d5f

qml.v0 seems to be deprecated and doesn't work with the latest Go 1.3.1. Updating the README to reflect this.

Add Clampf and Clampd to glbase.

265c7b0

Thanks to Ignazio Di Napoli for reporting the issue.

Add back explicit GL linking to es2.

f59a4bb

Before 5.3 logic goes mainstream it cannot rely on qt to resolve the missing symbols.

Booleans are now native. Boolean/TRUE/FALSE gone.

1efc244

More glbase types, richer func tweaks.

0792804

Unmix glresult and result in funcReturnResult.

00ff374

lomoalbert and others added 24 commits October 8, 2014 10:19

Update setup.sh

7fdf7e3

apt-get install ubuntu-app-launch;"upstart-app-launch" >> "ubuntu-app-launch"

Update README.md

ab36fb4

Documentation updates.

Merge pull request #110 from vzever/v1

871e3a7

change "upstart-app-launch" to "ubuntu-app-launch"

README: fix requirements to refer to Go >= 1.2

18fd325

Merge branch 'v1' of github.com:go-qml/qml into v1

6e34c23

Update setup.sh

b65658d

apt-get install ubuntu-app-launch;"upstart-app-launch" >> "ubuntu-app-launch"

Update README.md

07cb71e

Documentation updates.

Fix bug in resource packing.

ad9c0dd

Fixes #107.

Merge branch 'v1' of github.com:go-qml/qml into v1

929da27

Merge pull request #105 from cristim/v1

1116cb9

Ported some of the qtquickcontrols examples.

Make sure context.file is not null before calling strlen

154c0d1

Fixes crash in ciborium

Merge pull request #144 from tsdgeos/v1

2ee7e5f

Make sure context.file is not null before calling strlen.

Porting go-qml to Go 1.6

826359a

Go 1.6 cannot have Go pointer stored into the cgo space. So instead we need to store all Go values in a map and pass a key to the cgo space. When needed the key can be used to retrieve the go value from the map.

change datatype the foldr from uintptr to C.GoRef

01021bc

Using the C.GoRef datatype instead of uintptr in the go code make it more clear what the variable contains.

refactor valueFold.

2628b57

added methods to the type so that we can get the GoRef and register the fold in the lookup table, then a function to destroy the reference when we are done with the valueFold.

added reference lookup for signal function

a4363f7

added reference lookup for go TypeSpec type

ea70551

fix missing goRef function

0309d2d

fix forgotten dereferenced datap pointer.

d4c4a72

When unpacking a DataValue of a DTGoAddr type, we forgot to dereference the datap pointer that contained the GoRef. Thanks to immesys on github, for pointing out the bug.

fixed MouseArea On Event call back refrence error

f9db098

@neclepsio on github.com found that when connecting a callback function on a MouseArea event the application would panic. This was cause by the extra derefrence on the interface of the function.

adding changes to work with 1.6

17ea716

Merge branch 'master' into go1.6-port

ab29fd7

updating readme

28c538d

Lining up genqrc between go-qml and amlwwalker forks

7d9d06b

jackman0 closed this Mar 29, 2018

jackman0 reopened this Mar 29, 2018

jamalsa mentioned this pull request Nov 1, 2018

Qt 5.11 Support #189

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cgo fixes via @amlwwalker via @SjB #186

cgo fixes via @amlwwalker via @SjB #186

jackman0 commented Mar 29, 2018

jackman0 commented Mar 29, 2018

jackman0 commented Mar 29, 2018

amlwwalker commented May 17, 2018 •

edited

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cgo fixes via @amlwwalker via @SjB #186

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cgo fixes via @amlwwalker via @SjB #186

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