1775161 - (Wdeprecated-this-capture) Fix and re-enable C++20 -Wdeprecated-this-capture warnings

Status: RESOLVED FIXED

(Firefox Build System :: General, task, P3)

Description

[Chris Peterson [:cpeterson]]

Attachment: Wdeprecated-this-capture_warnings.txt

The implicit capture of *this when the capture default is = is deprecated in C++20:

https://en.cppreference.com/w/cpp/language/lambda#Lambda_capture

See the attached log file for the 48 -Wdeprecated-this-capture warnings currently reported in mozilla-central.

However, due to inconsistencies in how clang and gcc handle explicit this captures in -std=c++17 mode, we can't fix these warnings (without ugly #ifdefs) to make this code compatible with both clang and gcc until after we build as -std=c++20 by default (bug 1768116).

class C {
  void memberFunction() {}

  void testCapture() {
    [=]() { memberFunction(); }();
    // Implicit capture of *this is OK in clang and gcc -std=c++17.
    // -Wdeprecated-this-capture warning in clang -std=c++20.
    // -Wdeprecated warning in gcc -std=c++20.

    [=, this]() { memberFunction(); }();
    // Explicit capture of *this is OK in clang and gcc -std=c++20.
    // -Wc++20-extensions warning in clang -std=c++17.
    // Error in gcc -std=c++17 with no way to suppress it.
  }
};

Comment 1

[Chris Peterson [:cpeterson]]

These -Wdeprecated-this-capture warnings only reported when compiled with -std=c++20. In the meantime, these warnings were downgraded from errors to warnings in bug 1781001 so fixing these warnings doesn't need to block updating to C++20.

Comment 2

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in clang-plugin tests. r?#static-analysis-reviewers

build/clang-plugin/tests/TestNoRefcountedInsideLambdas.cpp Line 636: implicit capture of 'this' with a capture default of '=' is deprecated
build/clang-plugin/tests/TestNoRefcountedInsideLambdas.cpp Line 639: implicit capture of 'this' with a capture default of '=' is deprecated
build/clang-plugin/tests/TestNoRefcountedInsideLambdas.cpp Line 660: implicit capture of 'this' with a capture default of '=' is deprecated
build/clang-plugin/tests/TestNoRefcountedInsideLambdas.cpp Line 663: implicit capture of 'this' with a capture default of '=' is deprecated

Comment 3

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in dom. r?#dom-core

dom/clients/manager/ClientHandleOpParent.cpp:89:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

dom/media/ChannelMediaDecoder.cpp:406:17 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/MediaCache.cpp:1978:9 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

dom/media/webrtc/jsapi/MediaTransportHandler.cpp:1034:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:1050:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:1283:9 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:561:11 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:586:15 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:635:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:765:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:811:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:897:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:915:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:946:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandler.cpp:993:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:121:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:132:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:143:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:156:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:185:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:227:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:240:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:260:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:279:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:296:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:308:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:334:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:346:13 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
dom/media/webrtc/jsapi/MediaTransportHandlerIPC.cpp:93:14 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 4

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in extensions/webrequest. r?#extension-reviewers

toolkit/components/extensions/webrequest/StreamFilterParent.cpp:338:7 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:361:7 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:420:5 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:426:7 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:615:11 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:633:11 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
toolkit/components/extensions/webrequest/StreamFilterParent.cpp:699:7 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 5

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in gfx/thebes. r?#gfx-reviewers

gfx/thebes/gfxPlatformFontList.cpp:1707:20 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
gfx/thebes/gfxPlatformFontList.cpp:1942:40 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 6

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in image/decoders. r?tnikkel

image/decoders/nsBMPDecoder.cpp:435:20 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsGIFDecoder2.cpp:454:20 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsICODecoder.cpp:644:20 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsIconDecoder.cpp:38:34 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsJPEGDecoder.cpp:194:34 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsJXLDecoder.cpp:79:34 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
image/decoders/nsPNGDecoder.cpp:362:34 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 7

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in ipc/ipdl tests. r?#ipc-reviewers

ipc/ipdl/test/gtest/TestAsyncReturns.cpp:64:9: warning: implicit capture of 'this' with a capture default of '=' is deprecated [-Wdeprecated-this-capture]

ipc/ipdl/test/gtest/TestAsyncReturns.cpp:72:9: warning: implicit capture of 'this' with a capture default of '=' is deprecated [-Wdeprecated-this-capture]

ipc/ipdl/test/gtest/TestHangs.cpp:134:1: warning: implicit capture of 'this' with a capture default of '=' is deprecated [-Wdeprecated-this-capture]

Comment 8

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in layout. r?#layout-reviewers

layout/forms/HTMLSelectEventListener.cpp:739:23 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
layout/generic/nsFlexContainerFrame.cpp:3796:18 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
layout/generic/nsFlexContainerFrame.cpp:3802:18 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated
layout/style/FontFaceImpl.cpp:466:5 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 9

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in netwerk. r?#necko-reviewers

netwerk/ipc/DocumentLoadListener.cpp:975:15: error: implicit capture of 'this' with a capture default of '=' is deprecated [-Werror,-Wdeprecated-this-capture]

netwerk/protocol/http/nsHttpConnectionMgr.cpp:3011:9 [-Wdeprecated-this-capture] implicit capture of 'this' with a capture default of '=' is deprecated

Comment 10

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Fix -Wdeprecated-this-capture warnings in widget/android. r?#geckoview-reviewers

widget/android/GeckoEditableSupport.cpp:653:21: error: implicit capture of 'this' with a capture default of '=' is deprecated [-Werror,-Wdeprecated-this-capture]
widget/android/GeckoEditableSupport.cpp:748:7: error: implicit capture of 'this' with a capture default of '=' is deprecated [-Werror,-Wdeprecated-this-capture]

Comment 11

[Chris Peterson [:cpeterson]]

Attachment: Bug 1775161 - Re-enable -Wdeprecated-this-capture warnings. r?#firefox-build-system-reviewers

And re-enable gcc's -Wdeprecated warnings, which were only disabled
because gcc didn't have a more precise flag to disable its warnings
about C++20 deprecated this captures.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/4bfa5608a199
https://hg.mozilla.org/integration/autoland/rev/60c0db17b1a8
Fix -Wdeprecated-this-capture warnings in clang-plugin tests. r=nika
https://github.com/mozilla-firefox/firefox/commit/39db7a135e18
https://hg.mozilla.org/integration/autoland/rev/2616ebcc10bb
Fix -Wdeprecated-this-capture warnings in dom. r=dom-core,webrtc-reviewers,smaug,bwc,padenot
https://github.com/mozilla-firefox/firefox/commit/8422d11245b3
https://hg.mozilla.org/integration/autoland/rev/6792c2db86a0
Fix -Wdeprecated-this-capture warnings in extensions/webrequest. r=extension-reviewers,robwu
https://github.com/mozilla-firefox/firefox/commit/6c613d23c0ce
https://hg.mozilla.org/integration/autoland/rev/a906e032683a
Fix -Wdeprecated-this-capture warnings in gfx/thebes. r=gfx-reviewers,lsalzman
https://github.com/mozilla-firefox/firefox/commit/d4665c788bc6
https://hg.mozilla.org/integration/autoland/rev/74b9a73893af
Fix -Wdeprecated-this-capture warnings in image/decoders. r=tnikkel
https://github.com/mozilla-firefox/firefox/commit/eeb6297d6cf7
https://hg.mozilla.org/integration/autoland/rev/e3ac82aac61c
Fix -Wdeprecated-this-capture warnings in ipc/ipdl tests. r=ipc-reviewers,mccr8,nika
https://github.com/mozilla-firefox/firefox/commit/dcfa9d3b1cbb
https://hg.mozilla.org/integration/autoland/rev/04f668b3d2e0
Fix -Wdeprecated-this-capture warnings in layout. r=layout-reviewers,TYLin
https://github.com/mozilla-firefox/firefox/commit/5d2fbd15631e
https://hg.mozilla.org/integration/autoland/rev/66fc6fd04c98
Fix -Wdeprecated-this-capture warnings in netwerk. r=necko-reviewers,valentin
https://github.com/mozilla-firefox/firefox/commit/234bbfb8040d
https://hg.mozilla.org/integration/autoland/rev/2105d99307d1
Fix -Wdeprecated-this-capture warnings in widget/android. r=geckoview-reviewers,ohall
https://github.com/mozilla-firefox/firefox/commit/787c6031b6e3
https://hg.mozilla.org/integration/autoland/rev/91ec7dfaaecc
Re-enable -Wdeprecated-this-capture warnings. r=firefox-build-system-reviewers,ahochheiden

Comment 13

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/60c0db17b1a8
https://hg.mozilla.org/mozilla-central/rev/2616ebcc10bb
https://hg.mozilla.org/mozilla-central/rev/6792c2db86a0
https://hg.mozilla.org/mozilla-central/rev/a906e032683a
https://hg.mozilla.org/mozilla-central/rev/74b9a73893af
https://hg.mozilla.org/mozilla-central/rev/e3ac82aac61c
https://hg.mozilla.org/mozilla-central/rev/04f668b3d2e0
https://hg.mozilla.org/mozilla-central/rev/66fc6fd04c98
https://hg.mozilla.org/mozilla-central/rev/2105d99307d1
https://hg.mozilla.org/mozilla-central/rev/91ec7dfaaecc