[tcling] Suppress `-Wunused-result` diagnostics in wrappers generated by TClingCallFunc #9244

jalopezg-git · 2021-11-04T13:12:57Z

This pull-request suppresses -Wunused-result diagnostics for wrapper functions generated by TClingCallFunc (see below).

A TClingCallFunc wrapper function might look as the excerpt below, where the function denoted by func may have been annotated as [[nodiscard]]. Note that if ret == nullptr the result of the call is unused.

extern "C" void __cf_0(void* obj, int nargs, void** args, void* ret) {
   if (ret) {
      new (ret) (return_type) ((class_name*)obj)->func(args...);
   }
   else {
      ((class_name*)obj)->func(args...);
   }
}

In turn, this triggers warnings when used by cppyy/PyROOT, e.g.

>>> import ROOT
>>> v = ROOT.std.vector(int)()
>>> v.empty()
input_line_34:10:7: warning; ignoring return value of function declared with 'nodiscard' attribute
      [-Wunused-result]
      ((const vector<int>*)obj)->empty();
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
True
>>>

Changes or fixes:

Given the above situation, this commit supresses -Wunused-result diagnostics only for TClingCallFunc wrapper functions.

Checklist:

tested changes locally

This PR fixes #8622.

Sibling PR in roottest: root-project/roottest#791

phsft-bot · 2021-11-04T13:13:05Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

vepadulano

LGTM, thanks for finding this out it !

eguiraud · 2021-11-04T14:52:35Z

Would changing

((class_name*)obj)->func(args...);

to

(void)((class_name*)obj)->func(args...);

also fix it? (I can't judge if that's a better or worse solution :) )

pcanal · 2021-11-04T14:54:34Z

I think Enrico's solution might be slight better as it is a more local solution (and clarify the intent of the code).

phsft-bot · 2021-11-04T15:41:17Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

jalopezg-git · 2021-11-04T15:47:37Z

Would changing
((class_name*)obj)->func(args...);
to
(void)((class_name*)obj)->func(args...);
also fix it? (I can't judge if that's a better or worse solution :) )

Yes, of course. Changed! Thanks for the suggestion, @eguiraud!

phsft-bot · 2021-11-04T17:20:13Z

Build failed on mac11.0/cxx17.
Running on macphsft23.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

vgvassilev

Can we get a test for this, presumably in https://github.com/root-project/root/blob/master/core/metacling/test/TClingCallFuncTests.cxx

phsft-bot · 2021-11-04T20:28:55Z

Build failed on windows10/cxx14.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Warnings:

[2021-11-04T18:40:03.077Z] ghprbPullLongDescription=This pull-request suppresses -Wunused-result diagnostics for wrapper functions generated by TClingCallFunc (see below).\r\n\r\nA TClingCallFunc wrapper function might look as the excerpt below, where the function denoted by func may have been annotated as [[nodiscard]]. Note that if ret == nullptr the result of the call is unused.\r\nc++\r\nextern \"C\" void __cf_0(void* obj, int nargs, void** args, void* ret) {\r\n if (ret) {\r\n new (ret) (return_type) ((class_name*)obj)->func(args...);\r\n }\r\n else {\r\n ((class_name*)obj)->func(args...);\r\n }\r\n}\r\n\r\n\r\nIn turn, this triggers warnings when used by cppyy/PyROOT, e.g.\r\npython\r\n>>> import ROOT\r\n>>> v = ROOT.std.vector(int)()\r\n>>> v.empty()\r\ninput_line_34:10:7: warning: ignoring return value of function declared with 'nodiscard' attribute\r\n [-Wunused-result]\r\n ((const vector<int>*)obj)->empty();\r\n ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\nTrue\r\n>>>\r\n\r\n\r\n## Changes or fixes:\r\n- Given the above situation, this commit supresses -Wunused-result diagnostics only for TClingCallFunc wrapper functions.\r\n\r\n## Checklist:\r\n- [X] tested changes locally\r\n\r\nThis PR fixes PyROOT triggers a warning about [[nodiscard]] vector::empty with GCC11 #8622.

Failing tests:

…y TClingCallFunc A TClingCallFunc wrapper function might look as the excerpt below, where the function denoted by `func` may have been annotated as `[[nodiscard]]`. Note that if `ret == nullptr` the result of the call is unused. ``` extern "C" void __cf_0(void* obj, int nargs, void** args, void* ret) { if (ret) { new (ret) (return_type) ((class_name*)obj)->func(args...); } else { ((class_name*)obj)->func(args...); } } ``` In turn, this triggers warnings when used by cppyy/PyROOT, e.g. ``` >>> import ROOT >>> v = ROOT.std.vector(int)() >>> v.empty() input_line_34:10:7: warning: ignoring return value of function declared with 'nodiscard' attribute [-Wunused-result] ((const vector<int>*)obj)->empty(); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ True >>> ``` Given the above, the second call expression will be casted to `void`. Closes issue root-project#8622.

phsft-bot · 2021-11-05T19:06:00Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-05T19:09:37Z

Build failed on ROOT-ubuntu16/nortcxxmod.
Running on sft-ubuntu-1604-1.cern.ch:/build/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:09:23.977Z] FAILED: /usr/bin/ccache /usr/bin/c++ -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../res -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../../clingutils/res -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../../foundation/res -I/mnt/build/workspace/root-pullrequests-build/root/interpreter/cling/include -Iginclude -I/mnt/build/workspace/root-pullrequests-build/root/core/base/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/foundation/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/cont/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/gui/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/meta/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/clib/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/rint/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/zip/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/thread/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/textinput/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/clingutils/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/base/v7/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/foundation/v7/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/unix/inc -Icore/metacling/test -I/mnt/build/workspace/root-pullrequests-build/root/test/unit_testing_support -isystem googletest-prefix/src/googletest/googletest/include -isystem googletest-prefix/src/googletest/googlemock/include -fdiagnostics-color=always -std=c++14 -pipe -Wshadow -Wall -W -Woverloaded-virtual -fsigned-char -pthread -O3 -std=c++14 -MD -MT core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o -MF core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o.d -o core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o -c /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx
[2021-11-05T19:09:23.977Z] /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:09:23.977Z] /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:11:02Z

Build failed on ROOT-debian10-i386/cxx14.
Running on pcepsft10.dyndns.cern.ch:/build/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:10:04.755Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:10:04.755Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:11:04Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-05T19:14:13Z

Build failed on ROOT-ubuntu16/nortcxxmod.
Running on sft-ubuntu-1604-1.cern.ch:/build/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:14:12.102Z] FAILED: /usr/bin/ccache /usr/bin/c++ -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../res -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../../clingutils/res -I/mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/../../foundation/res -I/mnt/build/workspace/root-pullrequests-build/root/interpreter/cling/include -Iginclude -I/mnt/build/workspace/root-pullrequests-build/root/core/base/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/foundation/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/cont/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/gui/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/meta/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/clib/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/rint/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/zip/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/thread/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/textinput/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/clingutils/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/base/v7/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/foundation/v7/inc -I/mnt/build/workspace/root-pullrequests-build/root/core/unix/inc -Icore/metacling/test -I/mnt/build/workspace/root-pullrequests-build/root/test/unit_testing_support -isystem googletest-prefix/src/googletest/googletest/include -isystem googletest-prefix/src/googletest/googlemock/include -fdiagnostics-color=always -std=c++14 -pipe -Wshadow -Wall -W -Woverloaded-virtual -fsigned-char -pthread -O3 -std=c++14 -MD -MT core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o -MF core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o.d -o core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o -c /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx
[2021-11-05T19:14:12.102Z] /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:14:12.102Z] /mnt/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:14:15Z

Build failed on ROOT-ubuntu2004/soversion.
Running on root-ubuntu-2004-1.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:14:07.595Z] FAILED: core/metacling/test/CMakeFiles/TClingTest.dir/TClingCallFuncTests.cxx.o
[2021-11-05T19:14:07.853Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:14:07.853Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:15:57Z

Build failed on ROOT-debian10-i386/cxx14.
Running on pcepsft10.dyndns.cern.ch:/build/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:15:00.663Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:15:00.663Z] /home/sftnight/build/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:17:33Z

Build failed on ROOT-performance-centos8-multicore/default.
Running on olbdw-01.cern.ch:/data/sftnight/workspace/root-pullrequests-build
See console output.

Errors:

[2021-11-05T19:16:38.990Z] /data/sftnight/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:296:23: error: missing template arguments before ‘RAII’
[2021-11-05T19:16:38.990Z] /data/sftnight/workspace/root-pullrequests-build/root/core/metacling/test/TClingCallFuncTests.cxx:300:8: error: expected primary-expression before ‘)’ token

phsft-bot · 2021-11-05T19:19:59Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-05T20:27:48Z

Build failed on mac11.0/cxx17.
Running on macphsft20.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

phsft-bot · 2021-11-05T22:26:32Z

Build failed on windows10/cxx14.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Failing tests:

projectroot.roottest.root.meta.tclass.roottest_root_meta_tclass_execSharedPtr_WILL_FAIL

core/metacling/test/TClingCallFuncTests.cxx

phsft-bot · 2021-11-07T18:22:16Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-07T18:49:07Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-07T18:58:04Z

Build failed on windows10/cxx14.
Running on null:C:\build\workspace\root-pullrequests-build
See console output.

Errors:

[2021-11-07T18:58:03.050Z] CMake Error at C:/build/workspace/root-pullrequests-build/rootspi/jenkins/root-build.cmake:1095 (message):

phsft-bot · 2021-11-07T19:06:56Z

Starting build on ROOT-debian10-i386/cxx14, ROOT-performance-centos8-multicore/default, ROOT-ubuntu16/nortcxxmod, ROOT-ubuntu2004/soversion, mac1014/python3, mac11.0/cxx17, windows10/cxx14
How to customize builds

phsft-bot · 2021-11-07T20:15:12Z

Build failed on mac11.0/cxx17.
Running on macphsft20.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

projectroot.tree.dataframe.test.gtest_tree_dataframe_test_dataframe_snapshot

vgvassilev

Lgtm!

jalopezg-git added bug affects:master in:Cling labels Nov 4, 2021

jalopezg-git requested review from Axel-Naumann, hahnjo, vgvassilev, eguiraud and vepadulano November 4, 2021 13:12

jalopezg-git requested a review from pcanal as a code owner November 4, 2021 13:12

jalopezg-git self-assigned this Nov 4, 2021

vepadulano approved these changes Nov 4, 2021

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jalopezg-git force-pushed the fix-issue-8622 branch from dd5fb59 to 2ea6e72 Compare November 4, 2021 15:41

jalopezg-git changed the title ~~[tcling] Ignore -Wunused-result diagnostics in wrappers generated by TClingCallFunc~~ [tcling] Suppress -Wunused-result diagnostics in wrappers generated by TClingCallFunc Nov 4, 2021

vgvassilev reviewed Nov 4, 2021

View reviewed changes

jalopezg-git force-pushed the fix-issue-8622 branch from 2ea6e72 to 6368084 Compare November 5, 2021 19:05

jalopezg-git force-pushed the fix-issue-8622 branch from 6368084 to 2e96179 Compare November 5, 2021 19:10

jalopezg-git force-pushed the fix-issue-8622 branch from 2e96179 to 8993573 Compare November 5, 2021 19:19

jalopezg-git requested a review from vgvassilev November 5, 2021 19:20

vgvassilev reviewed Nov 6, 2021

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core/metacling/test/TClingCallFuncTests.cxx Outdated Show resolved Hide resolved

jalopezg-git force-pushed the fix-issue-8622 branch from 8993573 to bd11bfe Compare November 7, 2021 18:22

[tcling] Add test against issue root-project#8622

ac2e418

jalopezg-git force-pushed the fix-issue-8622 branch from bd11bfe to 5dfb0c7 Compare November 7, 2021 18:48

jalopezg-git mentioned this pull request Nov 7, 2021

[tcling] Remove WILLFAIL_ON_WIN32 for roottest_root_meta_tclass_execSharedPtr root-project/roottest#791

Merged

[test] Moved FilterDiagsRAII class to ROOTUnitTestSupport.h

f216f65

jalopezg-git force-pushed the fix-issue-8622 branch from 5dfb0c7 to f216f65 Compare November 7, 2021 19:06

vgvassilev approved these changes Nov 7, 2021

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jalopezg-git merged commit 8844e28 into root-project:master Nov 7, 2021

jalopezg-git deleted the fix-issue-8622 branch November 7, 2021 22:55

Axel-Naumann mentioned this pull request Mar 15, 2022

MiniAOD warnings in 12_4_0_pre1 using 2021 data cms-sw/cmssw#37227

Closed

jalopezg-git mentioned this pull request Mar 15, 2022

[tcling,v6-24] Suppress -Wunused-result diagnostics in wrappers generated by TClingCallFunc #10120

Merged

jalopezg-git mentioned this pull request Apr 17, 2023

[cling] Ignore -Wunused-result in wrapped code #12654

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[tcling] Suppress `-Wunused-result` diagnostics in wrappers generated by TClingCallFunc #9244

[tcling] Suppress `-Wunused-result` diagnostics in wrappers generated by TClingCallFunc #9244

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[tcling] Suppress -Wunused-result diagnostics in wrappers generated by TClingCallFunc #9244

[tcling] Suppress -Wunused-result diagnostics in wrappers generated by TClingCallFunc #9244

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[tcling] Suppress `-Wunused-result` diagnostics in wrappers generated by TClingCallFunc #9244

[tcling] Suppress `-Wunused-result` diagnostics in wrappers generated by TClingCallFunc #9244

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