Supress warnings about nodiscard in dictionary generation with ROOT 6.22

added lhcb-lcg-test label

I recently ran into a similar problem (see the discussion lhcb/LHCb!2932 (merged)) where I added [[nodiscard]] which clang does recognise, but the dictionary generating code then caused clang to emit the following diagnositic:

input_line_182:10:7: warning: ignoring return value of function declared with 'nodiscard' attribute [-Wunused-result]
      ((const LHCb::RawEvent*)obj)->banks(*(LHCb::RawBank::BankType*)args[0]);

i.e. the dictionary code seems to generate function calls which have 'no effect' -- and I removed the [[nodiscard]] again. It would be much nicer if the generated code actively would avoid such warnings (as presumably it has good reasons to call this code, eg. make sure that the relevant symbol is linked into the library) and be changed to cast the result to void, i.e.:

       (void)((const LHCb::RawEvent*)obj)->banks(*(LHCb::RawBank::BankType*)args[0]);

as shown eg here Unfortunately, I never found out where the code is that generates this code....

Just as a side note, the failure in the pipeline comes from a change in https://gitlab.cern.ch/lhcb-core/lcg-toolchains.

If you rebase on master it goes away.

added 19 commits

b94384b7...f79f7a2c - 18 commits from branch master
d53edcc3 - gaudi_add_dictionary: if ROOT 6.22 then add -Wno-unknown-attributes to...

Compare with previous version

[2021-02-23 00:43] Validation started with lhcb-lcg-test#119
[2021-02-24 00:55] Validation started with lhcb-lcg-test#120
[2021-02-25 00:38] Validation started with lhcb-lcg-test#121
[2021-02-26 00:29] Validation started with lhcb-lcg-test#122
[2021-02-26 01:14] Validation started with lhcb-lcg-test#122
[2021-02-27 00:37] Validation started with lhcb-lcg-test#123
[2021-02-28 00:06] Validation started with lhcb-lcg-test#124
[2021-03-02 00:16] Validation started with lhcb-lcg-test#125
[2021-03-03 00:30] Validation started with lhcb-lcg-test#126
[2021-03-04 00:36] Validation started with lhcb-lcg-test#127
[2021-03-05 00:31] Validation started with lhcb-lcg-test#128
[2021-03-06 00:05] Validation started with lhcb-gaudi-head#2870
[2021-03-06 00:25] Validation started with lhcb-lcg-test#129
[2021-03-06 00:53] Validation started with lhcb-run2-gaudi-head#79
[2021-03-07 00:03] Validation started with lhcb-gaudi-head#2871
[2021-03-07 00:10] Validation started with lhcb-lcg-test#130
[2021-03-07 00:25] Validation started with lhcb-run2-gaudi-head#80
[2021-03-07 10:54] Validation started with lhcb-gaudi-head#2872
[2021-03-08 00:06] Validation started with lhcb-gaudi-head#2873
[2021-03-08 00:12] Validation started with lhcb-lcg-test#131
[2021-03-08 00:38] Validation started with lhcb-run2-gaudi-head#81
[2021-03-08 01:10] Validation started with lhcb-run2-gaudi-head#81

resolved all threads

changed milestone to %v35r2

assigned to @clemenci

added lhcb-gaudi-head label

mentioned in merge request !1183 (merged)

approved this merge request

merged

mentioned in commit 30ea297c

Supress warnings about nodiscard in dictionary generation with ROOT 6.22

Merge request reports

Activity