fix compilation error

14 jobs for master in 17 minutes and 31 seconds (queued for 1 second)
latest
Status Name Job ID Coverage
  Build
passed centos7 #10315

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passed centos8 #10316

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passed fedora30 #10312

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passed fedora31 #10311

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passed fedora32 #10310

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passed mageia6 #10321

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passed mageia7 #10322

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passed opensuse15.1 #10313

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passed opensuse-rolling #10314

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passed OSX #10309
osx

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passed ubuntu16.04 #10317

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passed ubuntu18.04 #10318

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passed ubuntu19.10 #10319

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passed ubuntu20.04 #10320

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