Compiler error: constexpr function never produces a constant expression [-Winvalid-constexpr]

[toco]

Building 5b66246 fails for me with the following errors:

cd /tmp/qdmr-20230618-35854-12ga0el/lib && /usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++ -DQT_CORE_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_POSITIONING_LIB -DQT_SERIALPORT_LIB -DQT_WIDGETS_LIB -Dlibdmrconf_EXPORTS -F/usr/local/opt/qt@5/lib -I/usr/local/opt/qt@5/lib/QtWidgets.framework/Headers -I/usr/local/opt/qt@5/lib/QtGui.framework/Headers -I/usr/local/opt/qt@5/include/QtUiTools -I/usr/local/include/libusb-1.0 -I/tmp/qdmr-20230618-35854-12ga0el/src -I/tmp/qdmr-20230618-35854-12ga0el/lib -isystem /usr/local/opt/qt@5/lib/QtCore.framework/Headers -isystem /usr/local/opt/qt@5/./mkspecs/macx-clang -isystem /usr/local/opt/qt@5/lib/QtNetwork.framework/Headers -isystem /usr/local/opt/qt@5/lib/QtSerialPort.framework/Headers -isystem /usr/local/opt/qt@5/lib/QtPositioning.framework/Headers -Wall -Wsign-compare -O3 -DNDEBUG -O3 -Wextra -std=gnu++14 -arch x86_64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk -fPIC -fPIC -MD -MT lib/CMakeFiles/libdmrconf.dir/hid_macos.cc.o -MF CMakeFiles/libdmrconf.dir/hid_macos.cc.o.d -o CMakeFiles/libdmrconf.dir/hid_macos.cc.o -c /tmp/qdmr-20230618-35854-12ga0el/lib/hid_macos.cc
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/ranges.cc:1:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/ranges.hh:5:
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:48:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMilliseconds(unsigned long long ms) {          ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:49:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(ms);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:51:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromSeconds(unsigned long long s) {                ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:52:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(s*1000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:54:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMinutes(unsigned long long min) {              ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:55:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(min*60000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
[ 22%] Building CXX object lib/CMakeFiles/libdmrconf.dir/dfu_libusb.cc.o
cd /tmp/qdmr-20230618-35854-12ga0el/lib && /usr/local/Homebrew/Library/Homebrew/shims/mac/super/clang++ -DQT_CORE_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_NO_DEBUG -DQT_POSITIONING_LIB -DQT_SERIALPORT_LIB -DQT_WIDGETS_LIB -Dlibdmrconf_EXPORTS -F/usr/local/opt/qt@5/lib -I/usr/local/opt/qt@5/lib/QtWidgets.framework/Headers -I/usr/local/opt/qt@5/lib/QtGui.framework/Headers -I/usr/local/opt/qt@5/include/QtUiTools -I/usr/local/include/libusb-1.0 -I/tmp/qdmr-20230618-35854-12ga0el/src -I/tmp/qdmr-20230618-35854-12ga0el/lib -isystem /usr/local/opt/qt@5/lib/QtCore.framework/Headers -isystem /usr/local/opt/qt@5/./mkspecs/macx-clang -isystem /usr/local/opt/qt@5/lib/QtNetwork.framework/Headers -isystem /usr/local/opt/qt@5/lib/QtSerialPort.framework/Headers -isystem /usr/local/opt/qt@5/lib/QtPositioning.framework/Headers -Wall -Wsign-compare -O3 -DNDEBUG -O3 -Wextra -std=gnu++14 -arch x86_64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk -fPIC -fPIC -MD -MT lib/CMakeFiles/libdmrconf.dir/dfu_libusb.cc.o -MF CMakeFiles/libdmrconf.dir/dfu_libusb.cc.o.d -o CMakeFiles/libdmrconf.dir/dfu_libusb.cc.o -c /tmp/qdmr-20230618-35854-12ga0el/lib/dfu_libusb.cc
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/interval.cc:1:
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:48:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMilliseconds(unsigned long long ms) {          ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:49:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(ms);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:51:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromSeconds(unsigned long long s) {                ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:52:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(s*1000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:54:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMinutes(unsigned long long min) {              ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:55:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(min*60000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
3 errors generated.
make[2]: *** [lib/CMakeFiles/libdmrconf.dir/ranges.cc.o] Error 1
make[2]: *** Waiting for unfinished jobs....
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/radio.cc:1:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/radio.hh:14:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/codeplug.hh:8:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/config.hh:44:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/contact.hh:8:
In file included from /tmp/qdmr-20230618-35854-12ga0el/lib/anytone_extension.hh:8:
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:48:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMilliseconds(unsigned long long ms) {          ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:49:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(ms);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:51:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromSeconds(unsigned long long s) {                ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:52:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(s*1000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:54:36: error: constexpr function never produces a constant expression [-Winvalid-constexpr]
  static inline constexpr Interval fromMinutes(unsigned long long min) {              ///< Unit conversion.
                                   ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:55:12: note: non-constexpr constructor 'Interval' cannot be used in a constant expression
    return Interval(min*60000ULL);
           ^
/tmp/qdmr-20230618-35854-12ga0el/lib/interval.hh:30:3: note: declared here
  Interval(const Interval &other);
  ^
3 errors generated.
make[2]: *** [lib/CMakeFiles/libdmrconf.dir/interval.cc.o] Error 1
3 errors generated.
make[2]: *** [lib/CMakeFiles/libdmrconf.dir/radio.cc.o] Error 1
make[1]: *** [lib/CMakeFiles/libdmrconf.dir/all] Error 2
make: *** [all] Error 2

Building with:

% clang -v
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.5.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

% cmake --version
cmake version 3.26.4

CMake suite maintained and supported by Kitware (kitware.com/cmake).

% make --version
GNU Make 3.81
Copyright (C) 2006  Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

This program built for i386-apple-darwin11.3.0

[hmatuschek]

Seems to be fixed in branch fix-clang-compiler-issue. Also added a CI workflow to check with clang-14. This issue will be closed automatically, once I merge that branch. Feel free to reopen it, if there are sill issues.

[toco]

Thank you for the very quick fix!