build: add -Wleading-whitespace #32482

1. 
   fanquake commented at 3:13 pm on May 13, 2025: member

   GCC 15 now has options to turn leading & trailing whitespace into compile failures: https://gcc.gnu.org/gcc-15/changes.html#c-family. Fix the few cases of leading tabs, and trailing whitespace, and then enable -Wleading-whitespace. Unfortunately, CMake/Qt will generate code that contains trailing whitespace:

   0[ 98%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/EJRQKI7XPS/qrc_bitcoin_locale.cpp.o
   1/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:5603:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   2 5603 | 
   3/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:8254:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   4 8254 | 
   5/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:9840:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   

   So -Wtrailing-whitespace could be enabled later, once Qts tooling is fixed.

2. 
   DrahtBot commented at 3:13 pm on May 13, 2025: contributor

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   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32482.

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3. DrahtBot added the label Build system on May 13, 2025
4. 
   hebasto commented at 3:19 pm on May 13, 2025: member

   GCC 15 now has options to turn these into compile failures: https://gcc.gnu.org/gcc-15/changes.html#c-family. Fix the few cases of leading tabs, and trailing whitespace, and then enable these options.

   Concept ACK on that.

   Unfortunately, CMake/Qt will generate code that contains trailing whitespace:

   0[ 98%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/EJRQKI7XPS/qrc_bitcoin_locale.cpp.o
   1/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:5603:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   2 5603 | 
   3/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:8254:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   4 8254 | 
   5/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:9840:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   

   Will need to resolve that somehow.

   I’ll look into it.

5. fanquake referenced this in commit c521192d8b on May 16, 2025
6. fanquake force-pushed on May 16, 2025
7. 
   hebasto commented at 4:36 pm on May 30, 2025: member

   GCC 15 now has options to turn these into compile failures: https://gcc.gnu.org/gcc-15/changes.html#c-family. Fix the few cases of leading tabs, and trailing whitespace, and then enable these options.

   Concept ACK on that.

   Unfortunately, CMake/Qt will generate code that contains trailing whitespace:

   0[ 98%] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/EJRQKI7XPS/qrc_bitcoin_locale.cpp.o
   1/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:5603:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   2 5603 | 
   3/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:8254:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   4 8254 | 
   5/root/bitcoin/build/src/qt/bitcoinqt_autogen/EWIEGA46WW/qrc_bitcoin.cpp:9840:2: warning: trailing whitespace [-Wtrailing-whitespace=]
   

   Will need to resolve that somehow.

   I’ll look into it.

   Addressed in #32648.

8. univalue: change leading whitespace to spaces b2d20514ca
9. crypto: remove leading/trailing whitespace in sha256_sse4.cpp e9fa092a2f
10. build: add -Wleading-whitespace

    This is available in GCC 15. See
    https://gcc.gnu.org/gcc-15/changes.html.

    93087de15f
11. fanquake force-pushed on Jul 2, 2025
12. fanquake renamed this:
    build: add `-W[leading|trailing]-whitespace`
    build: add `-Wleading-whitespace`
    on Jul 2, 2025
13. fanquake marked this as ready for review on Jul 2, 2025
14. 
    fanquake commented at 1:08 pm on July 2, 2025: member

    Dropped -Wtrailing-whitespace for now. That could be added when Qts tools are fixed.

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