Created attachment 867350 [details] emerge --info and build log dev-qt/qtshadertools-6.5.2 appends -O2 after user-set CXXFLAGS, thus overriding flags like -O3. Below are some of the lines, the rest are in the log. [10/87] /usr/bin/x86_64-pc-linux-gnu-g++ -DGLSLANG_OSINCLUDE_UNIX -DQT_EXPLICIT_QFILE_CONSTRUCTION_FROM_PATH -DQT_NO_DEBUG -DQT_NO_EXCEPTIONS -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I/var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2_build/src/glslang/BundledGlslang_Spirv_autogen/include -I/var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2/src/glslang/../3rdparty/glslang -isystem /usr/lib64/qt6/mkspecs/linux-g++ -isystem /usr/include/qt6 -march=native -O3 -pipe -flto=auto -fno-semantic-interposition -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -O2 -std=c++17 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -w -fno-exceptions -Wsuggest-override -MD -MT src/glslang/CMakeFiles/BundledGlslang_Spirv.dir/__/3rdparty/glslang/SPIRV/SpvTools.cpp.o -MF src/glslang/CMakeFiles/BundledGlslang_Spirv.dir/__/3rdparty/glslang/SPIRV/SpvTools.cpp.o.d -o src/glslang/CMakeFiles/BundledGlslang_Spirv.dir/__/3rdparty/glslang/SPIRV/SpvTools.cpp.o -c /var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2/src/3rdparty/glslang/SPIRV/SpvTools.cpp [12/87] /usr/bin/x86_64-pc-linux-gnu-g++ -DGLSLANG_OSINCLUDE_UNIX -DQT_EXPLICIT_QFILE_CONSTRUCTION_FROM_PATH -DQT_NO_DEBUG -DQT_NO_EXCEPTIONS -DQT_NO_JAVA_STYLE_ITERATORS -DQT_NO_NARROWING_CONVERSIONS_IN_CONNECT -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -I/var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2_build/src/glslang/BundledGlslang_Oglcompiler_autogen/include -I/var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2/src/glslang/../3rdparty/glslang -isystem /usr/lib64/qt6/mkspecs/linux-g++ -isystem /usr/include/qt6 -march=native -O3 -pipe -flto=auto -fno-semantic-interposition -Werror=odr -Werror=lto-type-mismatch -Werror=strict-aliasing -O2 -std=c++17 -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -w -fno-exceptions -Wsuggest-override -MD -MT src/glslang/CMakeFiles/BundledGlslang_Oglcompiler.dir/BundledGlslang_Oglcompiler_autogen/mocs_compilation.cpp.o -MF src/glslang/CMakeFiles/BundledGlslang_Oglcompiler.dir/BundledGlslang_Oglcompiler_autogen/mocs_compilation.cpp.o.d -o src/glslang/CMakeFiles/BundledGlslang_Oglcompiler.dir/BundledGlslang_Oglcompiler_autogen/mocs_compilation.cpp.o -c /var/tmp/portage/dev-qt/qtshadertools-6.5.2/work/qtshadertools-everywhere-src-6.5.2_build/src/glslang/BundledGlslang_Oglcompiler_autogen/mocs_compilation.cpp
*** This bug has been marked as a duplicate of bug 911822 ***