https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70092
Bug ID: 70092 Summary: Enhance -Wunused-but-set-parameter when the parameter is also read Product: gcc Version: 5.2.1 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: hadrien-gcc at psydk dot org Target Milestone: --- I found a bogus piece of code in a real program, here is a simplified version: bool getValue(int value) { value = 42; value++; return true; } The bug comes from the missing & in the parameter declaration, the fix is: bool getValue(int& value) ... I build with -Wall and -Wextra, and I was wondering why -Wunused-but-set-parameter could not catch this error. If I remove the "value++;" line, it triggers the warning as expected. If I put back the line, of if I rewrite it "value = value + 1;", the warning disappears. I think it would be helpful if -Wunused-but-set-parameter was able to catch this pattern. Command line: g++ -fPIC -std=c++11 -Wall -Wextra *.cpp -o exe g++ -v: Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 5.2.1-22ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs --enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-5 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)