The following is reduced from the example in N3290 subclause 5.1.1 [expr.prim.general] paragraph 5: class Outer { void f() { struct Inner { int c[sizeof(*this)]; // error: not inside a member function of Inner }; } }; GCC does not provide a diagnostic for this although, the declaration in question runs afoul of the constraint in paragraph 4 for the subclause by using "this" elsewhere in the member-declarator. ## Compile command: g++-4.8 -std=c++11 nestedClassThisNonStaticDataMemDiag.cc ## Actual output: (No diagnostics; clean compile). ## Expected output: (Error message). ## g++ -v: Using built-in specs. COLLECT_GCC=/usr/bin/g++-4.8 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.1-2ubuntu1~12.04' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --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-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-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 --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 4.8.1 (Ubuntu 4.8.1-2ubuntu1~12.04)
I actually think this is http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1837 Which means it has the following status: [Accepted at the November, 2020 meeting as part of paper P1787R6 and moved to DR at the February, 2021 meeting.]